104 CHAPTER 3 Bladder outlet obstruction

Bladder outlet obstruction and retention in women

In women this condition is relatively rare (~5% of women undergoing pressure-flow studies have BOO, compared with 60% of unselected men with LUTS).1

It may be symptom-free, present with LUTS or as acute urinary retention. In broad terms, the causes are related to obstruction of the urethra (e.g., urethral stricture, compression by a prolapsing pelvic organ such as the uterus, post-surgery for stress incontinence) or have a neurological basis (e.g., injury to sacral cord or parasympathetic plexus, degenerative neurological disease, e.g., MS, diabetic cystopathy).

Voiding studies in women

Women have a higher Qmax (maximal flow), for a given voided volume than that of men. Women with BOO have lower Qmax than those without BOO. There are no universally accepted urodynamic criteria for diagnosing BOO in women.

Treatment of BOO in women

Treat the cause (e.g., dilatation of a urethral stricture; repair of a pelvic prolapse). Where this is not possible (because of a neurological cause such as MS or spinal cord injury), the options are as follows:

•Intermittent self-catheterization (ISC) or intermittent catheterization by a caregiver

•Indwelling catheter (preferably suprapubic rather than urethral)

•Mitrofanoff catheterizable stoma

Where urethral intermittent self-catheterization is technically difficult, a catheterizable stoma can be constructed between the anterior abdominal wall and the bladder, using the appendix, Fallopian tube, or a narrowed section of small intestine, known collectively as the Mitrofanoff procedure. It is simply a new urethra that has an abdominal location, rather than a perineal one, and is therefore easier to access for ISC.

For women with a suprasacral spinal cord injury with preserved detrusor contraction and urinary retention due to detrusor-sphincter dyssynergia (DSD), sacral deafferentation combined with a Brindley stimulator can be used to manage the resulting urinary retention.

Fowler syndrome

Fowler syndrome is a primary disorder of sphincter relaxation (as opposed to secondary to, for example, SCI). Increased electromyographic (EMG) activity (repetitive discharges on external sphincter EMG) can be recorded in the external urethral sphincters of these women (which on ultrasound are of increased volume) and is hypothesized to cause impaired relaxation of external sphincter.

It occurs in premenopausal women, typically aged 15–30, often in association with polycystic ovaries (50% of patients), acne, hirsutism, and menstrual irregularities. It may also be precipitated by childbirth, gynecological or other surgical procedures.

106 CHAPTER 3 Bladder outlet obstruction

Urethral stricture disease

A urethral stricture is an area of narrowing in the caliber of the urethra due to formation of scar tissue in the tissues surrounding the urethra. The disease process of anterior urethral stricture disease is different from that in the posterior urethra.

Anterior urethra

The process of scar formation occurs in the spongy erectile tissue (corpus spongiosum) of the penis that surrounds the urethra (spongiofibrosis). Causes include the following:

•Inflammation (e.g., balanitis xerotica obliterans [BXO]), gonococcal infection leading to gonococcal urethritis (less common today because of prompt treatment of gonorrhea)

•Trauma

• Straddle injuries—blow to bulbar urethra (e.g., cross-bar injury)

•Iatrogenic—instrumentation (e.g., traumatic catheterization, traumatic cystoscopy, TURP, bladder neck incision)

The role of nonspecific urethritis (e.g., Chlamydia) in the development of anterior urethral strictures has not been established.

Posterior urethra

Fibrosis of the tissues around the urethra results from trauma—pelvic fracture or surgical (radical prostatectomy, TURP, urethral instrumentation). These are essentially distraction injuries, where the posterior urethra has been pulled apart, and the subsequent healing process results in the formation of a scar, which contracts and thereby narrows the urethral lumen.

Symptoms and signs of urethral stricture

•Voiding symptoms—hesitancy, poor flow, post-micturition dribbling

•Urinary retention—acute, or high-pressure acute-on-chronic

•Urinary tract infection—prostatitis, epididymitis

Management of urethral strictures

When the patient presents with urinary retention, the diagnosis is usually made following a failed attempt at urethral catheterization. In such cases, avoid the temptation to blindly dilate the urethra. Dilatation may be the wrong treatment option for this type of stricture—it may convert a short stricture that could have been cured by urethrotomy or urethroplasty into a longer and denser stricture, thus committing the patient to more complex surgery and a higher risk of recurrent stricturing. Place a suprapubic catheter instead, and image the urethra with retrograde and antegrade urethrography to establish the precise position and the length of the stricture.

Similarly, avoid the temptation to inappropriately dilate a urethral stricture diagnosed at flexible cystoscopy (urethroscopy). Arrange retrograde urethrography so appropriate treatment can be planned.

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