Doppler and Rh negative Pregnancy Flashcards
Doppler of uterine artery
Role: predict PIH in female pregnant
Diastolic notch normal
Diastolic notch disappears in normal preg by 22–23
Wks of pregnancy.
What if diastolic notch persist beyond 24wks
Abnormal
Indicates during this pregnancy pt will develop PIH
Doppler of umbilical artery
Normal
As period of gestation increase….. Resistance of blood vessels decrease….. diastolic flow increases.
S/D ratio < 3
Abnormal Doppler of umbilical artery
- IN PIH: pressure increases…… Peripheral vascular resistance increases…. Diastolic flow decreases.
S/D ratio increases ≥ 3. - ABSENT END DIASTOLIC FLOW:
If period of gestation<32 wks– steroids, frequent fetal monitoring.
If POG ≥ 34wks termination of pregnancy - REVERSED END DIASTOLIC FLOW:
POG < 32wks– steroids, frequent fetal monitoring, MgSo4 for neuro protection of fetus.
POG ≥ 32 wks TOP.
Doppler of middle cerebral artery
Done in 2 cases
1. Fetal anemia: peak systolic velocity
2. IUGR: end diastolic flow
Pulsatality index.
Increased peak systolic velocity is seen in
- Fetal anemia
- Twin to twin transfusion syndrome
- Twin anemia polycythemia sequence
- Parvovirus infection B19
- Rh isoimmunization.
- Vasaprevia
Doppler summary
- For assessing UPI
- For redistribution of blood flow
- For fetal anemia
- For cardiac failure
1. Umbilical artery Doppler S/D ratio≥ 3 at ≥ 28 wks 2. Middle cerebral artery Doppler — end diastolic flow 3. MCA — peak systolic velocity 4. Ductus venosus.
Best way to asses IUGR
Doppler
1st change: amniotic fluid index( oligohydramnios) + umbilical artery Doppler.
2nd change: MCA.
What are Rh antigens
Location
c,C,D,E,e
Most important is “D”
If D is present them Rh positive if absent Rh negative.
Located on short arm of chromosome no. 1.
What is Rh negative pregnancy
Mother Rh negative
Fetus Rh positive
If fetal blood (Rh antigen)contacts mothers blood stimulates immune system to form Rh antibody
1st IgM releases but it cannot cross placenta
Next IgG crosses placenta……. Antigen antibody reaction leads to
* Fetal hemolysis… Fetal anemia
* Fetal bilirubin increased: jaundice ≥ 20 kernicterus.
* Hepatomegaly, bone marrow hyperplasia…..erythroblastosys fetalis.
* Fetal edema
* Fetal hydrops.
3 grades of manifestations in fetus of Rh negative isoimmunization.
Risk factors for mother.
- Fetal anemia
- Icterus neonatorum
- Hrdrops fetalis– gravist.
Mother: PIH
Polyhydramnios.
Role of anti D in Rh negative female
If Rh negative has been given anti D before hand…..
Fetal RBC enter mothers circulation…. Fetal RBC and anti D in mothers blood form ag- ab reaction…..
Fetal blood cells hemolized even before they could stimulate mothers immune system……. So mother immune system doesn’t firm Rh antibody.
300 mcg of anti D can neutralize only 15ml of fetal blood. Which is safe.
Hence no fetal hemolysis.
How to know whether fetal RBCs stimulated immune system or not?
INDIRECT COOMBS TEST. Done on mother’s blood
- If test is negative then mother’s immune system not yet stimulated. So we can give anti D.
- If test positive already stimulated. No use of giving anti D.
Pregnancy conditions where antiD is given
Abortion: except< 12 wks.
Ectopic pregnancy
Molar preg evacuation
Chorionic villi sampling
Amniocentesis
APH
Trauma
Fetal death
Unexplained vaginal bleeding
Fetal blood sampling
External cephalic version
After delivery..........when baby blood group Rh +ve
Direct coomb test in baby blood group –ve. Give antiD as prophylaxis for next pregnancy.Female with Rh –ve pregnancy with indirect coombs test +ve.
Antibody titre?
IF ANTIBODY TITRE < 1:16 :-
* Less ab’s
* Not much damage
* Repeat ab testing every 4 weekly
Deliver between 37- 38wks.
IF AB TITRE ≥ 1:16 :-
* Large ab
* Destroy RBC of fetus………. Fetal anemia
Next step: PSV of MCA Doppler
!______________________|______________________!
<1.5mom ≥ 1.5 mom
Keep repeating MCA Doppler significant anemia
Every weekly or 2wkly do USG to rule out
Deliver pt btw 37-38wks hydrops fetalis.
