We all pass stool on a daily basis and it is an essential process whereby the body rids the system of wastes. Most of the time we do not give the process of defecation any further thought but it is important to understand what should be considered normal and where a problem may like. Changes in bowel habit can sometimes be the earliest symptom of several serious and even life-threatening diseases.
What is a bowel movement?
Define Bowel Movement
A bowel movement is the term used to describe the process of defecation. It is where stool (feces) is expelled from the gut through the anus. Most people have at least one bowel movement a day and it should be painless and relatively effortless. The stool should be soft, smooth and elongated (sausage-shaped) when there are no underlying problems that can cause bowel movement problems.
Meaning of Bowel Movement
The term bowel movement can sometimes be misleading. There is movement throughout the digestive tract, from the mouth to the anus. This movement is caused by muscles in the wall of the gut that rhythmically contract and relax to push food and wastes along its length. The bowels refer to the small intestine and large intestine, where most digestion occurs and where stool is formed.
The colon, the main part of the large intestine, is responsible for reabsorption of water to ensure that the fluid mixture within it takes on a more solid form to become stool, storage of stool and eventual evacuation of the stool. It is also known as the large bowel (large intestine). Once the colon becomes stretched with stool, a person feels an urging to have a bowel movement.
Eventually strong contractions in the colon wall pushes the stool into the rectum. From here the rectum pushes out the stool through the anal canal, past the the two anal sphincters and out through the anus into the environment. This process is referred to as a bowel movement or in medical terms as defecation. Sometimes stool or feces is also referred to as bowel movement. Therefore the term bowel movement is often used loosely to describe both defecation and feces.
How many bowel movements per day?
The number of times a person has a bowel movement can vary greatly among individuals. Bowel habit refers to the frequency of stool that is a regular pattern for a person. Normal bowel habit is considered to be between three bowel movements per day to three bowel movements per week. It is important to note that normal bowel habit also means that passing stool is not difficult nor painful.
Some people may have only one or two bowel movements in a day, whereas others may have one bowel movement every second day. As long as the bowel habit is within the three times daily to three times weekly range, it is considered to be normal. More frequent bowel movements will be considered as diarrhea. Less frequent bowel movement are a sign of constipation.
Normal Bowel Movement
Normal bowel movement is/does:
- Passed 3 times daily to 3 times weekly.
- Not difficult to pass out.
- Not require straining to push out the stool.
- Not painful.
- Not causes burning, pain or bleeding of the anorectal region.
In addition to the frequency and ease of bowel movements, the texture, consistency and shape of stool also determines what can be considered as normal bowel habit or not. According to the Bristol Stool Chat, normal stool should be soft, smooth (sometimes with cracks) and sausage-shaped (elongated). Hard, round or ragged stool is a reflection of constipation while watery or entirely liquid stool is seen with diarrhea.
Types of Bowel Movement Problems
Most of us know the two most common bowel movement problems – diarrhea and constipation. Both of these abnormalities in bowel habit are just a sign of an underlying bowel problem. Therefore diarrhea and constipation are seen in an array of different digestive, dietary, lifestyle and even systemic problems.
Diarrhea is defined as having more than three bowel movements with a 24 hour period where the stool is loose to watery in consistency. In strict terms, it is also defined as passing more than 200gm (about 7oz) to 200ml (about 6.8oz) within a 24 hour period.
Conditions where diarrhea may be present includes:
- Food intolerance
- Food poisoning
- Gastroenteritis, enterocolitis and colitis
- Inflammatory bowel disease (IBD)
- Irritable bowel syndrome (IBS)
- Laxative overuse
- Malignancy, such a colorectal cancer
Most of the time diarrhea arises suddenly and is intense (acute diarrhea). This is often due to an infection or food poisoning. It lasts for a few days and usually resolves on its own thereafter.
Constipation is defined as having less than three bowel movements within a 24 hour period where the stool is hard, difficult to pass out and requires straining. While diarrhea is usually acute, constipation tends to be a chronic problem which persists for months and even years.
Conditions where constipation may be present includes:
- Bowel obstruction
- Irritable bowel syndrome (IBS)
- Poor nutritional habits, such as low fiber diet
- Spinal cord injury
However, in most cases constipation is due to unknown causes which is also referred to as idiopathic. There may be no underlying disease yet constipation persists. The next most common cause of constipation is inadequate fiber and water intake, which is a problem particularly with the modern diet of processed foods.
Functional Bowel Disorders
Various diseases that may cause constipation and diarrhea have been discussed above. However, there can be fluctuations in bowel habit that may not be due to any disease. It is an abnormality that appears to be due to unusual activity of the bowel and is referred to as a functional bowel disorder.
The most well known of these disorders is irritable bowel syndrome (IBS). It appears to be due to overactivity within the bowel that leads to diarrhea-predominant IBS or underactivity of the bowels that leads to constipation-predominant IBS. Abdominal pain is a common feature in IBS.
Sometimes diarrhea and constipation may occur without abdominal pain and is not due to any disease. In this case it is referred to as functional diarrhea or functional constipation. It is believed that most cases of constipation could be classified as functional constipation.