Voiding difficulty

A joint International Urogynecological Association/International Continence Society (ICS) Report on terminology for female pelvic floor dysfunction defines ‘voiding difficulty’ as ‘abnormally slow and/or incomplete micturition’ (Haylen et al 2010). The diagnosis is obtained by symptoms (see below) and urodynamic investigations, and should be based on repeated measurements to confirm abnormality.

Abnormally slow urine flow rates, as determined by uroflowmetry, are best referenced to nomogram charts which provide a range of normality for urinary flow rates in relation to volume voided; abnormal flow is defined as flow under the 10th centile (Haylen et al 1989). To encourage the use of these charts, a larger version of the original charts has been republished recently (Haylen et al 2008a).

Abnormally high postvoid residuals (i.e. volume left in the bladder at the completion of micturition) depend on the method used for measurement and the timing of the measurement after micturition, taking into account renal input of 1–14 ml urine/min (Haylen et al 2010).

Upper limits of postvoid residuals of 30 ml (using immediate ultrasound assessment) and 50–100 ml (using urethral catheterization) have been proposed (Haylen et al 2010).

Acute retention of urine

This is defined as a generally, but not always, painful, palpable or percussable bladder, when the patient is unable to pass any urine when the bladder is full (Haylen et al 2010).

Chronic retention of urine

This is defined as a non-painful bladder where there is a chronic high postvoid residual (Haylen et al 2010).

Effects of age on voiding function

The incidence of voiding dysfunction in women increases with age (Haylen et al 2008b), and the process of ageing may decrease detrusor contractility and increase urethral rigidity.

Urodynamic studies have shown that both peak flow rate and detrusor pressure during voiding decrease with advancing age. Older women are also more likely to strain abdominally during voiding and to have higher residual urine volumes (Malone-Lee and Wahedna 1993).

With advancing age, anatomical changes occur in the bladder wall leading to reduced bladder contractility (e.g. increased collagen content in the detrusor muscle, reduction in the number of cholinergic nerves, dedifferentiation of detrusor muscle cells). Changes leading to urethral atrophy and increased rigidity also occur (e.g. reduced striated muscle and vessel content, increased connective tissue).

While it is not clear whether voiding dysfunction is due to ‘normal’ ageing of the lower urinary tract or to the presence of disease processes, age is the only risk factor that has been consistently associated with the development of postoperative voiding dysfunction after anti-incontinence surgery. Increased urethral rigidity may increase the likelihood of causing obstruction, and reduced detrusor contractility may reduce the ability to cope with it.

It is not clear whether the menopause has an effect on voiding which is distinct from age. There are no studies showing that the menopause per se has a deleterious effect on voiding function. However, the distal urethra is oestrogen dependent and therefore susceptible to postmenopausal atrophic changes; the reduction in urethral functional length seen after the menopause is likely to be a manifestation of this process. There is evidence that these changes are more pronounced in a minority (18%) of postmenopausal women (Smith 1972). These women may have increased urethral rigidity and may be predisposed to the development of voiding dysfunction should they undergo pelvic or anti-incontinence surgery.

Postoperative voiding dysfunction

Surgery for stress incontinence

Surgery for stress incontinence is an important cause of impaired bladder emptying in women. There is no universally accepted definition of voiding dysfunction after incontinence surgery, and voiding function is often reported empirically in studies (e.g. as ‘time required for resumption of voiding’ or ‘time of catheter removal’). In most cases, postoperative voiding problems are short term, but they can persist in the long term and lead to profound alterations in quality of life. Prolonged or ‘late’ voiding dysfunction after incontinence surgery may also affect patients who did not have ‘early’ dysfunction in the immediate postoperative period. This may be due to failure to obtain an early diagnosis, progressive effects of scarring or onset of new pathology.

Women with stress incontinence may already have some impairment of voiding function, which may make them more vulnerable to the obstructive effects of surgery. This is suggested by differences in several urodynamic (voiding) variables noted in these women. For example, in contrast with normal women, women with stress incontinence are more likely to strain during voiding, and to initiate voiding with a Valsalva manoeuvre as opposed to pelvic relaxation. They also void with significantly lower detrusor pressures, and up to 15% have been shown to void without a contraction (Figure 54.3; Karram et al 1997). It is not clear whether this is due to the lower mean urethral pressure of women with urodynamic stress incontinence, or whether there is a real impairment of detrusor muscle function in these women.

