A 36-year-old female pesented to a gynecological hospital with a significant bleeding from the genital tract and a 1-month delay of menstruation. Bimanual examination revealed soft barrel-shaped cervix. Uterus was of normal size, somewhat softened. Appendages were unremarkable on both sides. Speculum examination revealed that the cervix was cyanotic, enlarged, with the external orifice disclosed up to 0,5 cm. Urine hCG test was positive. What is the most likely diagnosis?