Anorectal Evaluations: Diagnosing & Treating Benign Conditions

Perianal skin tags

Perianal skin tags, while a nuisance, are not pathologic in most instances and pose no threat to health. They are an outgrowth of normal skin, appearing as loose, flesh-colored perianal tissues (see Figure 3). Tags range in size from a few millimeters to a centimeter long and can occur alone or in multiples.

Perianal skin tags are diagnosed clinically and require no labwork or imaging. Visual inspection is typically sufficient to distinguish tags from pathologic lesions such as condyloma or abscess. If there is uncertainty, however, biopsy or referral to a specialist is warranted.

Certain medical conditions can predispose a patient to development of perianal skin tags. They can be sequelae of thrombosed external hemorrhoids.^8,11 They are also common in patients with Crohn disease.¹¹ Perianal skin tags are not, however, the result of anal intercourse or sexually transmitted infections.

Treatment is usually not indicated for perianal skin tags. If the tags interfere with hygiene or cause perianal discomfort or significantly decreased quality of life, however, patients may seek removal. These patients should be referred to a colorectal specialist for evaluation for excision.

Anal fissures (fissure in ano)

The most common cause of severe anorectal pain is fissure.⁴ A fissure is an elliptical tear, or split, in the lining of the anal canal that causes spasm of the anal sphincters. The tear is distal to the dentate line and thus intensely painful.^2,5 Common cited causes of fissures are trauma from passage of large, hard stools, straining, or diarrhea.¹⁶

Fissures can usually be visualized by spreading the posterior anus apart (see Figure 4). They are most commonly located in the posterior or anterior midline, though they can occur anywhere around the anus.^2,4 Often, a sentinel tag—appearing as a taut, flesh-colored skin tag—is present at the external pole of the fissure.^5,11 DRE and anoscopy should be avoided, as they will trigger intense pain and spasm of the sphincters.

Fissures are characterized as acute (present ≤ 3 months) or chronic (> 3 months).^9,11 Visually, acute fissures typically have clean edges, with the appearance of a paper cut to the mucosa, while chronic fissures have indurated, heaped-up edges, often with exposure of the underlying sphincter muscle.¹⁷

They tend to be exquisitely painful, as the mucosa distal to the dentate line is highly innervated. Patients report pain akin to “passing shards of broken glass” with bowel movements, which is often accompanied by a fear of defecation and bright red blood on the toilet paper or dripping into the water.¹¹ The pain, caused by spasm of the sphincters, typically starts during a bowel movement and lasts minutes to hours afterward.

Initial treatment is aimed at relaxing the sphincters, as well as softening stool to prevent further trauma and allow the fissure to heal. Patients should be educated about the importance of adequate fiber intake to prevent constipation and straining. A daily bulk fiber supplement, in addition to a high-fiber diet (20-25 g/d), has been shown to result in healing of 87% of acute fissures.¹⁶ Sitz baths in plain warm water, three to four times a day, can encourage relaxation of the sphincters and increase local blood flow, both of which help with fissure healing.¹⁶ Topical medications can also be prescribed. These include compounded nitroglycerin 0.2% or nifedipine 2.0%, which act to reduce the spasm by relaxing smooth muscle, as well as increase blood flow to the lesion.^12,14

Most acute fissures will heal with the regimen of high fiber intake, sitz baths, and topical medication. For refractory or chronic fissures, referral to a colorectal specialist for more invasive treatment is appropriate. Additionally, fissures that are not located in the typical posterior or anterior midline might indicate an atypical etiology, such as Crohn disease, tuberculosis, leukemia, or HIV, and thus patients who present with fissures in these locations should also be referred to a colorectal specialist.^2,4,11,18

Pruritus ani

Pruritus ani, known as perianal dermatitis, is a benign condition that presents with intense perianal itching and burning. It is the second most common anorectal condition after hemorrhoids and affects up to 5% of the US population.^2,9,11,19

Pruritus ani often develops secondary to local irritation of the skin (eg, from prolonged exposure to moisture), leading to an inflammatory response within the superficial skin layers. The irritation causes patients to scratch the skin, resulting in trauma, excoriation, and ulcer formation and leading to a cycle of further inflammation, exacerbation of symptoms, and persistent scratching.

