appendix in immunology

Molecular Immunogenetics

THE APPENDIX

The Appendix

Introduction 1889 Mac Burney described location, the

clinical features of appendicitis and the importance of operative intervention and muscle-splitting incision.


The Appendix

Surgical AnatomySurface anatomyDevelopment: diverticulum of ceacum

appearing in the 8th week of lifePositions: constant base, tip varies (retroceacal,

pelvic, subcaecal, preileal, pericolic)Blood supplyLocation during surgerySurrounding anatomical structuresPart of the gut lymphoid tissue.



The appendix sits at the junction of the small intestine and large intestine. It’s a thin tube about four inches long. Normally, the appendix sits in the lower right abdomen.

The function of the appendix is unknown. One theory is that the appendix acts as a storehouse for good bacteria, “rebooting” the digestive system after diarrheal illnesses. Other experts believe the appendix is just a useless remnant from our evolutionary past. Surgical removal of the appendix causes no observable health problems.


For years, the appendix was credited with very little physiological function. We now know, however, that the appendix serves an important role in the fetus and in young adults. Endocrine cells appear in the appendix of the human fetus at around the 11th week of development. These endocrine cells of the fetal appendix have been shown to produce various biogenic amines and peptide hormones, compounds that assist with various biological control (homeostatic) mechanisms. There had been little prior evidence of this or any other role of the appendix in animal research, because the appendix does not exist in domestic mammals.


Among adult humans, the appendix is now thought to be involved primarily in immune functions. Lymphoid tissue begins to accumulate in the appendix shortly after birth and reaches a peak between the second and third decades of life, decreasing rapidly thereafter and practically disappearing after the age of 60. During the early years of development, however, the appendix has been shown to function as a lymphoid organ, assisting with the maturation of B lymphocytes (one variety of white blood cell) and in the production of the class of antibodies known as immunoglobulin A (IgA) antibodies. Researchers have also shown that the appendix is involved in the production of molecules that help to direct the movement of lymphocytes to various other locations in the body


In this context, the function of the appendix appears to be to expose white blood cells to the wide variety of antigens, or foreign substances, present in the gastrointestinal tract. Thus, the appendix probably helps to suppress potentially destructive humoral (blood- and lymph-borne) antibody responses while promoting local immunity. The appendix--like the tiny structures called Peyer's patches in other areas of the gastrointestinal tract--takes up antigens from the contents of the intestines and reacts to these contents. This local immune system plays a vital role in the physiological immune response and in the control of food, drug, microbial or viral antigens. The connection between these local immune reactions and inflammatory bowel diseases, as well as autoimmune reactions in which the individual's own tissues are attacked by the immune system, is currently under investigation.

The Appendix

Acute Appendicitis Epidemiology

Most common surgical emergency.Slightly more common in men.Incidence are falling from 100 to 50 in 100 000 (1975-1991).1 in 6 of the population will have an appendectomy.In Saudi Arabia incidence are comparable to western figures? More common in European societies (Diet).? Relation to class status.Age > 2 yrs, (associated with lymphoid development).Up to 16% of appendicectomies are normal 75% are in women


The Appendix

Acute Appendicitis Pathology I

Luminal obstruction. Lymphoid hyperplasia 60% Faecolith 35%. Inspissated barium. Fruit seeds. }<4% Worms. < 1% Extra-luminal obstruction eg Ca Cecum

Raised intra-luminal pressure Mucus accumulation Multiplication of bacteria. ( E.Coli, Bacteroids, peptostreptococcus, Psuedomonas) Venous and lymphoid congestion and.


The Appendix

Acute Appendicitis Pathology II

Impaired arterial flow, thrombosis and gangrene. Perforation may occur through devitalized tissue.

Histological terms used:

Catarrhal appendicitis Suppurative ;;; Necrotic ;;; Gangrenous ;;; Perforated ;;; Appendicular mass

The risk of perforation is not inevitable.


The Appendix - Acute Appendicitis Clinical Features I

Only 55% have classical features.Atypical 45%History 24-36 hoursAbdominal pain: (diffuse and periumbilical, localizing to the RIF)Anorexia (almost always).Vomiting (75%).Low grade fever.

