Sperm morphological abnormalities as indicators of dna fragmentation and fertilization in assisted reproduction

Background. To determine the relationship between sperm morphological abnormalities, DNA fragmentation and fertilization rate in IVF and ICSI. Methods. Sperm samples from 10 IVF and 20 ICSI cycles were analyzed. Morphology was assessed according to strict criteria, and DNA fragmentation was measured by terminal deoxynucleotidyl transferase (TdT)-mediated fluorescein-dUTP nick end labelling (TUNEL) using a flow cytometry. Results. There was a significant difference in the amount of morphological abnormalities between sperm samples with low (< 20 %) and high (≥ 20 %) degree of DNA fragmentation. The percentages of amorphous heads (10 vs. 4 %) and overall head abnormalities (42 vs. 30 %) were significantly higher in sperm samples with elevated degree of DNA fragmentation. No correlation was found between sperm DNA fragmentation and fertilization rate after IVF and ICSI. When the predominant morphological abnormality in sperm samples was determined, a negative correlation was found between the percentage of spermatozoa with elongated heads and fertilization rate in ICSI (r = –0.45, P < 0.05). The fertilization rate after IVF was lower in the case of acrosomal abnormalities (35.3 %), compared to the cases of other predominant morphological abnormalities. Conclusions. Head abnormalities, especially amorphous heads, are related to elevated degree of DNA fragmentation. Predominant abnormal form in sperm samples, such as elongated heads and acrosomal abnormalities, may affect fertilization in ART.