Incomplete Bowel Movement and Causes of Tenesmus

Most of us have experienced instances where a bowel movement did not feel complete. We may use a range of terms to describe this type of bowel movement, including unsatisfied or incomplete. There may still be the urge to pass stool after the bowel movement and sometimes an inability to defecate despite this urging.

There are several reasons for this incomplete bowel movement sensation. Sometimes may be due to the incomplete emptying of the rectum. Stool may therefore still be retained with the rectum. However, at other times this incomplete feeling can occur even though there was complete evacuation of the stool in the rectum.

What is Tenesmus?

The persistent urge to pass stool despite having a bowel movement is known as tenesmus. We all experience the defecation urge prior to having a bowel movement. As the bowels are emptied, this urge gradually subsides. However, with tenesmus this urging to pass stool persists and is not relieved with a bowel movement.

Why does the urge persist?

As mentioned, the persistent urge may be due to incomplete emptying of the rectum. The stretched rectal walls coupled with mass movements in the colon is responsible for this sensation. It is influenced by other stimuli, apart from stretching of the colon and rectal wall. With bowel emptying, this sensation diminishes and a person feels relieved.

In tenesmus, the sensation to defecate or feeling that the bowel movement was incomplete exists despite the bowel being empty. Attempting to defecate will result in little or no stool, however the urge persists for hours or even days. It is characterized by a nagging, persistent urge to defecate often accompanied by pain, intestinal cramps and straining during a bowel movement.

Causes of Incomplete Bowel Movement

The feeling of having an incomplete bowel movement associated with only partial emptying of the bowels may occur for various reasons, including constipation, anxiety, rectal masses and disturbances during defecation that prevents a person from having a complete bowel movement. Other factors like hemorrhoids may cause a person to quickly end a bowel movement in order to avoid exacerbating the problem.

With tenesmus, the bowel movement is usually complete and the rectum empty but the sensation to defecate persists. This may be related to a mass in the rectum (not stool) causing this sensation, abnormal stretching of the rectal walls, irritation or damage of the rectal wall and nerves, exaggerated defecation reflexes or overactivity of the colonic motility.

Anorectal Masses

A number of different types of masses in the colon, rectum and/or anus can cause an incomplete bowel movement sensation. These masses occupy space and even when stool is passed out, the mass may cause a sensation of fullness. Some masses may also contribute to constipation.

  • Anorectal abscess is a collection of pus (abscess) in the region where the anus and rectum meet.
  • Colonic polyps are outgrowths that protrude from the walls of the colon. Most of these growth are benign (non-cancerous) but some polyps have the potential to become cancerous.
  • Colorectal cancer is a malignant growth in the colon and/or rectum. It is one of the most common types of cancer and also among the deadliest.
  • Large / thrombosed hemorrhoids is when the rectal arteries become inflamed and swollen (hemorrhoids) and eventually occluded by a blood clot (thrombosis).
  • Fecal impaction is where the feces becomes a hard mass, cannot be passed out during a bowel movement and obstructions the passage of stool during defecation.

Damage, Irritation or Scarring of the Bowel

Inflammation may occur in the bowels for various reasons, ranging from injury to infection and autoimmune diseases. The bowel tissue can be damaged and in severe cases even scar tissue may develop in the affected area.

  • Inflammatory bowel disease (IBD) is where inflammation occurs in the bowels and sometimes in other parts of the gut, possibly due to autoimmune factors. There are two types – Crohn’s disease, ulcerative colitis
  • Infectious colitis is inflammation of the colon due to a bacterial, protozoal or viral infection. Most cases are mild and acute but some can be severe.
  • Radiation proctitis/colitis is inflammation of the colon/rectum due to radiation exposure (often therapeutic radiation therapy to target neighboring tumors).

Colorectal Motility Disorders

Movement through the bowels is made possible by the contraction and relaxation of muscl ein the bowel wall. This is also responsible for pushing stool out of the colon and rectum during defecation. Disorders in bowel movement primarily involve the large intestine but could extend as high up as the end portion of the small intestine.

  • Diarrhea due to any cause like infectious gastroenteritis affects normal bowel movements and usually speeds up the motion within the bowels.
  • Constipation due to any cause also impacts on normal movement through the bowels and feces may accumulate and stretch the bowels so it cannot contract (pseudo-obstruction).
  • Irritable bowel syndrome (IBS) patients may also report tenesmus and it is often related to large hemorrhoids as well. This is often seen with diarrhea-predominant IBS where the urge does not subside after a bowel movement.
  • Fecal incontinence is where a person loses bowel control and may be unable to hold back defecation till an appropriate time. There are various causes of fecal incontinence and along with involuntary bowel movements, tenesmus is often present.

Treatment of Tenesmus

Tenesmus is a symptom of some underlying bowel condition. There is no specific treatment for tenesmus on its own. Instead treatment should be directed at the underlying cause. This may require dietary and lifestyle changes, medication and even surgery at times. Some of the dietary and lifestyle measures which can help to relieve tenesmus in certain instances are similar to the management of conditions like constipation.

  • Maintain adequate hydration on a daily basis. Adults should drink at least 2 liters (about 64 fl oz) of water daily. This applies to water on its own and not other beverages.
  • Ensure sufficient fiber intake by eating high fiber foods. Fresh and raw fruits and vegetables as well as wholegrains should constitute most of the food intake.
  • Minimize alcohol and caffeine intake as these substances are diuretics which increase water loss. As a result, stool may not be soft and easily passed out.
  • Try to increase physical activity through a dedicated exercise program. Even simple activities like walking daily can with bowel habit.

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