Caesarean Scar Ectopic Pregnancy in Early Gestation: A Scoping Review of Definitions and Diagnostic Approach

Caesarean scar ectopic pregnancy (CSEP) is defined by the implantation and development of a gestational sac inside a caesarean scar defect, but variations in classification systems and diagnostic criteria exist.

This study aimed to systematically review the different criteria used in the medical literature to diagnose CSEP in the first trimester of pregnancy.

Systematic search of PubMed, MEDLINE and Google Scholar from September 1990 to January 2024.

We included prospective and retrospective observational studies published in English reporting on imaging criteria used to diagnose CSEP.

Two reviewers independently reviewed retrieved articles and performed data extraction using a priori-developed data collection form. Findings were tabulated and synthesised in a narrative format.

A total of 22 studies, involving 1749 CSEP cases, met the inclusion criteria. Diagnostic modalities varied, with eight different classification systems reported across 11 studies, with the remaining 11 studies not specifying a classification system. Histology was used as a reference standard in 59% (13/22), intraoperative features in 18% (4/22) and a combination of both in 23% of studies (5/22). Seventy-two percent of studies (13/18) that used histology as a reference standard did not provide specific histological criteria for diagnosing CSEP.

This review highlights the wide variability in diagnostic approaches, imaging criteria and classification systems used in the first-trimester diagnosis of CSEP. The absence of a universally accepted reference standard for CSEP diagnosis poses a major challenge for prospective studies evaluating diagnostic accuracy.