We all know when we need to have a bowel movement. It tends to feel like a pressure or pushing sensation in the lower abdomen and pelvis. The feeling to have a bowel movement is known as urging. It happens when the rectum fills with stool. This stretching of the rectal wall triggers urging. It compels us to seek a suitable setting, usually a toilet, to pass stool. Once the bowel movement is complete, this urging sensation subsides.
However, this does not always occur as expected. There are many reasons why the bowels may not feel ‘empty’ after defecation. Difficulty passing stool for any reason can lead to this ‘unsatisfied’ feeling. This incomplete bowel movement sensation is not always due to stool still being in the rectum. Sometimes the rectum is empty but the sensation to pass stool persists.
What is tenesmus?
Tenesmus is the persistent urge to have a bowel movement even after passing stool. It can vary in intensity. Most people experience it as an incomplete bowel movement sensation. In other words, it feels like the rectum still contains stool. However, attempting to pass stool again is usually unsuccessful and the sensation persists. Future bowel movements do not completely resolve the uncomfortable sensation.
There are certain conditions where tenesmus is prominent even without there being any abnormal bowel habit (constipation or diarrhea). It can be ongoing for days, weeks and even months. The nagging sensation is uncomfortable but it is not usually considered to be serious. Although tenesmus itself is just a symptom, it may occur with serious conditions like colorectal cancer.
It can be confusing to differentiate an abnormal sensation from urging due to feces in the rectum. Normal bowel habit varies from two movements a day to up to three movements per week. If a person has regular bowel movements with soft stool of reasonable volume, then any persistent urge may be tenesmus. It is important to consult with a medical professional for further investigation.
Read more on abnormal urging to pass stool.
Causes of Tenesmus
There are several reasons why tenesmus may occur. It may be due to incomplete emptying of the rectum during defecation. The remaining feces causes the rectal walls to remain stretched. It is this stretching that is responsible for the urge to defecate that we all experience on a daily basis.
Stretch receptors in the rectal wall are stimulated and send signals to the spinal cord. It is these signals that we perceive as the urge to defecate. If the rectal wall is inflamed then the stretch receptors are abnormally stimulated. This may cause the urging sensation even when the rectum is empty.
Nerve disorders can also cause abnormal stimulation of the nerves that carry the urge signals to the spinal cord. Again it is perceived as an urge to defecate even when there is no need to pass stool, when the rectum is empty or after having a bowel movement.
Any mass in the rectum, even if it is not feces, can also cause tenesmus. This may include enlarged blood vessels, benign tumors and even cancerous growths. An uncommon but possible cause is a foreign body inserted in the rectum through the anus.
Read more on constant feeling to pass stool.
The walls of the rectum and anal canal as well as the anus can become inflamed for various reasons. Injury, irritation, infections and other causes of inflammation may be responsible for the incomplete bowel movement feeling.
- Inflammatory bowel disease – Crohn’s disease, ulcerative colitis.
- Infectious colitis – infection of the colon with inflammation of the colonic wall.
- Injury following diagnostic procedures like a colonoscopy, insertion of suppositories or anal intercourse.
- Radiation proctitis/colitis – inflammation of the colon/rectum due to radiation exposure (often therapeutic radiation therapy to target neighboring tumors).
Scar tissue can also form in the anorectal region with severe or long term inflammation. This scar tissue may cause an ongoing sensation of needing to defecate.
Mass in the Anus and Rectum
Apart from feces, various other masses may occur in the region of the anus and rectum. These masses are abnormal. Some are serious while most are not despite the discomfort it causes. Apart from incomplete bowel movement feeling, many people also describe it as a feeling of ‘something stuck’ in the rectum or anus.
- Anorectal abscess which is a collection of pus in the anal/rectal region.
- Benign tumors including colon polyps. Some polyps have the potential to become cancerous.
- Colorectal cancer.
- Impacted feces which is hard compressed stool that cannot be passed out.
- Large / thrombosed hemorrhoids (swollen, distended veins) also known as piles.
Abnormal Bowel Motility
Contractions in the colon and rectum are also responsible for the urging to pass stool. The muscle activity pushes food and stool through the bowels and also expels stool from the rectum during defecation. If there are abnormalities in these contractions then stool may not be emptied fully. Ongoing contractions may also be perceived as a persistent urge to defecate (tenesmus).
This may be seen with the following conditions:
- Constipation where bowel motility may be slower or weaker than normal.
- Diarrheal illnesses like gastroenteritis or colitis for any reason.
- Irritable bowel syndrome (IBS) also tend to experience tenesmus which may be due to the abnormal bowel motility or complications like hemorrhoids.
- Fecal incontinence which is mainly due to nerve and muscle disorders.
Diet and Lifestyle Remedies
When an incomplete bowel movement feeling is due to some disease or disorder then medical treatment is required. Sometimes surgery is necessary. However, if the problem is with bowel habit like constipation then some simple dietary and lifestyle measures may be helpful.
- Increase dietary fiber. Supplements are useful but a diet rich in fibrous foods, like fruits and vegetables.
- Drink at least 2 liters of water daily. Along with dietary fiber, water helps to soften the stool and provide bulk.
- Exercise is helpful. People who are sedentary are more likely to experience constipation. Even a simple workout like walking after a meal can be helpful. Read more on bowel movement exercises.
- Avoid diuretics. These are substances, like caffeinated and alcoholic drinks, that increase fluid loss from the body and can worsen constipation.