A 26-year-old patient has had three consecutive spontaneous abortions early in the second trimester. As part of an evaluation for this problem, the least useful test would be

A major cause of spontaneous abortions in the first trimester is chromosomal abnormalities; however, the causes of losses in the second trimester are more likely to be uterine or environmental in origin. Patients should be screened for thyroid function, diabetes mellitus, and collagen vascular disorders. There is also a correlation between patients with a positive lupus anticoagulant and recurrent miscarriages. A hysterosalpingogram should be performed to rule out uterine structural abnormalities, such as bicornuate uterus, septate uterus, unicornuate uterus, submucous fibroids, or intrauterine adhesions. Endometrial biopsy is performed to rule out an insufficiency of the luteal phase or evidence of chronic endometritis. If no abnormalities are found, both the husband and wife should be karyotyped to see if a balanced translocation or 45, X mosaicism exists. A postcoital test is useful for couples who cannot conceive but does not address post conception losses.