Medical and surgical management of pelvic floor disorders affecting defecation.

Three-dimensional endoanal ultrasonography (3D-EAUS) provides excellent anatomical details of the anal sphincter complex, including coronal and segmental sections. It is well-tolerated and inexpensive. The sphincter anatomy can be evaluated spatially, and "damaged" sphincter integrity and volume, as well as fistulous track(s) or potential fluid collections can be assessed 21 .

MR Defecography (MRD) visualizes the pelvic viscera and supporting soft-tissue structures without radiation but not widely available. It can be performed with a closed or open system. Open MRI acquires images in a sitting position, simulating true defecation. In a closed-configuration MRI system, images are acquired in the supine position 22 . A recent study demonstrated that Dynamic MRD with an open-configuration and low-field tilting MR system is feasible 23 .

Pelvic floor disorders are common and cause significant bowel problems. The pelvic floor is a complex muscular apparatus within the pelvis and serves defecation, micturition, and sexual function. The most common pelvic floor disorders are fecal and urinary incontinence and pelvic organ prolapse. Approximately 23.7% of women have at least one pelvic floor disorder and 2.9% pelvic organ prolapse 1 . Here, we focus on recent advances in the management of pelvic floor disorders affecting defecation, with a brief overview of pathophysiology and diagnosis. These disorders affect both women and men and necessitate a multidisciplinary team approach involving colorectal surgeon, gastroenterologist, pain specialist, physical therapist, radiologist, urogynecologist, and urologist.

The pelvic floor has superficial and deep muscle layers that interlace and envelope the rectum, bladder and uterus. The superficial layers include the internal anal sphincter (IAS) and external anal sphincter (EAS), perineal body, and transverse perinei muscles 2 . The deeper pelvic muscles, also known as levator ani, consist of the pubococcygeus, ileococcygeus, and puborectalis. The puborectalis maintains anorectal angulation and creates a mechanical barrier for stool flow and maintains pelvic floor integrity and its disruption/dysfunction may cause common pelvic floor disorders 3 , 4 . The pelvic floor receives nerve supply from the pudendal and perineal nerves and sympathetic and parasympathetic nerves. Branches from the sacral nerve roots of S2, S3, and S4 innervate the pelvic floor muscles. The puborectalis muscle (middle layer of pelvic floor muscle) is actually innervated by the pudendal nerve and the deep muscles (pubococcygeus, ileococcygeus, and coccygeus) are innervated by the direct branches of sacral nerve roots S3 and S4. [3] Pudendal nerve damage may cause dysfunction of puborectalis muscle and EAS muscles (both constrictor muscles) and this in turn may cause fecal incontinence. During normal defecation, the voluntary effort of bearing down increases the intra-abdominal pressure, together with the contraction of the rectum and perineal muscles. Simultaneously, the anal sphincters and puborectalis relax, the anorectal angle widens, and the perineum descends. These sequential movements facilitate the movement of stool from the rectum resulting in stool evacuation. ( Figure 1 ).

Rectal prolapse is defined as an abnormal protrusion of all layers of the rectal wall through the anus. The incidence is 2.5/100,000, with the highest incidence among elderly women. In younger people, the gender ratio is equal 37 . The primary mechanism is excessive straining, that over many years gradually weakens the pelvic floor and its support structures. The repeated injury to the pudendal nerve and other nerves weakens the IAS and EAS and the puborectalis. The lax anal sphincters offer very little counter-acting resistive force during defecation, thereby leading to an abnormal protrusion of the rectal wall through the anus. Other causes for prolapse include pudendal neuropathy from either aging or obstetric injury. Most patients present with anal protrusion and/or passage of blood, or symptoms of obstructed defecation or fecal incontinence 38 . Pre-existing dysmotility, DD, or intussusception also predispose. Anal inspection may reveal normal anal area but when the patient bears down the prolapsed rectum is visible, often edematous and sometimes with a friable and ulcerated mucosa. Rectal prolapse is graded into four types: grade 1=up to anal verge; grade 2=prolapse outside the anus but reduces spontaneously; grade 3=prolapses outside the anus but can be manually reduced; and grade 4=prolapse cannot be reduced manually.

This provides information regarding the ability to expel a 50-ml water-filled balloon placed in the rectum. Normal expulsion time is one minute. It has 80–90% specificity and 97% negative predictive value for identifying dyssynergia. Although it has a sensitivity of only 50%, it is a simple and useful screening procedure to identify constipated patients who do not have dyssynergia 16 .

