Vasectomies may be less reversible than thought

Men considering having a vasectomy, believing the procedure might later be reversible, may want to think even more carefully about their decision. Research presented today in Cheltenham, UK, at the annual meeting of the British Fertility Society, suggests that even if the surgical effect of a vasectomy can be undone, the longer term effects on sperm production may not be so reversible.

Vasectomies work by deliberately obstructing the tube that carries sperm from the testis, thereby preventing sperm, which continues to be produced, from being ejaculated. Researchers from the School of Medicine, Obstetrics and Gynaecology at Queen's University, Belfast, studied men who had vasectomies as a form of contraception after having children ten years ago. Years after the vasectomy, they found the men had a much lower sperm production rate compared to those (fertile) men who hadn't ever had the operation. In addition, the pregnancy success rate using ICSI (intracytoplasmic sperm injection ) - a modified IVF treatment in which a single sperm is injected into an egg to fertilise it - was more than 50 per cent lower for the vasectomised men, although the researchers said that a larger cohort was needed in future studies in order to prove these results.

The Belfast study focused on 21 men who had vasectomies and 39 non-vasectomised men. Sperm was obtained from each of the men by testicular biopsy. The researchers found that those who had a vasectomy had sperm counts at 3.6 million sperm per gram of tissue, compared to 11.2 million sperm per gram in the other men: almost three times lower. They also found that although the samples of the vasectomised men showed normal level of Sertoli cells (cells that help nourish the sperm during development in the testes), the actual number of developing sperm cells was lower than in the other men.

Dr Carmel McVicar, who presented the work, said the research team did not expect to see 'this reduction in sperm count or pregnancy due to previous vasectomy and ongoing studies are attempting to decipher the reasons for it'. She added: 'Men attend our clinic every week wanting to have a second family with a new partner. Men who are considering vasectomy certainly need to think very carefully about the long-term consequences to their future fertility'.

At the same conference, another Belfast-based research team presented findings which lend further weight to the theory that smoking cannabis can be damaging to a man's fertility. THC (tetrahyrocannabinol) - the active chemical ingredient found in cannabis - was found to impede the motility (movement and drive) of sperm and its ability to break through the outer layer of the egg. Sperm samples treated with THC were found to be up to 45 per cent less likely to move in a forwards direction and nearly 30 per cent of the treated sperm failed to produce the enzymes needed to penetrate an egg.