Gastroenterology and Hepatology Board Review: Pearls of Wisdom, Third Edition
Section V LARGE INTESTINE
CHAPTER 29. Disorders of the Pelvic Floor and Anorectum
Yehuda Ringel, MD
True/False: Hemorrhoidal disease is more frequently associated with constipation than with diarrheal disorders.
False. Studies suggest that hemorrhoidal disease is more frequently associated with diarrheal disorders.
Describe the classification of internal hemorrhoids according to their clinical severity.
Internal hemorrhoids are classified according to their degree of protrusion and prolapse as follows:
Procidentia refers to complete prolapse of the rectum. What are other forms of rectal prolapse?
Procidentia involves visible protrusion of all the rectal layers through the anus. Two other forms of rectal prolapse are mucosal prolapse in which only the distal rectal mucosa protrude through the anus and occult rectal prolapse, which refers to internal intussusception of rectal tissue without visible protrusion through the anus.
A 62-year-old female patient complains of a mass that intermittently protrudes through her anus. What is the differential diagnosis?
Prolapsing internal hemorrhoids, anorectal varices, mucosal prolapse, rectal prolapse, anal/rectal polyps, anal/rectal tumors, and hypertrophic anal papillae.
True/False: Cirrhotic patients usually develop hemorrhoidal disease secondary to portal hypertension.
False. Anorectal varices, not hemorrhoids, develop as a result of portal hypertension. They represent the communication between the portal circulation through the superior hemorrhoidal veins and the systemic circulation through the middle and inferior hemorrhoidal veins.
True/False: The classic endoscopic appearance of solitary rectal ulcer syndrome is a shallow, discrete 1–4 cm ulcer located at the posterior wall of the rectum 4–15 cm from the anal verge.
False. The name is a misnomer. The appearance in many patients with this condition includes multiple ulcers, hyperemic mucosa, or a polypoid lesion(s). In addition, although the lesion(s) may be found on the posterior wall of the rectum, they are more commonly located on the anterior wall of the rectum.
What functional and morphological abnormalities can be associated with solitary rectal ulcer syndrome?
Solitary rectal ulcer syndrome is associated with some form of rectal redundancy and prolapse or mucosal prolapse and thicker muscularis propria in the rectal wall. The condition is commonly associated with high anal sphincter pressure, failure of the puborectalis to relax during defecation, and persistent straining and delayed rectal evacuation. Biofeedback treatment may improve rectal blood flow and help ulcer healing.
What conditions predict a favorable response to biofeedback (pelvic floor retraining) therapy for fecal incontinence?
The ability to contract the external sphincter during squeezing, some degree of rectal sensation, cooperative patient (ie, no cognitive impairment, mental retardation, dementia, or psychosis), and no evidence of complete denervation on electromyography.
True/False: Anal and rectal carcinomas are more common in men.
False. Rectal carcinoma is more common in men, whereas anal canal tumors are nearly twice as common in women.
True/False: Because of the anus’ location at the very distal part of the gastrointestinal tract and its easy accessibility for digital examination, anal canal tumors produce symptoms early in the course of the disease and are usually diagnosed at an early stage.
False. In about 60% of the patients with anal canal tumors, the tumor is discovered late. Indeed, 15%–30% of patients are found to have metastatic spread at presentation. The symptoms are usually mild and nonspecific. Approximately 25% of patients with anal canal tumors are symptom-free and the tumor is found incidentally during a routine examination.
True/False: Adenocarcinoma is the most common malignant tumor of the anal canal.
False. The most common tumor of the anal canal is squamous cell carcinoma (70%–80%). Adenocarcinoma is a rare tumor of the anal canal.
True/False: Most benign, idiopathic anal fissures develop in the posterior midline of the anal orifice and often have a skin tag at the external edge and/or hypertrophied anal papilla at the internal edge.
True. Benign, idiopathic anal fissures commonly develop in the posterior midline. Fissures in lateral or anterior position, presence of warning signs, and appearance in older age should raise concern and may require further evaluation.
What is the rationale for the management and the treatment options for chronic anal fissure?
Therapy aims to break the cycle of pain, spasm, and ischemia thought to be responsible for the development of the fissure. Goals of treatment include pain relief, relaxation of the internal anal sphincter, and institution of atraumatic passage of stool. Available treatment options include:
• Bulking agents and stool softeners.
• Warm Sitz baths two to three times a day.
