Determining the viability of early pregnancies: two case reports

Journal of Family Practice, Oct, 1991 by Pamela M. Davis

The use of both serum [beta]-HCG levels and ultrasonograms helps to eliminate the uncertainty. Between 6 and 9 weeks, the use of [beta]-HCG can be helpful with an inconclusive ultrasonogram and can predict abortion in 95% of cases.[2,3,22] Jouppilla et al[1] reported, however, that the [beta]-HCG level and gestational sac diameter were usually normal between 6 and 9 weeks of gestation, even in pregnancies that later aborted.[1] Nyberg et al[23,24] concluded that when ultrasound findings are uncertain, a disproportionately low [beta]-HCG level is supportive evidence for an abnormal pregnancy, and serial [beta]-HCG levels complement ultrasound predictions.[25,26] These studies point out that normal values do not guarantee future viability, and that abnormal values usually portend a poor outcome, but not with complete certainty.

Widespread recommendations from the family practice and obstetrics literature encourage the use of a simple 48-hour doubling time standard without emphasis on its limitations.[8,13,14] Thus, in case 1, the radiologist's original ultrasonogram interpretation of "most consistent with a blighted ovum," (confirmed 1 week later by a "no change" reading) was "substantiated" by the failure of [beta]-HCG levels to double appropriately. The difficulties encountered in case 2 might have been avoided when the original inconclusive ultrasonogram, again reading possible blighted ovum, was compared with the initial [beta]-HCG level of 120,000 mIU/mL. Instead, the serial imperative was obeyed in search of 48-hour doubling, and a large drop in value (still unexplained) nearly initiated evacuation of the uterus.

Do the current techniques used to establish first trimester viability justify active intervention when fetal demise is suspected? Levels of [beta]-HCG vary widely as previously discussed, and the practitioner cannot forget the human variables intrinsic to a laboratory test: specimen collection, sampling, testing quality, and communicating results. The ultrasonogram's scope and resolution has magnified in the last decade, but is also subject to human skill and experience. The literature and the community experience suggest that the confidence placed in both ultrasonography and serum [beta]-HCG levels may be greater than the accuracy of the test warrants. The physician can be misled in using test results as absolutes without seriously examining their potential fallibility. Both techniques have proved invaluable for managing patients with suspected ectopic pregnancy. This potentially lethal condition makes their margins of error accetable. The potential morbidity of awaiting spontaneous miscarriage of nonviable embryos has not been defined, however, nor can it be measured against the consequences of terminating a viable fetus. The cursory references in the literature to possible complications of a delayed expulsion of a spontaneous abortion (maternal infection, hemorrhage, and anxiety) are not equivalent to the known morbidities of an ectopic pregnancy.[16,27,28]