The ability of a single serum progesterone value to identify abnormal pregnancies in patients with beta-human chorionic gonadotropin values less than 1,000 mIU/mL.

OBJECTIVE

To determine the test performance of a single serum progesterone value <5.0 ng/mL for detecting ectopic pregnancy or other abnormal pregnancies in symptomatic ED patients with beta-hCG levels <1,000 mIU/mL.

METHODS

A prospective study of progesterone levels was performed in consecutive ED patients presenting to an urban teaching hospital from December 1995 to March 1997 with abdominal pain and/or vaginal bleeding, a positive qualitative beta-hCG, and a quantitative beta-hCG value <1,000 mIU/mL. Patients were excluded if they were status-post a dilatation and evacuation procedure, had insufficient serum to run the progesterone assays, or were lost to follow-up. Progesterone values were measured from the original beta-hCG sample. Final patient diagnosis was abstracted from hospital records.

RESULTS

127 patients met eligibility criteria. 39 patients were excluded, leaving a total of 88 enrolled patients. 76 patients with abnormal pregnancies were identified [9 ectopic pregnancies, 62 abnormal intrauterine pregnancies (IUPs), 5 abnormal IUPs vs ectopic pregnancies], 71 of whom had progesterone values <5.0 ng/mL [sensitivity 71/76 (94%), 95% CI 86-98%]. 12 patients with normal pregnancies were identified, all of whom had progesterone values > or =5.0 ng/mL [specificity 12/12 (100%), 95% CI 78-100%].

CONCLUSION

A single progesterone value <5.0 ng/mL has high sensitivity and specificity in detecting abnormal pregnancy in symptomatic ED patients with beta-hCG values <1,000 mIU/mL.