Constipation

Constipation is one of the most common digestive complaints worldwide, affecting approximately 10-15% of the global adult population at any one time. In Singapore, where dietary fibre intake is chronically low by international standards and a significant proportion of the population leads a sedentary lifestyle, constipation is extremely prevalent.

For most people, constipation is an occasional inconvenience that resolves with simple dietary and lifestyle changes. For a meaningful proportion, it becomes a chronic condition that significantly affects quality of life -- causing daily discomfort, bloating, anxiety, and time spent managing symptoms. And for a smaller group, constipation is not a lifestyle problem at all, but a symptom of an underlying medical condition that requires investigation and specific treatment.

Defining Constipation: More Than Just Frequency

A common misconception is that constipation means not having a bowel movement every day. In fact, normal bowel frequency ranges from three times a day to three times a week -- all of which are considered within the normal spectrum. Constipation is defined not by frequency alone but by the experience of difficult, strained, or incomplete defaecation.

Chronic constipation is diagnosed when two or more of the following have been present for at least three months:

Fewer than three spontaneous bowel movements per week
Straining in more than 25% of defaecation attempts
Hard or lumpy stools (Bristol Stool Chart Types 1-2) in more than 25% of defaecations
A sensation of incomplete evacuation after more than 25% of defaecations
Feeling that the stool is blocked or difficult to pass during more than 25% of bowel movements
Needing to use assistance, such as removing stool with a finger or supporting the area around the anus, to help pass stool in more than 25% of bowel movements

Loose stools are rarely present without the use of laxatives in true constipation. This distinguishes constipation from irritable bowel syndrome with constipation, where abdominal pain is a prominent feature alongside the constipation, and from functional diarrhoea.

Bristol Stool Chart: Describing Your Stool

The Bristol Stool Chart is a validated clinical tool used worldwide to standardise descriptions of stool consistency. Knowing where your stool falls on the chart is one of the most useful pieces of information you can bring to a medical consultation.

Type 1 (Separate hard lumps): Stool resembles little pebbles or rabbit droppings. Signifies severe constipation.
Type 2 (Lumpy, sausage-shaped): Stools are hard and difficult to pass. Signifies mild constipation.
Type 3 (Sausage-shaped with cracks): Stools have some surface cracks and requires effort to pass. Signifies normal stools to mild constipation.
Type 4 (Smooth, soft sausage or snake): Stools passes easily with the ideal consistency.
Type 5 (Soft with clear edges): Stools passes easily, but are slightly too soft. Signifies borderline normal to mild diarrhoea.
Type 6 (Fluffy pieces with ragged edges): Mushy and/or semi-solid stools. Signifies mild diarrhoea.
Type 7 (Entirely liquid): No solid pieces, stools are watery. Signifies severe diarrhoea.

Constipation is associated with Types 1 and 2 -- separate hard lumps or a hard, lumpy sausage. The ideal stool for comfortable, effortless defaecation is Type 3-4. Types 5-7 indicate progressively looser stools and diarrhoea.

Types and Causes of Constipation

Understanding the cause of constipation is the starting point for effective treatment. A cause that responds to dietary fibre will not respond to biofeedback physiotherapy -- and a cause that requires colonoscopy to exclude will not respond to any laxative. The six main categories of cause are:

Functional Constipation: The most common type of diarrhoea, where there is no clear structural or medical cause. It can occur when the colon moves stool too slowly (slow-transit), when the pelvic floor muscles do not relax properly (outlet dysfunction), or when stool is hard and difficult to pass despite normal bowel movement frequency (normal-transit constipation).
Diet and Lifestyle: Diet and Lifestyle Low dietary fibre intake, inadequate fluid intake, sedentary lifestyle, and ignoring or suppressing the urge to defaecate are the most common correctable causes. Travelling and changes to routine can also disrupt bowel habit temporarily.
Medications: Some medicines can cause constipation, especially opioid painkillers. Other common causes include antacids, iron and calcium supplements, certain antidepressants, antipsychotics, antihistamines, antispasmodics, and some blood pressure medicines.
Structural / Colorectal Causes: Constipation can be caused by physical blockage or changes in the bowel. Colorectal cancer is an important cause to rule out, especially in people over 50 or those with warning signs. Other causes include anal narrowing, rectocele, rectal prolapse, and pelvic organ prolapse.
Neurological Conditions: Conditions such as Parkinson’s disease, multiple sclerosis, spinal cord injury, diabetes-related nerve damage, and stroke can affect bowel movement and make it harder to pass stool. Constipation is a common and often early symptom of Parkinson’s disease.
Systemic and Metabolic: Conditions such as hypothyroidism, high calcium, low potassium, and kidney failure can slow bowel movement and cause constipation. Coeliac disease and inflammatory bowel disease can also sometimes cause constipation. Thyroid function may be checked in people with new-onset constipation.

