Importance: The value of morphology as a sperm parameter remains uncertain. Many studies have addressed the importance of morphology to predict the success of intrauterine insemination (IUI), but with conflicting results.
Objective: The aims of this study were to review the current literature, to query our own clinical experience via a retrospective, descriptive study, and to determine whether the diagnosis of isolated teratozoospermia influences pregnancy rate after IUI.
Results: We identified a large number of studies addressing this question. All were retrospective and most used different criteria to assess sperm morphology. Further complicating matters, the cutoff for normal morphology decreased from 15% to 4%. In our patient population, we found 12 cases of isolated teratozoospermia (10.43%). Only one of these produced an ongoing pregnancy and live birth. In all other cases, alteration of other sperm parameters coexisted (89.57%). These cycles produced a pregnancy rate of 13%, a nonsignficant difference. Pregnancy rates also were analyzed according to the percentage of normal morphology: 35.71% for less than 4%, 50% for 5% to 9%, and 14.29% for 10% to 14%. These rates did not differ significantly.
Conclusions and relevance: No consistent effect of sperm morphology on pregnancy rate was found in either the published literature or our own clinical experience. Larger and prospective studies are needed to identify any subtle effects of morphology on IUI outcomes that might exist.