BackgroundFetal bladder rupture causing urinary ascites is uncommon. It is generally related to invasive fetal medicine procedures or obstructive disorders such as in posterior urethral valves in male fetuses. An exceptional case of spontaneous bladder rupture in a female fetus occurred in a pregnant woman treated with high doses of opiates in an intensive care unit. This unusual obstetric situation leads to discussion of the possible causes of fetal bladder rupture, its management, and the pediatric prognosis.Case presentationWe report the case of a 30-year-old nulliparous black woman with a history of mesenteric cystic lymphangioma and multiple bowel resections leading to chronic malabsorption. During her pregnancy, our patient presented with an occlusive syndrome and major bilateral renal dilation. Urinary derivation resulted in iatrogenic bilateral ureteral perforation. Our patient thus presented with major uroperitoneum, bilateral pleural effusion and acute renal failure, treated by thoracic drainage and bilateral nephrostomy. Postoperative pain required treatment with level III analgesics. In this context, 5 days after morphine treatment introduction an enlarged fetal bladder was observed, followed 3 days later by voluminous fetal ascites. The diagnosis of spontaneous bladder rupture was suspected. After multidisciplinary discussion, expectant management was decided. At 31 weeks and 4 days gestation, our patient went into spontaneous labor with a subsequent vaginal delivery. The infant required resuscitation and paracentesis of ascites at birth. Her neonatal course was favorable with a simple urethral bladder drainage. Cystography at day 9 was normal. At 2 years of follow-up, the mother and the child have a normal course.ConclusionsAn iatrogenic origin of megacystis in a female fetus must be evoked in the event of maternal administration of high doses of opiates in the second part of her pregnancy. In our case, the megacystis was followed by spontaneous bladder rupture at 30 weeks of gestation, with a favorable maternal fetal issue.