Figure 54.3 Voiding without detrusor contraction (pelvic relaxation alone).

Postoperative voiding disorders have been reported to occur after most operations for stress incontinence. Prolonged voiding dysfunction is uncommon after urethral injectables, although an incidence of 5% has been reported (Khullar et al 1997). The colposuspension operation leads to postoperative voiding dysfunction in a mean of 12.5% of patients (Jarvis 1994). Laparoscopic and open colposuspension have the same incidence of postoperative voiding difficulty (Carey et al 2006). Results of a randomized study comparing the tension-free vaginal tape (TVT) procedure with colposuspension suggest that the incidence of voiding difficulty at 6 months is similar after both operations (7%), although patients experience earlier voiding in the immediate postoperative period after the TVT procedure (Ward and Hilton 2002). After the TVT procedure, 11% of women have been reported to need a catheter for more than 24 h (Vervest et al 2007), with only 2% needing tape release for prolonged difficulty (Kuuva and Nilsson 2002, Karram et al 2003, Vervest et al 2007). The transobturator tape (TOT) procedure has been shown to have a lower incidence of postoperative voiding difficulty than the TVT, possibly as it is less obstructive (Latthe et al 2007).

Voiding difficulty after incontinence surgery is multifactorial. In addition to temporary factors, as detailed above, permanent factors might be relevant from the outset. Some factors are obstructive and relate to the operative technique (e.g. excessive tape tension when using midurethral slings, or excessive bladder neck elevation at colposuspension), while others relate to the patient and her capacity to deal with obstruction (e.g. age and poor detrusor contractility). An intrinsically weak detrusor may be unable to cope with even the slightest increase in outflow resistance.

Postpartum voiding difficulty

Prolonged voiding difficulty in the postpartum period requiring self-catheterization is uncommon and has been reported to occur after less than 1% of deliveries (Glavind and Bjørk 2003). However, when using strict criteria [similar to those proposed recently by the International Urogynecological Association/International Continence Society (2010)], up to 43% of women have been shown to have some degree of voiding difficulty after delivery (Ramsay and Torbet 1993). Recognized risk factors for voiding difficulty in the immediate postpartum period are primiparity, instrumental delivery, epidural analgesia, prolonged labour, perineal trauma and poor bladder management resulting in overdistension. In addition to temporary factors (e.g. epidural, morphine, anaesthetic), other factors causing prolonged voiding dysfunction may be present (e.g. trauma to the bladder, pelvic floor muscles and nerves).

Neurological disease

The effects of neurological disease on bladder function and the upper renal tracts depend on the site of the lesion(s). Interruption of the mainly inhibitory pathways from the cerebral cortex to the pontine micturition centre (e.g. stroke, tumour, trauma, Parkinson’s disease) is likely to result in uninhibited detrusor contraction and incontinence. Interruption of the neural pathways from the pontine to the sacral centres [e.g. spinal cord injury, multiple sclerosis (MS)] may also lead to uninhibited contractions (neurogenic detrusor overactivity) with or without failure of relaxation of the urethral sphincter (detrusor sphincter dyssynergia). Interruption of the sacral reflex arc (e.g. diabetic neuropathy, low spinal cord tumours, lumbar disc prolapse) may lead to acontractility of the detrusor muscle (atonic bladder), with voiding difficulty and retention.

Impaired voiding function (e.g. detrusor sphincter dyssynergia) can potentially lead to high detrusor pressure, reflux and upper tract changes (e.g. hydronephrosis), resulting in renal failure.

Specific neurological conditions are discussed below.

Psychological factors

Psychological factors may cause or contribute to voiding dysfunction by centrally mediated, unconscious inhibition of either detrusor contraction, pelvic floor relaxation or both. This is confirmed by the inability of many individuals to void when there is a lack of privacy (so-called ‘paruresis’ or ‘shy bladder syndrome’).