• Conservative medical treatment includes topical nitroglycerin, topical nifedipine or diltiazem, and botulinum toxin injections. In one study, the injection of botulinum toxin into the internal anal sphincter was found to be more effective than topical application of 0.2% nitroglycerin ointment.
• Surgical treatment. Lateral internal sphincterotomy is reserved for fissures that have failed medical therapy.
A meta-analysis of four randomized trials found superior fissure healing with surgery over topical nitroglycerin treatment.
True/False: Pruritus ani is a relatively common symptom and a careful evaluation usually reveals the underlying etiology and leads to effective and successful treatment.
False. The differential diagnosis of pruritus ani is relatively wide. The symptom may be secondary to a variety of local or dietary irritants, medications, and a wide range of disease conditions including anorectal diseases (eg, fistula, fissure, prolapse), diarrheal conditions (eg, Crohn’s disease, ulcerative colitis, IBS), systemic disorders (eg, diabetes mellitus, Hodgkin’s lymphoma), dermatologic conditions (eg, psoriasis, seborrhea, atopic dermatitis), infections (eg, pinworm, Candida, Herpes simplex, HIV), and neoplasms (eg, extramammary Paget’s disease, squamous cell carcinoma, Bowen’s disease). There are no guidelines regarding the optimal diagnostic approach and, in the majority of the patients, the cause of pruritus ani remains unknown.
What is the prevalence of fecal incontinence?
The prevalence of fecal incontinence in the Western Hemisphere is 2%–7% and increases with age. Surveys have shown prevalence rates of 18% in the older female population and 45%–47% in nursing home residents and hospitalized elderly patients.
What information can be obtained from anorectal manometry?
Anorectal manometry provides an objective measure of anal sphincter and rectal function at rest and during defecatory maneuvers. This includes measurements of anal sphincter tone (at rest, during squeezing and during increase in intra-abdominal pressure), rectal sensation thresholds, and rectal compliance. It also provides information about anorectal reflexes that are important in continence and defecation processes.
What is the rectoanal inhibitory reflex (RAIR)? Why is it important and in which conditions is it typically absent?
The RAIR refers to the decrease in internal anal sphincter resting pressure that occurs in response to rectal balloon distension that is performed during anorectal manometry. This reflex, mediated by the myenteric plexus, plays an important role in the sampling and discrimination of rectal contents. Rectal distension also induces a pelvic splanchnic and pudendal nerve-mediated contractile response for the external anal sphincter—the rectoanal contractile reflex (RACR)—that prevents release of rectal contents. Absence of the RAIR should raise suspicion of Hirschsprung’s disease, megarectum, structural damage to internal anal sphincter, or a tonically contracted external anal sphincter.
Describe the imaging techniques available for clinical use in the evaluation of anorectal disorders and the information that can be obtained from each test.
• Endoscopic anal ultrasound is helpful in assessing the integrity of the anal sphincters. Endoanal ultrasound (EAU) is not helpful in the assessment of anal function.
• Evacuation proctography (defecography) is useful for assessing the defecation process. It can provide important information on functional parameters (eg, anorectal angle at rest and during straining, perineal descent, puborectalis contraction/relaxation, degree of rectal emptying, and retained stool) as well as abnormal anatomy (eg, pelvic organ prolapse, rectocele, and enterocele).
• Magnetic resonance imaging (MRI) with rapid sequences. Performed in specialized referral centers, this test can visualize both anal sphincter anatomy and global pelvic floor motion in real-time without radiation exposure. MRI can also identify atrophy of the external sphincter and puborectalis which may be found in some patients with fecal incontinence.
What are the differences between the internal and external anal sphincters and their role in maintaining continence?
The internal anal sphincter is composed of smooth muscle and is under the control of the enteric nervous system. Its main function is to maintain the resting tone of the anal sphincter. The external anal sphincter is composed of striated muscle innervated by the pudendal nerve (sacral branches S2 to S4) and is under voluntary control. The main role of the external anal sphincter is to contract voluntarily in response to a sudden increase in rectal or abdominal pressure so as to prevent inappropriate defecation.
What is the relative contribution of the internal and external anal sphincter muscles to the resting anal tone?
About 70% of the anal canal resting tone is derived from the internal anal sphincter and the remainder by the external anal sphincter muscle.
A manometric evaluation in a patient with fecal incontinence reveals a failure to increase anal sphincter pressure when asked to squeeze but a normal increase in pressure in response to coughing. Besides poor motivation or comprehension, what is the most probable explanation?
