Keywords

1 Introduction

Anal incontinence (AI) has been reported to occur in patients with concomitant urological disease, as a result of the condition itself or its treatment. Surgical operations for prostate cancer and bladder cancer, as well as radiotherapy, can lead to loss of anal function. Moreover, AI has been associated with lower urinary symptoms (including urgency, frequency, and incontinence) and it is considered a risk factor for urinary tract infections.

2 Urological Diseases Associated with Anal Incontinence

2.1 Prostate Cancer

2.1.1 Anal Incontinence After Radical Prostatectomy

Radical prostatectomy (RP) has been related to a high incidence of anorectal complications [1, 2] including AI, and the incidence is significantly higher after radical perineal prostatectomy (RPP). Urologists first recognized alterations in anorectal functions after RP in 1998 through a study conducted by Bishoff et al. [2]. In their survey, the authors reported AI in 5% and 18% of patients undergoing radical retropubic prostatectomy (RRP) and RPP, respectively. Similarly, the frequency of AI (daily, weekly, monthly or less than monthly occurrences) was significantly higher after RPP (3%, 9%, 3% and 16%) compared to RRP (2%, 5%, 3%, and 8%). RPP patients were more likely to wear a pad for stool leakage, experienced more accidents, had larger amounts of stool leakage and had less formed stools compared to RRP patients. Unfortunately, AI following RP is often underreported. Bishoff et al. reported that less than 50% of patients with AI had told the physician. Moreover, only 14% of patients undergoing RPP and 7% of those undergoing RRP with AI had ever told a health care provider about it, even when the incontinence was severe [2].

Surgical injury to pelvic region muscles and the anal sphincter complex or potential neuropraxia of the related nerves during RP may result in loss of anal function. Aydemir et al. performed a prospective manometric study to evaluate anorectal functions after RP. Their study demonstrated that external anal sphincteric pressure and internal anal sphincteric pressure significantly decreased after RPP. Although external anal sphincteric pressure and internal anal sphincteric pressure were also decreased in RRP, the difference was statistically insignificant [1].

The Expanded Prostate Cancer Index Composite (EPIC) is a comprehensive instrument designed to evaluate patient function and bother after prostate cancer treatment. It consists of four domains: urinary, bowel, sexual and hormone functions [3]. In their study, Koike et al. recorded a significantly higher EPIC bowel function score at only the 3-month follow-up in patients who performed robot-assisted RP (RARP) vs. laparoscopic RP (LRP) (96.9 vs. 92.9, p < 0.01). The difference in bowel function disappeared at postoperative months 6 and 12 [4].

2.1.2 Anal Incontinence After Radiotherapy for Prostate Cancer

External beam radiotherapy is an established curative treatment for prostate cancer. It can be prescribed as curative therapy alone or in combination with radical prostatectomy with curative, adjuvant or salvage intent.

AI is a known sequela of radiotherapy for prostate cancer, although it has received little attention in comparison with other toxicities and complications [5].

The potential mechanisms of AI related to radiotherapy include the detrimental effects of radiation exposure on the structure of the sphincter complex, either the muscle itself or the myenteric plexus that innervates the sphincters [5]. Only few published studies have addressed the anorectal function of patients before and after radiotherapy for prostate cancer. Yeoh et al. first investigated the change of anorectal function and showed a statistically significant difference in both the anal sphincter resting and squeeze pressures (resting pressure 54 mmHg before vs. 49 mmHg after; squeeze pressure 111 mmHg before vs. 102 mmHg after) at 4–6 weeks after radiotherapy [6]. Yeoh et al. also demonstrated a reduced rectal volume at threshold sensation (36 mL at baseline vs. 22 mL at 1 year) 1 year after radiotherapy [7]. The same authors demonstrated a reduction of both sphincter resting and squeeze pressures and a decrease in rectal volume at threshold and urge sensation at 2 years after radiotherapy [8]. However, the precise mechanism is not known and the relationship between dose-volume parameters and the severity of AI symptoms has not been fully established.

Overall, the incidence of soiling and AI after external beam radiotherapy has been reported to be 58% and 57% at 3 years, respectively, and 5% of patients have a moderate to severe complaint [5, 9].

