QuestionSBA
QuestionChoice
For potentially sensitising events after 20 weeks gestation, a minimum anti-D Ig dose of 500 IU should be administered within 72 hours of the event. A test for FMH is also required to guide further dosing.
49815
d
Administer 500 IU anti-D Ig prophylaxis within 72 hours, and perform a test for fetomaternal haemorrhage (FMH)
QuestionChoice
Rhesus isoimmunisation can occur when a rhesus negative mother has a baby which is rhesus positive. If any foetal red blood cells enter the maternal circulation (e.g. during birth or a "sensitising event"), the mother will form anti-D antibodies against them, which can cause rhesus haemolytic disease in the newborn.

Abdominal trauma is a potentially sensitising event. For potentially sensitising events between 12 and 20 weeks gestation, a minimum dose of 250 IU of anti-D Ig prophylaxis should be administered within 72 hours of the event.
49812
a
Administer 250 IU anti-D Ig prophylaxis within 72 hours
QuestionChoice
Routine antenatal anti-D prophylaxis is indicated where a rhesus negative mother has not been sensitised. Anti-D has no effect after sensitisation has already occurred.
49813
b
Arrange for two doses of 500IU anti-D Ig prophylaxis to be given at 28 and 34 weeks of pregnancy
QuestionChoice
For potentially sensitising events between 12 and 20 weeks gestation, a minimum dose of 250 IU anti-D Ig prophylaxis should be administered within 72 hours of the event. A test for FMH is not required.
49816
e
Perform a test for fetomaternal haemorrhage (FMH)
QuestionChoice
Abdominal trauma is a potentially sensitising event, so anti-D is indicated.
49814
c
Advise the woman to return for anti-D Ig prophylaxis only if vaginal bleeding occurs. If the pregnancy was less than 12 weeks gestation, anti-D would not be indicated unless there was repeated or heavy vaginal bleeding, or bleeding associated with abdominal pain
Concept
Chapter
# Overview

The D antigen is found on red blood cells and is an important antigen in the rhesus factor system.

Rhesus isoimmunisation can occur when a rhesus negative mother has a baby which is rhesus positive. If any foetal red blood cells enter the maternal circulation, the mother will form anti-D antibodies against them.

The maternal anti-D antibodies can cross the placenta in subsequent pregnancies and cause Rhesus haemolytic disease if the future baby is rhesus positive.

# Sensitisation events

“Sensitisation” events are events which cause foetal blood to cross the placenta into the maternal circulation and thus these are indications for anti-D prophylaxis.

Examples of sensitisation events include:

- Antepartum haemorrhage
- Placental abruption
- Abdominal trauma
- External cephalic version
- Invasive uterine procedures such as amniocentesis and chorionic villus sampling
- Rhesus positive blood transfusion to a rhesus negative woman
- Intrauterine death, miscarriage or termination
- Ectopic pregnancy
- Delivery (normal, instrumental or caesarean section)

# Testing

All mothers should be tested for rhesus status and anti-D antibodies at booking

# Management of the Rh-D negative mother

Presence of anti-D antibodies can result in incompatibility and haemolysis in future pregnancies. To attenuate this risk, anti-D antibodies are given to patients who have experienced a sensitising event. Anti-D is also given to all non-sensitised Rhesus negative mothers at 28 weeks. Note that anti-D has no effect once sensitisation has already occurred (it is prophylactic only).
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Rhesus isoimmunisation
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Obstetrics
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Rhesus isoimmunisation
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Ectopic pregnancy 1
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Rhesus isoimmunisation
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Haemolytic disease of the newborn
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Rhesus isoimmunisation
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Quesmed Tutorial: Haemolytic Anaemia
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A 23-year-old primiparous woman attends accident and emergency following a head-on car collision in which she was driving. She is currently 19 weeks pregnant. She has sustained minor bruising to the abdomen and chest from the seatbelt, but otherwise has no injuries. The foetal heart is auscultated and foetal wellbeing confirmed. There is no vaginal bleeding. The woman is reported to be rhesus negative.

What is the most appropriate management?
a