Colonic transit scintigraphy is indicated in patients with suspected colonic motility disorders or more diffuse disorders involving the stomach or small intestine. It quantifies slow colonic transit in patients with constipation and can influence patient management. Two methods have been described: 1. Colon transit of 111 In DTPA-labeled water consumed in a standard solid-liquid meal for gastric scintigraphy 2. A capsule (containing 111 In adsorbed on activated charcoal) coated with the pH-sensitive polymer methacrylate that dissolves in the alkaline terminal ileum, releasing the radioisotope into the lumen. The clinical utility of scintigraphic testing has been demonstrated in previous studies. The colonic transit scintigraphy is recommended for assessing colonic transit in patients with constipation or diarrhea but is available in a limited number of centers 18 .

Digital rectal exam (DRE) is a useful bedside screening tool. The exterior inspection can detect skin excoriation, squamous cell cancer, skin tags, anal fissures, fistulas or hemorrhoids. The perineal sensation (to exclude neuropathy) is evaluated by gently stroking the perianal skin with a cotton bud in all four quadrants. Digital penetration may reveal a stricture, spasm, tenderness, mass, blood or stool. If there is a lack of awareness of stool in the rectum this may suggest rectal hyposensitivity. Primarily, the resting tone is evaluated, followed by asking the subject to squeeze it is possible to evaluate the anal sphincter and puborectalis muscle. The patient is asked to push and bear down as if to defecate, and during this maneuver, the examiner should perceive relaxation of the external anal sphincter and/or the puborectalis muscle, together with perineal descent. An absence of these normal findings should raise the index of suspicion for an evacuation disorder such as dyssynergic defecation. DRE has a sensitivity of 77% and specificity of 87% for detecting dyssynergia 7 , but is infrequently performed, even by gastroenterologists, and there is lack of training 8 .Thus, a concerted effort is needed to improve the training of digital rectal examination.

Solitary rectal ulcer syndrome (SRUS) is characterized by erythema and single/few ulcers. Its etiology remains obscure but is often associated with evacuation disorders. The annual incidence of SRUS is 1–3.6/100,000; 80% of patients are less than 50 years of age 72 with slightly higher prevalence in females. Rectal intussusception is often present and evacuation is delayed 73 , 74 . Ulceration is thought to occur during repeated forceful straining against an immobile pelvic floor or DD together with trauma from digital manipulations and ischemic necrosis of the prolapsing rectal mucosa 75 . Patients present with rectal bleeding and/or pain, mucus discharge, straining and tenesmus and a feeling of incomplete evacuation. Majority use digital maneuvers but rarely admit. About 55% present with constipation, 20–40% with diarrhea, and 25% are asymptomatic, and 25% are misdiagnosed or treated as inflammatory bowel disease. In some patients, an underlying psychologic disorder, such as obsessive-compulsive disorder may be present 74 .

The Wireless Motility Capsule (WMC) (Smart Pill Corporation, Buffalo, NY), is a wireless pH, temperature and pressure recording capsule. This novel, valuable ambulatory technique of assessing regional (gastric, small bowel, colonic) and whole-gut transit time without radiation offers a standardized method of identifying normal and slow colonic transit 18 – 20 and recommended as useful by the American Neurogastroenterology & Motility Society. Currently the FDA has approved the SmartPill GI Monitoring System, version 2.0, for the evaluation of colonic transit time in patients with suspected chronic constipation, and for evaluating patients with suspected gastroparesis.

This test provides information regarding rectal and anal pressures at rest and during simulated defecation. During rectal balloon distention it provides information regarding rectal compliance and sensation, and recto-anal reflexes 10 . Normal subjects can exhibit dyssynergia when attempting to defecate in the left lateral position; hence manometric changes are best assessed with the patient on a commode and with a sensation of stooling 11 , 12 . The best method to diagnose dyssynergia is to distend a balloon in the rectum and ask the subject to attempt evacuation in a sitting position 13 , 14 . Four patterns of dyssynergia have been described, and their identification helps tailor biofeedback therapy. Type I is adequate push effort with paradoxical anal contraction, type II is impaired push effort with paradoxical anal contraction, type III is impaired anal relaxation with adequate push effort, and type IV is impaired push effort with impaired anal relaxation. These patterns were established with the conventional manometry, which is very useful and still widely used in many centers. The new HRM system, (Sierra Scientific Instruments, Los Angeles, CA) allows interpolation of manometric recordings from 12 circumferential pressure sensors into a detailed topographical plot. This system can provide a greater resolution of the intraluminal pressure changes with more anatomical detail, hopefully leading to a better assessment of common pelvic floor disorders 15 . ( Figures 2A, 2B )

