Sperm recovery and survival: Two tests that predict in vitro fertilization outcome

Objectives: To determine if human sperm recovery during swim-up and sperm survival after 24 hours, as obtained from a screening semen specimen, are predictive of subsequent IVF and clinical pregnancy rates (PRs) and to determine if these techniques can identify men with normal semen analysis parameters and poor IVF success. Design: Historical prospective study. Setting: All semen evaluations and IVF cycles were performed at the University of Pittsburgh, Magee-Womens Hospital, Pittsburgh, Pennsylvania. Patients, Participants: Couples undergoing IVF at Magee-Womens Hospital from August 1988 through June 1993. Interventions: A screening semen analysis and swim-up procedure were performed on all couples undergoing IVF. The number of spermatozoa recovered after swim-up and the percentage of motile spermatozoa present after a 24-hour incubation were recorded. Main Outcome Measures: Fertilization and PRs were compared according to the parameters obtained from routine semen analysis, the number of spermatozoa obtained with swim-up, and the percentage of motile spermatozoa at 24 hours. Results: Using χ² or Fisher's exact test, fertilization rates were significantly different according to the number of spermatozoa recovered after swim-up (≤2.0 and >2.0 x 10⁶ spermatozoa recovered, 48.3% versus 71.4%) as were PRs (16.9% versus 29.8%). Similarly, the percentage of motile spermatozoa present at 24 hours (≤20% and >20%) discriminated between fertilization rates (45.9% versus 65.8%) and PRs (16.4% versus 36.5%). Among a subset of men with normal semen analyses and total motile sperm counts ≥ 40 x 10⁶, the results from swim-up and survival discriminated between men with high and low fertilization and PRs. Receiver operating characteristic analysis revealed that swim-up results better discriminated between pregnant and nonpregnant IVF patients than sperm motility, but that the percentage of motile spermatozoa present at 24 hours was no better in this regard than sperm motility. Conclusions: The number of spermatozoa recovered after swim-up and the percentage of spermatozoa that maintain their motility after 24 hours were both helpful in assessing IVF and PRs and may be helpful in altering physicians to a subset of men having normal semen analysis parameters yet poor IVF success.