Ectopic pregnancy on the uterosacral ligament post-double frozen embryo transfer in an endometriosis patient: case report and review of management and treatment options.

Background: Ectopic pregnancy (EP) is a serious obstetric condition that can be life-threatening, with various risk factors contributing to its development. In particular, in vitro fertilization (IVF) techniques may lead to an increased rate EP. Additionally, also endometriosis seems to be related to this particular obstetrical condition.

Case Report: We report a rare case of ectopic pregnancy on the uterosacral ligament (USL) along with a suspected coexisting tubal ectopic pregnancy following IVF. The patient is a 48-year-old woman in menopause, with a history of pelvic endometriosis, who experienced sudden abdominal pain and vomiting at eight weeks of amenorrhea after undergoing a double heterologous frozen embryo transfer. Thorough examination and pelvic ultrasound, we diagnosed a hemoperitoneum due to a suspected heterotopic EP on the left USL and contralateral tube. Due to the sudden worsening of the patient's condition, we opted for a surgical procedure. An urgent laparotomy revealed a severe hemoperitoneum caused by an EP implanted on the left USL and a malacic, bleeding contralateral tube, both of which were removed, and hemostasis was then guaranteed. The histopathologic exam confirmed the EP on the left USL and an edematous tube without product of conception (POC).

Conclusions: Comparing our case with others reported in the current literature, it appears that the etiopathogenetic mechanisms leading to this urgent obstetrical condition are various and not fully understood. Despite those circumstances, the present case highlights the importance of considering non-tubal ectopic pregnancies in the context of risk factors, including IVF techniques, endometriosis, and advanced age, in cases of abdominal pain and hemoperitoneum after a single or double embryo transfer. The treatment, which involves different professional figures, should be executed as soon as possible, with the aim of preserving the patient's life and any future desire for pregnancies.