Rhesus

Question 1

Name 2 complications maternal Rh alloimmunisation

Answer 1

• Erythroblastosis foetalis
• haemolytic disease of the newborn

Question 2

ANC diagnosis and testing for rhesus disease? (5)

Answer 2

• Determine Rh status
• if negative, test for antibodies (INDIRECT COOMBS)
• if none, retest at 28 weeks
• if antibodies and >1:8, refer to foetal unit for further evaluation
• Cff - DNA can be considered to determine rhesus status of foetus. If also negative, there’s no need for anti-d prophylaxis

Question 3

How perform routine antenatal Rh disease prophylaxis?

Answer 3

• Offer anti-d to all non-sensitised Rh negative pregnant women
• single dose 300 ug at 28 weeks or 2 doses 100 ug at 28 and 34 weeks

Question 4

How perform postnatal Rh disease prophylaxis? (4)

Answer 4

• Do rapid Rh on baby cord blood
• 100 ug anti-d to all women within 72 hours of delivery to Rh + infant
• 300 ug if suspected larger fetomaternal haemorrhage
• kleihauer Betke test within 2 hours of delivery to calculate additional anti-d needed if fetomaternal haemorrhage > 4 ml

Question 5

What is kleihauer Betke test

Answer 5

Use within 2 hours of delivery to identify size of fetomaternal haemorrhage by identifying presence of foetal RBCs in maternal blood. To see how much additional anti-d is required for mom

Question 6

Name 7 causes large feto-maternal haemorrhage that may lead to Rh alloimmunisation

Answer 6

• Antepartum haemorrhage
• traumatic deliveries including c/s
• manual removal of placenta
• stillbirths, foetal deaths
• abdominal trauma in 3rd trimester
• twin pregnancies at delivery
• unexplained foetal hydrops

Question 7

Dose of anti-d prophylaxis after fetomaternal haemorrhage? (2)

Answer 7

• IM dose 100 ug will neutralise 4 ml (50 ug if < 20 weeks )
• for each ml >4 ml, give 25 ug anti-d
• give ASAP within 72 hours

Question 8

Name indications anti-d prophylaxis (13)

Answer 8

• Antepartum haemorrhage
• routine antenatal if mom - and baby + (300 ug at 28 weeks)
• surgical evacuation of miscarriage (50 ug <12 weeks, 100 ug 12 weeks or more)
• spontaneous complete/incomplete miscarriage 12 weeks or more (100 ug)
• threatened miscarriage > 12 weeks (100 ug. If continued intermittent bleed give 50 ug 6 weekly)
• ectopic
• medical/surgical top
• Invasive prenatal diagnostic procedures eg amniocentesis, chorio-villus sampling…
• other intrauterine procedures: shunts, embryo reduction, laser
• external cephalic version
• foetal death, stillbirth
• any abdominal trauma 3rd trimester
• other causes large fetomaternal haemorrhage: traumatic deliveries incl. C/s, manual removal placenta, twin pregnancy at delivery, unexplained foetal hydros

Question 9

Management Rh alloimmunised patient in first affected pregnancy? (5)

Answer 9

• Determine foetal Rh status. If negative, no need for management
• titre <1:8: repeat monthly till 24 weeks, then repeat 2 weekly
• titre 1:8 : assess for foetal anaemia by measure middle cerebral artery peak systolic velocity (mca -psv)
• if serial mca-psv < 1,5 Mom (multiples of median ), induce at 37 - 38 weeks
• if mca-psv >1,5 Mom, refer to foetal unit. Consider foetal transfusion of red packed cells.

Question 10

Management Rh alloimmunised patient if previously affected pregnancy?

Answer 10

Maternal titres not useful. Follow up middle cerebral artery peak systolic velocity at foetal unit for foetal anaemia.