An increase in external anal sphincter pressure in response to an abrupt increase in intra-abdominal pressure is triggered by receptors in the pelvic floor and mediated through a spinal reflex arc. Lesions of the cauda equina or sacral plexus will result in loss of both the reflex response and the voluntary squeeze. Higher spinal cord lesions may result in the findings described in the question.
What are the treatment options for patients with fecal incontinence?
• Conservative measures including diet changes, skin care, and occasionally, antidiarrheal medications.
• Biofeedback therapy using a rectal balloon with anal manometry or a surface electromyography device. Patients are taught to contract the external anal sphincter when they perceive balloon distention. Patients can also be trained to increase their perception of rectal distention.
• Sacral nerve stimulation, a recent FDA-approved implantable device for treating urinary, and fecal incontinence. This is a staged procedure that involves a trial of temporary external stimulation for 3 weeks followed by permanent implantation of the device subcutaneously if improvement is noted during the temporary stimulation.
• Surgical options for patients with anal sphincter defects not responding to conservative management include anal sphincteroplasty, artificial anal sphincter, and dynamic graciloplasty. Diverting colostomy may be considered in patients who have failed all other options.
What are typical findings on physical examination and anorectal manometry in patients with proctalgia fugax?
Proctalgia fugax is one of the functional disorders of the anorectum. The diagnosis is based on symptoms alone. There are no specific findings on physical examination or anorectal manometry testing.
A 40-year-old female complains of recurrent episodes of dull “pressure-like” pain in the rectum that last for hours and are often brought on by sitting or lying down. Posterior traction of the puborectalis on rectal examination produces tenderness and pain. What is the diagnosis?
The description is typical of levator ani syndrome. This syndrome is one of the functional disorders of the anorectum. The diagnosis is based on the presence of characteristic symptoms and tenderness and discomfort on puborectalis palpation during rectal examination. Evaluation is often required to exclude alternative diseases.
True/False: Levator ani syndrome and proctalgia fugax frequently coexist.
True. Although the two disorders can be distinguished on the basis of duration, frequency, and quality of pain, they coexist more often than expected by chance.
What are functional defecation disorders? Name two recognized subtypes of these disorders.
Functional defecation disorders describe important etiologic subtypes of functional constipation that involve delayed or obstructed defecation that may coexist with slow colonic transit. The multinational working team (Rome Committee) defines two subtypes of functional defecation disorders: Dyssynergic defecation characterized by paradoxical contraction or inadequate relaxation of the pelvic floor muscles during attempted defecation and inadequate defecatory propulsion characterized by inadequate rectal propulsive forces during attempted defecation.
True/False: The multinational working team (Rome Committee) recommends that the diagnosis of functional defecation disorders be based on symptoms of constipation and abnormal diagnostic anorectal physiological tests including manometric, electromyographic, and/or radiologic evidence of failure of the pelvic floor to relax when attempting to defecate.
True. The rationale for these diagnostic criteria is based on the recognition that symptoms alone do not consistently distinguish patients with functional defecation disorders from those without. Thus, to meet the diagnostic criteria for functional defecation disorders, patients must satisfy diagnostic criteria for functional constipation and have at least two of the following:
• Evidence of impaired evacuation, based on balloon expulsion test or imaging.
• Inappropriate contraction of the pelvic floor muscles or less than 20% relaxation of basal resting sphincter pressure by manometry, imaging, or EMG.
• Inadequate propulsive forces assessed by manometry or imaging.
True/False: Digital rectal examination is a reliable way to identify dyssynergic defecation in patients with chronic constipation.
True. Studies have shown that digital rectal examination is a reliable tool (75% sensitivity, 87% specificity, and 97% positive predictive value) for identifying dyssynergia in patients with chronic constipation. It can also detect normal, but not abnormal, sphincter tone. Digital rectal examination may be useful to direct the selection of appropriate patients for further physiologic testing and treatment.
True/False: The majority of patients with pelvic floor dyssynergia will benefit from biofeedback (pelvic floor retraining) treatment.
True, when performed in experienced centers. Approximately two-thirds of these patients can learn to relax the external anal sphincter and puborectalis muscles with biofeedback training and report associated decreases in both straining during defecation and the feeling of incomplete evacuation.
True/False: Rectocele and mucosal intussusception are commonly present in healthy, asymptomatic individuals.
True. Rectocele, mucosal prolapse, and rectal intussusception have been commonly reported in healthy asymptomatic subjects. Therefore, these findings should be interpreted with caution since they may not necessarily suggest a causal relationship with defecation disorders.
