Rectal Tenesmus Symptoms, Causes, and Treatment

Tenesmus is a medical term used to describe the sensation of being unable to empty your bowel after having defecated. When used on its own, the word tenesmus typically refers to the bowel and rectum. By contrast, the sensation of being unable to empty your bladder after urination is referred to as vesicle tenesmus. Tenesmus is primarily associated with inflammatory bowel diseases, both infectious and non-infectious.

The diagnosis of the underlying cause may involve a stool culture, blood tests, colonoscopy, or a biopsy. Pain medications and antispasmodics may be prescribed to help alleviate symptoms while the underlying cause is being treated.

Symptoms

Symptoms of tenesmus may be constant or intermittent and will usually be accompanied by pain, cramping, and involuntary straining. Depending on the underlying cause, you may also experience the following:

• Gas
• Bloating
• Rectal itching
• Rectal discharge and bleeding (caused by excessive straining or an inflammatory condition that compromises colorectal tissues)

Causes

While the cause of tenesmus is not well understood, it is believed that inflammation of the bowel may stimulate both somatic nerve fibers that instigate physical sensations and autonomic nerve fibers that modulate smooth muscle contractions. Overstimulation of these nerves may not only make it feel as if there is residue inside the bowel, but it can also trigger contractions that we recognize as the onset of a bowel movement.

Severe diarrhea or constipation can also cause scarring of bowel tissue. If this happens, it not only makes passing stool more difficult, it can make it feel as if there is more in the bowel than there actually is. Localized sores or growths can do the same.

There are numerous conditions that can trigger tenesmus, including:

• Celiac disease
• Chronic constipation
• Chronic diarrhea
• Colorectal cancer
• Crohn's disease
• Diverticulosis or diverticulitis
• Dysentery
• Gastroenteritis
• Irritable bowel syndrome (IBS)
• Ischemic colitis
• Pelvic floor disorders
• Prolapsed hemorrhoid
• Rectal abscess
• Rectal gonorrhea, chlamydia, and syphilis
• Ulcerative colitis

Tenesmus can affect people who have undergone radiation therapy for cervical cancer, rectal cancer, prostate cancer, or colon cancer. When this happens, it is referred to as radiation proctitis.

Diagnosis

Tenesmus is not a medical condition but rather a symptom of a condition. As such, your doctor will want to uncover the underlying cause by first reviewing your medical history, family history, and current symptoms. This would likely include questions about your bowel habits, diet, and lifestyle.

Based on the diagnostic clues, your doctor will want to perform tests to explore the more likely causes, like IBS, while excluding potentially serious ones like rectal cancer. This may involve:

• Hemoccult test to check for blood in the stool
• Stool culture to check for disease-causing bacteria
• Complete blood count (CBC) to detect infection or anemia
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to check for generalized inflammation
• Computed tomography (CT) scan of the abdomen and pelvis
• Barium X-ray to check for bowel obstruction or perforation
• Magnetic resonance imaging (MRI) to check for tumors and other soft tissue abnormalities
• Colonoscopy to examine the entire colon
• Sigmoidoscopy to examine the lower part of the colon
• Colon biopsy, typically obtained during colonoscopy
• Screening for sexually transmitted diseases

Treatment 

While tenesmus is typically resolved by treating the underlying condition, other treatments may be prescribed to help ease the symptoms. These may include:

• Laxatives to help ease constipation
• Antidiarrheals like Imodium (loperamide) or bismuth sulfate
• Increased dietary fiber and water to normalize bowel movements
• Anti-inflammatory drugs, taken orally or rectally
• Tricyclic antidepressants
• Antispasmodic drugs like Bentyl (dicyclomine) or Levsin (hyoscyamine) to help ease involuntary muscle contractions
• Immune-modulating drugs like Imuran (azathioprine) and Purinethol (6-mercaptopurine) to suppress inflammation associated with Crohn's disease or ulcerative colitis
• Methadone to alleviate intractable rectal pain associated with advanced colorectal cancer
• Percutaneous Tibial Nerve Stimulation (PTNS) for people with pelvic floor disorders

Tenesmus is largely unresponsive to opioids drugs. Benzodiazepines and phenothiazines, traditionally used to treat tenesmus, have little clinical evidence to support their use.

A Word From Verywell

While you may feel uncomfortable discussing tenesmus with your doctor, doing so is important as it may be the sign of a medical condition in need of treatment. This is especially true if the symptom is persistent, worsening, or accompanied by bleeding, tarry stools, narrow stools, weight loss, fever, vomiting, or the inability to defecate.