understanding the complete blood count with...

CONTINUING EDUCATION

Understanding the Complete Blood CountWith Differential

Beverly George-Gay, MSN, RN, CCRNKatherine Parker, MEd, RN

The complete blood count (CBC) with differential is one of the mostcommon laboratory tests performed today. It gives informationabout the production of all blood cells and identifies the patient’soxygen-carrying capacity through the evaluation of red blood cell(RBC) indices, hemoglobin, and hematocrit. It also provides informa-tion about the immune system through the evaluation of the whiteblood cell (WBC) count with differential. These tests are helpful indiagnosing anemia, certain cancers, infection, acute hemorrhagicstates, allergies, and immunodeficiencies as well as monitoring forside effects of certain drugs that cause blood dyscrasias. Nurses in theperianesthesia arena are frequently challenged to obtain and evalu-ate all or parts of the CBC as a part of the patient’s preoperative,intraoperative, and postoperative assessments. An enhanced under-standing of this laboratory test is essential to providing quality care.

© 2003 by American Society of PeriAnesthesia Nurses.

Objectives—Based on the content of this article, the reader should be able to (1) discuss thephysiology of blood cell production; (2) describe the usefulness of the complete blood count (CBC);(3) identify and differentiate the roles of the different types of leukocytes; (4) describe the charac-teristics of red blood cell (RBC) structure and function; (5) discuss the indications for CBC as part ofthe perianesthesia evaluation; and (6) explore the nursing indications related to CBC findings in theperianesthesia setting.

THE COMPONENTS OF the complete bloodcount (CBC) include a hemogram and differen-tial white blood cell (WBC) count. The hemo-gram includes the enumeration of WBCs, redblood cells (RBCs), and platelets; it also pro-vides determinations of hemoglobin, hemato-crit, and RBC indices (Table 1). The WBC countwith differential enumerates the different WBCtypes. Together, the components of the CBCevaluate primary diseases of the blood and bone

Beverly George-Gay, MSN, RN, CCRN, is the Nurse Educatorfor Critical Care for the Department of Education andKatherine Parker, MEd, RN, is a Nurse Educator for theDepartment of Education at the Virginia CommonwealthUniversity Health System, Richmond, VA.

Address correspondence to Beverly George-Gay, MSN, RN,CCRN, 11824 Club Ridge Dr, Chester, VA 23836; e-mailaddress: [email protected].

© 2003 by American Society of PeriAnesthesia Nurses.1089-9472/03/1802-0007$35.00/0doi:10.1053/jpan.2003.50013

Journal of PeriAnesthesia Nursing, Vol 18, No 2 (April), 2003: pp 96-11796

marrow, which include disorders such as ane-mia, leukemia, polycythemia, thrombocytosis,and thrombocytopenia. The CBC also evaluatesmedical conditions that secondarily affect theblood and bone marrow resulting in hemato-logic manifestations such as infection, inflam-mation, coagulopathies, neoplasms, and toxicsubstance exposure. In many instances, specificsymptomatology of a medical condition maynot be present and hematologic changes on theCBC may be the only finding present. Thesechanges prompt investigation to then identifythe medical condition.

To foster the understanding of the usefulness ofthe CBC, the function and life cycle of thevarious cells are introduced. Test indications,characteristics, abnormal findings, and applica-tions for the perianesthesia nurse are discussed.

Screening

“Screening” usually refers to testing patientswho are asymptomatic and have no physicalsigns of disease. However, symptoms or physi-cal signs may be very insensitive indicators ofsome diseases. In the perianesthesia setting, theuse of the CBC as a screening tool constantlyundergoes revision. Factors such as the preva-lence of disease in a population, the medicaland financial impact of missing a “problem,” thecost per problem found, financial reimburse-

ment, and societal judgments determine whenscreening tests are indicated. Medicare does notsupport the use of the CBC as a screening tool;to be cost effective, the CBC should only beordered when indicated.2

Indications

Preoperative evaluation should include a his-tory, a physical examination, laboratory tests,and an assessment of surgical risk to identifycoexisting diseases and complicating condi-tions. To decrease the risk of morbidity andmortality in the perianesthesia setting, the CBCis used to assist with the identification of pa-tients who are at risk for complications of inad-equate tissue perfusion during the procedureand those with a possible infectious or inflam-matory process.3,4

General indications for a CBC that are consid-ered medically reasonable and are accepted byMedicare are as follows:

● The hemogram should be evaluated forany patient with signs, symptoms, orconditions associated with anemia orpolycythemia. See Table 2 for specificsigns, symptoms, and conditions.

● The platelet count should be evaluatedfor patients with findings or conditionsassociated with increased or decreasedplatelet production, destruction, or dys-function (Table 2). The platelet count isusually obtained as part of the hemo-gram.

● The WBC differential should be evalu-ated for any patient with signs, symp-toms, or conditions associated with in-fections, inflammatory processes, bonemarrow alterations, and immune disor-ders (Table 2). The WBC count has alsobeen recently identified as a possible riskstratification tool for mortality in acutecoronary syndromes.5

● A hemoglobin and hematocrit (H&H)alone may be appropriate if there is onlya need to assess the oxygen-carrying ca-

Table 1. Complete Blood Count

WBC 4,500 to 11,000/�LDifferential white cell count See Table 7RBC 4.0 to 6.2 million/�LHct

Women 35% to 47%Men 8 to 64 yr 39% to 50%Men 65 to 74 yr 37% to 51%

HgbWomen 12 to 16 g/dLMen 14 to 18 g/dL

RBC indicesMean corpuscular volume 82 to 93 �m3

Mean corpuscular Hgb 26 to 34 pgMean corpuscular Hgb concentration 31% to 38%

Platelet count 150,000 to 400,000 �L

Data from Chernecky et al.1

UNDERSTANDING THE CBC WITH DIFFERENTIAL 97

pacity of blood before surgery for pa-tients who do not have the previouslylisted signs, symptoms, or conditions(Table 2). The H&H may be helpful inthe intraoperative and postoperativephase of care to assess and track forblood loss but can be misleading becauseof the intercompartmental fluid shiftsthat occur during surgery and because ofthe dilutional effects of crystalloid ther-apy.

Specific perianesthesia indications for the CBCalso take into account the level of surgical com-

plexity for a given procedure. In general, minorprocedures are those with very low risk of largefluid shifts or significant blood loss. Minor pro-cedures include soft tissue and eye procedures;minor ortho; as well as ear, nose, and throat andurologic procedures, among others. Keep inmind that a “minor” procedure may turn into a“moderately complex” procedure as complica-tions are identified or develop. Major proce-dures are those that are often prolonged, oftenwith high risk of large fluid shifts or signifi-cant blood loss. They often involve major bodycavities. These include major abdominal, vascu-

Table 2. Signs, Symptoms, and Conditions That May Warrant a CBC or Parts of a CBC

Hemogram

(Findings Related to Anemia)

Hemogram

(Findings Related to Polycythemia)

Hemogram

(Findings Related to Platelet Dysfunction) WBC With Differential

PallorWeaknessFatigueWeight lossBleedingAcute or suspected blood loss

from injuryHematuriaHematemesisHematocheziaPositive fecal occultNeuropathyMalnutritionTachycardiaKnown malignancySystolic heart murmurCongestive heart failureDyspneaAnginaPostural dizzinessSyncopeNailbed deformitiesKnown malignancyJaundiceHepatomegalySplenomegalyLymphadenopathyUlcers of the lower extremities

FeverChillsRuddy skinConjunctival rednessCoughWheezingCyanosisClubbing of the fingersOrthopneaHeart murmurHeadacheMemory changesSleep apneaWeaknessPruritusDizzinessExcessive sweatingMassive obesityGastrointestinal bleedingParesthesiasMyocardial infarctionStrokeThromboembolismHepatomegalySplenomegalyCOPDDiastolic hypertensionCongenital heart diseaseTransient ischemic attackVisual symptoms

Gastrointestinal bleedGenitourinary tract bleedBilateral epistaxisThrombosisEcchymosisPurpuraJaundicePetechiaeFeverHeparin therapySuspected DICShockPreeclampsiaMassive transfusionRecent platelet transfusionCardiopulmonary bypassRenal diseasesHypersplenismNeurologic abnormalitiesViral or other infectionThrombosisExposure to toxic agentsExcessive alcohol ingestionAutoimmunue disorders

(SLE, RA)HepatomegalySplenomegalyLymphadenopathy

FeverChillsSweatsShockFatigueMalaiseTachycardiaTachypneaHeart murmurSeizuresAltered consciousnessPain such as headacheAbdominal painArthralgiaOdynophagiaDysuriaRedness/swelling of skin soft

tissue or jointUlcers of skin or mucous

membraneGangreneBleedingThrombosisPulmonary infiltrateJaundiceDiarrheaVomitingOpportunistic infections as

oral candidiasisHepatomegalySplenomegalyLymphadenopathy

Abbreviations: COPD, chronic obstructive pulmonary disease; DIC, disseminated intravascular coagulation; SLE, systemic lupus erythematosus; RA,rheumatoid arthritis.

