Serum progesterone testing to predict ectopic pregnancy in symptomatic first-trimester patients.
OBJECTIVE
This study was conducted to prospectively measure the accuracy of serum progesterone levels to detect ectopic pregnancy.


METHODS
Seven hundred sixteen symptomatic first-trimester emergency department patients with abdominal pain or vaginal bleeding at a tertiary care military teaching hospital had progesterone levels measured by radioimmunoassay with results unavailable to the treating physician. All patients were monitored until a criterion standard diagnosis of intrauterine pregnancy or ectopic pregnancy was confirmed.


RESULTS
A 14-month derivation phase (n=399) used receiver operating characteristic curve testing to select a cutoff value of progesterone less than 22 ng/mL. A 12-month validation phase (n=317) then retested this cutoff value. Combining both phases, there were 434 (61%) viable intrauterine pregnancies, 229 (32%) nonviable intrauterine pregnancies, and 52 (7. 3%) ectopic pregnancies, of which 17 were ruptured. Sensitivity, specificity, positive predictive values, and negative predictive values (95% confidence intervals) for progesterone levels less than 22 ng/mL to detect ectopic pregnancy were 100% (94% to 100%), 27% (23% to 30%), 10% (7% to 12%), and 100% (98% to 100%), respectively.


CONCLUSIONS
Given similar disease prevalence, roughly one fourth (178/716) of symptomatic patients can be classified as low risk (0%, 95% confidence interval 0 to 2%) for having an ectopic pregnancy using a progesterone cutoff of 22 ng/mL. Whether implementation of rapid progesterone testing can safely expedite care and reduce the need for urgent diagnostic evaluation or admission remains to be determined.
Buckley
Robert G
RG
From the Departments of Emergency Medicine,(*) Clinical Investigations,(‡) Radiology,(§) and Obstetrics and Gynecology,(∥) Naval Medical Center San Diego, San Diego, CA.
King
Kerry J
KJ
From the Departments of Emergency Medicine,(*) Clinical Investigations,(‡) Radiology,(§) and Obstetrics and Gynecology,(∥) Naval Medical Center San Diego, San Diego, CA.
Disney
Jeffrey D
JD
From the Departments of Emergency Medicine,(*) Clinical Investigations,(‡) Radiology,(§) and Obstetrics and Gynecology,(∥) Naval Medical Center San Diego, San Diego, CA.
Riffenburgh
Robert H
RH
From the Departments of Emergency Medicine,(*) Clinical Investigations,(‡) Radiology,(§) and Obstetrics and Gynecology,(∥) Naval Medical Center San Diego, San Diego, CA.
Gorman
John D
JD
From the Departments of Emergency Medicine,(*) Clinical Investigations,(‡) Radiology,(§) and Obstetrics and Gynecology,(∥) Naval Medical Center San Diego, San Diego, CA.
Klausen
Jack H
JH
From the Departments of Emergency Medicine,(*) Clinical Investigations,(‡) Radiology,(§) and Obstetrics and Gynecology,(∥) Naval Medical Center San Diego, San Diego, CA.
D015746:Abdominal Pain / Q000175:diagnosis / Q000209:etiology; D000328:Adult; D015415:Biomarkers / Q000097:blood; D016001:Confidence Intervals; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011271:Pregnancy, Ectopic / Q000097:blood / Q000175:diagnosis*; D011374:Progesterone / Q000097:blood*; D011446:Prospective Studies; D012372:ROC Curve; D011863:Radioimmunoassay; D012042:Registries; D012680:Sensitivity and Specificity; D014592:Uterine Hemorrhage / Q000175:diagnosis / Q000209:etiology
D015415:Biomarkers; D011374:Progesterone