Urinary Incontinence (UI) means involuntary escape of urine. There are eleven types of UI:
¨ True Urinary Incontinence - continuous escape of urine, due to genito-urinary fistula
¨ Overflow incontinence - the urinary bladder is maximally full and added urine will escape; seen in neurologically impaired patients
¨ Urge and Urge incontinence - when there is a rapid and strong desire to void. It is mostly due to an organic cause in the lower urinary tract, e.g., infection, stone in the urinary bladder, or a tumor, etc.
¨ Stress UI or SUI - genuine
¨ Detrusor Over activity, (DO) Detrusor Instability, (DI) Urge, Overactive bladder, Irritable bladder - when there is an abrupt and strong desire to void, mostly due to non-organic cause
¨ Mixed UI - is more common than SUI or DO alone
¨ Nocturia - Rising up at night, twice or more times; the patient might not be able to hold up till reaching the toilet, and urine escapes
¨ Nocturnal enuresis - it is a disease of childhood, but it may persist till adulthood
¨ Functional UI - the patient feels the desire to void, but she is unable, or unwilling to reach the toilet to void, e.g., visual and\or physical or psychological impairment
¨ Transient UI - when there is an infection, fever, drugs, (alpha blockers), alcohol, delirium, severe fear, etc
¨ Post voiding dribbling - urethral diverticulum
True urinary incontinence: when there is continuance escape of urine is due to genito-urinary fistula, which is mostly traumatic, the trauma may be:
1. Obstetric trauma: direct obstetric trauma, or indirect obstetric trauma (necrotic fistula).
2. Surgical trauma as might be seen after hysterectomy, radical pelvic surgery or pelvic repair.
3. Radiological trauma
But it can be due to a malignant fistula, e.g., cancer cervix or cancer urinary bladder, rarely cancer vagina. Infection, is seen only in destructive infections as TB of the urinary bladder.
Stress urinary incontinence, SUI, is involuntary escape of urine, through the urethra, on sudden increase of Intra-abdominal, intra-vesical pressure e.g. on coughing, laughing, jumping, sneezing, etc. This name, stress urinary incontinence, SUI, was given by Sir Eardly Holland in 1923. Professor Abdel Fattah Yousef named the condition Sphincter incontinence however the name did not gain popularity because of the lack of evidence that SUI is due to sphincter defect.
Stress urinary incontinence is classified, later, to two types, genuine stress urinary incontinence, and detrusor instability, (DI), detrusor over activity, (DO) However when the 2 conditions overlap it is known as Mixed urinary incontinence. Also surgical correction of genuine SUI corrects DO in almost half the patients.(1, 2 & 15).
Urinary Continence depends on:
1. Equal transmission of pressure. The presence of the bladder neck and upper part of the urethra above the pelvic floor, so that, there is a direct, and equal influence of intra – abdominal pressure on the bladder, bladder neck and the intra – abdominal part of the urethra
2. Mucous membrane seal:
a. Mucous membrane co-aptation.
b. Special vascular cavernous plexus in the lamina propria pushing the mucous membrane to act as a seal.
3. Petros and Ulmsten “Integral” theory of urinary continence - In summary, this theory mention that urinary continence depends on three items:
a. The pubococcygeus muscle lifts the anterior vaginal wall to compress the urethra.
b. The pelvic floor muscles draw the hammock upwards closing the bladder neck.
c. The anterior vaginal wall must be tough, and not lax.
4. The hammock theory: DeLancey’s theory The pelvic floor muscles and fasciae act as a hammock supporting the bladder neck, and the upper part of the urethra. Urethral closing pressure, UCP, depends upon transmission of pressure to the bladder neck and the proximal urethra against the rigid support of the pelvic floor muscles, fasciae and the anterior vaginal wall.
5. The length of the urethra - Stress urinary incontinence is seen with short urethra, so shortening of the urethra may cause stress urinary incontinence.
6. Urethral Sphincters - Some consider the internal urethral sphincter is the one responsible for urinary continence, while others like Professor Gosling consider the external urethral sphincter is the responsible one. Performing urethral pressure profilometry, the highest pressure is in the mid-urethra, so some conclude there is a third mid-urethral physiological sphincter. So which urethral sphincter is responsible for urinary continence?
a. internal urethral sphincter
b. external urethral sphincter
c. 3rd mid-urethral sphincter
Stress urinary incontinence, detrusor over activity and mixed urinary incontinence are attributed to many factors e.g.
