Cesarean Scar Evaluation Using Saline Infusion Sonography in Women With Previous Pregnancy in Scar

Over the past few decades, cesarean delivery rates worldwide have risen considerably. The surgery may lead to deficient uterine scar healing, thinning of the myometrium and formation of cesarean scar defects or uterine scar niche. The prevalence of clinically relevant cesarean scar defects is unclear and has been reported between 20-88%, it is identified by using transvaginal ultrasound or saline-infused sonography in non-pregnant patients. Women may be asymptomatic or present a wide gynecologic sequela including cesarean scar pregnancy, abnormal uterine bleeding, dysmenorrhea, chronic pelvic pain, infertility, and increased risk of complications during gynecologic procedures such as uterine evacuation and insertion of intrauterine device.

Cesarean scar pregnancy (CSP) is defined as an early pregnancy implantation in the scar from a prior cesarean delivery. This pregnancy is implanted in a fibrous scar tissue and may lead to substantial risk for severe maternal morbidity such as adherent placenta, second or third trimester uterine dehiscence or rupture, severe maternal bleeding, and adherence to adjacent tissues. The prevalence of scar pregnancy is reported to be between 1:1800-2500 pregnancies, with increasing diagnosis in the last decade due to increasing use of transvaginal ultrasound early in pregnancy and possible increased physician awareness of this condition.

The ultrasound criteria for CSP have been redefined recently, and now propose transvaginal ultrasound as the imaging technique of choice at this early stage. In 2022, the Niche Task-force convened a Delphi consensus to develop a standardized sonographic evaluation and reporting system for a CSP in the first trimester. According to this consensus, CSPs were classified into three subgroups, Subgroup A in which the largest part of the gestational sac protruded towards the uterine cavity, subgroup B in which the largest part of the gestational sac was embedded in the myometrium, and subgroup C in which the gestational was partially located outside the outer contour of the cervix or uterus. This sonographic classification has yet to be validated clinically.

In the present report the investigators aim to evaluate the uterine cavity and potential cesarean scar defects or niche in women with history of CSP using saline infused sonography. In the second stage of the research, we will classify the past cesarean pregnancies according to the new Delphi criteria and examine correlation between the different CSP subgroups and presence of cesarean scar defects.