Management of a Delayed Diagnosed Acardiac Twin Pregnancy with TRAP Sequence

A 27-year-old primigravida at 23 weeks of gestation was referred due to polyhydramnios in a spontaneously conceived MCMA (monochorionic monoamniotic) twin pregnancy. 

Previous ultrasounds at 12 and 18 weeks revealed a normal fetus and a deceased twin with generalized edema. Subsequent assessment at our center uncovered a large mass with generalized edema, consistent with an acardiac twin. The acardiac twin had underdeveloped upper limbs a fully formed skull with poorly developed brain structures, and the lower extremities and spine were well-formed, lacking a heart but with visible kidneys. Doppler examination revealed a single arterial-type vessel with reversal flow to the acardiac mass, confirming the diagnosis.

The pump twin exhibited hydrops fetalis (HF) and heart failure; a detailed examination revealed no other abnormalities. The acardiac twin weighed 78% of the pump twin's weight. Due to severe polyhydramnios and maternal dyspnea, amnioreduction was performed, aiding subsequent interventions. 

Radiofrequency ablation (RFA) successfully occluded the umbilical cord in the acardiac twin, and intrauterine transfusion (IUT) was performed to address severe fetal anemia in the pump twin.

Following IUT, the pump twin's hydrops resolved and cardiac function improved. The patient was discharged 48 hours post-IUT. At 36 weeks, a female newborn weighing 2400 g was delivered vaginally with normal Apgar scores. The acardiac twin weighed 230 g. Poor prognostic factors for the pump twin were managed effectively, including hydrops, abnormal Doppler velocimetry, weight ratio > 0.7, and polyhydramnios. The complexity of the Twin Reversed Arterial Perfusion (TRAP) sequence highlights the importance of physician awareness, timely referrals, and expert management in addressing this rare complication in monochorionic twin pregnancies.

Source: Rahimi-Sharbaf F, Shirazi M, Hessami K, Saleh M, Golshahi F, Saeedi S, Shirdel Abdolmaleki A, Mousavi Vahed SH, Nouri B, Sahebdel B. Case Reports in Obstetrics and Gynecology. 2023 Aug 30;2023.