SONOGRAPHIC MARKERS PREDICTING OUTCOMES IN PREGNANCY OF UNKNOWN LOCATION

Objective: To evaluate whether initial sonographic markers can predict the ultimate diagnosis in patients with pregnancy of unknown location (PUL). Design: Retrospective cohort study. Materials and Methods: We reviewed 162 patients with PUL at a tertiary care system in 2024. Sonographic variables from initial transvaginal ultrasound included free fluid, endometrial thickness, echotexture, decidual sign, gestational sac, corpus luteum, and adnexal mass. Final outcomes were intrauterine pregnancy (IUP), spontaneous abortion (SAB), ectopic pregnancy (EP), or lost to follow-up (LTFU). ANOVA, Kruskal-Wallis, and chi-square/Fisher’s exact tests were used as appropriate. Binary logistic regression identified independent predictors of EP. Significance set at p<0.05. Results: Of 162 patients, 17.9% had IUP, 46.9% SAB, 8.6% EP, and 26.5% were LTFU. Patients with EP were older than those with IUP or SAB (p=0.04) and more likely to have a history of miscarriage (p<0.001). An adnexal mass was found in 53.9% of EPs but was absent in IUP and present in only 6.8% of SABs (p<0.001). Thin endometrium (<1.0 cm) was more common in EP and SAB (p=0.05), and corpus luteum was more frequently seen in EP (p<0.001). While presence of free fluid alone was not significantly different, fluid volume varied significantly by outcome (p=0.04). Only adnexal mass remained an independent predictor of EP (OR 15.8, 95% CI 1.15–217.37, p=0.04). Conclusions: The presence of an adnexal mass is a strong predictor of ectopic pregnancy in PUL. Other markers such as thin endometrium and corpus luteum may aid in distinguishing ectopic from intrauterine or resolving pregnancies.