True psychogenic urinary dysfunction is uncommon but is usually accompanied by obvious psychological or psychiatric features, such as conversion disorder (hysteria) and anxiety. There is often a precipitating stressful ‘trigger’ event. A history of sexual abuse may be present.

Idiopathic bladder neck obstruction

This is a poorly defined, infrequent condition characterized by failure of the urethral sphincter to relax, and possibly hypertrophy, with urodynamic variables showing high pressure and low flow in the absence of neurological or urological abnormality. It was originally described in a cohort of young women with polycystic ovaries and voiding difficulty (Fowler’s syndrome; Fowler et al 1988). The cause is unknown. There is a suggestion that α-blockers may be beneficial in these patients (Athanasopoulos et al 2009).

Pelvic organ prolapse

Although the majority of women with pelvic organ prolapse (POP) can void effectively, there is an association between POP and voiding dysfunction (Coates et al 1997, Haylen et al 2008b). Symptoms of voiding difficulty (Digesu et al 2005) and high postvoid residuals (Haylen et al 2008b) are more common in women with POP. Urodynamic evidence of voiding difficulty has been found to correlate with POP severity, with high-grade cystocoele being the most common anatomical defect leading to voiding difficulty (Romanzi et al 1999). Severe prolapse of the posterior vaginal compartment has also been shown to have a negative effect on voiding function (Myers et al 1998, Dietz et al 2002). Kinking of the urethra (by a prolapse of the anterior vaginal compartment) or direct pressure on the urethra and bladder neck (by a prolapsing uterus or posterior vaginal compartment) are possible mechanisms of obstruction, leading to voiding difficulty.

Overactive bladder symptoms and occult stress incontinence often coexist with voiding difficulty in women with pelvic organ prolapse (Romanzi et al 1999).

Prolapse correction with a pessary has been shown to improve voiding function in the majority of women with both pathologies (Romanzi et al 1999). In most women with severe prolapse and voiding difficulty, corrective surgery restores voiding successfully (Fitzgerald et al 2000, Liang et al 2008).

Bladder overdistension

Bladder overdistension can be iatrogenic (i.e. the result of a delay in the diagnosis of voiding difficulty, with delayed catheterization), and this event per se can also lead to further and sometimes prolonged voiding difficulty. Studies of bladder function after overdistension, mostly in animal models and in men with retention associated with prostatic hypertrophy, have shown reduced bladder contractility. This is probably due to denervation, stretch damage to the detrusor muscle, and metabolic injury due to ischaemia and reperfusion. The time of recovery after such injury has not been investigated in women, but is likely to depend on the cause of the bladder overdistension, the amount of fluid retained and the time of retention.

Infrequent voiding can lead to chronic bladder overdistension and voiding difficulty, but evidence for this is lacking.

Others

In addition to anaesthetics and analgesics, drugs with anticholinergic action (e.g. antidepressants, antipsychotics, oxybutinin etc.) can potentially worsen voiding function and precipitate retention in individual cases. However, antimuscarinic therapy was not found to worsen voiding function in a series of women with overactive bladder and mild voiding difficulty (postvoid residuals of ≥100 ml) (Robinson et al 2003).

Intravescical Botox for treatment of the overactive bladder has been shown to increase postvoid residuals, but retention requiring self-catheterization is uncommon (Duthie et al 2007), with one large series reporting an incidence of 4% (Schmid et al 2006).

Pelvic masses (e.g. fibroids, retroverted gravid uterus, ovarian cysts, faecal impaction, haematocolpos) can cause voiding difficulty due to a direct pressure effect.

Infections (e.g. urethritis, cystitis, vulvovaginitis) can cause acute retention due to inflammation and pain, with genital herpes and sacral herpes zoster possibly also due to nerve impairment.

Urethral pathology, other than the effects of incontinence surgery (e.g. tumours, strictures, diverticulae, foreign bodies and stones), may rarely cause voiding difficulty.

Lichen’s sclerosus can cause complete fusion of the labia and closure over the urethral meatus, resulting in voiding difficulty.

