Case Report: Missed diagnosis of twin reversed arterial perfusion sequence discovered at delivery: lessons from poorly monitored monochorionic twin pregnancy.

Twin reversed arterial perfusion (TRAP) sequence is an extremely rare and serious complication that occurs specifically in multiple monozygotic pregnancies. Early sonography and Doppler examination are the cornerstones for an accurate diagnosis. This is a case of an acardiac acephalus twin who was misdiagnosed during pregnancy and discovered at vaginal birth after 36 weeks of gestation in a 31-year-old woman, gravida three para two. The pregnancy was poorly followed up and was mistakenly considered a singleton. It is a rare complication that affects monochorionic multiple pregnancies and is the best explanation for the associated morphological abnormalities. Diagnosis can be made through ultrasound examination at an earlier stage of pregnancy, enabling effective monitoring of the healthy twin who is at the risk of heart failure and anemia. There are many therapeutic methods aimed at preserving the healthy fetus from complications by suppressing the vascularization of the acardiac fetus. This case highlights a rare and serious complication of monochorionic twin pregnancy and emphasizes the need for multidisciplinary care. Radiologists and obstetricians should be attentive to pregnant women who have an abnormal tissue mass alongside a normal twin without any cardiac activity. An ultrasound scan is essential for the accurate diagnosis of the TRAP sequence; an early diagnosis and treatment can help save the pump twin and increase its chances of survival without cardiac complications.