Chapter 53 Anus

Disorders of the Anal Canal

The anal canal can be the site of rare lesions. Most conditions arising in this area, however, are common and benign but may be incapacitating and interfere with patients’ daily quality of life. Moreover, these disorders are often misdiagnosed or maltreated, leading at times to disastrous consequences. A better knowledge of the functional anatomy of this portion of the gastrointestinal tract, as well as recent changes in our understanding of its physiology and that of the pelvic floor, should facilitate diagnosis and management of these ailments and result in more favorable outcomes.

Anatomy

The anal canal, which extends for a distance of approximately 4 cm from the anorectal ring to the hairy skin of the anal verge, is the distalmost portion of the alimentary canal. Its lining, as well as its musculature, has important features that together with the pelvic floor structures, contribute significantly to the regulation of defecation and continence. Its borders include the coccyx posteriorly, ischiorectal fossa and its contents bilaterally, and perineal body and vagina in women and urethra in men anteriorly.

Anal Canal Musculature

The anal canal musculature, with its sphincteric apparatus, is the terminal muscular channel of the gastrointestinal tract and can be conceptualized as two tubular structures overlying each other. The inner component is the continuation of the smooth circular layer of the rectum forming the thickened and rounded internal sphincter, which ends 1.5 cm below the dentate line, slightly cephalad to the external sphincter (intersphincteric groove). The outer component is a continuous sheet of striated muscle constituting the pelvic floor, which is comprised of the levator ani muscle, puborectalis muscle, and external sphincter (Fig. 53-1). The latter is elliptical and engulfs the anal canal and internal sphincter, beyond which it terminates in a subcutaneous portion. The other two portions, the superficial and deep divisions, constitute a single muscular unit, which is continuous superiorly with the puborectalis and levator ani muscles. The external sphincter, bulbospongiosus, and transverse perineal muscles meet together centrally on the perineum and constitute the perineal body. The funnel-shaped configuration of the paired levator ani muscles form the major part of the pelvic floor and their fibers decussate medially with the contralateral side to fuse with the perineal body around the prostate or vagina.

FIGURE 53-1 The anal canal mechanism is comprised of two components, visceral and somatic, each of which is tubular. The visceral tube is enclosed by a skeletal muscle tube whereby continence is maintained. A, Diagrammatic representation of the skeletal muscle component. B, Composite arrangement after insertion of a simple visceral component.

(From Parks AG, Gordon PH, Hardcastle JD: A classification of fistula-in-ano. Br J Surg 63:1–12, 1976.)

The internal sphincter, which is innervated by the autonomic nervous system, is independent of voluntary control, whereas the external sphincter, which is supplied by the inferior rectal branch of the internal pudendal nerve and perineal branch of the fourth sacral nerve, is under voluntary control.

The epithelium that lines the anal canal incrementally transitions from normal, squamous, hair-bearing skin to gastrointestinal columnar epithelium in the short distance between the anal verge and top of the anal canal (Fig. 53-2). At the verge, the skin becomes anoderm, which is a modified squamous lining without skin appendages, such as hair. At the level of the dentate line, the squamous and columnar epithelium comingle; this is referred to as the anal transition zone. Finally, cephalad to the top of the anal canal, the lining becomes exclusively gastrointestinal columnar epithelium. These epithelial distinctions are helpful for understanding the basis and treatment of benign and malignant conditions. For example, fistulas developing from the condition of hidradenitis suppurativa can only arise from the appendages of skin, so this disorder can only occur below the dentate line, typically outside the anal verge. In contrast, fistulas that are derived from crypto glandular disease arise within the glands at the level of the dentate line and Crohn’s fistulas typically arise in the gastrointestinal tract above the dentate line. These distinctions help differentiate the diagnoses. For cancer cases, the histology is the key to understanding the likely origin, behavior, and management of the disease. Squamous cell lesions that arise in the anal margin skin or anoderm are treated with wide excision as skin cancers (margin lesions) or with radiation chemotherapy (anal canal). Adenocarcinomas arising in the distal rectum or within the anal canal are usually treated with surgical removal of the rectum, with the adjunctive use of radiation and chemotherapy.

