Umbilical Cord Thrombosis

Umbilical cord thrombosis is clot in the umbilical vein or artery. It results from stasis, vessel injury or hypercoagulability, and is linked with true knots, torsion, cord entanglement, umbilical vein varix, funisitis, maternal diabetes and thrombophilia. It matters because it is associated with growth restriction, fetal heart abnormality and stillbirth.

• Risk factors: maternal diabetes, thrombophilia, hypertension, cord abnormality, chorioamnionitis, growth restriction.
• Usually found at histology after fetal loss.
• Antenatal diagnosis is uncommon.

Women are usually well until reduced fetal movements or fetal death. The finding may be incidental on a scan.

• Reduced fetal movements.
• Fundal height small for dates in chronic cases.
• Differential diagnosis: cord haematoma, umbilical vein varix, cord cyst, true knot, cord compression, fetal anaemia, placental insufficiency.
• Complications: fetal growth restriction, fetal hypoxia, stillbirth, preterm birth, neonatal thrombosis, neonatal death.

The approach is ultrasound with Doppler, with a search for the cause.

• Ultrasound: echogenic material in the cord vessel, a dilated vessel with absent flow on colour Doppler, or cord swelling.
• Umbilical artery Doppler, estimated fetal weight, amniotic fluid index, cardiotocography.
• Maternal tests: glucose or HbA1c, blood pressure, full blood count, antiphospholipid antibodies, protein C, protein S and antithrombin where available.
• Placental and cord histology after birth.

The principle is close surveillance with delivery as soon as the fetus is viable and mature enough, or earlier if the heart rate or Doppler worsens.

• Supportive: admit; cardiotocography once or twice daily; daily fetal movement counts; left lateral rest; control maternal diabetes; 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 when delivery is likely; magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks; enoxaparin 40 mg subcutaneous daily with aspirin 150 mg oral at night for maternal thrombophilia or antiphospholipid syndrome; insulin or metformin 500 mg oral with meals increased to 1 g 12-hourly (maximum 2.5 g daily) for diabetes; oxytocin 10 IU IM at birth.
• Procedures: delivery at 34 to 37 weeks for a stable fetus, at once for abnormal cardiotocography, absent or reversed end diastolic flow or reduced movements; caesarean section for abnormal tracing; induction at 37 weeks if monitoring is normal.
• Special groups: women with antiphospholipid syndrome continue enoxaparin 40 mg subcutaneous daily for 6 weeks after birth.
• Red flags: reduced fetal movements, abnormal cardiotocography, absent end diastolic flow, bradycardia.
• Follow-up: Doppler and growth scans every 1 to 2 weeks; cardiotocography twice weekly; newborn examination for thrombosis; thrombophilia testing and counselling after birth.