A 30-year-old woman complains of fever of 38.7°C, pain in the lower abdomen, and dysuric disorders. She has history of an artificial abortion performed 3 days ago. Bimanual examination detects that the cervix is cylindrical, the opening is closed, the body of the uterus is slightly enlarged, painful, and soft. The uterine appendages are not palpable. Purulent-hemorrhagic discharge is being produced. Blood test results: leukocytes 10.109/L, band neutrophils 12%. What is the most likely diagnosis in this case?