Vasectomy has long been touted as a simple and effective contraceptive method that was easily reversible in the event that the man might want to father children in the future. But the medical community's confidence has been shaken by researchers in Thailand who found that men who had undergone vasectomy reversal had high levels of chromosomal abnormalities in their sperm. Professor Nares Sukchareon, of Chulalongkorn University, Bangkok, revealed his findings to attendees at the European Society of Human Reproduction and Embryology conference, warning that doctors needed to be aware of this problem and monitor carefully children born to fathers who had undergone a reversal.
Professor Sukchareon arrived at his conclusions after studying men with obstructive azoospermia, where sperm are created but cannot be mixed with ejaculatory fluid due to a physical obstruction (such as a vasectomy). He found that such men had high rates of chromosomal aneuploidy (an abnormal number of specific chromosomes) and diploidy (two sets of chromosomes rather than one). "The rate of abnormality was about 10 times higher than the aneuploidy and diploidy rate in normal fertile men", explained Sukchareon. "This raised a lot of questions, so we decided to study the rates of these abnormalities in ejaculated sperm after vasectomy reversal. If these sperm continued to have a high rate of aneuploidy and diploidy, we would know that obstruction by vasectomy must affect spermatogenesis in the longer term."
Sukchareon did find a significant correlation between the duration of the obstruction in post vasectomy-reversal men and the number of abnormal sperm, and also between the length of time after vasectomy reversal and the total sex chromosome aneuploidy rate - i.e. the longer ago the reversal, the better the chances of producing normal sperm. "This study raises a lot of questions", said Sukcharoen. "Is the abnormal spermatogenesis reversible, and if so, how long will it take before things get back to normal? Perhaps more importantly, will babies born after vasectomy reversal have problems themselves?"
To answer these questions, Sukcharoen and his team are beginning a new line of investigation. "We are collecting sperm during vasectomy reversal operations and will compare the aneuploidy rate of these and of the sperm we will collect each month in the future from the same men. This will help us understand what the dangers are. But in the meantime, I think that doctors need to be very aware of the possibility that babies born after vasectomy reversal may have problems."
Sukcharoen believes the risks may be greatest when babies are conceived using assisted reproductive techniques like IVF. "[The] findings may not affect babies conceived naturally after such a procedure, since the female genital tract may select the best sperm for fertilization. But this is still uncertain, and until we know more it would probably be safer to freeze ejaculated sperm before vasectomy," he noted.
Based on material from the European Society for Human Reproduction and Embryology