What are the causes of tenesmus?

Causes of Tenesmus

Tenesmus—the painful sensation of incomplete rectal evacuation—has four primary etiologic categories: inflammatory bowel disease (particularly ulcerative colitis and pouchitis), sexually transmitted infections causing proctitis, malignancy, and functional/structural disorders.

Inflammatory Bowel Disease

Ulcerative Colitis and Ulcerative Proctitis

• Tenesmus is a cardinal symptom of ulcerative colitis, occurring alongside bloody diarrhea, urgency, and colicky abdominal pain 1.
• In ulcerative proctitis (inflammation limited to 15 cm from the anal verge), tenesmus is particularly prominent and distressing, often accompanied by rectal bleeding, urgency, fecal leakage, and incontinence 1.
• Up to one-third of patients with ulcerative proctitis paradoxically experience constipation alongside tenesmus 1.
• The symptom results from rectal inflammation causing persistent sensation of needing to defecate despite an empty rectum 2.

Pouchitis

• Pouchitis develops in up to 50% of patients within 10 years after ileal pouch-anal anastomosis (IPAA) for ulcerative colitis 1.
• Tenesmus is a defining symptom of pouchitis, occurring with increased stool frequency, liquidity, abdominal cramping, urgency, and pelvic discomfort 1.
• Risk factors include primary sclerosing cholangitis, extraintestinal manifestations, and non-smoking status 1.
• Diagnosis requires endoscopic and histological confirmation in conjunction with symptoms 1.

Sexually Transmitted Infections

Infectious Proctitis

• Proctitis from receptive anal intercourse causes tenesmus limited to the distal 10-12 cm of rectum, with anorectal pain and rectal discharge 1, 3, 4.
• The four primary pathogens are Neisseria gonorrhoeae, Chlamydia trachomatis (including LGV serovars), Treponema pallidum, and herpes simplex virus 1, 3, 5.
• Herpes proctitis can be especially severe in HIV-infected patients, causing particularly intense tenesmus 1, 5.
• Lymphogranuloma venereum (LGV) serovars of C. trachomatis cause severe proctitis with bloody discharge and perianal ulcers 4, 5.

Proctocolitis from Enteric Pathogens

• Campylobacter, Shigella, and Entamoeba histolytica cause proctocolitis extending beyond 12 cm, with tenesmus accompanied by diarrhea and abdominal cramps 1, 5.
• These infections occur through oral-fecal contact or contaminated food/water 1.
• Dysenteric symptoms including fever, tenesmus, and blood/pus in stool occur in 55-96% of Salmonella infections 3.

Malignancy

Rectal and Pelvic Tumors

• Malignant rectal pain and tenesmus cause significant morbidity in cancer patients at all disease stages 6.
• Approximately 11% of colovesical and colovaginal fistulae are caused by malignancy, which can present with tenesmus 1.
• Carcinomas may rarely arise in chronic anal fistulae in Crohn's disease, presenting with tenesmus and mass-like thickening 1.
• The mechanism involves tumor infiltration causing rectal hypersensitivity and persistent sensation of incomplete evacuation 6.

Structural and Functional Disorders

Rectal Prolapse

• Tenesmus in rectal prolapse creates a vicious circle where straining worsens the prolapse, likely triggered by rectal hypersensitivity 7.
• Both full-thickness and mucosal/incomplete prolapse can cause severe tenesmus 7.
• The symptom duration averages 10.8 months before patients seek treatment 7.

Solitary Rectal Ulcer Syndrome

• Solitary rectal ulcer syndrome causes tenesmus associated with chronic straining, abnormal defecatory behavior including digitating, and multiple unsuccessful toilet visits 8.
• Additional symptoms include rectal bleeding, mucus discharge, altered bowel habit, and incontinence 8.
• The condition is often accompanied by rectal prolapse 8.

Radiation-Induced Proctitis

• Radiation proctitis causes tenesmus and bleeding as late complications of pelvic radiation therapy 3.
• The inflammation results from radiation damage to the rectal mucosa 3.

Opportunistic Infections in Immunosuppressed Patients

• Cytomegalovirus causes severe proctitis with tenesmus in immunosuppressed HIV-infected patients 1, 5.
• Mycobacterium avium-intracellulare, Cryptosporidium, Microsporidium, and Isospora can cause enteritis with tenesmus in HIV-infected individuals 1, 5.

Clinical Pitfalls

Common diagnostic errors include:

• Failing to obtain detailed sexual history in patients with infectious proctitis, missing sexually transmitted causes 4, 5.
• Not assessing HIV status, which dramatically affects disease severity and treatment approach 4, 5.
• Assuming all tenesmus in inflammatory bowel disease patients represents active colitis, when it may indicate pouchitis, cuffitis, or irritable pouch syndrome 1.
• Missing malignancy when soft tissue mass or malignant-appearing lymphadenopathy accompanies anorectal inflammation 1.
• Overlooking medication-induced causes, particularly NSAIDs which can exacerbate ulcerative colitis 1.