Sunday, September 16, 2012

Obstructed Sling: Can’t Pee From Your Sling? How to Prevent it and What to Do If This is Your Problem.

Sling surgery may be the perfect combination of mixing the art and science of medicine. Urinary incontinence, for which sling surgery is indicated, is a well-known quality of life problem that millions of women in the US and worldwide experience. When stress urinary incontinence is bothersome enough and conservative measures have failed, a sling is indicated to correct it. There are many surgical procedures for stress incontinence, but the sling has become the standard of care, and the mesh sling has become the most performed and the standard of care in the US and worldwide as well.

Balancing dryness after a sling with the ability to void urine is of paramount importance. One would not want to reasonably trade being constantly wet with being dry but unable to pee. Therefore a work up before sling surgery is necessary. Urodynamics should always be performed to determine what the preoperative bladder function is in order to properly determine whether and which type of sling should be performed. The two archetype slings are the retropubic “TVT”, and the transobturator “TVTO”, but there are many iterations of these original types that are equally successful. The minislings, such as the Miniarc as one example, are not well studies and fall under the recent 522 FDA requirement for further studies.

Sling obstruction essentially means, that even if placed correctly, the female patient cannot void. This does not mean 1 or two days, or even 7 days, but obstruction is considered if the patient still needs a catheter for at least 28 days. The rate of retention can be as high as 10% with this definition. What’s important to determine is when the inability to void began after surgery. It can present with obvious symptoms: straining, weak stream, sense of incomplete emptying, bladder cramps/spasms, urinary frequency, burning with urination and UTIs. Obstruction can even occur after many years and symptoms and a work up are needed to properly determine this.

Urodynamics are needed to access a variety of things in terms of bladder and urethral function. Of paramount importance is how strong (or weak) is the bladder contraction. Even if placed well, if the bladder contraction is weak, then the patient may not void well and the sling will act to obstruct the flow. A normal bladder contraction is required to overcome the normal resistance of the urethra and all the more so if a sling is present.   Women who void by Valsalva (or straining), and do no not necessarily relax to void, are at risk for retention after a sling as well. The sling will simply do what it is designed to do- block urine from coming out when a woman strains, whether it is during aerobics or straining to void.

Retropubic slings, whether mesh or autologous tissue, tend to hug the urethra more snugly and have a tendency to lead to retention and obstructive symptoms. This generally does not occur with transobsturator sling, as this type of sling is configured more splayed out. Both types have equal efficacy in curing stress incontinence. Retropubic slings may be favored if incontinence is more severe, or if a prior sling failed, yet, an important judgment call is deciding between being 95% dry with a transobturator sling even if the incontinence is severe, versus begin “105%” dry with a retropubic sling, which may make the patient dry but is now causing obstruction. “Dry” does not always mean “perfect”.  If may be better to leak rarely with a sling, than have constant trouble with emptying.

A weaker flow rate on Urodynamics, higher residual bladder urine before surgery, or older patients (>75 yrs), many also be at risk for post sling obstruction.  Alternatively, if a sling erodes into the urethra or extrudes into the vagina, sling obstruction symptoms will likely occur. In addition, if a bladder prolapse is not identified or fixed at the time of sling surgery, or if one develops later, the sling will effectively kink off the urethra at the point where the bladder drops. It will be difficult to empty the bladder in these cases as well. If the sling is not positioned well, either too close to the urethral opening or too far back off the urethra or if it migrates after placement, the sling can obstruct as well. These constitute the discoverable pre- and intra-operative factors that are the science of sling surgery.

Physician factor is equally important. There is really no standardized way of preventing obstruction. Each physician performs tensioning as he/she sees fit based on the sling type, body habitus, degree of incontinence and urodynamic factors. Retropubic tissue slings are most difficult to “eyeball”, and can obstruct right away or tighten and obstruct over time. This type of arbitrary tensioning of slings underscores the physician’s experience in performing slings. The more a physician has done, and the more slings the physician may also have re-done, whether his own or from another physician, the better the physician is at setting sling tension. That is the art of sling surgery without a doubt. As the old saying goes “caveat emptor”, let the buyer beware. Seek out a physician that is experienced in incontinence diagnosis and treatment.

A thorough pelvic exam, cystoscopy and urodynamics after the sling are required to evaluate and determine the correct treatment plan. Sometimes biofeedback or pelvic floor retraining may be all that is required if no obstruction is suspected or diagnosed. Sling transection, removal, or incision and release of the urethra is often needed if obstruction is diagnosed, and often will remedy the problem. However, this must be balanced with the risk of recurrence incontinence. Some patients may opt to self-catheterize versus risking being wet again after sling release. If diagnosed early enough, the sling maynot need to be removed, but rather can be loosened.

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