Comparison of serum progesterone as an indicator of pregnancy nonviability in spontaneously pregnant emergency room and infertility clinic patient populations.

OBJECTIVE: To compare the predictive value of serum progesterone in identifying nonviable pregnancy in symptomatic spontaneously pregnant emergency department patients and asymptomatic patients attending an infertility clinic.
DESIGN: Retrospective study.
SETTING: Tertiary-care academic health center. PATIENT(S): One hundred thirty-seven pregnant patients who presented to the emergency department for whom clinical outcomes were available, and 123 consecutive patients who became pregnant during treatment at the infertility clinic. INTERVENTION(S): Serum progesterone measurement. MAIN OUTCOME MEASURE(S): The sensitivity, specificity, and predictive value of serum progesterone <45 nmol/L in identifying nonviable pregnancies were determined for each of the groups. RESULT(S): Sensitivity and specificity of serum progesterone <45 nmol/L in predicting nonviable pregnancies were 88.6% and 87.5%, respectively, in spontaneously pregnant patients who presented to the emergency department with pain or bleeding and 58.8% and 100% in infertility patients who had undergone controlled ovarian hyperstimulation for in vitro fertilization or intrauterine insemination. Sensitivity and specificity for all other infertility clinic patients were variable. CONCLUSION(S): The predictive value of low serum progesterone in identifying nonviable pregnancies varies with patient populations.