Cesarean scar pregnancy

Abstract

A 33-year-old woman with a history of light vaginal bleeding was referred for an ultrasound scan at 4 weeks' gestation. In her previous pregnancy she had an emergency Cesarean section at term due to a failure to progress. Her medical and surgical histories were unremarkable. The uterine cavity appeared empty on transvaginal ultrasound scan. A small gestational sac measuring 11 mm in diameter was identified at the level of the internal os (Figure 1). The gestational sac was implanted anteriorly overlying the uterine Cesarean section scar, which appeared as a thin hyperechoic band transgressing the anterior uterine wall at the base of the uterovesical fold. An increased peritrophoblastic blood supply was demonstrated on Doppler examination adjacent to the anterior aspect of the gestational sac, confirming implantation outside the uterine cavity. Ultrasound image showing a small 4-week gestational sac implanted anteriorly into the Cesarean section scar. The maternal serum human chorionic gonadotropin (hCG) level was 9730 IU/L and the serum progesterone was 11 nmol/L, suggestive of a non-viable pregnancy. In view of this result and the finding of the pregnancy being implanted outside the uterine cavity, into the Cesarean section scar, the woman was offered surgical termination of pregnancy. The procedure was uncomplicated and her urinary pregnancy test was negative 2 weeks later. A histology report confirmed the presence of products of conception in the surgical specimen. Ultrasound diagnosis of pregnancy implanted into a Cesarean section scar has been described only recently and there is no agreement on the appropriate diagnostic criteria. According to Vial et al. 1 the diagnosis is based on the visualization of trophoblast, located between the bladder and the anterior uterine wall. Discontinuity of the anterior uterine wall should also be visible on the sagittal view. In order to avoid false-positive diagnosis of Cesarean scar pregnancy in women presenting during the cervical phase of incomplete miscarriage, implantation into the scar should be demonstrated by Doppler examination showing high-velocity, low-impedance peritrophoblastic flow. The implantation into the scar should be further confirmed by applying gentle pressure on the cervix during a transvaginal ultrasound scan. A gestational sac implanted outside the uterine cavity will remain in place during such a maneuver, whilst a cervical miscarriage will be easily displaced2. However, a prospective evaluation of these diagnostic criteria in correlation with pregnancy outcomes needs to be conducted.