FIGURE 53-2 The anal canal extends for a distance of 2 to 4 cm from the anal verge to the top of the anal canal musculature. The epithelium that lines the anal canal incrementally transitions from normal, squamous, hair-bearing skin to gastrointestinal columnar epithelium. Between the anal verge and dentate line, the lining is referred to as anoderm, and from the dentate line to the top of the anal canal it is referred to as the anal transition zone.

The lining also provides clues to the pattern of innervation or sensory perception and can help guide the appropriate surgical approach. External hemorrhoids below the dentate are sensitive to touch and therefore anesthesia (locoregional or general) is required for surgical management. Internal hemorrhoids above the dentate can be manipulated without the need for anesthesia, in a manner analogous to the treatment of gastrointestinal polyps.

Physiology

The physiology of the anal canal and pelvic floor is complex, but the advent of more sophisticated means to evaluate its functions (e.g., manometry, defecography, evacuability testing, electromyography) has improved our understanding of it. The principal function of the anal canal is the regulation of defecation and maintenance of continence. The ability to control defecation depends on the coordinated functions of the sensory and muscular activities of the anus, the compliance, tone, and evacuability of the rectum, the muscular activities of the pelvic floor, and the consistency, volume, and timing of the colonic fecal movements. Perturbations of any of the critical functions can result in fecal incontinence (Table 53-1).

Table 53-1 Common Causes of Fecal Incontinence

CATEGORY	MECHANISM	COMMON CAUSES
Functional	Fecal impaction; dilated internal anal sphincter	Pelvic floor dyssynergia (difficulty relaxing sphincter when defecating), drug side effect, idiopathic, spinal cord injury
	Diarrhea; rapid transit and/or large volume	Irritable bowel syndrome; infectious and metabolic causes of diarrhea
	Cognitive, psychological; social indifference	Dementia, psychosis, willful soiling
Sphincter weakness	Sphincter muscle injury	Obstetric trauma, motor vehicle accident, foreign body trauma
	Pudendal nerve injury	Obstetric trauma, diabetic peripheral neuropathy, multiple sclerosis, idiopathic
	Central nervous system injury	Spina bifida, traumatic spinal cord injury, cerebrovascular accident, multiple sclerosis
Sensory loss	Afferent nerve injury: unable to detect rectal filling	Diabetic neuropathy, spinal cord injury, multiple sclerosis

Adapted from Whitehead WE, Wald A, Norton NJ: Treatment options for fecal incontinence. Dis Colon Rectum 44:131–142, 2001.

The anal canal, which has a mean length of 4 cm, lengthens with squeezing of the external sphincter and shortens with straining. Resting pressure, or tone, which depends largely on the internal sphincter, averages 90 cm H₂O and is lower in women and older patients than in men and younger patients. This high-pressure zone increases resistance to the passage of stool. Squeeze pressure, generated by contraction of the external anal sphincter and puborectalis muscle, more than doubles the intra–anal canal resting pressure. This maximal increase lasts for a minute, at the most; consequently, squeeze pressure serves only to prevent leakage on presentation of the rectal content to the proximal anal canal at inappropriate times. The principal mechanism that provides continence is the pressure differential between the rectum (6 cm H₂O) and anal canal (90 cm H₂O). The anorectal angle is produced by the anterior pull of the puborectalis muscle as it encircles the rectum at the anorectal ring and contributes to fecal continence. This angle may act as a flap valve or have a sphincter-like function. Maneuvers that sharpen this angle augment continence, whereas those that straighten it favor defecation.

Anorectal sensation allows discrimination of the character of the enteric content—gas, liquids, or solids—and detection of the need to pass that content through sensory receptors located in the rectal muscular wall or pelvic floor musculature. The fact that such sensations persist after proctectomy and ileoanal anastomosis suggests that the receptors are situated in the pelvic floor. For the enteric content to reach the anal canal for discrimination, the internal sphincter must relax while the rectum distends and contracts, the rectal anal inhibitory reflex. This reflex involves inhibitory neurons of the myenteric plexus, which innervate the internal sphincter, and intramural nerves and neurotransmitters. Transient relaxation of the internal anal sphincter brings the rectal content into contact with the sensory mucosa of the proximal anal canal so that it can be recognized. Other factors important to continence include rectal compliance, tone, and capacity, rectal filling and emptying, and stool volume and consistency.

Diagnostic Evaluation of the Anus

Systematic evaluation of anorectal disorders includes a careful history and physical examination of the anal canal area before elaborate laboratory testing.

