Sperm morphology and in vitro fertilization outcome: a direct comparison of World Health Organization and strict criteria methodologies.

OBJECTIVE

To perform a direct comparison of two sperm morphology methodologies with regard to IVF outcome.

DESIGN

Blinded comparison of two methods of morphology assessment using the same morphology slides.

PATIENTS

Data were obtained from 132 couples in a consecutive series of patients undergoing IVF.

MAIN OUTCOME MEASURES

Two practical end points were selected for analysis for each couple: the presence of any fertilization and the number of fertilized eggs. Normal traditional morphology was defined as > or = 40% normal forms in a sample and normal strict criteria was defined as > or = 4%.

RESULTS

Traditional morphology demonstrated a higher sensitivity and negative predictive value than strict criteria (87% versus 61%, and 68% versus 36%, respectively). Positive predictive value and specificity were also numerically greater but did not reach statistical significance. Abnormal traditional morphology, but not strict criteria, was associated with reduced fertilization even among samples with normal sperm concentration and motility. Samples with normal morphology were associated with a greater number of fertilized eggs per couple than those with abnormal morphology: this difference was 3.2 fertilized eggs for traditional morphology and 1.6 for strict criteria. Overall, for samples with < 40% by traditional morphology only one case yielded more than two fertilized eggs. In contrast, up to five fertilized eggs were noted for the lowest strict criteria scores.

CONCLUSIONS

Comparison of traditional morphology and strict criteria with regard to IVF outcome favored traditional morphology in several areas. In particular, low scores were more predictive of poor IVF outcome.