EP07.30: A case of patent urachus prenatal diagnosis by ultrasonography and fetal MRI

Patent urachus is a rare congenital anomaly that is a spectrum of umbilical disorders. It was due to failure of involution of normal embryologic tissues that connect the developing bladder to the umbilical cord. Accurate diagnosis of allantoic cyst of the umbilical cord is a major importance as it is commonly associated with omphalocele, urinary tract obstruction and urachal anomalies. We report a case of patent urachus recently diagnosed prenatally in our hospital. A 24-year-old woman referred to our hospital due to fetal abdominal cyst at 16+0 weeks of pregnancy. NIPT and MSAFP result was low risk. On ultrasound, a 6 cm hypoechoic cyst was located near the fetal anterior abdomen and was connected to the fetal bladder. No other anomalies were found on the ultrasound. We performed fetal MRI for accurate diagnosis. At pregnancy 21+5weeks, fetal MRI showed a 6.5 cm cystic lesion communicating with the bladder. As the pregnancy progressed, the umbilical cord cyst shrank to 3 cm. A 3,005g female was delivered by elective C-sec at 38+1 weeks of gestation. At physical examination, patent urachus was connected to umbilical cord and urine was leaked. Next day of delivered, paediatrics inserted Foley's catheter in newborn's bladder. But urine was leaked from umbilicus. At the 11th day of delivered, laparoscopic surgery for the excision of patent urachus and bladder repair was performed. The neonate kept on a Foley's catheter for 10 days and discharged home. The incidence of urachal anomaly is considered difficult to determine because some have asymptomatic or undiagnosed allantoic abnormalities. Postoperative complications are uncommon during the procedure, and overall the patient's long-term prognosis is excellent. Patent urachus may require surgical treatment after birth, so prenatal diagnosis is important.