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Updated: May 1, 2026
FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
Human chorionic gonadotropin discriminatory zone in ectopic pregnancy: does assay harmonization matter?
Diana Desai1, Jun Lu2, Sara P Wyness2
1Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah.
Objective:
To determine the effect that lack of hCG assay harmonization has on the interpretation of a serum hCG concentration with regards to the hCG discriminatory zone.
Design:
A multisite method comparison study.
Setting:
Clinical laboratories.
Patient(S):
Eighty serum samples containing various concentrations of hCG.
Intervention(S):
None.
Main Outcome Measure(S):
Concentrations of hCG obtained from seven hCG reagent platforms.
Result(S):
The hCG concentrations were significantly different across hCG reagent platforms. Seventy-one percent of assay pairs showed significant differences with samples selected based on hCG concentrations between 1,500 and 3,500 IU/L as determined by a comparative method. Relative to the comparative method, the calculated hCG discriminatory zones for five assays were within 9%, and one assay was within 40% of the target concentrations of 1,500 and 3,500 IU/L.
Conclusion(S):
Despite significant differences in hCG concentrations across hCG immunoassays, an hCG concentration within a discriminatory zone of 1,500-3,500 IU/L can be used for all but one commonly used hCG reagent platform.