Viani et al. reported that intensity-modulated radiotherapy (IMRT) reduced the delivery of significant radiation doses to the bladder and rectum using a similar target volume compared to three-dimensional conformal radiotherapy (3DCRT). This dosimetric advantage resulted in a lower rate of acute/late grade ≥ 2 gastrointestinal toxicity (such as AI) for IMRT compared with 3DCRT (7% vs. 24%, respectively) [10].

Commonly, AI presents during or shortly after radiotherapy. However, it may be persistent as a late radiation-related event and often does not resolve spontaneously. It has been reported that development of bowel symptoms during the acute phase of radiotherapy (up to 120 days post-treatment) is a predictor of the same problems in the medium to long term [9].

Studies show that it may still persist at 15 years after external beam radiotherapy in 20% of patients [11]. Some studies reported the new onset of AI at 2 years after radiotherapy while others reported an incidence gradually increasing throughout the follow-up period [12, 13].

Studies comparing the outcome and complications of RP alone, radiotherapy alone, or RP combined with radiotherapy for locally advanced prostate cancer, reported that the likelihood of RP patients developing bowel urgency was lower than those who had received radiotherapy alone [5].

It has been hypothesized that the radiation dose influences rectal damage and the severity of rectal toxicity. However, available studies evaluating the relationship of radiation dose and occurrence of AI have given contradictory conclusions.

Syndikus et al. found that the impairment of the subjective perception of sphincter control was higher in the group treated with dose-escalated conformal radiotherapy (74 Gy) compared to standard conformal radiotherapy (64 Gy), with a hazard ratio of 9.25 for incontinence [14].

In their large prospective study of conformal radiotherapy, Fellin et al. found only correlation between late rectal bleeding and dose–volume histogram parameters and failed to find a statistically significant relationship between the dose–volume histogram parameters and AI 3 years after the treatment [15].

The incidence of AI has been reported to be similar in patients treated with brachytherapy. A study on prostate cancer patients receiving high-dose brachytherapy showed 11–25% of patients reporting symptoms of AI that did not remit throughout the follow-up-period up to 88 months [16, 17].

Treatments for AI after radiotherapy include topical phenylephrine, an alpha1-adrenoceptor agonist that has been shown to increase internal anal sphincter pressures. Use of the phenylephrine gel was reported to improve incontinence scores in a small retrospective case series in which half of the patients had been treated for prostate cancer. However, the clinical significance of its efficacy is debatable as only half of the patients in the study felt the gel was of use [18].

2.2 Anal Incontinence Following Radical Cystectomy for Bladder Cancer

Radical cystectomy (RC) followed by a urinary diversion is the gold standard for localized muscle-invasive bladder cancer. During RC the entire bladder is removed, and it is recommended that this is combined with pelvic lymphadenectomy. Parts of the intestines may be used to create a urinary diversion.

Long-term bowel disorders after RC are an underestimated issue. Available data demonstrate that, overall, about 30% of the subjects undergoing RC report problems with the physiological emptying process of stool including bowel movement, awareness of need for defecation, motoric rectal and anal function, sensory rectal function, and straining ability [19]. Patients undergoing RC also complain of problems with sensing and controlling the rectum leading to a sense of decreased stool evacuation capacity, difficulties in the initiation of the emptying reflex and decreased straining capacity. Moreover, increased defecation frequency, urgency, leakage, soiling and flatulence also occur among these patients [19].

Nerve dysfunction due to direct surgical damage to nerves or altered metabolism (e.g., malabsorption of electrolytes and vitamins), as well as deficient physiological function of the pelvic floor muscles caused by direct injury to the muscles or nerves, may contribute to AI after RC [20].

Thulin et al. evaluated long-term defecation disturbances in patients who had undergone RC for bladder cancer [19]. Of all 452 patients with urinary diversion, 35 (8%) reported fecal leakage and 33 (7%) reported soiling at least every month. Moderate and much bother by the fecal leakage was reported by 31% (17 of 54) of those with noncontinent urostomy, 70% (19 of 27) of those with continent reservoir and 44% (25 of 57) of those with orthotopic neobladder. Bother due to soiling was correspondingly reported by 35% (16 of 46) of those with noncontinent urostomy, 70% (14 of 20) of those with continent reservoir and 51% (25 of 49) of those with orthotopic neobladder [19].