1. Descent of the bladder neck and upper part of the urethra below the pelvic floor. But, SUI can be present in absence of genital descent. There may be Genital descent with no SUI.
2. Loss of urethro-vesical angle. But, SUI is absent in spite of the absence of the urethra-vaginal angle. SUI is present in spite of good UV angle.
3. Funneling of the bladder neck. SUI is present in spite of absence of funneling. No SUI is detected with funneling of the bladder neck.
4. Axial rotation of the urethral, urethral hyper mobility.
5. Shortness of the urethra. But, amputation of distal half of the urethra e.g. radical vulvectomy for cancer vulva does not lead to SUI.
6. Intrinsic sphincter defect (ISD)
Surgical correction of SUI - the surgical correction of SUI aims at:
1. Elevation of the upper part of the urethra above the pelvic floor.
2. Elongation of the urethra.
3. Angulation of the urethra, and restoring the urethra-vesical angle.
4- Plication of the funnelled bladder neck.
5. Support of the mid-urethra
6. Periurethral injection of different materials
7. Application of an artificial sphincter
At first, all efforts for the surgical treatment were focused on the bladder neck. Several operations were innovated as:
1. Plicatory operations for the funneled bladder neck such as Kelly, Kelly-Kennedy operations.
2. Vesico-urethropexy, as Marshall-Marketti-Krantz operation, MMK operation.
3. Burch, brilliantly, makes use of the upper part of the vagina with its intimate relation with the urethra to make bi-lateral urethro-vaginal fixation to Cooper’s ligaments, on both sides, instead of to the symphysis pubis.
4. Sling operations are innovated as Aldridge operation, Bologna operation, with recent several ingenious bladder-neck suspension operations, e.g., Long needle bladder-neck suspension with or without cystoscopic guidance as for example, Pereyra, Stamey, and Raz operations.
More attention has been paid, nowadays, to the midurethra in the surgery for incontinence, as for example with excellent operations such as:
¨ TVT, tension free vaginal tape.
¨ Suprapubic arc sling, SPARC.
¨ Intra-vaginal sling, IVS. and
¨ Trans- obturator tape, TOT, and TOT-O(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 & 13)
Recently we put forward a new concept describing the mechanism of micturition and the factors controlling urinary continence(14, 15, 16, 17, 18, 19, 20, 21 & 22). Urinary continence depends on two main factors, one inherent and one acquired:
I. The acquired factor (Second stage of micturition): Is an acquired behavior gained by learning and training in early childhood how to maintain a high alpha sympathetic tone at the internal urethral sphincter keeping it closed all the time until voiding is needed or desired(14).
II. The inherent factor: Is the presence of an intact and strong internal urethral sphincter. The internal sphincter is a collageno-muscular tissue cylinder that extends from the bladder neck down to the perineal membrane. The structure of the internal urethral sphincter, it is mainly a cylinder composed of compact collageno-muscular tissue. It extends from the bladder neck down to the perineal membrane. It is lined by urothelium. The muscle fibers intermingle with the collagen fibers in the mid-thickness; the muscle layer is controlled by alpha-sympathetic nerves T10-L2. Collagen is the most abundant protein in humans. Collagen accounts for one third of human protein by mass. Collagen fibers are usually found in bundles of fibers and provide strength to the tissues. Each fiber is made up of fibrils, chemically it has a high content of hydroxy-proline and hydroxy-lysine. Many different types of collagen are identified on the basis of their molecular structure.Type I is the most abundant being found in the dermis, bone, dentin, tendons, fascia, sclera, and organ capsules.
Understanding the mechanism of micturition and the factors controlling urinary continence, voiding troubles can be better explained and managed. Functional disturbance, and/or structural damage of the internal urethral sphincter will lead to Urinary incontinence.
A. Functional disturbance:(3)
1. Failure to gain the acquired behavior of having high alpha sympathetic tone, completely, or partially, will lead to Nocturnal Enuresis.
2. Sympathetic over activity, e.g., pain, spinal cord lesion will lead to retention of urine, overflow incontinence.
3. Sympathetic failure e.g., severe fear, deep anesthesia will lead to transient urinary incontinence.
B. Structural damage of the internal urethral sphincter(3)
1. Whole thickness damage, this leads Genito-urinary fistula and subsequently to True urinary incontinence.
2. Partial thickness damage(2)
a. damage from outside, more common; is mostly caused by child birth trauma, this will cause weakness of the internal urethral sphincter with subsequent SUI, DO, and/or Mixed urinary incontinence.
b. damage from inside, less common; this will lead to urethral diverticulum, and subsequently will lead to post-voiding dribbling.