Data from Centers for Medicare and Medicaid Services (CMS). Available at www.cms.hhs.gov/ncd/searchdisplay.asp?NSD_ID�61&NCD_vrsn_num�1.

GEORGE-GAY AND PARKER98

lar, cardiothoracic, orthopedic, gynecologic/urologic, head and neck, and neurologic proce-dures. Levels of surgical complexity from level 1(minor) to level 5 (major) are described in Table3. The American Society of Anesthesiologists’(ASA) physical status classification system is an-other tool that can be used to assess the pa-tient’s current health status and overall periop-erative risk (Table 4). Although imprecise, it is away to predict the patient’s anesthetic/surgicalrisks. The higher the ASA class, the greater therisks.

For the patient who is asymptomatic and activewith a reliable benign history and undergoing aminor procedure, an H&H assessment may beall that is necessary or may not be indicated atall. For those patients undergoing major proce-dures, a CBC with platelets should be com-pleted. The CBC is indicated for elderly patients

(�65 years of age) as part of their preoperativeassessment because of the comorbidities associ-ated with this age group as it may uncoverclinical problems that were not picked up onphysical examination.6 Patients classified withan ASA score of 3 or greater should have a CBCbefore their surgical procedure. In addition tothe general indications for CBC in Table 2,situations requiring a CBC before a surgicalprocedure are listed in Table 5.

Optimally efficient testing entails considerationof a combination of factors including the age,gender, and reliability of the patient; the surgi-cal procedure; and the type of anesthesia beingused. Older or less reliable patients may bemore likely to have an unsuspected abnormalitypicked up by a “screening” test. Major proce-dures are associated with significant physiologicstress. Existing medical conditions, which may

Table 3. Levels of Surgical Complexity

Level 1● Minimal risk to the patient independent of anesthesia● Minimally invasive procedures with little or no blood loss● Often performed in an office setting with the operating room principally for anesthesia and monitoring● Includes breast biopsy, removal of minor skin or subcutaneous lesions, myringotomy tubes, hysteroscopy, cystoscopy, fiberoptic

bronchoscopyLevel 2

● Minimal to moderately invasive procedure● Blood loss less than 500 mL● Mild risk to patient independent of anesthesia● Includes diagnostic laparoscopy, dilatation and curettage, fallopian tubal ligation, arthroscopy, inguinal hernia repair, laparoscopic lysis of

adhesions, tonsillectomy/adenoidectomy, umbilical hernia repair, septoplasty/rhinoplasty, percutaneous lung biopsy, extensive superficialprocedures

Level 3● Moderate to significantly invasive procedure● Blood loss potential 500 to 1,500 mL● Moderate risk to patient independent of anesthesia● Includes hysterectomy, myomectomy, cholecystectomy, laminectomy, hip/knee replacement, major laparoscopic procedures,

resection/reconstructive surgery of the digestive tract; excludes open thoracic or intracranial proceduresLevel 4

● Highly invasive procedure● Blood loss greater than 1,500 mL● Major risk to patient independent of anesthesia● Includes major orthopedic-spinal reconstruction, major reconstruction of the gastrointestinal tract, major vascular repair without postoperative

ICU stayLevel 5

● Highly invasive procedure● Blood loss greater than 1,500 mL● Critical risk to patient independent of anesthesia● Usual postoperative ICU stay with invasive monitoring● Includes cardiothoracic procedure; intracranial procedure; major procedure on the oropharynx; major vascular, skeletal, neurologic repair


be of little concern during a brief and minorprocedure, may cause problems during and af-ter a long and complex surgery. Preoperativeevaluation should reflect this need for an in-creased level of preparedness and monitoring.

Timing of the CBC

A CBC completed within 2 months of a proce-dure is acceptable unless a change is suspectedas a consequence of disease, medication, ortreatment. Repeat testing is indicated for abnor-mal results or for patients with normal resultswho have conditions in which there is a con-

tinued risk for the development of hematologicabnormalities.

Blood

The average adult has approximately 5.5 L ofblood, consisting of plasma and cells. Plasmamakes up 55% of the blood components andconsists of proteins, water, and some wasteproducts. Cells, of which there are 3 maintypes, make up the other 45%. They consist of(1) WBCs (leukocytes), of which there are sev-eral subtypes; (2) RBCs (erythrocytes); and (3)platelets (thrombocytes).

All blood cells are produced in the bone mar-row from a mother cell called the pluripotential(multipotential) stem cell (PSC). This PSC un-dergoes stages of differentiation until it be-comes committed to either the erythrocyte,thrombocyte, or one of the leukocyte subtypes(Fig 1). Under normal conditions, only matureblood cells should be found circulating in theblood. Alterations in the production and func-tion of these blood cells provide informationabout the patient’s diagnosis, prognosis, re-

Table 4. ASA Classification

Class Description Examples

1 A normal healthy patient with no systemic illness Healthy with good exercise tolerance2 A patient with well-controlled systemic illness, but

without functional restrictionsWell-controlled hypertension, diabetes, without systemic effects; no

evidence of COPD, anemia, or obesity3 A patient with significant degree of systemic effects that

limits activitiesControlled heart failure, stable angina, or history of myocardial

infarction; diabetes with systemic sequela; uncontrolledhypertension; morbid obesity

4 A patient with severe systemic illness associated withsignificant dysfunction and a constant potential threatto life

Unstable angina, symptomatic heart failure, renal failure requiringdialysis

5 A patient in critical condition, who is at substantial riskof death within 24 hours with or without operativeprocedure

Multiple organ dysfunctions, hemodynamically unstable sepsis,poorly controlled coagulopathy

6 A patient declared brain dead undergoing organ removalfor donor purposes

E This symbol is added to any of the above classes todesignate an emergency

Data from www.asahq.org, www.nurse-anesthesia.com/generalanesthesia.htm, and www.vh.org/adult/provider/anesthesia/proceduralsedation/asapatientclassification.html. Accessed December 2002.

Table 5. Situations Requiring Preoperative CBCEvaluation

● Abnormal bleeding (� platelets)● Heavy ETOH use (� platelets)● Potentially toxic medications (eg, which cause bone marrow

depression)● Infection (� differential)● ASA score of �3● Vascular surgery● Anticipate prosthetic device or hardware placement● Anticipate �500 mL blood loss, invasive monitoring, or ICU (�

platelets)● Level 4 or 5 surgery

Abbreviation: ETOH, alcohol.


sponse to therapies, and their recovery. Thelaboratory procedure that gives us this informa-tion is the CBC.

Obtaining the Blood Sample

The blood sample is obtained via venipunctureand is collected in a lavender top tube, which isthe nationally accepted color standard. Theblood sample will remain useable for analysis atroom temperature for up to 10 hours, afterwhich time the sample deteriorates and is not tobe considered reliable. The blood sample canalso be kept refrigerated and remain useable foras long as 18 hours. The sample should never befrozen. The patient should ideally be at rest for10 to 15 minutes before obtaining the sample.Automated electronic devices perform enumer-ation of the blood cells. Blood cell counts arereported per microliter. Morphology is deter-mined by stained smears.

The WBC Count With Differential

The WBC count with differential determinesthe total number of WBCs (also called leuko-cytes) with a percentage of each type. Themajor function of the WBC is to defend thebody against organisms and injury. WBCs arethe main players in infectious/inflammatory andimmune responses. To appreciate the role ofthe WBC, a brief review of inflammation/infec-tion and immunity is provided.