If >38 suspect perforationTenderness, guarding and rebound: Be gentleRovsing’s, psoas, obturator signs: unreliable and late


Full History Duration, severity, onset, System review. and examination: General, throat, chest…..etc

The Appendix - Acute Appendicitis Clinical Features IITender Appendicular massAtypical:

(loin, high RUQ, deep pelvic) Diarrhea ( not always gastroenteritis) Urinary frequency

The Extremes of Age:Children < 5 rapid progressionPain in the elderly is less intense


The Appendix - Acute Appendicitis InvestigationsWhite cell count: high sensitivity 96%, low specificityUrine analysisPlain Xray, nonspecificUltrasound highly sensitive (80-90%), excludes

other pathologies. Computer Tomography: More superior to USS in diagnostic

accuracy.Barium enema: Good accuracy, but technically

difficult and false positives are common.LaparoscopyActive observationComputer aided diagnosis.Peritoneal lavage


The Appendix - Acute Appendicitis The Very YoungDiagnosis may be more difficult to establish,

WBC is likely to be normal (12% are normal).

Children are more likely to progress to perforated appendix

(? Under-developed Greater Omentum).


The Appendix - Acute Appendicitis The Very OldGreater morbidity and mortalityLess typical presentationCancer may be a possibility as an

underlying cause.Perforation of 50% and mortality of 20%

has been reported


The Appendix - Acute Appendicitis The Pregnant

Implications: Clinical Findings, Lab Ix, SurgeryImplications: Clinical Findings, Lab Ix, Surgery1: 2000 pregnancies.More common in the first two trimestersThe appendix is pushed superiorly and

laterallyWBC > 15 Premature Labor 10-15% with surgeryPerforated appendix leads to fetal death in

20%Rapid diagnosis and treatment is advised.


The Appendix - Acute Appendicitis In AIDS Patients

Be aware of CMV or Kaposi sarcoma as the underlying cause

WBC may not rise


The Appendix - Acute Appendicitis The ManagementPreop:

IVI, analgesia, IV antibiotics

Conventional appendicectomyTypes of incisionsLaparoscopic appendicectomy: (questions regarding pain, hospital stay,

operation time, to daily activity, wound infection)


The Appendix - Acute Appendicitis Post-Operative1. Check the vitals2. Check the abdominal signs and bowel

movement3. Check the wound4. Advise on mobilization5. In OPD:

1. Check wound2. Check the Histology


The Appendix - Acute Appendicitis PrognosisMortality: from 0.2% to 1%Complications increase with perforation Morbidity:

Wound abscess, Wound infection (less with MacBurney’s

incision), Wound dehiscence Intra-abdominal abscess, Faecal fistula, Intestinal obstruction, Adhesive band, inguinal hernia. Fertility


The Appendix - Acute Appendicitis ProblemsMass palpable pre-operatively

Appendix is normal at operation

Tumor is found in appendix

Prophylactic appendicectomy


The Appendix – Chronic Appendicular Conditions Chronic Appendicitis

A loose term referring to a multitude of conditions associated with RIF pain and in which pathology of the appendix has been found.


The Appendix – Chronic Appendicular Conditions Appendicular Mass

Results from either:1. Localized by edematous, adherent

omentum and loops of small bowel2. Appendicular abscess

Incidence is 10% Higher in children Management controversy:

Interval vs Immediate appendicectomy


The Appendix – Chronic Appendicular Conditions Tumors of The Appendix

Carcinoid: Arise from Kluchitsky cells Mean age 20-40 Yellow bulbar mass In F>M In third decade of life Usually lies near the tip In the absence of LN spread with <2 cm in

diameter appendicectomy is sufficient. Otherwise a R hemicolectomy is necessary.

Adenocarcinoma and Lymphoma.



Referance

•Ajmani ML, Ajmani K (1983). the position length and arterial supply ofvermiform appendix. Anatomisecher Anzeiger 153(4): 369-374•Al-fallouji MM, Mchbrien MP (1993). Appendectomy in Al-fallouji MAMebrien MP (edn) Evolution of some important surgical proceduresHeadway press, Great Britain pp.273.•Badoe EA (1994). The appendix: in Badoe EA Achampong E, Jaja MO(editors) Principle and Practice of surgery including pathology in thetropics, second edn. Tema Ghana publishing corporation 1199-501.•Bakheit MA, Warille AA (1999) Anomalies of the vermiform appendix andPrevalence of acute appendicitis in Khartoum East Afr med. j.,1616:336-340.•Balteazar EJ, Gade M (1976). The normal and abnormal development ofappendix Radiology 121:599 -604•Birnbaum BA Wilson SR (2000). Appendicitis at the millennium, radiology215:337-348

appendix in immunology

Documents

appendix acts

appendix introduction

fetal appendix

molecular immunogenetics

white blood cells

week of development

endocrine cells

little physiological