Twin Reversed Arterial Perfusion Sequence in a Spontaneous Monochorionic Diamniotic Twin Pregnancy: A Case Report

Background: Twin reversed arterial perfusion (TRAP) sequence is a rare complication unique to monochorionic twin pregnancies, characterized by a normal "pump" twin perfusing an acardiac, nonviable co-twin through placental vascular anastomoses.Case presentation: We report the case of a 28-year-old primigravida with a spontaneous monochorionic diamniotic (MCDA) twin pregnancy diagnosed at 22 weeks of gestation with features consistent with TRAP sequence.Twin 2 was acardiac and acephalic.The pregnancy was managed conservatively with regular ultrasound monitoring and assessment of the pump twin's well-being.The patient was B-positive and developed mild intrahepatic cholestasis of pregnancy (with serum bile acids of 21 mol/L).At 36 weeks, she underwent an elective lower segment cesarean section (LSCS) and delivered a live female infant weighing 1,950 gm.The acardiac twin was nonviable.Conclusion: Early diagnosis and individualized monitoring of the TRAP sequence are critical in optimizing maternal and fetal outcomes, particularly in spontaneous MCDA twin gestations.