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Interference of exogenous HCG on pregnancy tests
I Noci1, O Saltarelli, E Coccia
1Department of Obstetrics and Gynecology, University of Florence, Italy.
Acta Europaea Fertilitatis
|November 1, 1987
Summary
New sensitive pregnancy tests may show false positives when exogenous human chorionic gonadotropin (HCG) is administered for ovulation induction. This study confirms low-threshold tests can be positive after HCG treatment.
Area of Science:
- Reproductive Endocrinology
- Clinical Chemistry
- Diagnostic Testing
Background:
- Recent advancements have introduced highly sensitive urinary pregnancy tests capable of detecting low levels of human chorionic gonadotropin (HCG).
- The administration of exogenous HCG is a common practice in assisted reproductive technologies to induce ovulation.
- Potential interference of exogenous HCG with sensitive pregnancy detection assays has not been fully elucidated.
Purpose of the Study:
- To investigate whether exogenous HCG administered for ovulation induction can interfere with sensitive low-threshold urinary pregnancy tests.
- To compare the performance of low-threshold and traditional high-threshold pregnancy tests in the presence of exogenous HCG.
Main Methods:
- Six healthy female volunteers received three sequential intramuscular doses of 5,000 U of HCG.
- Daily blood and urine samples were collected for HCG assay via ELISA.
- Urine specimens were tested using both a traditional high-threshold (2000 U/L) and a low-threshold (50 U/L) pregnancy test.
Main Results:
- Plasma HCG levels peaked on day 8 post-ovulation (average 73.7 U/L), with individual levels ranging from 24-124 U/L.
- Urinary HCG levels exceeded the 50 U/L detection limit of the low-threshold test on days 8-10 in most subjects, and on days 11-12 in a proportion of subjects.
- The low-threshold pregnancy test yielded positive results in the majority of subjects during days 8-10 and in some subjects up to day 12, while the high-threshold test remained negative throughout.
Conclusions:
- Exogenous HCG administered during the luteal phase can lead to false positive results with highly sensitive low-threshold urinary pregnancy tests.
- The increased sensitivity of modern pregnancy tests necessitates careful interpretation in patients who have received HCG therapy.
- Clinicians should be aware of this potential interference when assessing pregnancy status after ovulation induction with HCG.
Keywords:
BiologyClinical ResearchComparative StudiesEndocrine SystemEvaluationExaminations And DiagnosesGonadotropinsGonadotropins, Chorionic--analysisHormonesHuman VolunteersLaboratory Examinations And Diagnoses--complicationsLaboratory ProceduresOvulationPhysiologyPregnancy TestsReproductionResearch MethodologyStudies