History

Important symptoms include bleeding, pain, discharge (mucoid, purulent, or fecal), and change in bowel habits. It is also paramount to know about associated illnesses, medications, family history, bleeding tendency, and exposure through travel or sexual contact.

Bleeding is a common presenting symptom of benign and malignant conditions of the anus and large bowel. Details regarding the type of bleeding can help differentiate between anorectal and large bowel disorders. Inquiry into the type of bleeding should include whether the blood is dark or bright red or associated with clots, whether it is mixed with the stool or separate, and whether it drips into the toilet bowl or only appears on the toilet paper. Blood that drips, is separate from stools, and is bright red is usually seen with bleeding internal hemorrhoids. Blood on toilet tissue may be associated with minor hemorrhoidal disease but also with anal fissure. Clots or melena indicate colonic or more proximal bleeding, respectively. Although a careful bleeding history may suggest a specific cause, consideration must always be given to proximal bowel evaluation to exclude the possibility of more serious conditions, such as cancer. This is particularly important when examination cannot confirm a bleeding source, when patients are at increased risk for cancer by age or family history, or when bleeding does not resolve promptly after treatment of the presumed source. When there is doubt, evaluate the proximal bowel.

Anorectal pain occurring during or immediately after stooling that is described as severe is usually associated with anal fissure. Pain that may or may not be related to stooling and is throbbing in nature is most often seen with an abscess or poorly draining fistula. Pain totally unrelated to stooling is likely to be associated with proctalgia fugax or levator ani syndrome, a condition characterized by painful episodes of short duration (<20 to 30 minutes); these often occur at night and are relieved by walking, warm baths, or other maneuvers. To ascertain change in bowel habits, it is necessary to establish the previous pattern of bowel habit by careful inquiry. Constipation may mean different conditions to different patients, and it is important to know whether the condition is of recent onset or chronic to determine the course of investigation.

Physical Examination

The left lateral position, with the buttocks projecting slightly beyond the edge of the table, and the prone jackknife position are both suitable for evaluation of anal conditions. Inspection with good lighting should precede any other type of examination. Skin tags, excoriations, scars, and any changes in color or appearance of perianal skin are easily recognized. A patulous anus may indicate incontinence and possibly prolapse. Inspection while straining may help determine the presence of hemorrhoidal or rectal prolapse in multiparous women, and a protruding anus may be an indication of descending perineum syndrome. A careful and systematic digital examination with a well-lubricated index finger gradually inserted into the anal canal helps the examiner appreciate any mass, induration, or stricturing and assess the resting tone and strength of the squeeze pressure of the anal sphincter. In men, the prostate should be palpated; in women, the posterior vaginal wall should be pushed forward to detect rectocele.

After the preliminary evaluation has been completed, proctosigmoidoscopy after enema preparation enables satisfactory visualization of the anorectum. Early signs of mucosal inflammation include the loss of the vascular pattern with erythema, granularity, friability, and even ulcerations. Gross lesions, such as polyps or carcinoma, should be readily identifiable. Any suspicious area or mass should be sampled for biopsy, with the patient’s permission, so that a precise histopathologic diagnosis can be established. On withdrawing the proctoscope, the anorectal area can be assessed for mucosal prolapse, hemorrhoids, fissure, polyps, and so forth. The anoscope can also be used for the same purpose; it optimizes the evaluation of lesions confined to the anus.

Other investigations may include barium enema, flexible sigmoidoscopy or colonoscopy, and stool examination, especially if infectious diarrhea or a sexually transmitted disease (STD) is suspected. Special studies, such as manometry, defecography, and electromyography, may help in the assessment of anorectal incontinence, constipation, or any other pelvic floor disorders. Ultrasonography and magnetic resonance imaging (MRI) have shown promise in the evaluation of anorectal suppurative processes. The indications and usefulness of these tests are discussed later under the specific disorders.

Pelvic Floor Disorders

Incontinence

A National Institutes of Health (NIH) State-of-the-Science Conference on the Prevention of Fecal and Urinary Incontinence in Adults was conducted in 2007.¹ Several important conclusions were reached, including that fecal and urinary incontinence will affect more than 25% of all U.S. adults during their lives. Fecal incontinence is now recognized as having serious effects, causing people to suffer physical discomfort, embarrassment, stigma, and social isolation. Furthermore, the panel concluded that financial costs and caregiver burden are substantial and may be underestimated because of underreporting.

