Rh Negative Pregnancy & Hydrops Fetalis😍

Rh Negative Pregnancy

  • Mother: Rh-ve.
  • Fetus: Rh+ve.

Rh-ve Female's 1st Antenatal Visit:

  • Check husband's ABO/Rh.
    • If husband is Rh+ve → 50% chances fetus will be Rh+ve (high risk pregnancy).
  • Indirect Coombs test (ICT) performed during 1st antenatal visit to check for Rh antibodies. Repeated at 28 weeks.

Results:

  • ICT -ve: Rh non-isoimmunized pregnancy.
  • ICT +ve: Rh isoimmunized pregnancy.

Pathology

  • If mother is Rh- & baby is Rh+
    • Fetal blood enters maternal circulation
    • Stimulates production of maternal antibodies against fetal RBC
    • Hemolysis in subsequent pregnancy
    • erythroblastosis fetalis/ Rh incompatibility → ↑bilirubin
    • Unconjugated bilirubin crosses blood brain barrier
    • Deposited in basal ganglia → Kernicterus

Management of Rh Nonimmunized Pregnancy

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Anti-D

  • ROGAM → bcz IgG
  • has a limited duration of action
    • Half-life: ~3 weeks
  • Protection duration: ~12 weeks only
  • If given at first visit (e.g., 8 weeks), it won’t last until term.
      • → The woman would again become unprotected later.

Measurement of Anti D

  • Test done to calculate dose of Anti D: Kleihauer-Betke test.
  • Reagent: Citric acid phosphate buffer.
  • Dose: 300 mcg of Anti D can neutralize:
    • 30 mL of fetomaternal hemorrhage (Abruptio, maternal trauma).
    • 15 mL of fetal Red Blood Cells (RBCs).
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If ICT is negative at first antenatal visit.

  • Repeat ICT at 28 weeks of gestation.
    • If still negative:
      • Give Anti D 300 mcg (Antepartum prophylaxis).
      • 1500 IU
      • To protect current pregnancy.
  • Deliver between 39-40 weeks.
    • During delivery:
      • Methyl ergometrine Counteracted (C/I) in Rh -ve pregnancies.
      • Early cord clamping.
    • After baby is born:
      • Prerequisites for postpartum prophylaxis:
        • Rh status: Positive (+).
        • Direct Coombs test: Negative (-).
      • Give Anti D 300 mcg to mother (Postpartum prophylaxis).
      • Within 72 hours (ideal) - 28 days post delivery (maximum).
      • Done to protect future pregnancies.

Note

  • Methyl ergometrine is C/I in
    • Rh negative
    • Cardiac
    • Twin pregnancy

NOT AN INDICATION for Anti D

  • Threatened and complete abortion in T1
  • Cordocentesis
  • ICT negetive
  • Husband is Rh negetive
  • Baby is Rh negetive

Other Indications for Anti D:

  • 1st Trimester
    • Dose: 50 mcg (100 mcg)
    • Abortion.
    • Ectopic pregnancy.
    • Molar pregnancy.
    • Medical Termination of Pregnancy
    • Chorionic Villus Sampling
  • 2nd and 3rd Trimester
    • Dose: 300 mcg IM / 1500 IU
      • Best time: at 28 weeks
    • Trauma.
    • Antepartum Hemorrhage
    • Amniocentesis.
    • External Cephalic Version
    • Manual removal of placenta.
    • Fetal death.

Management of Rh Isoimmunized Pregnancy

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  • If ICT is positive either at first antenatal visit or at 28 weeks.

Next step:

  • Assessment of antibody titre.
    • Critical titre = 1:16.

Titre < 1:16 (1:2, 1:4, 1:8):

  • Repeat titre every 4 weeks.
  • Fetal monitoring begins at 32 weeks.
  • Delivery:
    • Between 37-38 weeks.
    • Methyl ergometrine is Counteracted (C/I).
    • Delayed cord clamping.

Titre ≥ 1:16 (1:16, 1:32, 1:64): Next step:

  • Check PSV of middle cerebral artery (MCA).
    • PSV ≤ 1.5 MOM
      • Fetal Anemia Absent
      • Repeat MCA Doppler every 2-4 weeks.
      • Fetal monitoring begins at 32 weeks.
      • Delivery at 37-38 weeks.
    • PSV ≥ 1.5 MOM
      • Fetal Anemia Present
      • Next step: Cordocentesis/Per-umbilical blood sampling (PUBS).
        • Only indication is to know exact hematocrit in Rh isoimmunized pregnancy.
        • Fetal blood taken from umbilical vein.
          • Hematocrit < 30%:
            • ≥ 35 weeks POG: Termination of pregnancy.
            • < 35 weeks POG: Intra-uterine blood transfusion.
          • Hematocrit ≥ 30%:
            • Repeat Hb and hematocrit weekly.
            • MCA Doppler: Every week.
            • Fetal monitoring: From 32 weeks.
            • Delivery: 37–38 weeks
ㅤ
Hb level
Hematocrit
Intrauterine transfusion
< 8
< 30%
Hydrops fetalis
< 5
< 15%

Delivery in Rh-ve Pregnancy

  • Mode of delivery: Vaginal.
  • Cord clamping:
    • In Rh negative pregnancy
      • If ICT is negative, early cord clamping.
      • If Indirect Coombs Test (ICT) is positive, delayed cord clamping.

Hydrops Fetalis (HF)

Very important to remember

  • Increased unconjugated bilirubin
  • Increased fetal urobilinogen
  • Hypoalbuminemia

Based on USG findings:

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  • Presence of ≥ 2 of:
    • Pericardial effusion.
    • Ascites.
    • Pleural effusion.
  • Or Anasarca + any 1.
  • Note: Placentomegaly and polyhydramnios are seen in hydrops
    • but are not included in diagnostic criteria.

Causes:

  • Immune HF:
    • Rh negative pregnancy (most common cause).
    • ABO incompatibility.
  • Nonimmune HF:
    • CVS disease (most common cause).
    • Chromosomal disorders.
    • Parvovirus infection.
    • Syphillis, Toxoplasmosis, CMV
    • Twins stage 4
    • Mnemonic: PSC Toxic