12.1.1

Introduction

• 1.
  

  Urinary incontinence (UI) is a common disorder that affects approximately 25% of the general population according to large epidemiological studies.

  
  
• 2.
  

  Several factors have been implicated in UI, including parity, operative vaginal delivery, length of labour, obesity, chronic cough, depression, anxiety, poor health status, lower urinary tract symptoms, previous hysterectomy, and smoking.

  
  
• 3.
  

  UI is a cause of significant morbidity and cost, estimated at over £500 million, representing 1% of the healthcare budget, in the United Kingdom, €400 billion in Europe, and between $25 and $50 billion in the United States.

  
  
• 4.
  

  Data related to quality of life (QoL) show that the impact of the disorder can be detrimental irrespective of the patients’ age. Specifically, patients with UI suffer from depression, anxiety, and sexual dysfunction. The symptomatology is worse when obesity is also present as women with a body mass index (BMI) greater than 30 kg/m ² tend to have more severe symptoms.

12.1.2

Epidemiology

• 1.
  

  Norwegian EPICONT (Epidemiology of Incontinence in the County of Nord-Trøndelag) study, which included 34,755 women, researchers observed that obesity had a significant impact on UI (stress, urgency, and mixed).

  
  
• 2.
  

  It has also been estimated that 11% of the global population suffers from overactive bladder (OAB) and 8% from UI.

  
  
• 3.
  

  Known risk factors for UI include parity, vaginal childbirth, large babies, perineal trauma, operative delivery, increasing maternal age, prior hysterectomy, and BMI, which is another compounding factor.

  
  
• 4.
  

  A study has also shown that with each increase in BMI unit, the odds ratio (OR) of developing UI increases by 1.6 and women with BMI that exceeds 35 kg/m ² have a prevalence that peeks at 67.3%.

  
  
• 5.
  

  A recent meta-analysis of prospective cohort studies assessed the relationship between overweight/obesity and the risk of UI in young and middle-aged women; the risk of developing UI increased by about a third in women in the overweight category (35%) and nearly doubled in women with obesity (95%).

  
  
• 6.
  

  The effect of age on the prevalence of incontinence becomes minimal after the completion of the fifth decade of life; however, the severity of symptoms becomes more pronounced after 70 years of age. Several factors contribute to this, including chronic ischemia of the lower urinary tract as well as the higher prevalence of abdominal obesity.

12.1.3

Pathophysiology urinary incontinence in the obese population

• 1.
  

  BMI correlates with intra-abdominal pressure, which increases intravesical pressure and exerts increased force on the pelvic floor, hence increasing the risk for stress urinary incontinence (SUI). Furthermore, increased intra-abdominal pressure can lead to the weakening of the pelvic floor innervations and musculature.

  
  
• 2.
  

  Chronically increased BMI is also associated with an elevated risk of UI in later life. Symptom severity also appears to worsen with the duration of increased BMI status, again confirming the detrimental effect of obesity on continence.

  
  
• 3.
  

  Functional disability and mobility problems often accompany gross obesity and are further risk factors for UI.

  
  
• 4.
  

  In women, an increase in adiposity is generally associated with a nearly linear increase in over active bladder (OAB) prevalence.

  
  
• 5.
  

  This contrasts with men, in whom as adiposity increases, the prevalence of OAB decreases to a certain point (BMI 27.5 kg/m ² ), after which as adiposity increases, the OAB prevalence increases again.

  
  
• 6.
  

  In women, this relationship has been attributed to biomechanical (and neuroendocrine) factors, whereas men, who have greater pelvic floor strength, may be less susceptible to these forces with fewest symptoms in the overweight range.

  
  
• 7.
  

  The aetiology and pathophysiology of idiopathic overactive bladder is poorly understood even in the general population; hence, no clear mechanism of the association between an overactive bladder and obesity is available.

  
  
• 8.
  

  The systemic inflammatory state and oxidative stress associated with visceral obesity might play a role in development of OAB. Administration of an antioxidant agent has shown positive effects on LUTS in obese mice.

