In the article we present a case of a 20-year-old patient, who was treated in our hospital due to endometriosis. She underwent a routine laparoscopy. Four hours later she developed hypotension, pulse acceleration, signs of peritoneal irritation and muscle guarding. We immediately decided to perform an explorative laparotomy. We found about 1500 ml of smooth blood and blood clots in the peritoneal cavity. Unfortunately we did n'ot manage to find the source of the bleeding. The case we present is an example of a rare complication, connected probably with the damage of a vessel in the umbilical ring, causing difficulties both in the diagnosis and management.