Inflammation and Infection

The inflammatory process is triggered by cellinjury, which can be caused by a variety ofconditions such as trauma, burns, ischemia, sur-gery, snakebite, caustic chemicals, and ex-tremes in heat and cold, as well as infectiousmicroorganisms. It is important to rememberthat although all infections are accompanied byinflammation, not all inflammation is accompa-

Fig 1. Blood cell differentiation. Reprinted with permission from Garrett.16


nied by infection. In the perianesthesia setting,surgical incisions would be the most commontrigger of inflammation.

Any damage to the vascular endothelium or themast cell will trigger an inflammatory response,which is orchestrated by inflammatory cyto-kines. Cytokines are hormonelike protein medi-ators responsible for the cell-to-cell commu-nication that regulates local and systemicphysiologic and pathologic interactions. Thecells of the vascular endothelium have beenrecently identified as a major player in theinflammatory process.

The mast cell (cellular bag of granules) is an-other important activator of the inflammatoryresponse. Mast cells are found in connectivetissues intimately surrounding blood vessels andin mucosal surfaces. Once endothelial or mastcells are injured or damaged, they release in-flammatory cytokines, which orchestrate themanifestations of inflammation.

Manifestations of inflammation include a shortperiod of vasoconstriction to limit bleeding fol-lowed by vasodilation. Vasodilation increasesblood flow to the area, bringing nutrients andlarge amounts of WBCs. Vasodilation also re-sults in hyperemia (redness and warmth). An-other manifestation is increased capillary per-meability, which allows for the immigration ofWBCs from the blood vessel to the interstitialspaces where they can phagocytize unwantedorganisms and debris. The WBCs also releasecytokines to call more WBCs to the area andto perpetuate the inflammatory response. In-creased capillary permeability also allows forthe exudation of plasma and plasma proteinsresulting in edema. The edema may cause pres-sure on the nearby nerves resulting in pain.

Immunity

In the immune process, specific types of WBCsrespond to specific microorganisms. Immunitycan be classified as either cell mediated or hu-moral. Cell-mediated immunity involves spe-cific types of WBCs called T lymphocytes or Tcells. These T cells will attack host cells within

tissue that have been infected by microorgan-isms, as well as cancer cells. Cell-mediated im-munity provides primary defense against vi-ruses, fungi, slow-growing bacteria, and tumors.

Humoral immunity or antibody-mediated im-munity involves the production of antibodiesby B cells and mainly occurs in body fluid suchas plasma and lymph. Humoral immunity pro-vides primary defense against bacteria. Cell-me-diated immunity is initiated frequently first, butboth cell-mediated and humoral immunity canbe initiated simultaneously. Both types of immu-nity require specific types of WBCs to be effec-tive.

White Blood Cells

Although the medical term for the WBC is leu-kocyte, the term WBC will be used in this articlefor the sake of simplicity. WBCs can be dividedinto 2 main groups: phagocytes and immuno-cytes. Phagocytes are WBCs that have the capa-bility to attach to, engulf, and release enzymesto kill and degrade unwanted microorganismsand debris. The WBCs that are phagocytic in-clude neutrophils, eosinophils, basophils, andmonocytes. Immunocytes include the lympho-cytes, WBCs that drive the immune response.

A more common manner in which WBCs aredivided is by the presence of granules in thecytoplasm. Those WBCs that contain granulesin their cytoplasm are neutrophils, eosinophils,and basophils. WBCs that do not contain gran-ules in their cytoplasm include monocytes andlymphocytes (Fig 2). For the purpose of thisdiscussion, WBCs will be divided into granulo-cytes and nongranulocytes.

Granulocytes

Granulocytes get their name from the granulespresent in their cytoplasm. These granules con-tain biochemical mediators that serve inflamma-tory and immune functions. Granulocytes alsocontain enzymes in their cytoplasm capable ofdestroying microorganisms and catabolizing de-bris ingested during phagocytosis. They takeabout one week to develop in the bone mar-


row. They circulate for only about 6 to 12 hoursin the blood stream and 2 to 3 days after enter-ing the tissue.

Neutrophils

Neutrophils are a type of granulocyte and aremature cells that account for more than half ofall the WBC subtypes in circulation. They arealso called segmented neutrophils (segs) orpolymorphonuclear neutrophils (PMNs) orpolys because the nucleus of these cells consistsof 3 to 5 lobes connected by thin strands.Highly motile, these cells are the first to arrive(usually within 90 minutes) in response to acuteinflammation or infection; they migrate out ofthe capillaries and into the inflamed tissue sitein a process called diapedesis or emigration.The neutrophils ingest microorganisms and de-bris and then die, forming purulent exudate,which is removed by the lymphatics or throughthe epithelium.

When there is an increased demand for neutro-phils, as in response to acute infection, imma-ture neutrophils may be released from the bonemarrow. These immature cells have unseg-

mented nuclei that resemble bands or rods.Thus, immature neutrophils are called bands orstabs. They are normally found only in very lowpercentages in circulating blood.

Eosinophils

Eosinophils function principally to ingest andkill multicellular parasites. They are also effec-tive in detoxifying antigen-antibody complexesthat form during allergic reactions. People withchronic allergic conditions such as atopic rhini-tis and extrinsic asthma typically have elevatedcirculating eosinophil counts. Eosinophils arebelieved to play a role in downregulating hyper-sensitivity responses by neutralizing histamine,inhibiting mast cell degranulation, and inactivatingslow-reacting subtances (SRS) of anaphylaxsis.

Basophils

Basophils are associated with systemic allergicreactions. Similar to mast cells, basophils havegranules that contain proinflammatory chemi-cals such as histamine, serotonin, bradykinin,and heparin. They release their granules in re-sponse to stimulation by immune cells. Ba-sophils circulate in the blood stream, whereas

Fig 2. Granulocytes and nongranulocytes. Reprinted with permission from Catalano.8


mast cells are found in connective tissue. Theaverage basophil has a life span of days, but themast cell can live weeks to months.

Nongranulocytes

Nongranulocytes, as mentioned earlier, areWBCs that do not have granules in their cyto-plasm. Inclusive in this group are monocytesand lymphocytes.

Monocyte/Macrophage

Monocytes are the largest of the WBCs and areyoung cells found freely circulating in blood oren route to a tissue location. Once the youngmonocyte leaves the blood stream and enterstissue, it transforms into a mature macrophage.Macrophages live within tissue spaces in wide-spread locations. These cells have differentnames related to the particular tissue in whichthey are found, ie, the Kupffer cells are macro-phages that live in the liver. Because of thecomplex connection of these cells to the bloodstream and the tissue, monocytes and macro-phages are described as one system, called themononuclear phagocyte system. Table 6 iden-tifies specific macrophages and the particulartissue in which they are found.

Macrophages arrive on the scene in about 5hours after injury and become the predominantleukocyte within 48 hours. Because macro-phages lie within the tissue spaces, they areusually the first cell to engulf and process theantigen and present it to the immune cells(lymphocytes) in a manner that will stimulate aspecific immune response to that particular an-tigen. In other words, the macrophage, in aspecial process, can destroy the organism whilekeeping its cell surface markers to give to thelymphocytes so that they can always identifythat particular organism and mount a specificdefense against it.

Lymphocytes

Lymphocytes are also nongranulocytes and areresponsible for immune responses to specificorganisms. They are the most numerous circu-lating WBC after neutrophils. There are 2 major

classes of lymphocyte: the T lymphocyte (Tcell) and the B lymphocyte (B cell). Both T andB cells can be sorted into subtypes based oncharacteristic surface molecules on them calledcluster of differentiation (CD). Cluster of differ-entiation surface molecules assist in definingthe function of the different lymphocyte sub-types.

T cells. The T cell matures in the thymus andis responsible for cell-mediated immunity aspreviously described. The T cell can also stim-ulate the B cell, triggering humoral/anti-body-mediated immunity (also previously de-scribed). The T cell has several subtypes thatcan be divided into regulator or effector cells.

