The evaluation of the sperm migration test as a predictor for success with intrauterine insemination

The objective of this study was to prospectively evaluate the sperm migration test (SMT) as a discriminator in couples undergoing intrauterine insemination (IUI).

261 couples underwent 797 IUI treatment cycles involving gonadotropin stimulation in the three year period. All had a diagnosis of unexplained infertility. All male partners underwent a repeat standard seminal analysis and SMT prior to the female partner undergoing controlled ovarian stimulation.

Despite apparently normal seminal analyses before referral, in 22 samples the sperm concentration, motility or morphology were abnormal (WHO criteria). Of these, 20 couples underwent 109 cycles and achieved 2 pregnancies giving a pregnancy rate of 1.8% per cycle and a cumulative pregnancy rate of 10% per couple. From the remaining couples with normal seminal analyses, 71 had an SMT <5 million/mL and 168 had an SMT >5 million/mL. The suboptimal SMT group underwent 276 cycles (3.89 cycles per couple) and achieved 18 pregnancies giving a pregnancy rate of 6.5% per cycle and a cumulative pregnancy rate of 25.4%. The normal SMT group underwent 412 cycles (2.45 cycles per couple) and achieved 60 pregnancies giving a pregnancy rate of 14.6% per cycle and a cumulative pregnancy rate of 35.7%.

We confirm that abnormal seminal analysis leads to poor pregnancy rates with IUI. However, an SMT <5 million/mL despite normal seminal analysis (WHO criteria) also leads to significantly worse pregnancy rates. We would recommend that prior to IUI, couples are screened using the SMT.