Subserosal pregnancy: Systematic review with proposal of new diagnostic criteria and ectopic pregnancy classification

Ectopic pregnancy (EP) is a pregnancy where the growing blastocyst implants outside the endometrial cavity. EP account approximately for 0.5-1% of all pregnancies, and extrauterine implant is the leading cause of woman mortality in the first trimester of gestation. Non-tubal pregnancies (NTP) account for less than 5% of all EP. NTP are accompanied by a 7-8 times higher risk of maternal mortality when compared to tubal pregnancies, and their treatment might sometimes be very challenging. Subserosal pregnancy (SP) has been defined as rare variant of intramural pregnancy, where a portion of the gestational sac was surrounded only by the serosa of the uterus. Whereas the treatment of the ectopic pregnancies is crucial for patients' lives and for adequate fertility sparing and considering the need for surgical treatment in many cases, an early diagnosis is important; thus we believe it g might be useful to define some criteria to guide subserosal pregnancy identification, and to distinguish it from other types of non-tubal ectopic pregnancy. A systematic review on Pubmed, Scopus, Web of Science and Google Scholar was performed. Case reports, randomized controlled trials, prospective controlled studies, prospective cohort studies, retrospective studies, and case series were considered eligible. In all databases mentioned were considered manuscripts published from 1990 up to March 2023. Only four articles were eligible for inclusion in this review. All patients underwent to surgical management in laparoscopy. The main risk factors for this type of ectopic pregnancy were previous uterine surgery with opening of the endometrial cavity and assisted reproductive techniques procedures. Considering our results, we propose new classification and diagnostic criteria for subserosal pregnancy, to distinguish it from other types of non-tubal ectopic pregnancies with the aim to preserve fertility following the most correct management.