12.1.4

Nonsurgical treatment for urinary incontinence

• 1.
  

  A large randomised trial investigating the impact of a 6-month weight-loss program on outcomes of UI included 338 overweight and obese women with at least 10 UI episodes per week. This study found that weight reduction in the intervention group was approximately 8.0 kg (compared to1.5 kg in the control group), and this was accompanied by a significant reduction in incontinence episodes at 6 months (47% vs 28%). The difference was significant, however, only for cases with stress UI.

  
  
• 2.
  

  Outcomes concerning the impact of bariatric surgery on UI have shown the improvement or resolution of UI in approximately 55% of cases. Stress UI was less likely to be treated (47% of cases) compared to urgency UI (53% of cases). Worsening and new onset UI was observed in approximately 3% of cases.

  
  
• 3.
  

  Another study reporting on the impact of bariatric surgery in women with UI showed that incontinence-specific QoL scores were improved by 14%, while the proportion of women who were cured from any type of UI reached 58%.

  
  
• 4.
  

  There is a reported 73% reduction in overactive bladder symptoms in patients after surgically induced weight loss compared to their baseline symptoms. A similar reduction in distressing overactive bladder symptoms has been described in studies with nonsurgical weight loss.

  
  
• 5.
  

  Conservative treatment of stress incontinence comprises pelvic floor exercises, supervised pelvic floor physiotherapy, electrical stimulation of pelvic floor muscles, and use of duloxetine.

  
  
• 6.
  

  Duloxetine was reported to be a useful alternative in obese patients with a good response in initial studies and has been described to have antiobesity and antibinge-eating properties, along with its known antidepressant effect in animal studies.

  
  
• 7.
  

  The dual effect of this drug may have a favourable impact on SUI in these patients by a variety of mechanisms including facilitation of weight loss.

12.2.1

Obesity and overactive bladder

• 1.
  

  Overactive bladder may be neurological or idiopathic in nature. The management of overactive bladder comprises bladder training, use of anticholinergics or more recently antimuscarinics, beta-3 agonists, neuromodulation, and cystoscopic injection of botulinum toxin.

  
  
• 2.
  

  Overactive bladder symptoms and their resulting distress are more common in obese patients compared to the general population.

  
  
• 3.
  

  A longitudinal study in changes in urinary function in parous women has shown that overactive bladder symptoms are more common in obese patients, similar to stress incontinence.

  
  
• 4.
  

  Obesity and poor lifestyle factors are markedly associated with incident or new-onset overactive bladder in a large database of >3000 patients. Such studies demonstrate a strong link with obesity and overactive bladder.

  
  
• 5.
  

  In a case control study, the distress caused by overactive bladder symptoms was considerably more in the obese group of patients. This may be due to coexisting mobility issues that prevent such patients from getting to the toilet in time when suffering urge incontinence and urgency.

The treatment of overactive bladder in the obese group of patients also comprises lifestyle changes and the use of medications.

12.2.2

Pharmacological treatment

• 1.
  

  Pooled data analysis of seven randomised placebo-controlled trials to evaluate the relationship between BMI and the efficacy or tolerability of solifenacin 5 and 10 mg has reported that baseline incidence of urge urinary incontinence (UUI) increased with increasing BMI and age. The treatment was effective for all OAB across all BMI categories, and between sexes.

  
  
• 2.
  

  Another trial and analysis had also shown a similar effect in another antimuscurinic and beta-3 agonist (mirabegron) and BMI was not associated with dose escalation.

12.2.3

Sacral neuromodulation

• 1.
  

  Only a few studies have explored predictors of treatment outcome with sacral neuromodulation.

  
  
• 2.
  

  Increased baseline BMI was found to decrease the chance of achieving ≥50% UUI episodes reduction.

  
  
• 3.
  

  The study model estimated that a woman with a BMI of 25 would have a roughly 50% greater chance of achieving ≥50% improvement in UUI compared with a BMI of 35.

  
  
• 4.
  

  In a prospective longitudinal study, investigators found that, among other factors, decreased BMI had a higher risk of reoperation.

  
  
• 5.
  

