OBJECTIVE: To determine the influence of the concentration of oval spermatozoa according to the strict morphology criterion in men with normal sperm concentration following the World Health Organization criteria on the results of classic IVF. MATERIALS AND METHODS: Based on review of patient charts, this study included infertile couples presenting with female causes for infertility or unexplained infertility, in whom men presented with normal spermogram values for sperm concentration, sperm motility, volume of ejaculate and total sperm count after semen processing greater than 20 million. Based on the value obtained in strict sperm morphology, patients were divided into three groups: in Group A, patients with values between 0% and 4%; in group B, between 5% and 14%, and in group C, patients with sperm morphology greater than 14%. The outcomes analyzed were oocyte fertilization rate, biochemical pregnancy rate, clinical pregnancy rate and rate of liveborns. RESULTS: A total of 244 cases met the inclusion criteria, 27 of them in group A, 165 in group B, and 52 in group C. The mean fertilization rate and the rate of liveborns were, respectively: 71.9% and 33.3% in group A; 80.9% and 24.2% in group B, and 78.8% and 28.8% in group C. There was no statistical difference among the groups in any of the outcomes analyzed. CONCLUSION: The values of strict sperm morphology, as proposed by Kruger and adopted by the World Health Organization, had no influence on the results of classic in vitro fertilization in the studied sample.

OBJETIVO: Descrever os resultados da injeção de espermatozóides imóveis com cauda flexível quando somente estavam presentes nas amostras espermatozóides imóveis. MÉTODOS: Estudo retrospectivo analisando os resultados dos procedimentos de injeção intracitoplasmática de espermatozóide, de 10 casais, realizados no nosso centro. A cauda do espermatozóide era considerada flexível quando esta se movia para cima e para baixo independente do movimento da sua cabeça, e era considerada rígida quando o movimento acontecia em bloco (cabeça e cauda). Os parâmetros de avaliação foram taxas de fertilização e gestação. RESULTADOS: A taxa normal de fertilização (presença de 2 pró-núcleos) encontrada foi 30,3% (40/132) e a taxa de fertilização anormal (presença de menos ou mais de 2 pró-núcleos) foi 6,81% (9/132). No total foram obtidos 52 embriões e foram realizados 9 procedimentos de transferência, a taxa de gestação encontrada foi de 11,12%. CONCLUSÕES: O teste de flexibilidade da cauda do espermatozóide é um método fácil e de baixo custo para avaliação da viabilidade de espermatozóides imóveis e pode ser usado como um método alternativo de determinação da viabilidade de espermatozóides. Esse teste nos parece ser mais simples e com menor risco quando comparado ao Swelling Test.

PURPOSE: The objective was to describe the results of the injection of immotile spermatozoa with flexible tails when only immotile spermatozoa are present in the semen sample. METHODS: A retrospective study was conducted to analyze the procedure results for 10 couples who participated in our intracytoplasmic sperm injection program. The sperm tail was considered flexible when it moved up and down independently of the head movement, and it was considered inflexible when the movement occurred together (tail plus head). The fertilization and pregnancy rate were analyzed. RESULTS: The normal fertilization rate (presence of 2 pronuclei) was 30.3% (40/132), and the abnormal fertilization rate (presence of less than or more than 2 pronuclei) was 6.81% (9/132). A total of 52 embryos were obtained with 9 transfer procedures performed (pregnancy rate: 11.12%). CONCLUSIONS: The sperm tail flexibility test (STFT) is an easy and cost-effective way for selecting viable immotile spermatozoa and can be used as an alternative method for determining the viability of spermatozoa. This test seems to be a simple and risk-free method when compared to the swelling test.