Uroflowmetry

In practical terms, most women with voiding difficulty require simple flow studies with measurement of post void residual urine with catheters or ultrasound. Features include changes in the normal bell-shaped curve, with intermittent or multiple peaked flow (suggestive of abdominal straining or unsustained bladder contractions) (Figure 54.4), and/or low flow rates. Although there are no clear-cut values, low peak flow rates of less than 12–20 ml/s have been used traditionally, with voided volumes of 150–200 ml. Postvoid residual urine volumes of more than 50–100 ml were arbitrarily considered abnormal.

Figure 54.4 Voiding difficulty with obstruction after colposuspension. Note prolonged interrupted flow.

It is now suggested that volume-specific nomograms should be used, with abnormal flow defined as under the 10th centile (International Urogynecological Association/International Continence Society 2010). Repeated measurements are necessary to confirm abnormality.

Upper limits of postvoid residuals of 30 ml using immediate ultrasound assessment and 50–100 ml using urethral catheterization have been proposed, taking into account renal input of 1–14 ml urine/min (International Urogynecological Association/International Continence Society 2009).

An alternative screening method, using a peak flow rate of less than 15 ml/s and/or postvoid residual urine volume greater than 50 ml with a minimum total bladder volume of 150 ml before voiding, has been shown to correlate well with the Liverpool nomograms (Haylen et al 1989), and could be used if nomogram charts are not available (Costantini et al 2003).

Uroflowmetry, however, is only a screening test. More complex urodynamic studies are advisable in the presence of coexistent overactive bladder symptoms, neurological disease or when the cause of voiding difficulty is unclear.

Pressure–flow studies

The assessment of voiding difficulty in the female, as in the male, relies on pressure–flow studies. In men, low flow in the presence of high detrusor pressure usually signifies obstruction (using nomograms), but this is less clear in women.

In an attempt to obtain cut-off values for the definition of obstruction in women, urodynamic studies have been performed in obstructed patients and compared with controls. For example, in repeated non-invasive flow studies, the presence of a peak flow rate of less than 12 ml/s, with a detrusor pressure at maximum flow of more than 20 cmH₂O (Figure 54.5), has been considered to be suggestive of obstruction and used to construct female nomograms (Blaivas and Groutz 2000). The practical value of these observations remains unclear, as the clinical and radiological criteria used to define obstruction are arbitrary. Symptoms are often non-specific, and anatomical evidence of obstruction is often missing using videourodynamics or cystourethroscopy (Groutz et al 2000).

Figure 54.5 Voiding difficulty with obstruction due to urethral diverticulum (peak flow rate 10 ml/s, maximum detrusor pressure 80 cmH₂O, postvoid residual 600 ml).

In contrast, other authors do not rely heavily on strict urodynamic criteria for the diagnosis of obstruction, and suggest that relative obstruction can exist in the presence of normal or low detrusor pressures (Foster and McGuire 1993, Carr and Webster 1997). Obstruction after incontinence surgery is therefore diagnosed purely on the basis of a clear-cut temporal relationship between surgery and the onset of persistent voiding difficulty. Successful urethrolysis has even been performed on women who had acontractile bladders after stress incontinence surgery (Figure 54.6; Foster and McGuire 1993, Carr and Webster 1997), thus challenging the concept that obstruction only exists in the presence of high pressures.

Figure 54.6 Voiding difficulty with acontractile bladder after colposuspension (volume voided 7 ml, postvoid residual 350 ml).

Videourodynamics

More detailed studies on patients with prolonged postoperative voiding difficulty can be performed using videourodynamics. However, anatomical abnormalities (e.g. a narrowed or deviated urethra) leading to obstruction are only detected in a minority of patients (Groutz et al 2000).

Cystourethroscopy

This has been reported to reveal urethral strictures or fibrosis in approximately half of women who had suspected obstruction during pressure–flow studies (Groutz et al 2000).

Electromyography

Surface or needle electrodes can be used to evaluate distal urethral sphincter function. Failure of the sphincter to relax can be documented in cases of Fowler’s syndrome (Fowler et al 1988). When used with urodynamics, simultaneous detrusor contraction and failure of relaxation of the sphincter can be observed in neuropathic patients (detrusor sphincter dyssynergia).