Clinical Evaluation

Determining the extent and nature of the problem should start by distinguishing true incontinence (i.e., complete loss of solid stools) from minor incontinence (i.e., occasional staining from seepage or urgency). Seepage of mucus from prolapsing hemorrhoids or from a large secretory villous polyp, urgency from colitis or proctitis, and overflow incontinence from fecal impaction may be confused with true incontinence. After true incontinence is established, the severity of the disability should be assessed by seeking information on control of flatus, liquid and solid stool, and effect on lifestyle and activities (see Table 53-1).²

Fecal incontinence is often multifactorial; defects in the sphincter may be the result of trauma from previous surgical procedures for hemorrhoids, fissures, or fistulas, forceful dilation of the anal canal, impalement injury, or obstetric injuries, either directly because of a tear or breakdown of episiotomy repair or indirectly from stretching of the pudendal nerve during labor, which may develop decades later. The NIH consensus panel concluded that for fecal incontinence, a routine episiotomy is the most preventable risk factor, but that additional risk factors include female gender, older age, and neurologic diseases, with contributions also from body mass, decreased activity, depression, and diabetes. The workup of fecal incontinence should include an evaluation of associated gastrointestinal disorders, such as diarrhea, which can aggravate disorders of continence (Fig. 53-3).³ The physical examination should confirm a weak resting tone and squeeze pressure or a patulous anus and the presence of scars, defects, deformities, or keyhole abnormalities. Examination can also exclude the presence of prolapse, hemorrhoids, or other contributory or associated anorectal abnormalities. Endoscopy excludes the diagnoses of proctitis, fecal impaction, rectal polyps, and colitis cystica profunda.

FIGURE 53-3 Clinical evaluation of fecal incontinence. EMG, Electromyogram.

(From Whitehead W, Bharucha AE: Diagnosis and treatment of pelvic floor disorders: What’s new and what to do. Gastroenterology 138:1231–1235, 2010).

Additional testing can be restricted to a few tests, depending on the extent of findings at examination.^4,⁵ Anal manometry confirms the extent of impairment of the internal and external sphincters by the resting and squeeze pressures, respectively. Manometry can also identify asymmetry, suggesting anatomic defects amenable to repair. Endoanal ultrasound has been recommended to detect occult defects and, in some centers with expertise, is considered more accurate than clinical or conventional methods of evaluation. Finally, electromyography of the pelvic floor can be used to differentiate between anatomic and neurogenic sources of incontinence, and pudendal nerve terminal motor latency testing can predict the likelihood of successful repair.

Treatment

Medical Management

Medical management is a preferred option for cases of mild incontinence and of generalized weakness in which reparable anatomic defects are not identified. A first-line approach includes the use of diet and medications to slow transit and increase stool consistency. Coupled with sphincter exercises, this may improve symptoms and restore normal function for mild cases.⁴ Biofeedback training focuses on strengthening of the anal musculature and improving anorectal sensation and is reported with variable success rates of approximately 75% for at least modest reduction in incontinence frequency, with 50% accomplishing complete continence. A bowel management program has been a successful approach for patients with anorectal malfunctions, Hirschsprung’s disease, and spina bifida.⁶ Of note, medical management can also be considered complementary to surgical therapy and may be carried out before and/or after surgery to optimize surgical results.

Surgical Repair

Surgical options range from the traditional approach of sphincter repair to the newer technique of sacral nerve stimulation and to the final step of colostomy creation. For discrete anatomic defects, the most common surgical approach is the direct overlapping sphincteroplasty, in which the separated muscular ends are dissected, reapproximated, and sutured (Fig. 53-4).⁷ Fecal diversion is not typically required for these repairs unless there are extenuating circumstances. The overlapping sphincteroplasty is associated with low rates of morbidity and mortality and reasonable rates of success with good to excellent results achieved in 55% to 68% of patients.⁴ Direct repair of anterior sphincter defects from obstetric injuries can be expected to restore fecal continence in 59% of patients. A study of 10-year outcomes after anal sphincter repair has suggested continued deterioration of function over time. For nonanatomic defects, postanal repair is advocated by some surgeons but reserved for highly select patients.

