What is Fistula
A fistula is an abnormal passage or connection between a hollow body cavity, like the bladder, and the surface of the body. A vesicovaginal fistula is a fistula connecting the bladder with the vagina: a urethro-vaginal fistula connects the urethra to the vagina. Vesico-vaginal and urethro-vaginal fistula result in severe urinary incontinence because there is uncontrollable leakage of urine through the fistula which bypasses the urethra and the sphincter. If the bladder was like a balloon and the knot that keeps the air from leaking out was like the sphincter, a fistula is like a hole in the balloon. These fistulas are almost always the result of complications from pelvic surgery (hysterectomy, prolapse repair and anti-incontinence surgery) or from childbirth injuries. Rarely, they may be caused by pelvic cancer.
In the industrialized countries of the world, obstetric injuries are exceedingly uncommon, but in the third world, particularly in Africa and Asia, childbirth injuries continue to exact a toll of enormous social and medical consequence. In the third world, fistulas are most often the result of prolonged labor, 24 hours or more, particularly when the fetus is very large compared to the size of the mother’s pelvis (maternal‑fetal disproportion). When there is such a disproportion, the head of the baby becomes stuck in the vaginal canal and presses on the bladder and urethra. If this lasts too long a time, the blood vessels in the mother’s vagina are compressed and the tissues cannot get enough oxygen. Without oxygen, the individual cells of the tissues begin to die. This is called ischemic necrosis. Ischemic necrosis destroys the tissue between the bladder and vagina resulting in a vesico-vaginal or urethro-vaginal fistula which cannot heal because of the damaged blood supply.
Surgical treatment of these terrible injuries has become a special interest of the Urocenter. We learned that by repairing the incontinence at the same time that the fistula is surgically repaired, it was possible to cure both the fistula and the incontinence in over 90 % of women, provided that a tissue graft bringing in a new blood supply (a Martius graft) was done in conjunction with a pubovaginal sling.
What Causes a Fistula?
In the industrialized countries of the world, like the USA, Canada and Western Europe, fistulas usually are the result of surgical complications from relatively simple operations such as anti-incontinence procedures, hysterectomy, prolapse surgery or urethral diverticulectomy. In addition, if not properly cared for, the injudicious use of indwelling urethral catheters may result in pressure necrosis, in other words tissue death, of the urethra. This is most commonly seen in quadriplegic or paraplegic women, but is occasionally encountered in otherwise normal women who have had a prolonged recovery after a devastating illness or injury. This form of injury is particularly disconcerting since it is entirely preventable by routine hygiene and observation. Rarely, urethro-vaginal or vesico-vaginal fistula may result from a laceration of the urethra and/or vesical neck sustained after trauma to the pelvis, particularly when there has been a fracture of the pubic bone. Rarely there may be local invasion of these tissues from cancer of the pelvis or damage from radiation treatment which results in a fistula.
How do You Diagnose a Fistula?
Regardless of the cause of the fistula, the consequences to the patient are devastating and the diagnostic and therapeutic challenges to the surgeon are considerable. Effective treatment begins with an accurate diagnosis and diagnosis begins with a high index of suspicion on the part of the physician. A high index of suspicion means that the doctor should suspect fistula whenever a woman complains of urinary incontinence shortly after childbirth, vaginal surgery of any type or hysterectomy. Further, he or she should be suspicious of fistula in any woman who complains of incontinence, but on examination, urine is not seen to leak from the urethra. Sadly, many, if not most fistulas are initially misdiagnosed because the symptoms are attributed to some other cause.
When a woman complains of incontinence, the sine-qua-non of diagnosis is for the doctor to actually witness the incontinence and see the urine leak from the urethra. If this simple axiom is followed, urinary fistulas should be correctly diagnosed in the vast majority of patients. The most common symptom of a urinary fistula is a constant or nearly constant leakage of urine, both day and night. Some women with small fistulas urinate fairly normally even though there is a continuous leakage; others leak so much that there is never enough in the bladder for them to urinate at all. In many fistula patients, the leakage is so bad that they constantly soak through incontinence pads which are changed frequently throughout the day. In the vast majority of patients the diagnosis will be obvious to your doctor if he does a physical examination when you have a full bladder. If you develop incontinence after childbirth or one of the operations listed above, you should be examined by your doctor, preferably with a full bladder. He should examine the vagina looking for the source of the urinary leakage. If the leakage is not seen, the doctor should pass a catheter and fill the bladder and look again. If the source is still not apparent, he or she might want to put some dye in through the catheter to help him or her visualize the leakage. Rarely, it will be necessary to do an X-ray or CAT scan to make the correct diagnosis. Once the diagnosis is confirmed, it is important to make sure that there are not other injuries to the bladder, urethra or ureters. Once an accurate diagnosis has been made and other injuries excluded, it is time to consider your treatment options.
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