OBJECTIVE: To assess whether the use of a laboratory test specific for intact human chorionic gonadotropin (hCG) would reduce the number of false-positive pregnancy test results. METHODS: From October 21, 2014, to January 20, 2015, and April 1, 2015, to June 2, 2015, all serum samples sent for pregnancy screening at a large cancer center with a value of 5 milli-international units/mL or greater total β-hCG were frozen and stored and then retested using intact hCG reagent. We compared the accuracy of total β-hCG and intact hCG results for the diagnosis of clinically confirmed pregnancy. A negative test was defined as 14 milli-international units/mL or less, our current institutional cutoff. We also assessed a cutoff of less than 5 milli-international units/mL, a historical cutoff to rule out pregnancy. RESULTS: We performed intact hCG testing on 64 patient samples, of which 34 had originally resulted positive when tested for total β-hCG. These included 21 cases of clinically confirmed pregnancy and 13 false-positive cases. No women were pregnant when their intact hCG concentration was 14 milli-international units/mL or less, and all pregnancies were detected at and above this concentration. Intact hCG reduced the number of false-positive pregnancy test results from 13 to 1, a 92% reduction (95% CI 64-99%), corresponding to a reduction in the false-positive rate from 38% (95% CI 22-56%) to 3% (95% CI 1-15%). CONCLUSION: The use of intact hCG reagent in patients with cancer reduces the rate of false-positive pregnancy test results without increasing the rate of false-negative test results.
OBJECTIVE: To assess whether the use of a laboratory test specific for intact humanchorionic gonadotropin (hCG) would reduce the number of false-positive pregnancy test results. METHODS: From October 21, 2014, to January 20, 2015, and April 1, 2015, to June 2, 2015, all serum samples sent for pregnancy screening at a large cancer center with a value of 5 milli-international units/mL or greater total β-hCG were frozen and stored and then retested using intact hCG reagent. We compared the accuracy of total β-hCG and intact hCG results for the diagnosis of clinically confirmed pregnancy. A negative test was defined as 14 milli-international units/mL or less, our current institutional cutoff. We also assessed a cutoff of less than 5 milli-international units/mL, a historical cutoff to rule out pregnancy. RESULTS: We performed intact hCG testing on 64 patient samples, of which 34 had originally resulted positive when tested for total β-hCG. These included 21 cases of clinically confirmed pregnancy and 13 false-positive cases. No women were pregnant when their intact hCG concentration was 14 milli-international units/mL or less, and all pregnancies were detected at and above this concentration. Intact hCG reduced the number of false-positive pregnancy test results from 13 to 1, a 92% reduction (95% CI 64-99%), corresponding to a reduction in the false-positive rate from 38% (95% CI 22-56%) to 3% (95% CI 1-15%). CONCLUSION: The use of intact hCG reagent in patients with cancer reduces the rate of false-positive pregnancy test results without increasing the rate of false-negative test results.
Authors: Laurence A Cole; Sarah A Khanlian; Almareena Giddings; Stephen A Butler; Carolyn Y Muller; Charles Hammond; Ernest Kohorn Journal: Gynecol Oncol Date: 2006-05-02 Impact factor: 5.482
Authors: Ann M Gronowski; Corinne R Fantz; Curtis A Parvin; Lori J Sokoll; Carmen L Wiley; Mark H Wener; David G Grenache Journal: Clin Chem Date: 2008-02-07 Impact factor: 8.327