FIGURE 53-4 Overlapping sphincteroplasty. A, A curvilinear incision is made midway between the anus and introitus, limited in its posterolateral extent to avoid pudendal nerve injury. The external sphincter ends are dissected, the scar excised when extensive, and the muscle ends reapproximated using overlapping suture technique. The levator ani muscles are also reapproximated. B, Tightness is judged by digital rectal examination. C, The wound edges are closed over drains, at times using a Y configuration to lengthen the perineal body.

(Courtesy Mayo Foundation for Medical Education and Research, Rochester, Minn.)

Highly specialized approaches to treating fecal incontinence include the dynamic graciloplasty, sacral nerve stimulation, and use of an artificial bowel sphincter. The transposition of the gracilis muscle is reserved for patients in whom the bulk of the anal sphincter is missing and requires total reconstruction. Sacral nerve stimulation, in contrast, is specifically designed for patients in whom the anal sphincter is intact but there is inadequate innervation. With proper patient selection, the success rates can be as high as 70%, at least in the short term. Finally, the complications associated with artificial sphincter include erosion, infection, and obstruction at defecation has limited enthusiasm for this approach.

Prolapse of the Rectum

Pathogenesis and Clinical Presentation

Prolapse of the rectum, or procidentia, is an uncommon problem of obscure cause characterized by full-thickness eversion of the rectal wall through the anus. The exact cause is unclear, but the disorder tends to predominate in women, those who strain excessively, and those with chronic mental disorders. The concept that rectal prolapse is the result of intussusception or infolding of the rectum or rectosigmoid has been strongly supported. As the intussusception progresses caudally, the intussusceptum gradually pulls the upper rectal wall away from its sacral and lateral moorings. With continued straining, the bowel continues to roll inside out until, initially, the mucocutaneous junction and eventually the rectal wall evert completely. This progressive phenomenon may explain why some patients have occult or hidden prolapse and why the sigmoid mesentery may elongate, the cul-de-sac may deepen, and the pelvic floor musculature may increasingly weaken. Such findings have been implicated as causative, but it is more likely that they are the result of the prolonged process of gradual prolapsing of the rectum.

The symptoms of early prolapse may be vague, including discomfort or a sensation of incomplete evacuation during defecation. A long history of constipation and excessive straining is common. When prolapse is complete, protrusion of the rectum is noted as a mass during and after defecation. In patients with occult prolapse, a feeling of pressure and sensation of incomplete evacuation may be the only symptoms.

Preoperative Evaluation

The preoperative assessment of the patient should focus on establishing the extent of the prolapse, patient’s overall health status, presence of associated conditions, such as constipation and pelvic floor disorders, and complications, such as incontinence. All these factors influence the operative and medical management. At history, almost 50% of patients have constipation and most have fecal incontinence.^8,⁹ By observing the patient while he or she is straining on the commode, the presence and extent of the prolapse can be verified. Complete prolapse demonstrates full-thickness rectal protrusion with concentric rings (Fig. 53-5). Frail older patients and those with high-risk comorbid conditions or limited life expectancy are ideally suited for perineal procedures. Younger patients, particularly those with constipation or evidence of pelvic floor defecating disorders, are best served with resection and fixation using open or laparoscopic approaches.

FIGURE 53-5 Complete rectal prolapse. The everted rectal wall appears as a tubular mass made up of several concentric mucosal folds.

(Courtesy Mayo Foundation for Medical Education and Research, Rochester, Minn.)

Complete lower gastrointestinal tract evaluations are performed as indicated. On endoscopy, redness of the anterior rectal mucosa or a solitary rectal ulcer 6 to 8 cm anteriorly may be present. A number of additional tests can be ordered but have limited value and are not typically required. Manometry documents the presence of sphincter damage but does not predict recovery. An abnormal pudendal nerve terminal motor latency predicts a high risk for postoperative anal incontinence but rarely influences the management. Defecography can demonstrate the extent of prolapse and transit studies can indicate the extent of constipation. Because a patient with significant prolongation in transit time may respond better to a more extensive colonic resection, this may be indicated for select patients with constipation.

Surgical Correction

Two general approaches are used to achieve surgical correction of rectal prolapse, the perineal approach, which includes the Delorme and Altemeier procedures, and the abdominal approach, which includes but is not limited to anterior resection, with or without rectopexy and mesh fixation. The perineal approach is less taxing on the patient yet has a higher recurrence rate; thus, it is ideally suited for patients with high operative risk and limited life expectancy. An abdominal approach is preferred for young healthy patients because they can tolerate the procedure with low risk and are less likely to suffer a recurrence requiring reoperation.

