Rh Disease

Question 1

What is the most common Rh antigen? Most preventable?

Answer 1

Rh: D

Question 2

At what point does Rh Compatibilty become an issue?

Answer 2

Sensitized upon contact with first fetus. Ab made

Reacts with Rh Ag in Second pregnancy

Question 3

What type of Ab can cross the placenta?

Answer 3

IgG Antibodies

Question 4

What is the fate of Fetal RBCs with attach maternal Antibody?

Answer 4

Sequestered by macrophages in the fetal spleen =>Hemolyzed => Fetal Anemia => Inc Bilirubin

Question 5

WHat are caues of RBC transfer?

Answer 5

Abortion/ectopic
partial molar preggo
Blighted ovum
Antepartum bleeding
Procedures
Platelet transfusion
Abdominal trauma
Postpartum

Question 6

How is Screening for Rh diseases done?

Answer 6

ABO and Rh Ab at 1st prenatal visit
@ 28 weeks
Postpartum
Neonatal blood tests can include ABO, Rh, DAT

Question 7

What is the difference between Direct and indirect Coombes test?

Answer 7

Indirect: Mix Rh+ cells with maternal cells
Anti Rh Ab will adhere
Direct: Mix infant’s RBCs with Coombes serum
Maternal Ab present if cells agglutinate

Question 8

WHat is the Critical Ab Titre for Hydrops Fetalis?

Answer 8

> 1.16

Question 9

What are the non-reliable US Parameters of Hydrops?

Answer 9

Placental thickness
Umbilical vein diameter
Hepatic Size 
Splenic Size
Polyhydramnios

Question 10

WHat are the reliable US indications of Hydrops?

Answer 10

Ascites, Pleural effusion, Skin edema (Walls of fetal bowel 1st sign)

Question 11

What is the Liley Curve?

Answer 11

Zone 1- Very low risk of fetal anemia
Zone 2- Mild to mod fetal hemolysis
Zone 3- Severe fetal anemia with HIGH probabilty of fetal death
(After 27 weeks)

Question 12

What is the Middle Cerebral Artery Doppler screening for?

Answer 12

Screening for Hydops before 35 weeks.

Question 13

How can fetal anemia be diagnosed?

Answer 13

Amniocentesis
Cordocentesis
US
-Hydrops
-Middle cerebral Artery Doppler

Question 14

What is the treatment of Fetal anemia?

Answer 14

Intravascular fetal transfusion

Preterm birth

Question 15

What are the risks of Rh Incompatibility?

Answer 15

Intrauterine fetal demise
Neonate apears limp, pale, edematous, Dyspnea and circ collapse
Hyperbilirubinemia => Jaundice and kernicterus

Question 16

How is Rh disease prevented?

Answer 16

RhoGAM

Anti-D immune globulin

Question 17

WHat is the Kleihauer-Betke test?

Answer 17

%fetal RBC in Maternal Circulation
Expose to Acid
Only fetal cells remain
ID with stain
Tells you amt of Fetal blood in maternal circ