I stumbled across this on BUPA's website and thought it may go part way to explaining why some CRS's are reluctant to give LIS to females.
Is there any reason why anal sphincterotomy shouldn't be performed in women?
Answer
Anal sphincterotomy isn’t recommended as the treatment of choice for women of childbearing age because it may increase their risk of being unable to control their bowel movements.
Explanation
Women who suffer trauma during childbirth are particularly at risk of developing problems with bowel control. A potential complication of anal sphincterotomy includes damage to the anal sphincter muscle, which can lead to problems with bowel control. For this reason, anal sphincterotomy isn’t recommended as the treatment of choice for women of childbearing age.
The advancement flap technique is a better option and offers considerable advantages for women of childbearing age. This procedure involves replacing the broken tissue in the fissure with healthy tissue. The operation may involve using a tissue graft taken from another part of your body or local skin or tissue flaps.