Perineal Procedures

The Delorme procedure is essentially a mucosal proctectomy and muscularis plicating procedure (Fig. 53-6). It is ideally applied to patients with up to 3 to 4 cm of prolapse, even though the mucosal tube resected can extend up to 15 cm. Even in frail older patients, the Delorme procedure is associated with low rates of mortality and major morbidity, approximately 1% and 14%, respectively.⁹ Incontinence improves in as many as 69% of patients. Prolapse recurrence is not uncommon and is likely underestimated because this procedure is performed in patients with limited life expectancies and therefore short follow-up.

FIGURE 53-6 Schematic representation of Delorme repair of complete rectal prolapse. Mucosal proctectomy is followed by muscular plication, anastomosing the proximal extent of the mucosal resection site to the distal mucosa, just proximal to the dentate.

(Courtesy Mayo Foundation for Medical Education and Research, Rochester, Minn.)

The Altemeier procedure is similar to the Delorme procedure, but rather than a mucosal resection, a full-thickness rectal resection is performed, starting 1 or 2 cm above the dentate line. The bowel and attendant mesentery are resected. Because the pelvic cavity is entered, injury to the small bowel must be avoided. A full-thickness anastomosis is accomplished after the full extent of resection is completed. For patients with incontinence, a levatorplasty may be added to the resection. Results are similar to those described for the Delorme procedure.⁸

Abdominal Procedures

The abdominal options include bowel resection and rectopexy, with or without mesh, performed alone or together. Complete mobilization of the rectum is required for the abdominal procedures; debate exists about whether the lateral stalks should be preserved.¹⁰ Preservation of the stalks is thought to yield better functional results but a greater risk for recurrence. Although the entire rectum is mobilized to the level of the levatores, if resection and anastomosis are being performed, they should be performed high rather than low in the rectum, essentially an anterior resection. This minimizes the risk for anastomotic complications. Rectopexy is performed by securing the rectum to the presacral tissues. Resection with rectopexy is associated with low recurrence rates (0% to 9%) and can be performed safely, with morbidity and mortality rates commensurate with any large bowel resection. Constipation improves in up to 50% of patients and incontinence in most patients.

Rectopexy alone with mesh fixation is a well-described procedure, preferred by some centers. The risks for resection and anastomosis are avoided and recurrence rates are generally low. Complications can result, however, from the presence of a foreign body, and symptoms of constipation are often aggravated. The abdominal procedures can be performed through standard laparotomy or using laparoscopic techniques. Results have suggested that postoperative recovery is typically faster after laparoscopic resection with rectopexy. Furthermore, rates of morbidities, mortality, recurrence, and functional improvement are the same with laparoscopic and open techniques.

Incontinence and Biofeedback

Because incontinence resulting from chronic stretching may or may not cause permanent pudendal nerve damage, many patients note improvement in continence after prolapse repair. The role of biofeedback for treating persistent postoperative incontinence or for preventing recurrent prolapse in patients with obvious pelvic floor dysfunction and a tendency toward excessive straining has not been well established. However, it can be beneficial to some patients and it is noninvasive, which encourages its use in select patients.

Rectocele

Clinical Evaluation

Patients with a rectocele present with a bulge or prolapse of the anterior rectal wall into the vagina. Symptoms attributable to a rectocele include the presentation of a vaginal bulge, inability to evacuate completely during defecation and, in most cases, the necessity to evacuate digitally through the vagina or through the rectum or perineum. The cause of rectoceles remains unclear; it is probably multifactorial because it is associated with a constellation of a number of pelvic floor disorders, including constipation, paradoxical muscular contraction, and neuropathies or anatomic disorders from childbirth.¹¹ Rectocele may coexist with other defecation disorders, such as slow-transit constipation or pelvic floor dysfunction, including pelvic organ prolapse, in which factors such as age, parity, obesity, constipation, pelvic surgery, and pulmonary and medical conditions may play a role. Associated disorders must be addressed to achieve resolution of all symptoms. A careful physical examination will reveal the size of the defect where the rectum prolapse extends to the vagina.

