Anal fistula differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Associate Editor(s)-in-Chief: Manpreet Kaur, MD [2]

Overview

Anal fistula must be differentiated from other causes of anal pain including anal fissure, thrombosed hemorrhoids, levator spasm, sexually transmitted disease, proctitis, hidradenitis suppurativa, infected skin furuncles, herpes simplex virus, tuberculosis, syphilis, actinomycosis and cancer.

Differentiating Anal fistula from Other Diseases

Anal fistula must be differentiated from other causes of anal pain, including anal fissure, thrombosed hemorrhoids, levator spasm, sexually transmitted disease, proctitis, hidradenitis suppurativa, infected skin furuncles, herpes simplex virus, tuberculosis, syphilis, actinomycosis and cancer.

Disease	Definition	Causes	Clinical Features	Diagnosis
Anal fistula	A epithelialized track formed between the anorectum and the perianal skin secondary to rupture of anorectal abscess Chronic manifestation of anorectal abscess	Anorectal abscess Crohn's Disease Radiation proctitis Lymphogranuloma venereum Actinomycosis	Anal pain with bowel movement and sitting Perianal discharge Perianal pruritus Presence of exteral opening on examination Perianal inflammation	Endoanal ultrasound Fistulography Computed tomography
Anal Fissure	Tear in the anoderm distal to the dentate line	Anal Trauma Receptive anal sex Inflammatory bowel disease	Pain with passing of stools Minimal bright red rectal bleeding on the toilet paper or stool On examination acute fissure appears as a fresh laceration Chronic fissure has raised edges with anal skin tag	Clinical diagnosis
Thrombosed external hemorrhoids	Engorged fibrovascular cushions lining the anal canal	Constipation Prolonged straining	Anal pain Anal pruritus Rectal bleeding with bowel movement Tenderness on examination with a palpable thrombus	Clinical diagnosis
Levator spasm	Severe, intermittent episodes of rectal pain	Seen in patients with perfectionistic, anxious somatic, and/or neurotic tendencies	Severe anal pain lasting for seconds to 5 minutes	Diagnosis is by Rome IV criteria It is diagnosis of exlusion
Proctitis	Epithelial damage to the rectum secondary to radiation, associated with minimal or no inflammation	Radiation therapy	Diarrhea within six weeks of radiation therapy Urgency Tenesmus Rectal bleeding	Biopsy
Hidradenitis suppurativa	Suppurative disorder of sweat glands	Causes unidentified	Anal pain Anal mass Recurrent and relapsing symptoms Nodules and scarring is demonstrated on examination	Clinical Diagnosis Biopsy should be done to rule out cancer
Infected skin furuncle	Well-circumscribed, painful, suppurative inflammatory nodule involving hair follicles	Staphylococcus aureus	Anal pain Inflammed and red, tender elevated pustular lesion on examination	Clinical diagnosis
Bartholin's abscess	Obstruction of the bartholin's ducts, results in abscess formation	E.coli	Vulvar pain Palpable bartholin gland on examination	Clinical diagnosis Incision and drainage