Sigmoidoscopy may reveal a small, shallow ulcer with a white slough or hyperemic mucosa on the anterior wall of the rectum ( Figure 5 ). The lesions can be multiple (30%), ulcerated (57%), polypoid (25%) or with patches of hyperemic mucosa (18%). SRUS is usually found on the anterior or anterolateral wall of the rectum, over a rectal fold, about 5–10cm from anus 76 . Histologically, the mucosa appears elongated with distorted glands at the base, with an edematous fibroblast-rich lamina propria and thickened inner circular muscular layer 77 . When the glands migrate down to the submucosa, bleeding may occur. Pathognomonic features in SRUS include: decussation of the two muscularis layers, nodular induration of the inner layer, and grouping of outer longitudinal layers into bundles 78 . Biopsy is needed to differentiate SRUS from ulcers due to other etiologies (NSAIDs, malignancy, endometriosis) 79 , 80 . Defecography may show other abnormalities such as rectal mucosal intussusception in 45–80% of subjects. Barium enema is unreliable 81 . Anorectal manometry does not help in establishing the diagnosis or predicting therapeutic response; however, it may reveal a number of physiological abnormalities such as dyssynergia in 80% of patients or a hypersensitive rectum, and prolonged BET 82 . Ultrasonography may show marked thickening of the IAS, submucosa, and EAS, as well as rectal wall and muscularis propria 78 .

Rectocele is an abnormal sac-like protrusion of the rectal wall either towards the vagina (anterior) and rarely towards the sacrum (posterior) that often becomes apparent during defecation ( Figure 3A, 3B ). It is common in adult women (20%), majority are small (<2 cm), asymptomatic, and require no treatment 49 , 50 . Rectocele is believed to be caused by weakness of the rectovaginal septum and/or pelvic floor; however, the exact etiology is not known. Obstetric injury and multiple vaginal deliveries have been proposed as precipitating factors. However, rectocele is also seen in nulliparous women 37 , 51 . There are no specific anorectal physiological findings for a rectocele, a previous study had reported that dyssynergic pattern of defecation was seen in 60% of patients with rectocele when compared to 24% without a rectocele 52 . However, a recent study showed similar prevalence 53 . Rectocele can be a cause or consequence of CC with excessive straining, and may be associated with DD or rectal mucosal intussusception, or excessive perineal descent. Whether it is a cause or an effect of these changes is unclear 3 , 52 . Excessive straining or childbirth may weaken the vaginal septum. Consequently, during defecation a pressure gradient is created between the higher intrarectal pressure and lower vaginal pressure producing a rectocele. Rectocele is usually asymptomatic, and is diagnosed by examination or defecography. Patients may report symptoms such as a feeling of incomplete evacuation, prolonged straining, or vaginal splinting. Some report a vaginal or perineal bulge and others describe a sensation of blockage or inability to evacuate 37 . Patients may complain of dyspareunia, anorectal/vaginal pain, fecal soiling, and urologic symptoms 54 .

Descending perineum syndrome (DPS) is characterized by ballooning and excessive descent of the perineum, often several centimeters below the bony outlet of the pelvis, during straining 64 ( Figure 4 ). Typically, patients present with a long history of painful defecation, excessive straining, and sense of incomplete evacuation or fecal incontinence 65 . One study showed a link between DPS, fecal incontinence, and abdominal hysterectomy 66 . DPS can be diagnosed on physical examination, or defecography. The most common abnormality is >4 cm perineal descent at rest or ≥3 cm perineal descent during a maximal push effort 67 . A perineometer, which measures the strength of voluntary contractions of the pelvic floor muscles, may be useful 68 . Dynamic MR imaging demonstrates simple or complex organ descent in all pelvic compartments and may become standard preoperative evaluation for pelvic floor abnormalities. The MR images facilitate planning of surgery and can increase rate of successful outcome, but is expensive and not widely available 69 .