Defecography, which can demonstrate dynamic information on the process of rectal emptying, is the only test that is specifically diagnostic for a rectocele.¹¹ It is probably the most useful test for understanding the relevance of the rectocele in the defecation process, even though there is no exact correlation between any single test finding and results from surgery. Further colorectal evaluations and tests can be ordered, as appropriate, for other symptoms or coexisting disorders.

Treatment

The optimization of bowel function through proper diet, fiber supplements, and good bowel habits is always appropriate as complementary therapy. Medical therapies, specifically biofeedback, have met with limited success, providing only partial relief in most patients but major relief in only a minority of patients.¹²

Surgical Treatment

Patients with rectoceles should be considered for surgical correction if the rectocele is larger than 2 cm and the patient has to perform digitally assisted defecation.¹³ Although gynecologic surgeons often perform a transvaginal repair, the defect between the vagina and rectum can be corrected using a transperineal approach, with or without mesh and including a levatorplasty, or using a transanal repair, with an anal mucosa flap and a plication technique without mesh. The repair should extend 7 to 10 cm above the anal canal. Symptomatic improvement can be anticipated in 73% to 79% of properly selected patients. Best results can be expected in patients who have a small rectocele, require digitally assisted evacuation, are without evidence of anismus, and can be repaired using a transperineal approach.

Common Benign Anal Disorders

Hemorrhoids

Clinical Presentation and Diagnostic Evaluation

Within the normal anal canal there are specialized, highly vascularized cushions forming discrete masses of thick submucosa containing blood vessels, smooth muscle, and elastic and connective tissue. They are located in the left lateral, right anterior, and right posterior quadrants of the canal to aid in anal continence. The term hemorrhoids should be restricted to clinical situations in which these cushions are abnormal and cause symptoms. The cause of hemorrhoids remains unknown. They may be no more than the downward sliding of anal cushions associated with gravity, straining, and irregular bowel habits. Hemorrhoids can be considered external or internal; the diagnosis is based on the history, physical examination, and endoscopy. External hemorrhoids are covered with anoderm and are distal to the dentate line; they may swell, causing discomfort and difficult hygiene, but cause severe pain only if actually thrombosed. Internal hemorrhoids cause painless, bright red bleeding or prolapse associated with defecation. Internal hemorrhoids are classified according to the extent of prolapse, which influences treatment options (Table 53-2). The patient may report dripping or even squirting of blood in the toilet bowl. Chronic occult bleeding leading to anemia is rare, and other causes of anemia must be excluded. Prolapse below the dentate line area can occur, especially with straining, and may lead to mucus and fecal leakage and pruritus. Pain is not usually associated with uncomplicated hemorrhoids but more often with fissure, abscess, or external hemorrhoidal thrombosis.

Table 53-2 Internal Hemorrhoids: Grading and Management

GRADE	SYMPTOMS AND SIGNS	MANAGEMENT
First degree	Bleeding; no prolapse	Dietary modifications*
Second degree	Prolapse with spontaneous reduction	Rubber band ligation
	Bleeding, seepage	Coagulation Dietary modifications
Third degree	Prolapse requiring digital reduction	Surgical hemorrhoidectomy
	Bleeding, seepage	Rubber band ligation Dietary modifications
Fourth degree	Prolapsed, cannot be reduced	Surgical hemorrhoidectomy
	Strangulated	Urgent hemorrhoidectomy Dietary modifications

* Dietary modifications include increasing consumption of fiber, bran, or psyllium and water. Dietary modifications are always appropriate for the management of hemorrhoids, if not for acute care then for chronic management, and for prevention of recurrence after banding and/or surgery.

The physical examination should include inspection during straining, preferably on a commode, digital rectal examination, and anoscopy (Fig. 53-7). Digital examination enables assessment of internal and external hemorrhoidal disease and anal canal tone and exclusion of other lesions, especially low rectal or anal canal neoplasms. Because almost all anorectal symptoms are ascribed to hemorrhoids by patients, it is essential that other anorectal pathologies be considered and excluded. Anoscopy is the definitive examination, but a flexible proctosigmoidoscopy should always be added to exclude proximal inflammation or neoplasia. Colonoscopy or barium enema should be added if the hemorrhoidal disease is unimpressive, the history is somewhat uncharacteristic, or the patient is older than 40 years or has risk factors for colon cancer, such as a family history. Depending on the degree of disease, treatment falls into two main categories, nonsurgical and hemorrhoidectomy.

