Diagnostic Challenges of an Abdominal Pregnancy in the Second Trimester

Abdominal pregnancies are a rare form of ectopic pregnancy, which presents a significant risk of maternal morbidity and mortality. We describe an unusual case of a late diagnosis of an abdominal pregnancy in the second trimester, which due to diagnostic challenges, was not detected on 1st trimester and subsequent antenatal ultrasound scans (USS). The abdominal pregnancy was later diagnosed at the repeat anomaly scan and confirmed with a pelvic MRI. This case of abdominal pregnancy is unique when compared to other reported cases, as the fetus was initially enclosed within the amniotic sac with normal liquor volume. Both transvaginal and transabdominal scans appeared to demonstrate an intrauterine pregnancy. The diagnosis of abdominal pregnancy was only made possible following rupture of the amniotic sac, leading to anhydramnios, which resulted in the repositioning of the fetus to the upper maternal abdomen. This case represents the challenges faced by obstetricians in diagnosing, managing, and counselling a woman when faced with an abdominal pregnancy.