Affiliation: Faculty of Medicine, Al Azhar University, Cairo, Egypt.
Urinary continence depends on, an intact internal urethral sphincter (IUS) with a high alpha-sympathetic tone gained by learning in childhood both create high urethral pressure. The IUS is a collagen-muscle tissue cylinder that extends from the bladder neck to the perineal membrane in both sexes. Childbirth trauma causes injury to the vagina and the intimately lying IUS. It lacerates the collagen frame of the IUS. A weak torn IUS will not stand sudden rise of abdominal pressure and urine leaks, stress urinary incontinence (SUI). Imaging with three-dimension ultrasound (3DUS) and MRI demonstrate the torn IUS and show the site and extent of the injury. Torn upper part of the IUS causes funneling and apparent descent of the bladder neck and leads to overactive bladder. Torn lower part leads to genuine SUI. Injury to the whole length leads to mixed- type of urinary incontinence and apparent shortening of the urethra with collapsed torn walls.
Fecal continence depends on a closed anal canal that depends on the integrity of both anal sphincters, the internal anal sphincter (IAS) and the external anal sphincter (EAS). It also depends on intact reactive nervous system and on an acquired high alpha-sympathetic tone at the IAS gained by training in early childhood. The IAS is a collagen-muscle tissue cylinder that surrounds the anal canal with the EAS surrounds it in its lower part. Torn EAS is obvious, but only imaging with 3DUS and MRI show an open anal canal with torn IAS in cases of fecal incontinence.