BHCG, Rhesus D and Progesterone

Rhesus Status

  • 15% of the population are Rhesus negative
  • Rh D immunoglobulin is administered to non-sensitised Rh D negative women to prevent the development of Rh D antibodies and in so doing prevent Rh D induced haemolytic disease of the newborn.
  • Administration
    • Anti-D only works on D antigens and should be given as soon as possible after the immunising event
    • Always try to give within 72 hours
    • If not offered within 72 hours then it can be given 9-10 days providing no maternal antibodies have been produced
  • Rh D Immunoglobulin is indicated whenever it is known or suspected that foetal red cells have entered the circulation of an Rh negative mother unless the father can be shown conclusively to be Rh D negative

Indication

Rhesus D negative mother with

  • Delivery of a rhesus positive infant
  • Abdominal trauma with potential placental separation eg MVA
  • Elective procedures such as amniocentesis, chorionic villus sampling (CVS) and external cephalic version (ECV)
  • During pregnancy with
    • Ectopic pregnancy
    • Spontaneous miscarriage:
      • Anti-D Ig should be given to all non-sensitised RhD negative women who have a spontaneous complete or incomplete abortion after 12 weeks of pregnancy
    • Threatened miscarriage:
      • Anti-D Ig should be given to all non-sensitised RhD negative women with a threatened miscarriage after 12 weeks of pregnancy. Where bleeding continues intermittently after 12 weeks’ gestation, anti-D Ig should be given at 6-weekly intervals
    • Antepartum haemorrhage (APH)

What dose should I give?

  • Aim for 20 micrograms of Anti-D for each ml of Rh D positive red cells – as determined by Kleihauer
  • In general no Kleihauer is required for early pregnancy disease
    • <12 weeks 250 IU or 50 micrograms anti-D
    • > 12 weeks 625 IU or 125 micrograms anti-D
  • Important for patients being discharged from DEM following an episode of light bleeding in early pregnancy with viable intra-uterine pregnancy
Stage of Pregnancy Clinical Indications Mandatory Tests

Dose of Anti-D

(Give within 72 hours)

First Trimester
(≤ 13 weeks)
Threatened abortion
Incomplete abortion
Missed abortion
Miscarriage
PV bleeding
Chorionic Villus Sampling
TOP
Blood Group
Antibody Screen
1 x 50 μg
250IU
Second and third Trimesters Antepartum Haemorrhage
Chorionic Villus Sampling
Amniocentesis
Cordocentesis
External Cephalic Version
Trauma
PV bleeding
Placental abruption
Therapeutic abortion
Blood Group
Antibody Screen
Kleihauer
1 x 125 μg/6 mL fetal cells in maternal circulation

625 IU

Postpartum Rh Positive baby
Du Positive Baby
Macerated Fetus (or other inability to obtain fetal blood
Blood group
Antibody Screen
Kleihauer

beta-Human Chorionic Gonadotrophin (β-HCG)

  • β-HCG – correlates to age of pregnancy and specific USS findings
  • First 60 days (weeks 4-8)
    • Double every 1.4 to 2.1 days
  • Taking two β-HCG 48 hours apart can be helpful
    • If repeat β-HCG in 48 hours shows an increase by <20% or a reduction it is 100% sensitive for foetal demise or ectopic
    • However the test cannot distinguish between foetal demise or ectopic
  • If β-HCG >50,000 ectopic pregnancy very unlikely

Serum progesterone Levels

  • Can be helpful in predicting pregnancy outcomes in the first 8/40
  • In contrast to rising β-HCG, the progesterone levels remain constant during the first 9-10 weeks and rise sharply after that
    • Progesterone <5ng/ml – usually non-viable pregnancy (ectopic, abortion)
    • Progesterone 5-25ng/ml – usually abnormal gestation
    • Progesterone >25ng/ml – strongly associated with viable intra-uterine pregnancy (IUP0
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