SUI, DO, DI and Mixed-type of urinary Incontinence are caused by weakness of the internal urethral sphincter. The weakness is mostly due to traumatic injury of the internal urethral sphincter causing a rupture, and/or split of the collagenous tissue cylinder, the essential constituent of the internal urethral sphincter. The torn weak internal urethral sphincter with a lower urethral closing pressure will, on sudden increases of intra-abdominal pressure, intra-vesical pressure, give way, with resultant leakage of urine. Leakage of urine will induce a rapid reactive sympathetic activity that will increase the sympathetic tone at the internal urethral sphincter preventing further loss of urine(15). The extent and the site (the level) of the damage in the internal sphincter will determine the type and the degree of the urinary incontinence, and the morphological changes seen on imaging the urethra.
Rupture in the Internal Urethral Sphincter
1. If it affects the whole length it will lead to apparent shortening of the functional urethral length and irregularity in shape on imaging.
2. If it affects the upper part only this will lead to loss of urethro-vesical angle, funneling of the bladder neck, urethral hyper mobility, and will lead to DO
3. If it affects the lower part only; this will appear on imaging as Flask-shape on three dimension-ultrasound, and will lead to genuine stress urinary incontinence.
A new operation is innovated to treat SUI, DO and mixed-type of urinary incontinence. It is a simple vaginal operation, which depends on identifying the rupture in the wall of the internal urethral sphincter and mending the torn wall with simple interrupted sutures, Urethro-raphy(17&18).
Furthermore another new operation “urethro-plasty”(22) is innovated to treat SUI, DO, DI and mixed types of urinary incontinence. It is a vaginal operation, which depends on identifying the rupture in the wall of the internal urethral sphincter and mending the torn wall with simple interrupted sutures, Urethro-raphy(17&18). In order to fortify the internal urethral sphincter, a rectangular piece of the anterior wall of the vagina about 2x5 cm. is cut and put on the repaired wall, and fixed longitudinally, to cover the finely mended sphincter wall. In addition, to the mechanical role it plays, it acts as an autologus source of collagen for the torn internal urethral sphincter. It, also, separates it from the overlying repaired anterior vaginal wall. It is fixed in place with three or more stitches. The anterior vaginal wall is then closed over the mended, fortified internal urethral sphincter.
The objectives of urethro-plasty are to reconstruct a strong internal urethral sphincter by finely mending the rupture, Urethro-raphy; and to re-enforce the wall; and to provide an autolgus source of collagen over the torn weak part, by putting and fixing longitudinally a rectangular piece of the vagina over the rupture. It also, separates the mended, fortified sphincter wall from the overlying anterior vaginal wall. We aim by such procedure, to restore a strong intact internal urethral sphincter, which can resist sudden increases of intravesical pressure. There is no risk of inducing an implantation dermoid cyst because of the absence of glands in the vaginal skin. The false impression of urethral hyper mobility and funneling of the bladder neck is caused by the damaged torn weak wall of the upper part of the internal urethral sphincter. Reconstruction and repair of the torn wall will restore the normal shape and station of the bladder neck and urethra. Also, it might be worth trying to put longitudinally a tape of synthetic material, e.g. Dacron, Teflon or Proline, instead of the vaginal graft, especially in cases of atrophic vaginal wall.
Legend of figures: (click thumbnails for a larger view to open in a new window)
|Figure 1: 3DUS picture showing a normal internal urethral sphincter. The internal sphincter has a thick wall with 3 sono ecchogenic characters. It extends from the bladder neck down to the perineal membrane.|
|Figure 3: MRI picture, Coronal section, of a normal continent woman, showing a normal internal urethral sphincter with compact thick wall extending from the bladder neck to the perineal membrane with closed lumen.|
|Figure 4: MRI picture, sagittal section, of a normal continent woman, showing a normal internal urethral sphincter with compact thick wall extending from the bladder neck to the perineal membrane with closed lumen.|
|Figure 5: MRI picture of a normal continent woman, showing a normal internal urethral sphincter with compact thick wall and a closed lumen as seen by cross section.|
|Figure 6: 3D ultrasonic picture in of patient with SUI grade III. The urethra is dilated, and with irregular outline. The sphincter wall is thin and torn.|
|Figure 8: The wall of the internal urethral sphincter, adherent, to the anterior vaginal wall is dissected and separated.|
|Figure 11: A flap from the vagina is put on the mended sphincter longitudinally, and fixed in place by one stitch, two or more stitches to be taken.|