FIGURE 53-7 Hemorrhoids. A, Thrombosed external. B, First-degree internal viewed through anoscope. C, Second-degree internal prolapsed, reduced spontaneously. D, Third-degree internal prolapsed, requiring manual reduction. E, Fourth-degree strangulated internal and thrombosed external.

(Courtesy Mayo Foundation for Medical Education and Research, Rochester, Minn.)

Treatment

Nonoperative Management

In many patients, hemorrhoidal symptoms can be ameliorated or relieved by simple measures, such as better local hygiene, avoidance of excessive straining, and better dietary habits supplemented by medication to keep stools soft, formed, and regular (see Table 53-2). A wide array of fiber supplements are now available over the counter. Symptoms of bleeding but not prolapse can be significantly reduced over a period of 30 to 45 days with the use of fiber supplements. Over-the-counter suppositories and anal salves, although popular, have never been tested for efficacy. Even though all patients should be counseled on dietary and fiber recommendations, patients with prolapse and internal plus external hemorrhoids benefit from additional interventions.

In the absence of symptomatic external hemorrhoids, second- and some third-degree internal hemorrhoids can be treated with office procedures that produce mucosal fixation. Although sclerotherapy, infrared coagulation, heater probe, and bipolar electrocoagulation have all been described, the simplest, most effective, and most widely applied office procedure is rubber band ligation. Rubber band ligation can be performed in the office without sedation through an anoscope, using a ligator (Fig. 53-8). Preferably, only one site should be banded each time. Because severe perineal sepsis and even deaths have been reported after rubber band ligation, patients should be instructed to return to the emergency department if delayed or undue pain, inability to void, or a fever develops. With one or more applications, symptoms are alleviated in 79% of patients.¹⁴ Because of the risk for bleeding and sepsis, it is preferable that patients not be taking antiplatelet or blood-thinning medications and that subacute bacterial endocarditis prophylaxis is administered to patients at risk. Rubber band ligation should be avoided in immunodeficient patients.

FIGURE 53-8 The band is advanced onto the end of the ligator instrument using a conical attachment (insets). The hemorrhoid is identified at a level proximal to the dentate; this area is tested for sensation before banding. Occluding the suction port of the ligator instrument draws the hemorrhoid into the open end of the ligator, at which time the instrument is fired. The banded hemorrhoid typically sloughs off in 1 week.

(Courtesy Mayo Foundation for Medical Education and Research, Rochester, Minn.)

Surgical Treatment

Hemorrhoidectomy is the best means of curing hemorrhoidal disease and should be considered whenever patients fail to respond satisfactorily to repeated attempts at conservative measures, hemorrhoids are severely prolapsed and require manual reduction, hemorrhoids are complicated by strangulation or associated pathology, such as ulceration, fissure, or fistula, or hemorrhoids are associated with symptomatic external hemorrhoids or large anal tags. The choice of anesthesia should be individualized based on the patient’s preference, build, and medical status. In most cases, local or regional anesthesia with mild sedation can be used effectively. For simple, thrombosed external hemorrhoids, excision in the office is best performed early in the course of the disease, during the period of maximum pain (Fig. 53-9). To remove complex internal or external hemorrhoids, an open or closed hemorrhoidectomy can be performed as an outpatient procedure.

FIGURE 53-9 Excision of thrombosed external hemorrhoid. The area is infiltrated with local anesthetic and the thrombosed hemorrhoid is excised sharply. The wound is left open.

(Courtesy Mayo Foundation for Medical Education and Research, Rochester, Minn.)

Closed hemorrhoidectomy provides simultaneous excision of internal and external hemorrhoids (Fig. 53-10). Preoperative and intraoperative assessment determines the number and location of hemorrhoids requiring excision; typically, three bundles are identified in the right anterior, right posterior, and left lateral positions. Using a large operative scope retractor, such as the Fansler, ensures that sufficient anoderm is preserved to avoid the long-term complication of anal stenosis. Postoperative complications include fecal impaction, infection, urinary retention and, rarely, arterial bleeding. Patients typically recover sufficiently to return to work within 1 to 2 weeks. As an alternative to the closed technique, the surgical wounds can be left open to reduce postoperative pain, but at the expense of longer healing times.