Symptoms of Constipation

The core symptoms are well recognised, but constipation can also produce broader systemic effects that patients may not associate with their bowel:

Primary bowel symptoms

Fewer than three spontaneous bowel movements per week
Straining: Needing to push hard or bear down for extended periods
Hard, dry, or lumpy stools that are difficult or painful to pass/li>
A feeling of incomplete evacuation -- the sense that the bowel has not fully emptied even after a successful bowel movement
A sense of obstruction or blockage at the anus or rectum
The need to use fingers or apply perineal pressure to assist stool passage

Associated symptoms

Bloating and abdominal distension: Often worse by the end of the day
Abdominal cramping or discomfort, particularly in the lower abdomen
Nausea, particularly when constipation is severe or associated with overflow
Reduced appetite: From the sensation of fullness and bloating
Haemorrhoids and anal fissures: Chronic straining is a primary cause of both; blood on the toilet paper from an anal fissure is commonly seen alongside severe constipation
Headache and malaise: Commonly reported by patients with chronic constipation, though the mechanism is not fully established

Risk Factors

People of all ages may suffer from occasional bouts of constipation. Certain risk factors may increase a person's risk of becoming chronically constipated. These factors include:

Female sex: Women are approximately twice as likely as men to have chronic constipation, particularly related to pelvic floor dysfunction, pregnancy, and hormonal factors
Older age: Stool movement in the colon slows with age, physical activity declines, fluid intake often decreases, and medication use (with constipating side effects) increases; constipation prevalence increases sharply from the 60s onwards
Low dietary fibre intake: The average Singaporean adult consumes 12-15g of fibre per day against the recommended 25-30g; this gap is one of the most significant modifiable contributors to constipation
Inadequate fluid intake: Insufficient hydration results in the colon absorbing more water from faecal material, hardening the stool
Sedentary lifestyle: Physical activity stimulates colonic motility; even a daily walk significantly reduces constipation risk in inactive individuals
Pregnancy and postpartum period: Progesterone relaxes smooth muscle including the colon, slowing transit; the enlarging uterus compresses the rectum in later pregnancy
Mental health conditions: Anxiety and depression are associated with constipation through gut-brain axis dysregulation; the gut-brain bidirectional relationship is increasingly recognised in functional bowel disorders
History of pelvic surgery, trauma, or childbirth injury: This can affect pelvic floor muscle coordination
Travel: Changes in diet, routine, fluid intake, and the reluctance to use unfamiliar toilets commonly trigger temporary constipation

Irritable Bowel Syndrome with Constipation (IBS-C) vs Functional Constipation

IBS-C and functional constipation share many features and are often confused by patients and clinicians alike. The key distinguishing feature is abdominal pain.

Functional constipation: the primary complaint is difficult or infrequent defaecation. Abdominal discomfort may be present but is not prominent, and does not consistently relate to bowel movements.
IBS-C: abdominal pain or cramping is a dominant symptom and is characteristically associated with bowel movements -- it improves after defaecation, or it is triggered by constipation. The pain component is required for the IBS-C diagnosis under Rome IV criteria.

How Constipation is Diagnosed?

Investigation is guided by the clinical picture -- lifestyle-related constipation in a young person with no alarm features needs no investigation beyond history and examination. Chronic constipation with alarm features, constipation that has not responded to adequate treatment, or constipation in a patient over 50 warrants a more systematic approach.

Physical and Rectal Examination: The abdomen is checked for swelling, tenderness, and built-up stool. A rectal examination checks for stool, haemorrhoids, anal fissures, or masses. Asking the patient to strain can also help identify pelvic floor problems or rectocele.
Blood Tests: Blood tests can help find underlying causes of constipation. They may include tests for anaemia, thyroid function, calcium levels, kidney function, blood glucose, and electrolytes.
Faecal Occult Blood Test (FOBT / FIT): This test checks for small amounts of blood in the stool that cannot be seen. A positive result, especially with constipation, may be a warning sign of bowel disease and may require a colonoscopy. It is also used for colorectal cancer screening.
Colonoscopy: A key test used to check for colorectal cancer, polyps, inflammatory bowel disease, and other bowel problems that may cause constipation. It is especially important for people with warning signs such as rectal bleeding, weight loss, anaemia, a new change in bowel habits after age 50, a lump, or a family history of colorectal cancer. Polyps can also be removed during the procedure.
Abdominal X-ray: A quick test that shows the amount and location of stool in the colon. It can help confirm significant constipation and detect an enlarged colon or rectum. However, it cannot rule out colorectal cancer or other bowel diseases.
Colonic Transit Study: he patient swallows small markers that can be seen on an X-ray. An X-ray is taken after a few days to see where the markers remain. Markers spread throughout the colon suggest slow-transit constipation, while markers mainly in the rectum suggest outlet dysfunction. This helps determine the type of constipation and guide treatment.