Rectal Tenesmus Symptoms, Causes, and Treatment

Tenesmus is a medical term used to describe the sensation of being unable to empty your bowel after you have already defecated. Tenesmus is commonly associated with inflammatory bowel disease (IBD) but may also be caused by hemorrhoids, infections, and even cancer.

The diagnosis may involve a stool culture, blood tests, colonoscopy, or a biopsy to identify the underlying cause. 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 but usually involve some or all of the following:

• Rectal pain
• Gas
• Bloating
• Cramping
• Itching
• Rectal discharge
• Rectal bleeding
• Involuntary straining

Causes

The cause of tenesmus is not well understood, but it is believed that inflammation or irritation may stimulate both somatic nerves (that instigate physical sensations) and autonomic nerves (that modulate smooth muscle contractions) in the bowel.

Overstimulation of these nerves may not only make it feel as if there is residue within the bowel but can also trigger contractions that we recognize as the onset of a bowel movement.

In addition, severe diarrhea or constipation can also cause scarring of bowel tissues. If this happens, it not only makes passing stools more difficult, but it can feel as if there is more in the bowel than there actually is. Sores or growths around the rectum or in the colon can do the same.

There are numerous conditions that can trigger tenesmus, including:

• Celiac disease
• Chronic constipation
• Chronic diarrhea
• Colorectal cancer
• Crohn's disease
• Diverticular disease
• Gastroenteritis
• Irritable bowel syndrome (IBS)
• Ischemic colitis
• Pelvic floor disorders
• Prolapsed hemorrhoid
• Rectal abscess
• Rectocele
• Sexually transmitted proctitis (including gonorrhea, chlamydia, or syphilis)
• Ulcerative colitis

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 these diagnostic clues, your doctor will want to perform tests to explore the more likely causes, like IBS, or exclude potentially serious ones, like rectal cancer.

Physical Exam

The physical exam is essential to the diagnosis of tenesmus. It helps the doctor see if there is any inflammation or abnormalities around the rectum, tenderness or pain in the abdomen, or signs of a sexually transmitted infection.

The procedure may involve a digital rectal exam (DRE). This involves the insertion of a gloved finger into the anus to check for hemorrhoids, blood, mucus discharge, infection, or abnormal growths.

Lab Tests

After the physical exam, the doctor will commonly order a battery of blood and stool tests to help narrow down the causes. These may include:

• Complete blood count (CBC): A battery of tests that can help detect infection (characterized by an increase in white blood cells) or anemia (due to decreases in red blood cells), among other things
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): Blood tests that detect generalized inflammation associated with infections, inflammatory diseases, and other causes
• Fecal blood occult: A test used to detect blood in a stool sample
• Stool culture: A test that checks for pathogenic (disease-causing) bacteria in a stool sample
• STD screening: A battery of tests used to detect gonorrhea, chlamydia, syphilis, and other sexually transmitted infections
• Carcinoembryonic antigen (CEA): One of several tumor marker tests that detects substances in blood suggestive of colorectal cancer

Imaging Studies

Before proceeding to more invasive procedures, the doctor may order imaging tests to help visualize the digestive tract. These may include:

• Barium X-ray: A type of X-ray in which a barium enema is used to highlight growths, obstruction, lesions, or perforation of the intestine
• Computed tomography (CT) colonography: An imaging technique involving multiple, composited X-rays that provide greater detail of the intestines, including the presence of polyps or tumors
• Magnetic resonance imaging (MRI): A type of scan using powerful magnetic and radio waves to create highly detailed images of soft tissues within the digestive tract

Procedures

If colorectal cancer is suspected or an anomaly is spotted on imaging studies, the doctor may refer you to a gastroenterologist for an exploratory procedure to directly visualize the colon. These minimally invasive endoscopic procedures include:

• Colonoscopy: A procedure using a flexible scope, called a colonoscope, to examine the entire colon
• Sigmoidoscopy: A version of colonoscopy limited to the lower part of the colon, called the sigmoid colon
• Colon biopsy: Performed during a colonoscopy or sigmoidoscopy to obtain a sample of tissue for evaluation in the lab

Treatment 

Tenesmus tends to improve once the underlying cause is identified and treated. Because the causes of tenesmus are so diverse, are the tenesmus-specific treatments.

A Word From Verywell

While you may feel uncomfortable discussing tenesmus with your doctor, it is important to do so. 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. None of these symptoms should ever be dismissed or ignored.