rh disease district 1 acog medical student education module 2008
TRANSCRIPT
![Page 1: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/1.jpg)
Rh DiseaseDistrict 1 ACOG Medical Student
Education Module 2008
![Page 2: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/2.jpg)
Rh Disease
Occurs during pregnancy when there is an incompatibility between the blood types of the mother and fetus
![Page 3: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/3.jpg)
Blood Types
A, B, O blood groups are specific types of proteins found on the surface of RBC’s
Also found in the cells and other body fluids (saliva, semen, etc)
O represents neither protein being present on RBC
Possible groups include: A, B, AB, or OA, B, O groups most important for
transfusions
![Page 4: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/4.jpg)
Rh Factor
Proteins (antigens) occurring only on surface of RBC’s
Rh + if proteins presentRh – if proteins absentA+, A-, B+, B-, AB+, AB-, O+, O-Most important for pregnancyInheritance is Autosomal Dominant15% Caucasian population is Rh-
![Page 5: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/5.jpg)
Nomenclature
Correct to say Rh(D) + or –Rh blood system has other antigens: C, c,
D, E, eD is by far the most common and the only
preventable oneWeak D (Du) also existsAlso non Rhesus groups such as Kell,
MNS, Duffy (Fy) and Kidd (Jk) exist
![Page 6: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/6.jpg)
Why Does Rh Status Matter?
Fetal RBC cross to maternal circulation
Maternal immune system recognizes foreign antigens if fetus Rh + and mother Rh –
Antibodies are formed against fetal antigens
Subsequent pregnancy with Rh+ fetus, immune system activated
and large amounts of Ab formed
IgG Ab cross placenta & attack fetal RBC
Fetal anemia, hydrops, etc
![Page 7: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/7.jpg)
![Page 8: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/8.jpg)
![Page 9: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/9.jpg)
![Page 10: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/10.jpg)
![Page 11: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/11.jpg)
![Page 12: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/12.jpg)
![Page 13: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/13.jpg)
Pathophysiology
Rh(D) antigen expressed by 30 d GAMany cells pass between maternal & fetal
circulation including at least 0.1 ml blood in most deliveries but generally not sufficient to activate immune response
Rh antigen causes > response than mostB lymphocyte clones recognizing foreign
RBC antigen are formed
![Page 14: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/14.jpg)
Pathophysiology cont…
Initial IgM followed by IgG in 2 wks- 6 mthsMemory B lymphocytes activate immune
response in subsequent pregnancyIgG Ab cross placenta and attach to fetal
RBC’sCells then sequestered by macrophages in
fetal spleen where they get hemolyzedFetal anemia
![Page 15: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/15.jpg)
![Page 16: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/16.jpg)
![Page 17: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/17.jpg)
Causes of RBC Transfer
abortion/ectopicpartial molar pregnancy blighted ovumantepartum bleeding special procedures (amniocentesis, cordocentesis,
CVS)external version platelet transfusion abdominal trauma inadvertent transfusion Rh+ bloodpostpartum (Rh+baby)
![Page 18: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/18.jpg)
General Screening
ABO & Rh Ab @ 1st prenatal visit@ 28 weeksPostpartumAntepartum bleeding and before giving
any immune globulin
Neonatal bloods ABO, Rh, DAT
![Page 19: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/19.jpg)
Gold Standard Test
Indirect Coombs:-mix Rh(D)+ cells with maternal serum-anti-Rh(D) Ab will adhere-RBC’s then washed & suspended in Coombs
serum (antihuman globulin)-RBC’s coated with Ab will be agglutinated
Direct Coombs:-mix infant’s RBC’s with Coombs serum-maternal Ab present if cells agglutinate
![Page 20: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/20.jpg)
+ Rh(D) Antibody Screen
Serial antibody titres q2-4 weeks If titre ≥1:16 - amniocentesis or MCA
dopplers and more frequent titres (q1-2 wk)
Critical titre – sig risk hydrops** amnio can be devastating in this settingU/S for dating and monitoring Correct dates needed for determining
appropriate bili levels (delta OD450)
![Page 21: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/21.jpg)
U/S Parameters
Non Reliable Parameters: Placental thickness Umbilical vein diameter Hepatic size Splenic size PolyhydramniosVisualization of walls of fetal bowel from small
amounts intraabdominal fluid may be 1st sign of impending hydrops
U/S reliable for hydrops (ascites, pleural effusions, skin edema) – Hgb < 70
![Page 22: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/22.jpg)
![Page 23: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/23.jpg)
Amniocentesis
Critical titre/previous affected infantAvoid transplacental needle passageBilirubin correlates with fetal hemolysis∆ optical density of amniotic fluid @
450nm on spectral absorption curveData plotted on Liley curve
![Page 24: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/24.jpg)
![Page 25: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/25.jpg)
Liley Curve
Zone I – fetus very low risk of severe fetal anemia
Zone II – mild to moderate fetal hemolysisZone III – severe fetal anemia with high
probability of fetal death 7-10 days
Liley good after 27 weeks98% sensitive for detecting anemia in
upper zone 2/ zone 3
![Page 26: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/26.jpg)
Middle Cerebral Artery Dopplers
Measures peak velocity of blood flowAnemic fetus preserves O2 delivery to
brain by increasing flowSensitivity of detecting severe anemia
when MCA >1.5 MoM approaches 100%Not reliable > 35 weeks GA
![Page 27: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/27.jpg)
Fetus at Risk
Fetal anemia diagnosed by: amniocentesis cordocentesis ultrasound
hydrops
middle cerebral artery Doppler
Treatment: intravascular fetal transfusion preterm birth
![Page 28: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/28.jpg)
Infant at Risk
Diagnosis: history of HDN antibodies? early jaundice < 24 hours cord DAT (“Coomb’s”) positive (due to HDN or
ABO antibodies)
Treatment: Phototherapy Exchange or Direct blood transfusion
![Page 29: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/29.jpg)
Prevention
RhoGAM (120mcg or 300mcg)Anti-D immune globulinPreviously 16% Rh(D)- women became
alloimmunized after 2 pregnancies, 2% with routine PP dose, and 0.1% with added dose @ 28 wks
![Page 30: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/30.jpg)
![Page 31: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/31.jpg)
Kleihauer-Betke Test
% fetal RBC in maternal circulationFetal erythrocytes contain Hbg F which is
more resistant to acid elution than HbgA so after exposure to acid, only fetal cells remain & can be identified with stain
1/1000 deliveries result in fetal hemorrhage > 30ml
Risk factors only identify 50%
![Page 32: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/32.jpg)
![Page 33: Rh Disease District 1 ACOG Medical Student Education Module 2008](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649c9e5503460f9495e7b6/html5/thumbnails/33.jpg)
Kleihauer Calculations
Fetal red cells = MBV X maternal Hct X % fetal cells in KB
newborn Hct
MBV – maternal blood volume (usually 5000ml)
Fetal cells X 2 = whole blood