Behavioral therapy remains the mainstay of treatment and includes reducing excessive straining, spending less than 5 minutes during evacuation, and discontinuing the use of digital maneuvers. These recommendations, together with biofeedback therapy improved symptoms in 67% of patients with sigmoidoscopic improvement in 30% 76 . A high-fiber diet showed a variable response rate of 19–70%, suggesting that although diet helps by itself, it is insufficient. Local treatment with topical steroids and sulphasalazine is generally ineffective. Although there is limited data, sucralfate enemas and topical human fibrin sealant have been tried 83 . A recent study suggests that Argon plasma coagulation (APC) may be useful in controlling bleeding and improving healing of ulcers, but controlled studies are lacking 84 . Biofeedback therapy appears to be effective, although RCTs are scarce. One study showed that 75% (12/16) of patients had symptomatic improvement with biofeedback therapy and 31% (5/16) had ulcer resolution on sigmoidoscopy 85 . Mucosal flow improved in patients who felt subjectively better after biofeedback. Another prospective study of 11 patients with refractory SRUS showed that biofeedback therapy improved straining effort and stool frequency, digital maneuvers were discontinued in 45% and bleeding ceased in 56%. Ulcer healing was reported in 10 patients: 4 had complete healing, 2 had >50%, and 4 had <50% 75 . Rectopexy with or without anterior resection should be performed in highly selected cases. Outcomes of surgery are often disappointing, because of either persistent symptoms, postoperative bleeding or sexual dysfunction 86 , 87 . ( Figure 6 ).

This is the most effective treatment for DD. The main purpose is to restore a normal pattern of defecation using “operant conditioning” techniques 30 . The primary goals: (i) correct the underlying dyssynergia; and (ii) improve rectal sensory perception. The goals are to improve abdominal push effort, facilitate pelvic floor relaxation, and expel artifical stool. The procedure involves placing a manometric probe into the rectum which in turn provides instant feedback to the patient regarding their performance and how the rectal and anal muscles are behaving. About 10–15 maneuvers are usually attempted in a single session, and the number of sessions and duration of each session are customized. Typically 4–6 sessions, one hour each are performed. Several randomized controlled trials have demonstrated that biofeedback therapy is superior to sham feedback, standard therapy, or laxatives in the management of patients with DD 31 , 32 . It was not beneficial for patients with isolated slow transit constipation 33 . Recently biofeedback has been shown to provide sustained improvement of bowel symptoms and anorectal function for up to one year, whereas standard therapy with laxatives was ineffective 34 . Also, home biofeedback therapy was as effective as office biofeedback therapy and more cost effective 35 , 36 . Home biofeedback therapy comprised of home training. The patients were instructed to insert a disposable 2 sensor probe into the rectum. The probe is attached to an LCD display box and provides visual input to the subject regarding their performance. The patients practiced at home twice a day for 20 minutes per session. When home biofeedback therapy was compared with the standard treatment of office biofeedback, there was no difference between the two treatments with both treatments showing significant improvement in the number of complete spontaneous bowel movements per week, dyssynergia pattern, balloon expulsion time, and bowel satisfaction score. Currently this treatment is not covered by insurance and could cost up to $400/month which may limit its application. ( Table 1 ).

Pelvic floor disorders that cause difficulty with defecation are very common and predominantly affect women. A gastroenterologist or colorectal surgeon is best suited to evaluate and manage these problems but there is lack of experience and working knowledge of these conditions. Physiologic tests such as ARM, balloon expulsion test, and imaging such as defecography and MRI play a key role in objective diagnosis. Biofeedback therapy is an established treatment not only for patients with DD but also for others such as SRUS. Dyssynergia may also co-exist with other structural disorders such as SRUS or rectocele. Hence, before considering surgery, biofeedback therapy should be considered. Correcting the underlying pathophysiological dysfunction offers patients a better control of their symptoms. ( Figure 7 ). Several surgical approaches including open, laparoscopic, trans-abdominal approach, stapled transanal rectal resection, and robotic colon and rectal resections have been advocated, and may prove useful in selected cases, but lack randomized controlled trials and rigorous outcome measures.

Dyssynergic defecation (DD) is characterized by paradoxical anal contraction, inadequate anal relaxation, and/or impaired push effort caused by incoordination of abdominal, rectal, and anal muscles 5 . The most common symptoms are excessive straining (84%), feeling of incomplete evacuation (76%), abdominal bloating (74%), passage of hard stools (65%) and less than 3 bowel movements per week (62%). Digital maneuvers are frequent (~35%), although infrequently reported 6 .