Perineal surgery, called perineoplasty, is a surgery performed on the muscle called the perineum that is inside the woman's vagina. This muscle causes the woman to control the urge to urinate and when she is weakened, this capacity is diminished and the woman may have involuntary urine leakage.
One of the causes of the perineum being weakened is the woman having a normal delivery, in which case the muscle becomes worn out leading to loss of urine. Not all women who go through a normal birth will have their perineum weakened. When labor is done without stress and in a natural way, the muscle will hardly suffer any injury.
When an episiotomy is done, it is exactly the perineum that is cut off, and then the muscle will become more weak for some time postpartum, leading to loss of urine.
In perineoplasty, the muscle is treated to react naturally, controlling the flow of urine. Another way to increase the strength of this muscle is by doing physical therapy, electrostimulation, and Kegel exercises.