Regulator T cells are so called because of theirregulatory functions of turning on or off theimmune response. There are 2 types of regula-tor T cells: the helper T cell and the suppressorT cell. The helper T cell is considered themaster switch of the immune system. Thesecells are surveyors, and when a specific antigenis presented to them, they release mediatorsthat influence and stimulate the production ofother immune cells including B cells. Helper Tcells have CD4 surface molecules on them.Suppressor T cells suppress the immune re-sponse once the infection is controlled.

Effector cells are T cells that have a directaction. The 2 types of effector cells are thecytotoxic T cell and the memory T cell. Thecytotoxic T cell carries the CD8 molecule onits surface. It attaches to identified infected

Table 6. Mononuclear Phagocyte System

Macrophage Tissue

Kupffer cells LiverAlveolar macrophage LungHistocytes Connective tissuePleural and peritoneal macrophages Serous cavitiesMicroglial cells Nervous systemOsteoclasts BonesMesangial KidneysLangerhans SkinDendritic cells Lymphoid tissue


cells and cancer cells and releases enzymes todestroy these cells. Cytotoxic T cells are par-ticularly effective at destroying virally in-fected cells, foreign cells, and mutant cells.7

Memory T cells are produced after invasionby a specific organism. They provide long-lasting immunity against that particular organ-ism and then wait to rapidly respond to asecond attack by the same organism. Theiraverage survival rate is about 5 years.

B cells. The B cell matures in the bone mar-row and is responsible for humoral, also knownas antibody-mediated, immunity. When an anti-gen (foreign body) is presented to the B cell,either by a macrophage or helper T cell, the Bcell becomes activated to produce plasma cells.The plasma cell then releases antibodies spe-cific for that specific antigen.

Natural killer cells. There is a third class oflymphocyte that does not have T- or B-cellmarkers called natural killer (NK) cells. NKcells are nonspecific and can therefore re-spond to a variety of antigens. They are veryeffective against tumor cells and virally in-fected host cells.

Evaluating the WBC Count WithDifferential

The white count differential is expressed incubic millimeters and in percentages. See Table7 for normal values of the differential.

Elevated Counts/Levels

An elevation in the total WBC count (WBC�11,000/�L) is called leukocytosis. Leukocyto-sis most commonly identifies infection, tissueinflammation, or tissue necrosis associated withdisorders such as acute myocardial infarction,burns, gangrene, leukemia, radiation exposure,extremes in heat or cold, or lymphoma.8 AWBC count of greater than 10,000 has beenassociated with increased mortality rates in pa-tients with acute coronary syndromes and isnow being used by some as a predictor ofadverse outcomes in these patients.5,9 The roleof inflammation in the pathogenesis of ischemic

stroke is also currently being studied. Patientswith elevated WBC counts during the strokeevent have been found to have a greater relativerisk of subsequent ischemic stroke than didthose with lower WBC counts.10 Thus, an ele-vated WBC count is being looked at as a predic-tor of ischemic stroke. Severely elevated totalWBC counts (�100,000), as seen in leukemia,promotes circulatory sludging and increasedblood viscosity. Venous thromboembolism(VTE) prophylaxis is required in these situa-tions.11

Leukocytosis may also occur in response tophysical and emotional stressors such as over-exertion, seizures, anxiety, anesthesia, and epi-nephrine administration. With stress leukocyto-sis, however, the WBC will return to normalwithin an hour. Certain medications such ascorticosteroids, lithium, and �-agonists may alsocause leukocytosis.

In the preoperative setting, an elevation in theWBC count frequently causes postponement orcancellation of a surgical procedure for furtherevaluation. If the total WBC count is elevated,the differential and the patient should be evalu-ated and the surgeon and anesthesia providernotified. The patient’s medication record andrecent history should also be closely reviewedto discriminate among stress leukocytosis, drugadministration, recent ischemia, myocardial in-

Table 7. Normal White Blood Cell Counts

Cell Type Absolute (�L) Differential (%)

Total WBC 4,500-11,000 100Granulocytes

Neutrophils 3,000-7,000 60-70Segmented 2,800-5,600 54-68Bands 150-600 3-5

Eosinophils 50-400 1-5Basophils 25-100 0-0.75

NongranulocytesMonocytes 100-800 3-7Lymphocytes (Immunocytes) 1,000-4,000 25-33

T cells 800-3,200 80*B cells 100-600 10-15*Natural killer 50-400 5-10*

*Percent of total lymphocyte count.


farction, or infection as possible causes. Anevaluation of the differential will allow for fur-ther discrimination.

Neutrophilia

Neutrophilia is an increase in the total neutro-phil count (including both segs and bands).Because neutrophils account for greater than96% of all granulocytes, neutrophilia may alsobe referred to as granulocytosis. It is the mostcommon cause of elevated WBC count.

Neutrophilia is most commonly caused by anacute bacterial infection. Neutrophil counts willrise 4 to 6 hours after an invasion by microor-ganisms. If findings do not suggest infection, amyeloproliferative disorder may be the cause.Myeloproliferative disorders include polycythe-mia vera and chronic myelocytic leukemia,which increases stem cell proliferation in thebone marrow. Elevations in neutrophil countsare also associated with obesity and cigarettesmoking. Additionally, neutrophil counts canincrease after the stress of surgery, but in thiscase, counts will quickly return to normal if noinfection is present.12

An elevation in segmented neutrophils is con-sidered a “shift to the right.” During tissuebreakdown from injuries such as burns, arthri-tis, myocardial infarction, hemorrhage, or elec-tric shock, neutrophils are called in to clean upthe damaged or dead cells. In this case, reservemature neutrophils are called in, thereby in-creasing the neutrophil count without calling inthe immature cells. A severely elevated neutro-phil count will be seen in certain pathologicconditions causing the neutrophils to becomehypermature. Hypermature segmented neutro-phils are those in which nuclear segmentation isimpaired, and there is an increased number ofsegments (�5). This is seen in liver disease,Down’s syndrome, and megaloblastic and per-nicious anemia.

An elevation in bands is referred to as a “shift tothe left,” which means that there is an increasednumber of immature neutrophils released from

the bone marrow and circulating in the blood.This occurs in response to overwhelming infec-tion when the numbers of mature neutrophilreserves have been depleted. Clinically, theterm shift to the left specifies an acute bacterialinfection has depleted the normal reserves ofmature neutrophils, and the bone marrow hashad to resort to releasing immature ones.

Generally, a shift to the right can be considereda result of tissue damage or necrosis, whereas ashift to the left can be considered a result of anoverwhelming infection. As mentioned earlier,however, an increased neutrophil count is themost common cause of an elevated WBC count.Although not common, the other types ofWBCs can also give rise to an elevation in WBCcount.

Eosinophilia

Eosinophilia identifies an increase in the eosin-ophil count. This count has been found toincrease with parasitic infections such as toxo-plasmosis and with infections by gastrointesti-nal parasites. Elevations have also been notedwith bronchoallergic reactions such as asthma,allergic rhinitis, and hay fever. Eosinophilia hasalso been noted with skin rashes.

Basophilia

Basophila is the most uncommon cause of anelevated WBC count. Increased basophil countshave been found in patients with hypersensitiv-ities compared with the general population.These patients should have a thorough allergyhistory obtained before any surgical procedure.

Monocytosis

Monocytosis, or increased monocyte counts,occur late during the acute phase of infectionand with chronic infections such as tuberculo-sis and subacute bacterial endocarditis (SBE).The patient with an elevated monocyte countshould be evaluated for further evidence ofthese possible conditions before surgical proce-dures. Monocytosis also occurs with Hodgkin’sdisease, multiple myeloma, some leukemias,and systemic lupus erythematosus.


Lymphocytosis

Lymphocytosis occurs in acute viral infectionssuch as mononucleosis, cytomegalovirus, mea-sles, mumps, and rubella. Elevated lymphocytecounts will also be noted in patients duringchronic infections and early in human immuno-deficiency virus (HIV) disease. Severely elevatedlevels would be seen with chronic lymphocyticleukemia (CLL).13

Decreased Counts/Levels

A decrease in the total WBC count (�4,500/�L) is called leukopenia. Leukopenia re-sults from decreased production of totalWBCs in the bone marrow or increaseddestruction of WBCs. Total counts will usu-ally fall with radiation therapy and chemo-therapy as the bone marrow is depressed.WBC counts fall to the lowest points 7 to 14days after induction of most chemothera-peutic agents and will then begin to in-crease as the bone marrow normalizes. Pa-tients receiving chemotherapy should havetheir WBC counts closely monitored. If leu-kopenia is present, the patient should beclosely evaluated and the surgeon and anes-thesia provider notified. Blood cultures, si-nus and chest x-rays, and urine and stoolcultures may also be necessary. As with anelevated WBC count, an evaluation of thedifferential will allow for further discrimina-tion.

