The predictive value of endometrial stripe thickness in patients with suspected ectopic pregnancy who have an empty uterus at ultrasonography

Abstract

Prior research suggests that, in patients with empty uteri at ultrasonography, endometrial stripe thickness may be predictive of ectopic pregnancy or the likelihood of obtaining chorionic villi after a dilatation and evacuation procedure (D+E). However, it is unclear whether the predictive value of endometrial stripe thickness is confined to patients with low beta- human chorionic gonadotropin (β-hCG) values. Objective: To determine whether endometrial stripe thickness is predictive of the risk of ectopic pregnancy or the likelihood of obtaining chorionic villi after D+E in patients with β- hCG values >1,000 mIU/mL or ≤1,000 mIU/mL. Methods: In an urban academic ED, the authors conducted a retrospective chart review of consecutive ED patients from August 1991 to August 1997 with abdominal pain or vaginal bleeding, a positive β-hCG value, and an empty uterus by transvaginal ultrasound examination. Patients were divided into four groups - group 1: endometrium thin, β-hCG value ≤1,000 mIU/mL; group 2: endometrium thick, β-hCG value ≤1,000 mIU/mL; group 3: endometrium thin, β-hCG value > 1,000 mIU/mL; and group 4: endometrium thick, β-hCG value >1,000 mIU/mL. The secondary analysis was limited to patients who had a D+E performed within 48 hours of the ED visit. The risks of ectopic pregnancy and the likelihoods of obtaining chorionic villi after D+E were compared using chi-square or Fishers' exact test where appropriate, with a p-value of 0.05 being significant. Results: 224 patients were enrolled in the initial analysis. Intergroup differences in the frequency of ectopic pregnancy were of borderline significance (p = 0.08). However, when the comparison was limited to the groups with β-hCG values ≤1,000 mIU/mL, the predictive value of endometrial stripe thickness reached statistical significance (group 1: 27/99 [27%], group 2: 2/28 [7%], p = 0.05). 79 patients had a D+E performed. Intergroup differences in the rate of obtaining chorionic villi were significant (p = 0.002). Group 1 had the lowest frequency of having chorionic villi identified (4/26 [15%]) and was the only group in which villi were obtained in fewer than 50% of cases. Conclusion: Endometrial stripe thickness may be predictive of the risk of ectopic pregnancy and the likelihood of obtaining chorionic villi at D+E. However, its predictive value appears to be confined to patients with β-hCG values ≤1,000 mIU/mL.