Ectopic pregnancies (EP) represent 2 % of pregnancies. Delayed diagnosis due to inadequate initial management of pregnancies of unknown location (PUL) is common. This study aimed to identify predictive factors for EP during the initial management of PULs, focusing on endometrial thickness (ET).

A retrospective study (January 2020-March 2022) analyzed PUL patients at CHIPS Hospital. Clinical, biochemical, and ultrasound data, including ET and hCG ratio were analyzed. The hCG ratio was defined as the serum β-hCG level at 48 h divided by the baseline level. Logistic regression identified predictors of EP, and the diagnostic performance was evaluated using the area under the receiver operating characteristic curve (AUC).

Among 208 patients, 67 (32.2 %) were diagnosed with EP. ET was significantly thinner in the EP group compared to non-EPs (8.6 mm vs. 13.6 mm, p < 0.01). The hCG ratio differed between groups, with EPs showing a mean ratio of 1.28 compared to declining ratios in miscarriages (0.52) and increasing ratios in intrauterine pregnancies (2.19, p < 0.01). An ET threshold of <10 mm maximized diagnostic accuracy, yielding a sensitivity of 79 %, specificity of 70 %, and AUC of 0.80. Multivariate analysis identified ET <10 mm (OR = 13.17, 95 % CI: 5.59–31, p < 0.001) and hCG ratio (1–2) (OR = 35.37, 95 % CI: 7.12–175, p < 0.001) as independent predictors of EP. The final model achieved an AUC of 0.85.

Endometrial thickness < 10 mm and an HCG ratio between 1 and 2 appear associated with EP in PUL patients. Integrating ET into diagnostic protocols could improve early detection and management, particularly in resource-limited settings. Prospective studies are needed to validate these findings and refine diagnostic algorithms.

Endometrial thickness

Ectopic pregnancy

Pregnancy of unknown location

Pelvic ultrasound

Pregnancy emergency

© 2025 The Authors. Published by Elsevier Masson SAS.