Tenesmus: The Feeling of Incomplete Bowel Emptying

What tenesmus feels like

The word comes from the Greek for "straining". People describe:

• feeling that they still need to go right after a bowel movement
• urgent, repeated trips to the toilet passing only small amounts, mucus or nothing
• cramping, aching or pressure in the rectum or lower belly
• straining that does not relieve the urge

Tenesmus is usually rectal. Bladder tenesmus (vesical tenesmus) is a similar feeling of incomplete bladder emptying, caused by bladder irritation or prostate problems.

Why it happens

The rectum contains stretch receptors that signal when it is full. When the rectal lining is inflamed, or a mass or hard stool sits in the rectum, those receptors fire constantly. The brain interprets this as a full rectum, triggering urges and straining even when it is empty. The inflammation can also cause muscle spasm.

Causes of tenesmus

Inflammatory bowel disease

• Ulcerative colitis: inflammation always starts in the rectum, so tenesmus is a hallmark symptom, with bloody diarrhea, mucus and urgency.
• Crohn's disease: tenesmus when the rectum or anus is involved, sometimes with fistulas and abscesses.

Proctitis

Proctitis is inflammation of the rectal lining. Causes include:

• ulcerative colitis limited to the rectum (ulcerative proctitis)
• sexually transmitted infections: gonorrhea, chlamydia (including LGV), herpes and syphilis, especially after receptive anal sex
• radiation therapy for prostate, cervical or rectal cancer
• antibiotics (C. difficile colitis)

Infections

Bacterial gut infections that inflame the colon and rectum, such as Shigella, Campylobacter, Salmonella and certain E. coli, and the parasite Entamoeba histolytica (amoebic dysentery), cause bloody diarrhea with marked tenesmus.

Anal and rectal problems

• Hemorrhoids, especially large internal ones, can feel like stool that has not passed.
• Anal fissure: a tear causing sharp pain and spasm.
• Rectal prolapse: the rectum slides down, causing a sensation of incomplete emptying and a bulge.
• Perianal abscess.

Constipation and motility disorders

• Constipation and fecal impaction: hard stool stuck in the rectum, common in older adults and people on opioids.
• Irritable bowel syndrome: a feeling of incomplete evacuation is common, without inflammation.
• Pelvic floor dysfunction: the muscles fail to relax during a bowel movement.

Cancer

Rectal cancer and other tumors in or near the rectum (prostate, cervical, ovarian) can cause tenesmus, often with bleeding, narrower stools, change in bowel habit and weight loss. See colorectal cancer.

Clues from accompanying symptoms

How doctors find the cause

A doctor will ask about bowel habits, blood and mucus, diarrhea or constipation, travel, sexual history, medicines, radiotherapy and family history. A digital rectal exam checks for masses, impaction, hemorrhoids and tenderness. Tests may include:

• stool tests for bacteria, parasites, C. difficile and calprotectin (a marker of bowel inflammation)
• swabs for gonorrhea, chlamydia and herpes
• blood tests for anemia and inflammation
• flexible sigmoidoscopy or colonoscopy to look at the rectum and colon and take biopsies
• MRI or CT for masses and abscesses

Treatment

Treatment targets the cause:

• Ulcerative colitis and proctitis: mesalamine suppositories or enemas work directly on the rectum; steroids, immune-modifying and biologic medicines for more extensive disease.
• Infections: antibiotics or antiparasitic medicines when indicated, plus fluids. Many viral and mild bacterial infections settle on their own.
• STI proctitis: specific antibiotics or antivirals, plus partner treatment.
• Constipation and impaction: fiber, fluids, stool softeners, laxatives, or manual removal for impaction.
• Hemorrhoids and fissures: fiber, sitz baths, topical treatments, or procedures.
• Pelvic floor dysfunction: biofeedback therapy with a specialist physical therapist.
• Rectal cancer: surgery, radiotherapy and chemotherapy.

Warm sitz baths for 10 to 15 minutes can ease rectal spasm and discomfort. Avoid straining for long periods on the toilet, which worsens hemorrhoids and pelvic floor problems.

Frequently asked questions

What is tenesmus?

Tenesmus is a persistent urge to have a bowel movement even when the bowel is empty, often with straining, cramping and passing little or nothing. It is caused by inflammation, irritation or a mass in the rectum.

Is tenesmus a sign of cancer?

It can be, but most tenesmus is caused by inflammatory bowel disease, infection, hemorrhoids or constipation. Rectal cancer is a less common cause. Tenesmus lasting more than 2 weeks, especially with bleeding, narrow stools or weight loss, should be checked with a colonoscopy.

How do you get rid of tenesmus?

Treat the cause: anti-inflammatory medicines for colitis or proctitis, antibiotics for some infections, fiber and laxatives for constipation, and treatments for hemorrhoids or fissures. Warm sitz baths ease spasm. See a doctor if it lasts more than a few days.

Can IBS cause tenesmus?

Yes. A feeling of incomplete evacuation is common in irritable bowel syndrome, without any inflammation. However, tenesmus with blood, fever, weight loss or night-time symptoms is not typical of IBS and needs further investigation.

Can stress cause a constant urge to poop?

Stress can worsen IBS and increase bowel urgency and the feeling of incomplete emptying. But stress alone should not cause bleeding, fever or weight loss. Persistent symptoms need medical evaluation to rule out inflammation or other causes.