Diagnosis of Amniotic Sac Herniation Into Uterine Dehiscence Using Combined Ultrasound and Magnetic Resonance Imaging—A Rare Complication Following Fetoscopic Laser Photocoagulation

A 27-year-old primigravida with monochorionic diamniotic (MCDA) twin pregnancy underwent fetoscopic laser photocoagulation at 17 + 1 weeks' gestation for Quintero stage II twin-twin transfusion syndrome (TTTS). On postoperative day 20, transabdominal ultrasound identified a cystic anechoic structure adjacent to the anterior uterine wall. Subsequent magnetic resonance imaging (MRI) demonstrated a 2-mm fistulous tract extending from the recipient twin's amniotic sac to the extrauterine cavity, consistent with amniotic sac herniation. Parental concerns prompted induced labor at 23 weeks, with follow-up imaging showing restoration of normal uterine architecture and uterine integrity. Due to contraceptive failure, the patient experienced an unplanned pregnancy and delivered a live infant vaginally within 1 year. The case highlights the critical role of comprehensive imaging modalities for diagnosing subtle postoperative complications. Advanced sonographic techniques and MRI facilitate the accurate detection of rare complications such as uterine dehiscence and amniotic sac herniation to optimize perinatal outcomes.