At present the 'jury is out' on vasectomy and cancer of the prostate with some studies showing it to be more common, some less common, and most showing no effects at all.  More large scale studies are needed but the current consensus is to have vasectomy but be a bit more watchful for prostate problems in later life.  

Bruising and Discoloration
Fairly extensive discolouration of the scrotum is common.  A pea sized lump at the operation site in response to suture material is usual for a few weeks.

Infection
With the antibiotics taken before the procedure the infection rate is now under one in two hundred.  If you develop redness and soreness or feel unwell within a few days let us or your doctor know.

Bleeding
By creating small 'raw' areas there is always a chance of internal bleeding - this risk diminishes rapidly each day but warrants complete rest on the first day and a quiet second day.  The chance of troublesome internal bleeding happening is about 1 in 500 - although it's not dangerous the internal blood clot remains a nuisance for several weeks, and is enough to make you wish you'd gone to the pictures instead.

Failure
The chance of immediate failure is about 1 in 1000 short term and is easily detected by the important post-op sperm test.  Long term failure runs at 1 in 10,000 and is considerably less than any other kind of contraception.

Spermatic Granuloma
After several months about 1 in 500 (probably less with current method) will develop an annoying lump on one side that causes pain before ejaculation. If this is bad enough to warrant removal, Dr Calveley also performs this simple operation, usually at no cost. Doing this is like doing one half of the original vasectomy.

Post Vasectomy Soreness
About 1 in 500 return with low grade pain without obvious cause, these people need an ultrasound scan and a urologist's opinion.