Neutropenia

Neutropenia is clinically defined as a neutrophilcount of less than 2,000/�L. Again, keep inmind that the majority of all granulocytes (neu-trophils, eosinophils, and basophils) are neutro-phils, which account for greater than 96% of allgranulocytes. Because of this, the terms granu-locytopenia (decreased granulocyte count) andneutropenia (decreased neutrophil count) areused interchangeably in the clinical setting.Neutropenia can occur with severe prolongedinfections that exhaust the bone marrow sup-plies, where the production cannot keep upwith the demand. It can also be because ofincreased destruction of WBCs that can occur

with increased splenetic pooling and destruc-tion as seen in hypersplenism or splenomegaly.Additionally, a variety of drugs can cause neu-tropenia such as certain antimicrobials, non-steroidal anti-inflammatory drugs, and someanalgesics. Other drugs include certain tricyclicantidepressants, anticonvulsants, antithyroids,cimetidine, and antidysrhythmic agents. Pa-tients with counts of less than 2,000/�L may beunable to mount an adequate defense whenchallenged by infection. These patients shouldbe protected from cross contamination andshould not undergo surgical procedures whenat all possible.

Severe neutropenia is defined as a neutrophilcount of less than 500/�L. This is also referredto as agranulocytosis because a count this lowis almost equivalent to not having any granulo-cytes at all. Neutrophil counts below 500/�Lpredispose the patient to serious bacterial infec-tion and opportunistic infections of the skin,mouth, pharynx, and lungs. As counts fall be-low 100, the chance of gram-negative and gram-positive sepsis and fungal infections increasesdramatically.

Other Reductions

Reductions in eosinophil (eosinopenia) and ba-sophil (basopenia) counts are uncommon be-cause so few of these cells normally circulate inthe blood. Monocytopenia is a rare occurrencebut has been seen with glucocorticoid therapy,hairy-cell leukemia, and aplastic anemia. Lym-phopenia, a decreased lymphocyte count, oc-curs normally as a person ages. Lymphopenia ismost significant with HIV and acquired immu-nodeficiency syndrome (AIDS). A CD4 count(remember the helper T lymphocyte has theCD4 marker on its surface) of less than 200 isone indicator of conversion from HIV to AIDS.

Nursing Implications

The perianesthesia nurse should keep in mindthat the WBC count is a part of a larger picture.One must look at the whole patient and put allinformation into proper perspective.14 Trendscan help to identify truly abnormal findings.


The surgeon and anesthesia provider should benotified for elevations in WBC count of greaterthan 11,000, or decreases less than 4,500. Rec-ognize that minor alterations may be a reflec-tion of age. One must determine whether thepatient has enough neutrophils to combat andprotect from infection when counts are low.

Leukocytosis commonly signals infection,whereas leukopenia indicates bone marrow de-pression that may result from viral infections ortoxic reactions. Be alert to signs and symptomsof infection, especially in patients with invasivelines, indwelling urinary catheters, surgicaldrains, and incision sites. General signs of infec-tion include fatigue, fever, a change in level ofconsciousness (LOC), dehydration, pharyngitis,or hypotension. More frequent temperaturemonitoring may be indicated.

Neutropenic precautions should be consideredfor severely immunocompromised patients andthose with severe neutropenia. Neutropenicprecautions include the following:

● Meticulous care of all intravenous linesand indwelling catheters

● Avoiding raw and uncooked foods, in-cluding fresh fruits and vegetables be-cause of microorganism contaminationfrom soil

● Avoiding crowds● Avoiding children who have just been

vaccinated● Avoiding indiscriminate use of antipyret-

ics● Avoiding steroid use, because they im-

pede mediator functions blocking in-flammation; thus, the patient will notshow the true signs of inflammation orinfection

● Reporting a temperature greater than38°C (100°F), chills, sore throat, dia-phoresis, or dysuria

Be suspect of the potential for septicemia inpatients with a neutrophil count of less than500/�L. Moving forward with any surgical pro-

cedure in patients with counts of less than2,000/�L should be considered only for emer-gent situations. Also note that patients withWBC counts greater than 100,000 are at anincreased risk for thrombosis because of in-creased blood viscosity. Ensure adequate fluidintake and VTE prophylaxis. See Table 8 forrecommendations regarding VTE prophylaxis inthe surgical patient. Patients with recent ische-mic stroke or myocardial infarction, and a con-comitant elevation in WBC count may be atincreased risk for mortality or morbidity.

Erythrocyte (RBC) Studies

The main function of the RBC is to carry oxygen(O2), which it picks up in the lungs, to the cellsof the body, and to transport carbon dioxidefrom the cell to the lungs for excretion. Essen-tially, RBCs are containers for hemoglobin(Hgb). Hgb is the oxygen-carrying protein of theRBC, which accounts for approximately 90% ofthe cells’ dry weight. Information about theRBC is obtained with a CBC but can also beobtained separately with a hemogram.

RBCs are produced at a rate of 2 million cellsper second, or 35 trillion cells per day. Theaverage life span is approximately 120 days. Themature RBC is a biconcave disk. This uniqueshape allows for a greater surface area for oxy-gen to combine with Hgb. RBCs have no nu-cleus, and therefore cannot divide. Like theWBC, the RBC is derived from the PSC in thebone marrow (Fig 1). The production of RBCsby the bone marrow is stimulated by low oxy-gen levels in peritubular cells of the kidney in aprocess called erythropoiesis. During erythro-poiesis, renal erythropoietic factor (an enzyme)is secreted in response to peritubular cell hy-poxia. This factor interacts with a plasma pro-tein to form erythropoietin, a hormone thatcirculates to the bone marrow to stimulate stemcells to produce more RBCs. RBCs are releasedfrom the bone marrow as reticulocytes andthen become mature RBCs in one day.

Vitamin B12, folic acid, and iron are also neededfor RBC metabolism. Vitamin B12 and folic acid


Table 8. Venous Thromboemolism Prophylaxis

Type of Surgical Procedure Recommended Prophylaxis

General surgeryMinor procedure without additional risk factors

in patients less than 40 years of ageMinor procedure with additional risk factors in

patients less than 40 years of ageMinor procedure in patients 40 to 60 years of age

without additional risk factorsMajor surgery in patients without additional risk

factors �40 years of ageNonmajor surgery with additional risk factors in

patients �60 yrMajor surgery in patients �40 yrs or with

additional risk factorsMajor surgery in patients �40 with multiple risk

factors

Low riskEarly ambulationModerate riskLDUH every 12 hours starting 1 to 2 hours before surgeryLMWH first dose generally before surgeryES or IPC device to start immediately before procedure and continue until fully

ambulatory

High riskLDUH every 8 hours, LMWH, or IPC device

Very high riskLDUH, LMWH, combined with mechanical method (ES or IPC device)

Gynecologic surgeryMajor surgery for benign disease without

additional risk factorsLDUH twice a day, alternatively, LMWH or IPC device started just before surgery

and continued at least several days postoperativelyExtensive surgery for malignancy LDUH three times a day

For additional protection use LDUH plus ES or IPC deviceUrologic surgery

Transurethral surgery or other low-risk procedure Prompt mobilizationMajor open urologic procedure LDUH, ES, IPC device, or LMWHHighest risk patients LDUH or LMWH and ES with IPC device

Orthopedic surgeryElective total hip replacement LMWH started 12 hours before surgery, may be started 12 hours postoperatively;

ES or IPC device should be addedLDUH, aspirin, dextran, and IPC alone are not recommended

Elective knee replacement LMWH or adjusted dose warfarin to maintain an INR of 2 to 3IPC is effective if used optimally; LDUH not recommended

Hip fracture surgery LMWH or adjusted dose warfarinNeurosurgery, trauma, & acute spinal cord injury

Intracranial neurosurgery IPC with or without ESLDUH or LMWH postoperatively are alternatives with a concern about

intracranial hemorrhageFor high-risk patients the combination of mechanical and pharmacologic

prophylaxis may be more effectiveTrauma LMWH started as soon as possible if no contraindications (risk of bleeding); if

contraindicated start ES and/or IPCIVC filter is recommended if proximal DVT is seen and anticoagulation is

contraindicated; IVC filter is not recommended for primary prophylaxisAcute SCI LMWH started as soon as possible; LDUH, ES, and IPC not recommended when

used alone. ES and IPC may benefit when used in combination with LMWH orLDUH, or if anticoagulants are contraindicated.

