Effect of abnormal hypo-osmotic swelling test on fertilization rate and pregnancy outcome in in vitro fertilization cycles

Objective: To assess the value of the hypo-osmotic swelling test in predicting fertilization, pregnancy, implantation, miscarriage, and live birth rates in IVF-ET cycles. Design: Prospective study. Setting: Academic tertiary referral center for fertility treatment. Patients: Three hundred twenty-six couples having IVF-ET for tubal damage or male factor infertility with the female partner <38 years of age. Interventions: Each male had a hypo-osmotic smelling test performed between 4 and 8 weeks before IVF-ET. Main Outcome Measures: Fertilization, implantation, miscarriage, and live birth rates. Results: Eighty of 326 men had abnormal hypo-osmotic swelling tests. An abnormal test was not associated with lower fertilization rates (odds ratio [OR] = 1.14; 95% confidence interval [CI] = 0.97 to 1.14) or pregnancy rate (OR = 0.98; CI = 0.50 to 1.96). However, although couples with a normal test had a miscarriage rate of 26.9% (14/52), in the group with an abnormal test the miscarriage rate was 50.0% (7/14) (OR = 0.37; CI = 0.09 to 1.49). This resulted in a reduction in the live birth rate from 14.1% in the group with a normal test to 11.8% in patients with an abnormal test (OR = 1.23; CI = 0.45 to 3.87). Conclusions: The hypo-osmotic swelling test has little value in predicting fertilization in IVF-ET procedures. However, an abnormal test may help predict adverse outcome if pregnancy is achieved.