The morphology of extracted testicular sperm correlates with fertilization but not pregnancy rates

Abstract

To investigate sperm morphology on the day of fresh testicular sperm extraction (TESE) with intracytoplasmic sperm injection (ICSI), and its effect on fertilization and pregnancy rates, as TESE in conjunction with ICSI results in high fertilization and pregnancy rates in most patients, but to our knowledge only one small study has assessed the morphology of retrieved sperm and found no correlation with the success of fertilization. In a retrospective database analysis in a large academic centre, 68 men had 75 cycles of TESE combined with ICSI from January 2004 until April 2006. Sperm obtained by TESE was morphologically analysed at high (x 400-600) magnification and used for ICSI on the day of tissue retrieval. Sperm were classified as being either normal, having an amorphous head, having a mid-piece defect or having multiple defects. The calculated percentage of abnormal sperm injected was compared with the normal fertilization rate using Pearson's correlation coefficient, and pregnancy rates between groups were compared using chi-square analysis. Fifteen cycles had all morphologically normal sperm; 21 cycles had 50-99% normal forms and 39 cycles had <50% normal sperm. There was a highly significant correlation between the percentage of normal sperm used for ICSI and fertilization rates (P = 0.007). Overall, 43 clinical pregnancies resulted in this series, i.e. three among the group with all normal sperm injected, 12 in the group with 50-99% normal sperm and 28 in the group with <50% normal forms. There were also 11 pregnancies in cycles that used no normal forms. Pregnancy rates did not differ significantly among the groups (P = 0.08). TESE with ICSI frequently results in successful pregnancy; normal morphology was highly and significantly associated with successful fertilization, but importantly there were still 10 clinical pregnancies in cycles where only abnormal sperm were used. Sperm morphology after TESE should be assessed at the time of the procedure, and whenever possible, morphologically normal sperm chosen for injection. However, it is reassuring that acceptable fertilization and pregnancy rates are still achievable in cases with no morphologically normal sperm available.