Diagnosis of ectopic pregnancy by the rate of increase of choriogonadotropin in serum: diagnostic criteria compared
Emancipator, K.; Bock, J.L.; Burke, M.D.
Clinical Chemistry 36(12): 2097-2101
1990
ISSN/ISBN: 0009-9147 PMID: 2253352 Document Number: 347909
We compare three methods for using the rate of change of human choriogonadotropin (hCG) concentration in serum to diagnose ectopic pregnancy. With Method I, the lower limit for the rate of increase of serum hCG in normal pregnancy is 66% per 48 h. With Method II, a different lower limit of normal is specified for each of four discrete sampling intervals of hCG. With Method III, the lower limit of normal is determined by a continuous discriminant function of the initial hCG concentration. If the initial hCG concentration is less than or equal to 2000 int. units/L (Second International Standard), all three methods have acceptable diagnostic efficiencies, and there are no statistically significant differences among conclusions from the methods. None of the three methods performs satisfactorily if the initial hCG concentration is greater than 2000 int. units/L. We recommend Method I because it is simpler than the other two.