Laboratory and clinical comparison of a rapid versus a classic progesterone radioimmunoassay for use in determining abnormal and ectopic pregnancies.
A rapid, solid-phase, nonextraction progesterone kit (n = 36) was compared with an established extraction method, liquid phase tritium radioimmunoassay for progesterone (n = 79). Logistic regression of the rapid method over the extraction method gave a correlation coefficient of r = 0.968. Logistic regression gave a discriminatory zone (abnormal vs normal pregnancy) of 22.58 ng/ml by the rapid method compared with 15 ng/ml for the extraction method (log Y = 0.253 + 0.936 log X). Similar sensitivity (100% and 100%), specificity (63% and 59%), and predictive values of positive and negative tests (positive predictive value = 91% and 75%, negative predictive value = 100% and 100%) were found using a discriminatory level of 15 and 20 ng/ml for the extraction method (n = 79) and rapid method (n = 76), respectively. Clinically, curettage for patients with values less than these discriminatory zones would have given unacceptable rates for termination of a potentially normal pregnancy (38%). Clinical comparison of abnormal (ectopic or abortion) and normal (term pregnancy) outcomes in two populations of women presenting with first-trimester bleeding revealed that progesterone levels would accelerate the workup in only a small percentage (27%, 15 of 56) of patients with ectopic pregnancies. The rate of ruptured ectopic pregnancies in the observed patients was similar (20%, 3 of 15) to studies using progesterone levels prospectively. Therefore in this retrospective analysis progesterone levels would have given no greater benefit than conventional management.
Peterson
C M
CM
Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City.
Kreger
D
D
Delgado
P
P
Hung
T T
TT
D000022:Abortion, Spontaneous / Q000097:blood / Q000175:diagnosis; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000175:diagnosis*; D011271:Pregnancy, Ectopic / Q000097:blood / Q000175:diagnosis*; D011374:Progesterone / Q000097:blood*; D011863:Radioimmunoassay / Q000379:methods; D012044:Regression Analysis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D011374:Progesterone