Transvaginal ultrasonography of the patient with caesarean scar pregnancy after curettage treatment failure. The uterine cavity and cervical canal were empty. A 5.4 × 3.7 × 3.7 cm mass implanted in the anterior wall of the uterine caesarean scar (arrow) embedded and surrounded by thin myometrium and separated from the endometrial cavity was visible on the retroverted uterus. Ultrasonography revealed that the mass was heterogeneous with a mixture of cystic and solid echogenicity. C = cervix; F = fundal endometrial cavity; M = mass; S = scar of caesarean section