Henningsohn et al. compared patients with continent cutaneous reservoirs and noncontinent urostomies (conduits) with baseline data from a matched control group [20]. The incidence of fecal leakage was statistically significantly increased after RC compared to the control population with relative risks of 6.2 (95% CI 2.4–16.0) and 4.2 (95% CI 1.3–14.1) for fecal leakage in patients with noncontinent urostomy and continent reservoir, respectively [20].

Frees et al. evaluated stool habits in patients who underwent continent cutaneous diversion using the ileocecal segment (Mainz pouch I [MzPI]) with an intussuscepted ileal nipple as efferent segment with those receiving an ileal conduit (IC) after radical cystectomy [21]. An increased stool frequency was reported in 60% of patients with MzPI as compared to 38% with IC. Soft stool consistency was reported in 31% of patients with MzPI compared to 2% with IC. Moreover, Frees et al. reported higher rates of diarrhea in patients with MzPI vs. IC (62% vs. 20%) [21].

3 Coexistence of Anal Incontinence and Lower Urinary Tract Symptoms

Experimental human and animal data suggest that the bladder and distal colon interact under both normal and pathological conditions. Pathological alterations in one of these organs may induce the development of cross-organ sensitization in the pelvis and may be responsible for clinical comorbidity of genitourinary and gastrointestinal tract dysfunctions [22].

AI has been associated with lower urinary symptoms including urgency, frequency, and urge incontinence [22]. Data from large trials showed a parallelism between lower urinary tract symptoms and lower gastrointestinal symptoms. The EPILUTS study of 2160 individuals indicated that both men and women with overactive bladder were much more likely to have AI than patients without overactive bladder symptoms [23]. Logistic regression controlling for demographic factors and comorbid conditions confirmed that overactive bladder status was a very strong predictor of AI [23].

In a community-based study, the prevalence of combined anal and urinary incontinence was reported at 6–9% [24]. Furthermore, the age-adjusted relative odds ratio of AI among women with urinary incontinence was 1.8 [22]. In a group of patients with urinary incontinence, complaints of AI and constipation were found more often than in a control group [25]. Khullar et al. interviewed 465 women attending a urodynamic clinic and provided them with a detailed bowel questionnaire to investigate their urinary and bowel symptoms. The reported incidence of AI was 15.3% and 26% on direct questioning and on the postal questionnaire, respectively [26].

AI was more common in women with a urodynamic diagnosis of detrusor instability than among women diagnosed as having genuine stress incontinence (30% vs. 21%, respectively) [26]. Soligo et al. investigated the prevalence of AI in 504 women referred to an outpatient urogynecology clinic and evaluated the relationship between lower urinary tract dysfunction and AI. Overall, 0.2% of patients were anally incontinent. Women with double incontinence showed higher scores for urinary urgency, which reached the established level of significance only in the subgroup with urge AI. Interestingly, a higher prevalence of detrusor overactivity was observed in this group [27]. Manning et al. evaluated whether patients with lower urinary tract dysfunction have concomitant AI when compared with age- and gender-matched community controls and whether they have predisposing factors that have led to lower urinary tract symptoms and concomitant AI. Both frequent and occasional AI were significantly more prevalent among all cases than among community controls (5% vs. 0.72% and 24.6% vs. 8.4%, respectively). Although symptoms of fecal urgency and anal urge incontinence were significantly more prevalent among those with a urodynamic diagnosis of detrusor instability, AI was not significantly more prevalent among females with genuine stress incontinence (5.1%) when compared with females with detrusor instability (3.8%) or any other urodynamic diagnosis [28].

Although these findings suggest a shared pathophysiology for lower urinary tract and gastrointestinal tract dysfunction, further studies are needed to determine if successful treatment of one or more of these conditions is accompanied by commensurate improvements in symptoms referable to the other organ system [23].

4 Urinary Tract Infections in Patients with Anal Incontinence

AI is considered a risk factor for urinary tract infections. Patients with AI have been reported to develop urinary tract infections almost three times as frequently as their anal-continent counterparts. The majority of the isolates found in urine cultures of the sample population are normally present in the gastrointestinal tract [29].