40 Anorectal Diseases
Disaya Chavalitdhamrong and Rome Jutabha
Anorectal disease refers to diseases of the anus and rectum such as hemorrhoids, anal fissures, anorectal abscesses, anal fistulas, and anal cancer. Inspection, perianal palpation, digital examination, abdominal examination, and rectovaginal palpation provide initial assessment. In cases of painful anal lesions, topical, regional, or even general anesthesia may be required. Anoscopy and sigmoidoscopy are often required for further evaluation. Rectal endoscopic ultrasound is particularly important in certain conditions. Patients may delay seeking medical advice because of embarrassment. Understanding of the pathophysiology and anatomy is critical to success in management of anorectal disease. We herein review anorectal diseases including its pathophysiology; inflammation, infection, vascular cause, neoplasm, and mechanical cause.
40.2.1 Crohn’s Disease
Symptoms and signs related to perianal disease occur in 35 to 45% of patients with Crohn’s disease (CD). The major perianal complications include anal fissures, anorectal fistulae, and abscesses. Conservative treatment of anorectal diseases in CD patients has been advocated given the high risk of complications and the evidence that spontaneous healing may also occur. 1
Fissures are present in up to 19% of patients with CD. 2 Anal fissure in CD may be asymptomatic or present with bleeding, deep ulceration, or anal pain, which may be worsened during evacuation. Nonhealing fissures or deeper ulcers may lead to fistula or perianal abscess formation. Chronic fissure can lead to stricture formation.
Treatments consist of keeping the area clean and dry. The first line of treatment should be medical management including nitroglycerin paste, topical calcium channel blockers, and botulinum toxin. 3 These treatments are successful in up to 80% of cases. 3 In the case of nonhealing symptomatic fissure, proctitis should be ruled out. 3 Topical nitroglycerin 0.2% has not been evaluated in anal fissure in CD. Surgery such as lateral internal sphincterotomy may require in fissures that are resistant to conservative treatment, but it should be reserved to carefully selected patients. 4 It was reported that 40% of patients suffered from postoperative complications even without active rectal disease. 4
Anorectal fistula develops in 20 to 30% of patients with CD. 2 Fistulae are usually the consequence of penetration of an abscess. The fistulous openings most commonly involve the perianal skin but can also be in the groin, vulva, and scrotum. Fistulae can be classified as simple (superficial, inter-, or transsphincteric fistula below the dentate line, with a single opening and no anorectal stricture or abscess), or complex (trans-, supra-, or extrasphincteric fistula above the dentate line, or a fistula with multiple external openings, associated abscess, or stricture, or rectovaginal fistula). 5
Fistula can present with anal pain, painful defecation, and perianal opening with purulent discharge. Physical examination may reveal perianal openings, pneumaturia, and passage of stool through the vagina if urinary bladder or vagina is involved, respectively. Evaluation of the anatomy includes probing under general anesthesia, fistulography, barium studies, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). 6 The combination of different imaging modalities appears to be more accurate than any one modality alone. 6
Treatment of the underlying CD is needed. A combined medical and surgical approach offers the best chance for success. Medication options include antibiotics (such as metronidazole and ciprofloxacin), immunosuppressives (6-mercaptopurine and azathioprine, cyclosporine, and tacrolimus), and immunomodulators (infliximab and adalimumab). 3 In the presence of proctitis, medical therapy should be continued until there is adequate resolution of proctitis. Surgery should be considered in patients with simple low intersphincteric fistulae or fistulae refractory to medical therapy or with severe symptoms.
Anorectal abscesses develop in 50% of patients with perianal CD especially in patients with anal fistulae. The abscesses can be seen at perianal area or can be felt via digital rectal examination or seen on CT scan.
Prompt surgical incision and drainage and treatment with broad-spectrum antibiotics are mandatory. In the presence of a fistula, a noncutting seton can be placed to prevent recurrence and facilitate drainage. 3
40.2.2 Perianal Abscesses
A perianal abscess is a collection of purulent material that arises from glandular crypts in the anus or rectum.
Patients with a perianal abscess often present with severe pain in the anal or rectal area. Purulent rectal drainage may be noted. Physical examination may reveal palpable perirectal mass. It is important to distinguish anorectal abscess from other perianal suppurative processes. 7
Anal abscesses should be drained early. The placement of a seton should be considered when the internal opening is identifiable. Antibiotic therapy is unnecessary in uncomplicated anorectal abscess. 7 The key to successful treatment is the eradication of the primary tract. As surgery may lead to a disturbance of continence, several sphincter-preserving techniques have been developed. 7
40.2.3 Anorectal Fistula
The most common etiology of an anorectal fistula is an anorectal abscess. Other causes of anorectal fistulae include CD, lymphogranuloma venereum, radiation proctitis, rectal foreign bodies, and actinomycosis.
A fistula can be explored with a fistula probe. The internal opening in the anus can be viewed by an anoscopic examination, while a sigmoidoscope may be required to view the internal opening in the rectum.