  In another study, the results suggested that lower BMI might predict reoperation; however, BMI was not significant when adjusted for other covariates.

  
  
• 6.
  

  A more recent retrospective review also failed to find any associations between obesity and reoperation.

12.2.4

Onabotulinum toxin A (BoNT-A)

• 1.
  

  Only one study had evaluated BMI as a predictive factor for treatment outcome for Onabotulinum toxin A in a cohort of women with idiopathic detrusor overactivity.

  
  
• 2.
  

  It is shown that besides smoking, higher BMI was associated with an increased risk of treatment failure.

12.3.1

Pathophysiology anal incontinence in the obese population

Several pathophysiological mechanisms have been proposed for AI.

• 1.
  

  Altered stool consistency is among the proposed factors that contribute to FI as obese patients report altered bowel habits that are accompanied by unformed stools.

  
  
• 2.
  

  A recent prospective case-matched study that compared obese patients to age- and sex-matched nonobese patients with FI reported that the rates of FI were comparable between the two groups, although stool inconsistency seemed to be more prevalent among obese patients.

  
  
• 3.
  

  Significant differences were also observed in anorectal manometry results with obese patients having higher upper- and lower part resting pressures, higher intra-abdominal pressure during effort, and increased maximum tolerable volume.

  
  
• 4.
  

  The baseline anal resting and squeeze pressures were also shown to be increased in obese women with FI, suggesting that the threshold for leakage lowers as the pressure increases.

12.3.2

Weight loss and anal incontinence

• 1.
  

  Data on improvements in AI after weight loss are sparse. The impact of bariatric surgery on AI symptoms is rather disappointing.

  
  
• 2.
  

  The most recent systematic review summarised evidence from 20 BS studies revealed a modest effect with a reduction of the odds of FI by approximately 20%; however, the change was not significant (OR 0.80, 95% CI 0.53, 1.21).

  
  
• 3.
  

  This observation may be attributed to the relatively small number of enrolled patients.

  
  
• 4.
  

  A study that investigated functional anorectal parameters obese women with pelvic floor disorders revealed that bariatric surgery had no impact on internal and external anal sphincter size and on mean anorectal angle during squeeze and during defecation.

12.3.3

Obesity and treatment for anal incontinence

• 1.
  

  AI is primarily treated with behavioural treatment that aims to reduce stool inconsistency.

  
  
• 2.
  

  Various treatment alternatives have been proposed, including bowel training, biofeedback, antidiarrhoeal drugs, and bulk laxatives (in cases of chronic constipation).

  
  
• 3.
  

  Neither of these methods has been evaluated in obese populations.

  
  
• 4.
  

  Sphincteroplasty remains the cornerstone of treatment in cases of damaged anal sphincter.

  
  
• 5.
  

  A study that included 15 obese and 64 nonobese women, with a median follow-up period of 64 months, showed that, although the risk of complications was comparable between the two groups, improvement was less evident in obese patients.

  
  
• 6.
  

  Perianal bulking has also been used and showed promising results, however, data in obese populations are unavailable and they cannot be yet recommended for the treatment of FI.

12.4.1

Weight loss and uterovaginal prolapse

Intensive nonsurgical and surgical methods of weight loss have not been shown to reverse the distressing nature or severity of symptoms of pelvic organ prolapse.

Weight loss in obese helps to stop the progression and worsening of symptoms of prolapse.

Weight loss may also help in reducing the postsurgical morbidity associated with obesity and prolapse surgery.

12.4.2

Pelvic organ prolapse surgery and obesity

Obesity is known to be associated with more complications in a postsurgical period due to restricted mobility and the resumption of activities of daily living.

Conservative measures such as the use of various types of pessaries should be considered as the first line of management.

The discussion about the route of surgery becomes more relevant in this group and it should be either vaginal or laparoscopic route to encourage early mobility.

The vaginal route has been reported to be associated with less febrile morbidity, postoperative ileus, and urinary infection.

There are no long-term follow-up studies reporting on the relationship between the success of prolapse surgery, or complications, and various classes of obesity.