Vasectomy should not be confused with castration; a vasectomy does not involve removal of the testicles and it affects neither the production of male sex hormones (mainly testosterone) nor their secretion into the bloodstream. Therefore sexual desire (libido) and the ability to have an erection and an orgasm with an ejaculation are not affected. Because sperm itself makes up a very small proportion of ejaculate, vasectomy does not affect the volume, appearance, texture or flavor of ejaculate. Similarly in females, hormone production, libido, and the menstrual cycle are not affected by a tubal ligation.
When a vasectomy is complete, sperm can no longer exit the body through the penis. They are broken down and absorbed by the body. Fluid content is absorbed by membranes in the epididymis, and solid content is broken down by macrophages and re-absorbed via the blood stream. Sperm is matured in the epididymis for about a month once it leaves the testicles, and approximately 50% of the sperm produced never make it to ejaculation in a non-vasectomized man. After vasectomy, the membranes increase in size to absorb more fluid, and more macrophages are recruited to break down and re-absorb the solid content.