True/False: Pelvic floor descent can be evaluated on physical examination.
True. With the patient in the left lateral decubitus position, the level of the perineum relative to the ischial tuberosities is observed. With the patient straining, the perineum should not descend beyond the outlet of the bony pelvis.
True/False: Fecal impaction can be definitively excluded by digital rectal examination.
False. Digital rectal examination can miss 30% of fecal impactions in the elderly because a large amount of feces can accumulate above the reach of the examining finger.
What are the indications for evacuation proctography (defecography) in the evaluation of anorectal and pelvic floor disorders?
The American Gastroenterological Association Medical Position Statement on anorectal testing techniques suggests the use of evacuation proctography in patients with constipation in whom functional defecation disorders, enterocele or anterior rectocele, are suspected as the cause of impaired defecation. There is no support for the use of this technique for other purposes.
What are the clinical findings of anorectal syphilis?
Anal chancres in the skin around the anus, anal or rectal ulceration, and rectal lesions resembling carcinoma have all been described. Enlarged and tender inguinal lymph nodes are often present. Serologic tests for syphilis should be performed prior to surgery for any atypical rectal lesion.
True/False: Vesicles on the perianal region and within the anal canal are commonly seen in anorectal herpes infections.
False. Although perianal vesicles are a characteristic finding in anorectal herpes infection, they are uncommon within the anal canal. Ulcerations of the anal canal are more commonly seen in anorectal herpes infection.
True/False: The intersphincteric space is the most common anatomic location of anorectal abscesses.
False. Perianal abscesses located just beneath the perianal skin are most common.
True/False: In at least one-half of ulcerative anal lesions in HIV-positive patients, no specific cause is found.
True. Diagnostic considerations include syphilis, tuberculosis, Mycobacterium avium-intracellulare, herpes simplex, cytomegalovirus, fungi, and neoplasm.
True/False: Anogenital condylomata acuminata caused by human papillomavirus (HPV) is associated with adenocarcinoma of the anus.
False. HPV (types 16 and 18) is associated with squamous cell carcinoma of the anus as well as the cervix and vulva. Condylomata acuminata and anal cancer may coexist; thus, it is advisable to obtain biopsies from suspected lesions and examine the anal canal before beginning treatment.
What is anal sampling and how is it related to the continence mechanism?
The anal canal is highly innervated and sensitive to pain, touch, and temperature. This allows differentiation between gas, solids, and liquids and allows for selective passage of rectal contents or voluntary contraction of the external anal sphincter to maintain continence. Loss of this anal sampling function may contribute to the development of fecal incontinence.
True/False: The most common cause of primary anorectal abscess and anorectal fistula is Crohn’s disease.
False. The most common cause of primary anorectal abscess and fistula is primary infection of anal cryptoglandular tissue. Other conditions that can be associated with anorectal abscesses and fistulae include Crohn’s disease, proctitis, and anorectal cancer.
What is the most common type/location of an anorectal fistula?
True/False: EAU and MRI are the most useful tests to diagnose an anorectal fistula.
True. EAU and MRI have been shown to be highly accurate in identifying a fistula and describing its anatomy. EAU is more easily performed and less expensive than MRI; however, it is also more difficult to perform in patients with severe anal pain. The modality of choice depends on local expertise, cost, and patient convenience.
True/False: A broad-spectrum antibiotic is the treatment of choice for an anorectal abscess.
False. The primary treatment of an anorectal abscess is surgical incision and drainage. Except in patients with diabetes mellitus, leukemia, and valvular heart disease, antibiotics are usually not required.
True/False: Up to 30% of women will have an anal sphincter defect on endoanal ultrasonography after their first vaginal delivery.
True. In addition, about 10% will complain of urgency or incontinence.
• • • SUGGESTED READINGS • • •
Bharucha AE, Wald A, Enck P, Rao SS. Functional anorectal disorders. Gastroenterology. 2006;130:1510-1518.
Whitehead WE, Bharucha AE. Diagnosis and treatment of pelvic floor disorders: what’s new and what to do. Gastroenterology. 2010;138:1231-1235.
Rao SS. Advances in diagnostic assessment of fecal incontinence and dyssynergic defecation. Clin Gastroenterol Hepatol. 2010;8: 910-919.
Camilleri M, Bharucha AE, Di Lorenzo C, et al. American Neurogastroenterology and Motility Society consensus statement on intraluminal measurement of gastrointestinal and colonic motility in clinical practice. Neurogastroenterol Motil. 2008;20:1269-1282.