Spontaneous bladder rupture (SBR) is a rare condition and often missed diagnosis, especially after a non traumatic vaginal delivery. A 32-year-old para 3 woman, consulted for abdominal pain and anuria two days after instrumental vaginal delivery with forceps for foetal distress in second sate of labour. Blood tests were suggestive of an acute renal failure. An abdominocentesis revealed a clear fluid looking like ascites. The ultrasound and computed tomography (CT) scan showed a large abdominal effusion. An exploratory laparoscopy revealed a bladder perforation which was sutured after laparotomy. SRB is extremely rare after a non traumatic vaginal delivery. It is associated with significant morbidity and mortality. Symptoms are mostly non-specific. It is suspected when post partum abdominal pain is associated with an effusion and renal failure signs. If suspected, the uroscanner remains the gold standard for diagnostic. Laparotomy is the standard surgical approach in this condition. Abdominal pain with elevated serum creatinine should be suspicious of SBR in post-partum.