Short-term management

Voiding difficulty is usually managed with indwelling urethral catheters (e.g. Foley catheters). These are generally well tolerated but have been reported to be unpleasant by more than one-third of patients (Vierhout 1998). Catheters come in a variety of sizes and are made with a variety of materials (e.g. latex, silicone, polyvinyl chloride). Specialized catheters, impregnated with silver or antibiotics, have been developed to reduce the risk of infection, with evidence that they reduce the risk of bacteriuria by one-third to one-half in the short term (Schumm and Lam 2008). There is weak evidence that antibiotic prophylaxis reduces the rate of symptomatic UTI in patients using a urethral catheter in the short term (Niel-Weise and van den Broek 2005).

Suprapubic catheters may be preferred when surgery has greater potential for obstruction (e.g. colposuspension) or when patients undergoing surgery are already known to have voiding difficulty. They are more practical and allow patients to attempt voiding without needing recatheterization. The residual urine volume can be measured easily. Compared with urethral catheters, they have a lower incidence of significant bacteriuria, voiding occurs earlier and patient acceptability is higher.

Early clean intermittent self-catheterization (CISC) has advantages compared with suprapubic bladder drainage in terms of hospital stay and sepsis. When considering potentially obstructive stress incontinence surgery, particularly in patients at high risk of voiding difficulty (see below), CISC should be discussed and taught beforehand as it is easier for patients to learn before rather than after surgery.

Long-term management

Indwelling urethral catheters are often used for chronic voiding difficulty, particularly in long-term care settings. While a variety of different catheters exist, insufficient evidence exists to recommend one over another (Jahn et al 2007).

Suprapubic catheterization is a better option than urethral catheterization. Epithelium will form in the tract in 6–8 weeks. A size 14F catheter should be used to keep the tract open and changed every 8–12 weeks. Vitamin C can acidify urine and prevent crust formation. There is usually no need for prophylactic antibiotics.

Indwelling catheters (urethral or suprapubic) are not ideal in the long term as they are conspicuous and demoralizing. Urethral catheters interfere with coitus and ambulation, and can be associated with incontinence due to bypass. They are associated with recurrent UTI, stones, strictures and urethral erosion, and need to be changed frequently or irrigated due to blockage.

Rather than indwelling catheters, the preferred treatment for chronic voiding difficulty is CISC. This is based on the principle that retention rather than catheterization is the cause of infection. The advantages over an indwelling catheter are lower incidence of UTI and improved mental status.

The frequency of catheterization depends on severity of the voiding difficulty and residual urine volume. Old age and disability are not necessarily an impediment, but motivation and manual dexterity are essential. Most patients performing CISC have bacteriuria not requiring antibiotics, and treatment is only required in those with symptoms. More frequent catheterization and an increased fluid intake may be helpful if symptomatic infections occur. At present, there is no evidence that the incidence of UTI in patients performing CISC is affected by variables such as the type of catheter (coated or uncoated) or the technique used (single/sterile or multiple use/clean) (Moore et al 2007).

CISC has been shown to be effective in the long term. Two-thirds of patients available for follow-up 10 years after commencing treatment were satisfied and still performing the procedure, with no evidence of renal impairment (Diokno et al 1983). Although long-term follow-up studies may suffer from selection bias — most available responders are treatment ‘successes’ — up to 80% of patients find CISC easy, with only a minority reporting severe pain (Kessler et al 2009).

General measures may also be helpful in individual patients. These include standing or leaning forwards during voiding, abdominal straining, double voiding, voiding at regular intervals and treating constipation.

Women who experience voiding difficulty after surgery or post partum should be reassured that voiding function often improves with time. A positive view of CISC should be given, with support from continence advisors.

Role of drug therapy

The effect of drugs for the treatment of voiding difficulty has been disappointing. α-Adrenoreceptor antagonists to relax the urethra (e.g. phenoxybenzamine hydrochloride, alfuzosin), detrusor-stimulating drugs such as cholinergic agents (e.g. bethanechol chloride), anticholinesterase (e.g. distigmine bromide) and prostaglandins have been used with inconsistent results. Due to their inconsistent effect and unproven value, drugs are not currently recommended for the prevention and treatment of voiding difficulty in women.