Medical conditionsAcute myocardial infarction For most patients, prophylaxis with LDUH or therapeutic doses of IV heparin are

recommended.Ischemic stroke LDUH, LMWH or the heparinoid, danaparoid; if anticoagulation is

contraindicated, use ES or IPC deviceGeneral medical conditions with risk factors LDUH or LMWH

NOTE. Risk factors include previous VTE, increasing age, major surgery, cancer, obesity, major trauma, lower extremity or hip fracture, pregnancy,history of myocardial infarction, stroke, heart failure, hormone replacement therapy, prolonged immobilization, burns, paralysis, hypercoagulablestates, indwelling femoral vein catheter, inflammatory bowel disease.

Abbreviations: LDUH, low-dose unfractioned heparin; LMWH, low molecular weight heparin; ES, elastic stocking; IPC, intermittent pneumaticcompression; IFC, inferior vena cava; DVT, deep vein thrombosis; SCI, spinal cord injury.

Data from Geerts WH, Heit JA, Clagett GP, et al: Prevention of venous thromboembolism, Sixth ACCP Consensus Conference on AntithromboticTherapy. Chest 119:132s-175s, 2001, and Hirsh J: Managing venous thromboembolism: Methodology for achieving positive outcomes. CME-Today(Cardiopulmonary and Critical Care) 1:11-15, 2002.


are needed for cell growth, DNA synthesis, andfor reproduction. Iron is needed for Hgb syn-thesis.

Several tests are done to determine the ade-quacy of the RBC structure and function, theRBC count, Hgb concentration, hematocrit(Hct), and RBC indices.

Erythrocyte (RBC) Count

The RBC count is the part of the CBC thatdetermines the number of RBCs found in acubic centimeter of blood. It is also expressedin International Units, which is the number ofRBCs per liter of blood. Electronic automateddevices perform the test. Although the totalRBC count does give information about theoxygen-carrying capacity of blood, Hgb and Hctprovide more precise information. See Table 9for normal values.

Hemoglobin

As previously mentioned, Hgb’s primary func-tion is to carry oxygen to the cells and removecarbon dioxide from the cells. Hgb is a complexprotein made up of heme and globin. It isproduced in the immature RBC. Synthesis stopsonce the cell matures in circulation. There areapproximately 300 million molecules of Hgb inone RBC. Hgb is measured in grams per decili-ter. See Table 10 for normal values.

The heme portion contains iron atoms and thered pigment, porphyrin. The heme portion isresponsible for the red color of blood. Whenthe RBC is saturated with oxygen, the red coloris brightest. The globin portion is made up of 4amino acid chains. One heme molecule at-taches to each of the 4 amino acid chains.Therefore, each Hgb molecule has 4 heme sitesthat can bind with 4 oxygen molecules. A Hgb

is considered fully saturated when it contains 4oxygen molecules. Hgb saturated with oxygenis called oxyhemoglobin. One should note thatoxygen saturation is a measure of the amountof oxygen combined with Hgb in the blood andshould not be confused with the partial pres-sure of oxygen (PO2), which is the amount ofoxygen dissolved in plasma. Hgb also functionsas a buffer for extracellular fluid and is capableof accepting hydrogen (H�) ions to prevent thebuildup of H� ions in the blood.

Hematocrit

Hct represents the percentage of the total vol-ume of RBCs relative to the total volume ofwhole blood in a sample. “Hematocrit” means“to separate blood.” With today’s method ofautomated cell counting, Hct is calculatedrather than centrifuged. See Table 11 for normalvalues. The surgeon and anesthesia providermust be notified for values of less than 20% orgreater than 60%. Swelling of the RBC secon-dary to hyperglycemia or hypernatremia mayproduce an elevated Hct. Excessively elevatedWBC counts may also alter the Hct.

Hgb and Hct levels parallel, in that Hct levels are3 times the Hgb level. To estimate values, youwould divide the Hct by 3 to estimate the Hgb,and multiply the Hgb by 3 to estimate the Hct.This relationship is altered if RBCs are abnormalin size or shape or if the synthesis of Hgb isdefective.

The RBC count, Hct, and Hgb are closely re-lated. Alterations in one are usually associated

Table 9. RBC Count

Conventional Units SI Units

Adult male 4.6-6.2 million/�L 4.6-6.2 � 1012/LAdult female 4.2-5.4 million/�L 4.2-5.4 � 1012/L

Table 10. Hemoglobin


Adult male 13.5-18 g/dL 135-180 g/LAdult female 12-16 g/dL 120-160 g/L

Table 11. Hematocrit


Adult male 40%-54% 0.40-0.54Adult female 38%-47% 0.38-0.47


with alterations in the other. As such, increasesand decreases in each are discussed together.

Increased Levels

An increase in the number of RBCs can bedescribed as either erythrocytosis or polycythe-mia. In the clinical setting, the terms are fre-quently used as synonyms. The term erythrocy-tosis, however, more accurately defines anelevated RBC count, whereas the term polycy-themia more accurately refers to a specificgroup of disorders. These disorders can be de-scribed as either primary polycythemia or sec-ondary polycythemia.

Primary polycythemia (vera) is an increase inthe number of RBCs secondary to a relativelyrare myeloproliferative disease of the bone mar-row involving the excessive production of redcell precursors. Secondary polycythemia de-scribes an increase in RBCs as a physiologiccompensatory mechanism (via erythropoietin)for decreases in oxygen delivery as seen incardiopulmonary diseases such as congestiveheart failure (CHF), cardiovascular malforma-tion, and chronic obstructive pulmonary dis-ease, as well as in those living in high altitudes.

Dehydration also causes a relative increase inRBC, Hgb, and Hct because of a decrease inplasma volume. This is clinically referred to ashemoconcentration and may be seen frequentlyin the perianesthesia setting. Other causes in-clude excessive exercise, anxiety, pain, and cer-tain drugs such as gentamycin and methyldopa(Aldomet), as well as with renal and liver tu-mors.

Decreased Levels

Decreased levels of RBCs, Hgb, and Hct areassociated with hemodilution and anemia. He-modilution occurs as plasma volume increasesfrom fluid therapy. Anemia is a reduction in thetotal number of circulating RBCs or a decreasein the quality or quantity of Hgb or in thevolume of packed cells (Hct). Nutritional ane-mias or anemias caused by chronic diseases arecaused by iron, folate, and vitamin B12 deficien-

cies. Acute anemias are caused by blood lossdue to hemorrhage, or by RBCs being destroyedfaster than the normal bone marrow can re-place them. Extreme RBC destruction occurs inconditions such as hemolytic or type II hyper-sensitivity blood transfusion reactions (hemoly-sis of RBCs because of ABO incompatibility).Other conditions causing anemia are those thatalter erythropoiesis such as renal failure, chemo-therapeutic agents (by suppressing the bonemarrow), and leukemia. Hemoglobinopathies(such as sickle cell anemia) and the thalassemiasare also causes of anemia. Age also plays a rolein anemia because there is a tendency for lowervalues in people over the age of 50. Lastly,during pregnancy there is a relative anemia asthe normal number of RBCs becomes dilutedfrom the increase in body fluid that occursduring pregnancy.

