Twin Pregnancy with One Fetal Demise

Twin pregnancy with one fetal demise is the death of one fetus in a twin pregnancy after the first trimester, with the other fetus still alive. The death is caused by fetal anomaly, growth restriction, twin to twin transfusion, cord accident, infection or placental disease. It matters because in monochorionic twins the surviving twin can suffer brain injury or death from acute blood loss into the dead twin.

• The risk of co-twin death and neurological injury is higher in monochorionic than in dichorionic twins.
• Immediate delivery does not prevent the injury, which happens at the time of death.

Women may notice reduced movements of one baby, bleeding, or have no symptoms. The finding is loss of one fetal heart on Doppler or ultrasound.

• One fetal heart absent.
• Mother usually well.
• Differential diagnosis: wrong detection of one heart, twin to twin transfusion syndrome, selective growth restriction, vanishing twin in the first trimester, conjoined twin loss.
• Complications: co-twin death, brain injury in the survivor, preterm labour, maternal coagulopathy (rare, after 3 to 4 weeks), preeclampsia, psychological distress.

The approach is confirmation by ultrasound with assessment of chorionicity and of the survivor.

• Ultrasound: absent cardiac activity in one twin, confirmed by a second observer; chorionicity from the first trimester scan.
• Survivor: middle cerebral artery peak systolic velocity for anaemia, growth, umbilical artery Doppler, amniotic fluid index, detailed anatomy including brain.
• Maternal fibrinogen, platelets, prothrombin time, and activated partial thromboplastin time at diagnosis and weekly if the dead twin is retained for more than 3 weeks; blood group and antibody screen; Kleihauer test.
• Fetal brain MRI of the survivor at 4 weeks after the death in monochorionic twins.

The principle is surveillance of the survivor and delivery by gestation, with intervention only for a clear indication.

• Supportive: counselling about the outlook, grief support and a plan for follow-up; admit for fetal assessment; cardiotocography after 28 weeks; birth in a unit with neonatal intensive care.
• Pharmacological: betamethasone 12 mg IM twice, 24 hours apart, between 24 and 34 weeks and 6 days if delivery is planned; magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks; aspirin 150 mg oral at night if started before the death and the woman has hypertension; blood transfusion or fibrinogen concentrate 2 to 4 g IV for coagulopathy; oxytocin 10 IU IM at birth then infusion of 20 IU in 1 litre sodium chloride 0.9 percent at 125 mL per hour for 4 hours.
• Procedures: expectant care to 34 to 36 weeks for monochorionic and to 37 to 38 weeks for dichorionic twins when the survivor is well; immediate delivery for survivor distress, severe preeclampsia, infection or coagulopathy; intrauterine transfusion for severe anaemia of the survivor in a fetal medicine unit; placental histology after birth.
• Special groups: RhD negative women give anti-D immunoglobulin 500 IU IM within 72 hours, increased by 125 IU for each 1 mL of fetal red cells above 4 mL.
• Red flags: abnormal survivor Doppler or cardiotocography, maternal bleeding or low fibrinogen, fever, severe hypertension, reduced movements of the survivor.
• Follow-up: growth scans every 2 weeks; fetal brain MRI at 4 weeks; newborn cranial ultrasound and neurodevelopmental review at 2 years.