Surgical treatment is the mainstay of therapy and is required in patients with symptomatic anorectal fistulae. The goal of surgical therapy is to eradicate the fistula while preserving fecal continence. Fistulotomy is the main surgical therapy. Fistulectomy and primary sphincteroplasty could be the therapeutic options for complex anal fistula. Reported success rates were very high and the risk of postoperative fecal incontinence was lower than after simple fistulotomy. 8 Permacol collagen paste and fibrin glue are new options for the treatment of anorectal fistula. 9 , 10 Permacol paste functions by filling the fistula tract with an acellular cross-linked porcine dermal collagen matrix suspension. It is shown to be effective in treating primary and recurrent anorectal fistula. 9 Fibrin glue is a novel treatment for anal fistulae. 10 Fibrin glue has shown to heal more complex fistulae than fistulotomy. 10
Infectious proctitis is the rectal inflammation caused by the infectious pathogens typically being sexually acquired. Among men who have sex with men (MSM) with clinical proctitis, chlamydia and gonorrhea are the most frequently identified pathogens in the rectum. 11 Approximately 85% of rectal gonorrhea and chlamydia infections are asymptomatic, and many patients who are infected rectally are not simultaneously infected at other anatomical sites. 12 The Centers for Disease Control and Prevention (CDC) recommends at least annual screening for chlamydia and gonorrhea in MSM at the urethral, pharyngeal, or rectal site based on recent exposure. 13
40.3.1 Chlamydial Infection
Chlamydia is the most frequently reported bacterial sexually transmitted infection. Chlamydial proctitis occurs primarily in MSM who engage in receptive anal intercourse, with a positivity in a screening population of 3 to 10.5%. 14 Chlamydia can also infect the rectum in women, either through receptive anal sex or spreading from the cervix and vagina. It can cause symptoms of proctitis including rectal pain, discharge, or bleeding. The incubation period for Chlamydia is 5 to 14 days. Infection can be caused by D-K and L serovars. Obtaining a diagnosis for rectal chlamydia can be challenging. Culture is limited to research and reference laboratories. Serology can support the diagnosis, but is not standardized and requires a high level of expertise to interpret. Antigen detection by swab has generally shown good sensitivity and specificity for urogenital chlamydia; however, for rectal swab, the limited data suggest a sensitivity of less than 50%. 15 Several studies have shown that nucleic acid amplification tests (NAATs) on rectal specimens are more sensitive than culture in detecting rectal chlamydia and still have high specificity. In particular, the use of a transcription-mediated amplification method seems to show consistently strong results. 16
Empiric therapy for both chlamydia and gonorrhea is indicated for acute proctitis. A regimen of doxycycline (100 mg twice daily for 7 days) or azithromycin (1 g orally once) plus a single intramuscular dose of ceftriaxone (250 mg) is active against both. Abstaining from sex for 1 week after initiation of treatment decreases transmission, and treatment of partners decreases reinfection. 17
40.3.2 Gonococcal Proctitis
Neisseria gonorrhoeae can be transmitted by oral–anal, anoreceptive intercourse, or spreading from cervical or urethral gonorrhea. Most women and approximately half of men with anorectal gonorrhea are asymptomatic. 18 The classic anoscopic examination of gonorrhea includes thick purulent discharge. NAATs are preferred tests. The transcription-mediated amplification shows greater sensitivity compared with culture and similar specificity. 19 NAATs do not require the careful handling required for culture and can detect both gonorrhea and chlamydia. 17 These are more expensive than culture and cannot provide information on antibiotic susceptibility. 17
Therapy for both gonorrhea and chlamydia with ceftriaxone and doxycycline is indicated for the treatment of patients with acute proctitis.
40.3.3 Herpes Simplex Virus
Both herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) can cause genital herpes (▶Fig. 40.1). 17 Transmission is via anal, vaginal, or oral sex. 17 Most people with HSV are asymptomatic. Clinical manifestations include vesicles, ulcers on or near the anus, genitals, or mouth. It can also manifest as proctitis. The first outbreak may be associated with fever, lymphadenopathy, or body aches. Recurrences are typical, shorter in duration and less severe. The standard diagnostic test is viral culture. 17 Polymerase chain reaction (PCR) test is more accurate and rapid. 17 Serologic tests are for recurrent disease. 17
There is no cure for herpes. Antiviral medications prevent or shorten outbreaks, reduce transmission rates, and decrease the duration of viral shedding. 17 Acyclovir 400 mg five times a day for 10 days is for herpes proctitis. Acyclovir 400 mg three times a day for 7 to 10 days is for perianal lesions (5 days for recurrent disease). Acyclovir 400 mg two times a day is for suppression. Antiviral alternatives include famciclovir and valacyclovir. 20
Anal chancres are painful and resolve after 3 to 6 weeks whether treated or not. Secondary syphilis may also include mucous membrane lesions of the anus and rectum. Condyloma lata may also develop in areas including the groin. The screening tests are venereal disease research laboratory (VDRL) and rapid plasma reagin (RPR). 17 The confirmation test is a treponemal test such as fluorescent treponemal antibody absorption (FTA-ABS) test. 17
A single intramuscular (IM) dose of 2.4 million units of benzathine penicillin G cures a person with syphilis for less than a year. 17 Additional doses are needed for those with syphilis for longer than a year. 17 All patients should undergo testing for human immunodeficiency virus (HIV). Follow-up should occur at 6 and 12 months after treatment. 17
40.3.5 Lymphogranuloma Venereum
It is caused by the species Chlamydia trachomatis. The serovars are most commonly L1, L2, or L3. Lymphogranuloma venereum (LGV) can result in proctocolitis with anal pain via anal receptive sex. It can progress to colorectal fistulae and strictures if not treated early. Diagnosis is generally based on clinical suspicion and can be verified by NAATS. 17
40.4 Vascular Cause
40.4.1 Ischemic Proctitis
Ischemic proctitis commonly occurs at the splenic, descending, and sigmoid colon (▶Fig. 40.2). 21 The rectum is involved in only 2 to 5% of cases because of its abundant collateral blood supply. 21 Risk factors include major vascular occlusive disease, disruption of collateral circulation, and low-flow state. 21 Although CT scan can suggest the diagnosis and identify other causes of clinical deterioration, colonoscopy remains the key test in diagnosing and determining the extent of ischemic change. 21
Treatment is nonoperative for nongangrenous ischemic proctocolitis, whereas surgery is necessary for gangrenous, transmural rectal ischemia. The extent of resection will be determined intra-operatively by the appearance of the bowel. 21