Physical exam may reveal circumferential erythematous and irritated perianal skin (see Figure 5). Linear or deep, punched-out excoriations may be present. Chronically, patients may develop lichenification with thick, whitened patches of skin.¹¹ In the absence of red flags such as unintentional weight loss, anemia, rectal bleeding, or a family history of colon cancer, no additional evaluation is required during the initial visit, though anoscopy can be used to rule out associated anorectal pathology.

Many different causes of pruritus ani have been reported (see Table 3). In the case of an identifiable cause, symptoms tend to resolve once the offending agent is eliminated. Up to a quarter of cases, however, are idiopathic, with no identifiable trigger.²⁰

Symptom management is thus key. Patients should be educated about lifestyle modification and informed that scratching will irritate the skin further and aggravate symptoms.^5,11 If incontinence or diarrhea is thought to cause symptoms, dietary modifications, a fiber supplement, dysmotility agents, and Kegel exercises to strengthen the sphincters and decrease anal leakage can be recommended.

The affected skin should be kept clean and dry at all times. Aggressive wiping and overzealous hygiene should be avoided. Sitz baths can help with hygiene. A topical astringent such as witch hazel can help remove excess moisture from the skin. A layer of protective skin barrier cream with zinc oxide, when applied over dry skin, can help protect the skin from leakage throughout the day.

A sedating antihistamine can reduce scratching during sleep. Topical hydro­cortisone 1% cream is effective for itch relief; this should be limited to five to seven days of consecutive use, however, as it can lead to pathologic thinning of the perianal skin. Topical capsaicin 0.006% cream has been shown to help alleviate intractable ­pruritus.^2,21

The goal of these measures is to break the cycle of irritation and inflammation and give the skin an opportunity to heal. If the patient fails to improve, referral to a colorectal specialist or, alternatively, a dermatologist, is warranted for perianal skin biopsy and more invasive treatment options.

Perianal abscess

A perianal abscess is an infected cavity filled with pus under pressure, located near the anus or rectum. It most often results from an acute infection of the anorectal glands located at the dentate line that tracks outward to the perianal skin.¹² Abscesses can also result from another disease process, such as Crohn disease, diabetes, or rectal trauma.^2,11

Localized pain, swelling, and drainage are common presenting symptoms of an abscess.^2,11 Systemic symptoms such as fever and chills may present later in the course but are rare.²

Treatment of the acute process is incision and drainage (I&D).^11,12 This can be accomplished in the office with injection of local anesthesia, followed by excision of an ellipse of skin overlying the cavity large enough to allow full drainage of the abscess. Use of drains and packing of the wound are usually not necessary. There is also no role for antibiotics unless the patient is diabetic or immunosuppressed or cellulitis is present.¹¹ In patients with systemic signs of illness, imaging such as CT or MRI of the pelvis can be used to assess for a deeper infection.^2,12

For most patients, I&D resolves the process. However, up to half of perianal abscesses progress to form a fistula, a tunnel connecting the infected anal gland to the external skin.^2,11,22 Indeed, abscesses and fistulae are part of the same infectious process, with the abscess representing the acute phase of infection and the fistula representing the chronic phase. On physical exam, in addition to the abscess site on the skin, a fistula may manifest as a palpable cord beneath the skin between the anus and the abscess opening.⁹ Additionally, the patient may report the abscess has been recurrent in nature, cyclically increasing in size and pain, then spontaneously draining.

A fistula requires surgical intervention for definitive treatment and should therefore prompt referral to a colorectal specialist. In the absence of fistula, however, a simple perianal abscess can be treated with I&D in the primary care setting.