Although all types of anemia will be seen in theperianesthesia setting, the most common causeof decreased RBC, Hgb, and Hct levels overall isblood loss or hemorrhagic anemia. Red celltransfusion is almost always indicated for a Hgbless than 6 g/dL and rarely indicated for Hgbgreater than 10 g/dL. Once the Hgb level fallsbelow 11 g/dL in an otherwise healthy adult,the kidney will begin to secrete increasingamounts of erythropoietin in a matter of hours.Unfortunately, it will take 3 to 6 days before arise in circulating RBCs will be noted. However,the decision to transfuse should never be dic-tated by a single Hgb trigger.15

Other RBC Values

Reticulocyte Count

The reticulocyte is an immature RBC found inthe bone marrow (Fig 1). There is a small per-centage of reticulocytes released into the bloodstream that accounts for approximately 0.5% to1.5% of the total RBC count. An increased countindicates the bone marrow is attempting toreplace sudden RBC loss from hemorrhage ordestruction. A decreased count would indicatebone marrow hypofunction. This count is nor-mally increased in pregnancy.


RBC Indices

RBC indices are calculated mean values that areused to define the size, weight, and Hgb con-tent of the RBC. They are mainly used to classifyanemias. RBC indices consist of mean corpus-cular volume (MCV), mean corpuscular hemo-globin (MCH), and mean corpuscular hemoglo-bin concentration (MCHC). See Table 12 fornormal values.

Mean corpuscular volume. MCV describesthe RBC by size or volume. This measure usesthe size of the RBC to identify possible causesof anemia as well as other disorders. The MCVclassifies RBCs as microcytic, normocytic, andmacrocytic. Microcytic cells are small or un-dersized. They are seen with iron deficiencyanemia and thalassemia. In hemorrhagic orhemolytic anemias, the decrease in oxygen-carrying capacity is caused by a decrease inthe number of RBCs; the cells that remain arenormal in size, thus the RBCs are normocytic.RBCs that are macrocytic are large or over-sized. These RBCs are seen in patients withpernicious or folate deficiency anemia. MCVis a calculated value obtained by dividing theHct by the RBC count.

Mean corpuscular hemoglobin. This valueis the index that measures the average weight ofHgb in the RBC. An alteration in MCH tends totrack along with the MCV. For example, a small-sized cell will have less Hgb within it comparedwith a large-sized cell, therefore its weightwould be lower. Decreases are related to micro-cytic anemias, and elevations are related to mac-rocytic anemias. Therefore, the MCH adds littleinformation independent of the MCV.

Mean corpuscular hemoglobin concentra-tion. This index is a measure of the averageconcentration of Hgb in the RBC per unitvolume. RBCs that contain less Hgb are hypo-chromic and are a pale color. Normal-coloredcells with normal amounts of Hgb are callednormochromic, and hyperchromic cells havean increased concentration of Hgb and arebright red in color.16


Polycythemic patients need to be monitored forsigns and symptoms of thrombus formation.Patients should be monitored closely for com-plaints of leg pain, changes in color, tempera-ture, and capillary refill in addition to initiatingVTE prophylaxis (Table 8) and ensuring ade-quate fluid administration. Sudden restlessness,anxiety, and dyspnea may herald a pulmonaryembolus. Changes in a patient’s level of con-sciousness or neurologic examination can warnof diminished cerebral blood flow and warn ofthe potential for stroke.

Anemic patients are at additional risk anytimethey must undergo surgical procedures. Be sureto request a type and crossmatch to ensure thatpatient-compatible blood will be available in theblood bank. Be alert to signs of blood loss,including but not limited to hypotension, tachy-cardia, restlessness, hypoxia, chest pain, fa-tigue, and occult blood positive stools and gas-tric specimens. In the preanesthesia setting, thedecision to transfuse the patient with Hgb be-tween 6 and 10 g/dL should be based on indi-vidual risk, such as type and extent of thesurgery, the ability to control the bleeding, andthe rate of uncontrolled bleeding. For electiveprocedures, Hgb of 10 g/dL or greater is recom-mended. Preoperative Hgb below 10 g/dL is anindication to postpone an elective case. If bloodtransfusion is required, expect the Hgb to riseby 1 g and the Hct by 3% for each unit of packedRBCs transfused.

Patient care activities may need to be deliveredin such a way as to reduce the patient’s fatigue,metabolic demand, and physical stress. Contin-

Table 12. RBC Indices


AdultMCV 82-93 �m3 82-93 fLMCH 26-34 pg 1.61-2.11 fmolMCHC 31-38% 19.2-23.58 mm/L


uous pulse oximetry is required to monitor forhypoxia. Be prepared to provide supplementaryoxygen and to promote adequate lung expan-sion through optimal patient positioning. Alsouse pulmonary hygiene strategies and teach pa-tients to perform turn, cough, and deep breathexercises.

Closely monitor intake and output in patientswith Hgb counts below 7 to 8 g/dL. Blood flowto the kidneys is diminished in these states, andthe patient is at risk for oliguria. Secure andmaintain intravenous access for these patients.Additionally, provide passive or active warmingmeasures because patients will complain ofcold and be pale in color.

RBC indices assist in classifying anemias. Ingeneral, be sure to fully assess a patient’s nutri-tional status and consult a dietitian for furtherworkup and intervention as appropriate.Wound healing can be grossly affected by nu-tritional anemias, and patients may require iron,zinc, and vitamin C supplements to promotesurgical wound healing. Patients will also re-quire teaching and need encouragement to in-clude iron-rich foods such as liver, red meat,raisins, peas, apricots, kidney beans, and forti-fied cereals and breads in their diets.

Increased RBC indices indicate an increasednumber of circulating immature RBCs in theperipheral circulation, increasing the patient’slikelihood of jaundice, stomatitis, and glossitis.Attention to mouth care will be essential. Theuse of soft bristle toothbrushes and cool, alka-line mouthwash is recommended. The patientshould be informed to avoid sour, tart, andspicy foods, as well as foods that are extremelycool or hot in temperature. Jaundiced patientswill require comfort measures and medicationsto reduce the discomfort associated with itching.

Platelets (Thrombocytes)

Platelets are the smallest of the cells found inblood. They are nonnucleated, flattened disk-shaped structures that can be round or oval.They have a lifespan of 9 to 12 days.

Platelets play a vital role in hemostasis; they,along with the coagulation factors, are respon-sible for hemostasis in small and medium-sizearteries and veins. Platelets aggregate or sticktogether to form the initial plug where there isdamaged endothelium. Clotting factors are thentriggered to form fibrin strands throughout theplug to firmly hold the plug together. For thecapillaries, platelets plug and stop bleeding bythemselves, thereby sealing the multitude ofminute ruptures that occur on a daily basis. Aplatelet plug forms within 3 to 5 minutes.

The platelet count only provides the number ofcirculating plates; it does not describe howadequately they function. The most indicativetest of platelet function is the “bleeding time.”

Increases in the platelet count or thrombocyto-sis are usually asymptomatic until counts reachgreater than 1,000,000 �/L, where increasedviscosity and inappropriate clotting may occur.A transient thrombocytosis with platelet countsof 450,000 to 600,000 �/L can be seen as aphysiologic response to physical stress, exer-cise, trauma, infection, and ovulation. Countsgreater than 600,000 �/L may be associatedwith myeloproliferative disorders of the stemcells in the bone marrow.

Thrombocytopenia or decreased platelet countis defined as a count of less than 150,000 �/L.Causes include depressed production by thebone marrow or increased consumption or de-struction as seen with idiopathic thrombocyto-penia. Bleeding usually does not occur untilcounts fall below 50,000 �/L if platelets arefunctioning normally. Small hemorrhagic areasunder the skin called purpura may occur at thislevel.


Patients with known thrombocytopenia are atrisk for bleeding, especially when counts fallbelow 50,000 �/L. Counts under 20,000 �/Lsignificantly increase the risk for mortality sec-ondary to hemorrhagic stroke or gastrointesti-nal hemorrhage.16 In these instances, consider


advocating for the postponement of surgicalprocedures and prepare for possible plate-let transfusion. Platelet transfusion is recom-mended prophylatically for the surgical patientwith a platelet count of less than 50,000 �/Lwho is undergoing a major procedure. Platelettransfusion may also be indicated if there isknown platelet dysfunction and microvascularbleeding despite adequate counts.16 For eachconcentrate of platelets transfused, expect theplatelet count to increase by 5,000 to 10,000�/L. Keep in mind that one aspirin will coat theplatelet, preventing it from aggregating for thelife of that platelet. A preoperative aspirin maybe more important than platelet count in ex-plaining a bleeding disorder.

