INTRAMURAL ISTHMIC PREGNANCY FOLLOWING PREVIOUS CESAREAN SECTION AND IN VITRO FERTILIZATION: A CASE REPORT WITH DISCUSSION OF THE MOLECULAR PATHOLOGY OF CESAREAN SCAR IMPLANTATION

Abstract

Intramural pregnancy is among the rarest forms of ectopic implantation, accounting for fewer than 1% of ectopic pregnancies, and is associated with a high risk of uterine rupture and life-threatening hemorrhage when the diagnosis is delayed. The molecular pathology of abnormal implantation at the cesarean scar and lower uterine segment is increasingly being defined and involves altered expression of extracellular matrix remodeling enzymes, dysregulated wound-healing pathways, and changes in endometrial receptivity markers. We report a 35-year-old woman with a previous cesarean section and secondary infertility who conceived following frozen embryo transfer and was diagnosed with an intramural isthmic pregnancy at 7 weeks of gestation. The diagnosis was established by high-resolution transvaginal ultrasonography and confirmed by pelvic magnetic resonance imaging, both of which demonstrated complete myometrial encasement of the gestational sac without communication with the endometrial cavity. A fertility-preserving combined approach was used, comprising laparoscopic excision of the gestational tissue with site-directed local methotrexate injection into the surrounding myometrial bed. The myometrial defect was repaired in two layers and the uterus was preserved. Serial beta-human chorionic gonadotropin titers fell from 38,640 mIU/mL preoperatively to 112 mIU/mL by postoperative day 21. Histopathology confirmed chorionic villi embedded entirely within myometrial smooth muscle fibers, without intervening decidualized endometrium. The case is discussed in the context of recent molecular and gene-expression studies of cesarean scar healing and lower-segment implantation, including data on the connective tissue growth factor (CTGF)–LRP1 axis, matrix metalloproteinase expression, integrin β3 and leukemia inhibitory factor as endometrial receptivity markers, and microRNA dysregulation at the cesarean scar niche.