Sperm size in patients with inflammatory bowel disease on sulfasalazine therapy.

The size of the heads of spermatozoa from eight men with chronic inflammatory bowel disease (IBD) treated with sulfasalazine (SS) were measured by image analysis. These were compared with the size of sperm heads from noncolitic men with normal semen indices and with the sperm head size of noncolitic oligospermic men. The patients on SS therapy had a significantly larger sperm head size for the 99th percentile than the noncolitic oligospermic men. After withdrawal of the drug, sperm head size increased further before becoming smaller. The size did not return to that of the sperm of men with normal semen indices during the period studied. Possible mechanisms for the increase in sperm size are discussed and its association with the reversible infertility caused by SS medication.