Remember that thrombocytosis commonly oc-curs after hemorrhage and surgical procedures.

Counts soon return to normal limits once thepatient recovers from the primary insult. Theneed for VTE prophylaxis (Table 8) for patientswith increased platelet counts also exists. Pa-tient teaching should include precautions tominimize the risk for infection and bleeding inpostsurgical recovery period.

Summary

It is clear that the needs of patients in theperianesthesia setting are driven by the contextof their respective surgical treatment plans.These needs become complex when integratedwith the magnitude of premorbid conditionsand drug profiles that exist for each individualpatient. Knowledge of a patient’s premorbidstate and medications should heighten the cli-nicians’ awareness and analysis of specific CBCand differential results.

References1. Chernecky C, Berger BJ (eds): Laboratory Tests and Diag-

nostic Procedures (ed 3). Philadelphia, PA, Saunders, 2001, pp372-376

2. Centers for Medicare and Medicaid Services (CMS): Na-tional Coverage Determinations for Blood Counts. Available atwww.cms.hhs.gov/ncd/searchdisplay.asp?NCD_ID�61&NCD_vrsn_num�1. Accessed December 2002.

3. Goodnough LT, Brecher ME, Katner MH, et al: Transfusionmedicine: Blood transfusion. N Engl J Med 340:438-447, 1999

4. Medicare Part B Model Local Medical Review Policy, Sub-ject: Blood counts. Avera Health Lab News. 4:2-4, 2000. Availableat www.averalabnet.com/newsletters/NewsJanFeb00.htm. Ac-cessed December 2002

5. Cannon CP, McCabe CH, Wilcox RG, et al: Association ofwhite blood cell count with increased mortality in acute myo-cardial infarction and unstable angina pectoris. Am J Cardiol87:636-639, 2001

6. Baylor College of Medicine: Geriatric assessment, medicalassessment, laboratory work-up. Available at www.geri-ed.com/modules/Asses/assess/medical_assessment.htm. AccessedDecember 2002

7. Banasik JL: Inflammation and Immunity, in Copstead LC,Banasik JL (eds): Pathophysiology Biological and Behavioral Per-spectives (ed 2). Philadelphia, PA, Saunders, 2000, pp 184-218

8. Catalano P: White blood cell count with differential, inGeorge-Gay B, Chernecky C (eds): Clinical Medical-SurgicalNursing. Philadelphia, PA, Saunders, 2002, pp 282-290

9. Sadovsky R: WBC predicts increased mortality in acuteMI. Am Fam Physician 64:1261, 2001

10. Koch-Kubetin S: WBC Count Predicts Stroke. OB GYNNews. 25:24, 2000

11. Tresler KM: Hematology screen, in Clinical LaboratoryDiagnostic Tests Significance in Nursing Implications (ed 3).Norwalk, CT, Appleton Lange, 1995

12. Abramson N, Melton B: Leukocytosis: Basics of clinicalassessment. Am Fam Physician 62:2053-2060, 2000

13. Gawlikowski J: White cells at war. Am J Nurs 92:44-51,1992

14. The ABCs of CBC: A common blood test. Mayo ClinicHealth Letter, August 2001, pp 4-5

15. American Society of Anesthesiologists: Practice Guide-lines for Blood Component Therapy. Available at www.asahq.org/practice/blood/blood_component.html. Accessed December2002

16. Garrett K: Red blood cell counts, in George-Gay B,Chernecky C (eds): Clinical Medical-Surgical Nursing. Philadel-phia, PA, Saunders, 2002, pp 274-282


Understanding the Complete Blood Count With Differential

1.4 Contact Hours

Directions: The multiple-choice examination below is designed to test your understanding of theComplete Blood Count With Differential according the objectives listed. To earn contact hours from theAmerican Society of PeriAnesthesia Nurses (ASPAN) Continuing Education Provider Program: (1) read thearticle; (2) complete the posttest by indicating the answers on the test grid provided; (3) tear out the page(or photocopy) and submit postmarked before February 28, 2005, with check payable to ASPAN (ASPANmember, $12.00 per test; nonmember, $15.00 per test); and (4) return to ASPAN, 10 Melrose Ave, Suite110, Cherry Hill, NJ 08003-3696. Notification of contact hours awarded will be sent to you in 4 to 6 weeks.

Posttest Questions

1. In the process of erythropoiesis, iron is needed fora. hemoglobin synthesis.b. DNA synthesis.c. reproduction.d. renal excretion.

2. When monitoring a patient who is not bleeding, the nurse would expect to find an increasein Hct of 3% after a transfusion of one unit of packed RBCs.a. Trueb. False

3. The amount of blood combined with Hgb is a measurement ofa. partial pressure of oxygen (PaO2).b. arterial-venous oxygen difference.c. oxyhemoglobin.d. oxygen saturation (SaO2).

4. In an adult patient with normal Hgb, the nurse will estimate the Hgb to be 10 g/dL if the Hctwas reported to be 30%.a. Trueb. False

5. Secondary physiologic polycythemia is caused by all of the following excepta. congestive heart failure.b. renal failure.c. high altitudes.d. chronic obstructive pulmonary disease.

6. Pernicious anemia is caused bya. alcoholism.b. chronic blood loss.c. vitamin B12 deficiency.d. iron deficiency.

7. An elevated reticulocyte count would be expected ina. a recovering trauma patient who lost significant amounts of blood.b. a patient with a chronic inflammatory disease.


c. a patient in renal failure.d. a patient with bone marrow hypofunction.

8. All of the following are included in the CBC excepta. erythrocyte sedimentation rate.b. neutrophil count.c. platelet count.d. bands.

9. A CBC is indicated for patients greater than age 65.a. Trueb. False

10. “Shift to the right” means thata. there is an elevation in bands.b. the patient probably has an acute viral infection.c. an acute hypersensitivity reaction is occurring.d. hypermature segmented neutrophils are present.

11. Neutropenic precautions involves all of the following excepta. reverse isolation.b. staying away from children recently vaccinated.c. reporting temperatures of greater than 38°C.d. avoiding indiscriminate use of acetaminophen.

12. The major cell of the immune response is thea. cytotoxic T cell.b. B cell.c. plasma cell.d. helper T cell.

13. Nutritional anemias as recognized in the RBC indices can assist in identifying patientsa. at risk for allergic reactions.b. in need of postoperative blood transfusion.c. at risk for poor wound healing.d. none of the above.

14. Once Hgb levels fall below 11 g in an otherwise healthy adult, the kidney will begin tosecrete erythropoietin in a matter of hours. A rise in circulating red blood cells will be notedwithina. 6 to 8 days.b. 3 to 5 days.c. 24 hours.d. 48 hours.

15. Venous thromboembolism prophylaxis is required for patients with total WBC countsgreater than 100,000.a. Trueb. False


ANSWERSSystem W010405. Please circle the correct answer1. a. 2. a. 3. a. 4. a. 5. a.

b. b. b. b. b.c. c. c.d. d. d.

6. a. 7. a. 8. a. 9. a. 10. a.b. b. b. b. b.c. c. c. c.d. d. d. d.

11. a. 12. a. 13. a. 14. a. 15. a.b. b. b. b. b.c. c. c. c.d. d. d. d.

Please Print

Name Nursing License No/State

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Social Security ASPAN Member #

EVALUATION: Understanding the Complete Blood Count With Differential(SD, strongly disagree; D, disagree; ?, uncertain; A, agree; SA, strongly agree)

SD D ? A SA

1. To what degree did the content meet theobjectives?

1 2 3 4 5

a. Objective #1 was met. 1 2 3 4 5b. Objective #2 was met. 1 2 3 4 5c. Objective #3 was met. 1 2 3 4 5d. Objective #4 was met. 1 2 3 4 5e. Objective #5 was met. 1 2 3 4 5f. Objective #6 was met. 1 2 3 4 5

2. The program content was pertinent,comprehensive, and useful to me.

1 2 3 4 5

3. The program content was relevant to mynursing practice.

1 2 3 4 5

4. Self-study/home study was an appropriateformat for the content.

1 2 3 4 5

5. Identify the amount of time required to read thearticle and take the test.

1 2 3 4 5

25 min 50 min 75 min 100 min 125 min

Test answers must be submitted before April 30, 2005, to receive contact hours.


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