A 28-year-old patient has been taken to a hospital for acute pain in the lower abdomen. There was a brief syncope. The delay ofmenstruation is 2 months. Objectively: the patient has pale skin, AP- 90/50 mm Hg, Ps- 110/min. Lower abdomen is extremely painful. Vaginal examination reveals uterus enlargement. There is positive Promtov's sign. Right appendages are enlarged and very painful. Posterior vault hangs over. What is the most likely diagnosis?