Oestrogen may be of benefit for women with genital atrophy causing obstruction and voiding difficulty.

Role of surgery

Urethral dilatation and urethrotomy may be effective in patients with voiding difficulty due to urethral narrowing, particularly after anti-incontinence procedures. However, the benefit seems to be short lived as scarring is likely to recur and may even result in worsening obstruction. In addition, stress incontinence has been reported to reappear (Delaere et al 1983). When this method is deemed necessary (e.g. for a traumatic stricture), repeated catheterization (e.g. CISC) is advisable to maintain patency.

Suprapubic and vaginal ‘take-down’ procedures involving urethrolysis, with or without additional resuspension procedures, have been described after retropubic procedures (e.g. colposuspension) (Foster and McGuire 1993, Carr and Webster 1997). Symptoms of voiding difficulty in these patients are usually combined with urgency symptoms. Despite the lack of uniformity with regards to patient selection, definition of obstruction, surgical treatment and outcome measures, it would appear that urethrolysis is a possible alternative to CISC. It may be suitable for patients who are unwilling or unable to perform the technique. However, the reported success rate is variable and unpredictable, and there is a risk of recurrent stress incontinence.

When voiding difficulty occurs after midurethral sling procedures, release of the tape can be performed. Loosening the tape by applying downward traction is usually possible in the immediate postoperative period (2–3 weeks), producing immediate symptomatic relief in most cases. Later, if scarring does not allow tape descent, transection of the tape (laterally or in the midline) has been described (Rardin et al 2002, Laurikainen and Kiiholma 2006, Segal et al 2006). While voiding function has been reported to improve in most women after late tape revisions, coexistent overactive bladder symptoms often remain unchanged (Segal et al 2006, McCrery 2007). The reported risk of recurrent stress incontinence after tape revision ranges from 5% to 50% (Klutke et al 2001, Rardin et al 2002, Karram et al 2003). Urethral injury may occur due to the formation of dense scarring between tape and urethra (Klutke et al 2001, Laurikainen and Kiiholma 2006).

Role of nerve stimulation

Unobstructive voiding difficulty can respond to techniques of nerve stimulation. The sacral nerves can be stimulated indirectly (posterior tibial nerve stimulation) or directly (sacral nerve stimulation). The precise mode of action is not known, and it is also not clear why the same techniques can help patients with an overactive detrusor muscle as well as an underactive detrusor muscle.

Posterior tibial nerve stimulation involves the placement of needle electrodes above the medial malleolus to stimulate the posterior tibial nerve, which contains mixed fibres from L5–S3. Early reports show objective improvement in voiding function, with approximately 60% of patients willing to continue treatment (Vandoninck et al 2004). However, the technique is time consuming and requires repeat stimulation.

Sacral nerve stimulation is a promising technique that uses an implantable system (Interstim device) to stimulate the pelvic nerves (at S3 level). An initial test procedure is performed to assess response, positioning a temporary electrode with an external stimulator. If appropriate, a permanent lead is then inserted and connected to a pulse generator positioned in the upper buttocks or anterior abdominal wall. In addition to unobstructed voiding difficulty, indications for sacral nerve stimulation include faecal incontinence, bladder overactivity and interstitial cystitis. A recent review reports a response rate for voiding difficulty of 38–68%, with good medium-term results in 58–76% of responders (Bosch 2006). Technical problems and adverse events are unfortunately common (e.g. pain at the stimulator site, new pain, pain at the lead site, lead migration, infection, transient electric shock, changes in bowel function), with a reoperation rate of approximately 50% (Bosch 2006). There are no reports of long-lasting neurological complications.

Other treatments

A suprapubic vibration device (Queen Square bladder stimulator) has been shown to improve voiding in some patients with neurogenic bladders (Dasgupta et al 1997). The device was only effective in patients with a postvoid residual of less than 400 ml, reducing the postvoid residual from a mean of 175 ml to a mean of 68 ml (Dasgupta et al 1997). However, there is no evidence of benefit in other types of voiding difficulty.

Urinary diversion can be considered in selected cases as a last resort (e.g. ileal conduit or Indiana pouch).