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 β-hCG levels <l,000 mlU/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 3-hCG, and a quantitative β-hCG value <l,000 mlU/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 P-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 ≥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 β-hCG values < 1,000 mlU/mL. Key words: progesterone; ectopic pregnancy; tubal pregnancy; intrauterine pregnancy; ultrasound; diagnosis.