A 24-year-old female patient complains of acute pain in the lower abdomen that turned up after a physical stress. She presents with nausea, vomiting, dry mouth and body temperature 36,6°C. She has a right ovarian cyst in history. Bimanual examination reveals that uterus is dense, painless, of normal size. The left fornix is deep, uterine appendages aren't palpable, the right fornix is contracted. There is a painful formation on the right of uterus. It's round, elastic and mobile. It is 7x8 cm large. In blood: leukocytosis with the left shit. What is the most likely diagnosis?