John F. O’Connor

Prospective assessment of early fetal loss using an immunoenzymometric screening assay for detection of urinary human chorionic gonadotropin.

Objective To develop an economical, nonradiometric immunoenzymometric assay (IEMA) for the detection of urinary human chorionic gonadotropin (hCG) in studies of early fetal loss. To be effective, the IEMA must have a sensitivity equal to the standard immunoradiometric assay (IRMA) and sufficient specificity to eliminate the need for screening most nonconceptive cycles with the expensive and labor-intensive IRMA. Design Two different assays were used to measure hCG in daily early morning urine samples from potential conceptive cycles. Setting Women undergoing donor artificial insemination (AI) were evaluated in a prospective study. Patients, Participants Ninety-two women volunteers were selected on the basis of apparent normal reproductive health. Interventions Artificial insemination with nonfrozen donor semen was performed by cervical cup twice each menstrual cycle at 48-hour intervals, and daily urine samples were self-collected throughout the menstrual cycle. Main Outcome Measures An IEMA was developed to detect urinary hCG using the same antibodies as in the standard IRMA; a study was designed to determine whether this nonradiometric assay could successfully detect the early fetal loss that was detected by the IRMA. Results Of 224 menstrual cycles analyzed by both assays, a total of six early fetal losses were detected by the IRMA. When the tentative screening rule was set to allow all six of these losses and 95% of future losses to be detected by the IEMA, an additional 34 false-positive results were detected by the IEMA. The specificity of the IEMA with this rule was calculated to be 84%. Conclusion An IEMA based on the same antibodies used for the standard IRMA can serve as an efficient screening assay for the detection of early fetal loss. When the IEMA is used in this manner, nearly 80% of screened menstrual cycles can be eliminated without further testing by the IRMA.

Measuring Human Chorionic Gonadotropin in the Absence of Implantation with use of Highly Sensitive Urinary Assays for Intact β-Core and Free β Epitopes

Abstract Objective: To determine if human chorionic gonadotropin (hCG) can be absorbed from the uterine cavity in the absence of an embryo. Design: Prospective study. Setting: University-based assisted reproduction program. Patient(s): Eight functionally agonadal patients (age range, 33–46 years) who were taking hormone replacement therapy so that they could receive donated oocytes. Intervention(s): Intrauterine instillation of 50 μL of hCG (10,000 IU) during a mock cycle before an attempt at oocyte donation. Main Outcome Measure(s): Spot urine measurements of different hCG epitopes (intact β, β-core, and free β) at timed intervals (12, 20, 44, and 68 hours after instillation). Result(s): All hCG epitopes were detected in the urine at the first sampling interval, and levels decreased in subsequent sampling intervals. Measurement of the serum hCG level confirmed that systemic absorption had occurred and that the urine measurements were not a result of specimen contamination through the cervix. Conclusion(s): hCG may be systemically absorbed into the blood through the uterine cavity, even in the absence of implantation, and its metabolites may be measured with use of highly sensitive urinary assays.