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Irritable Bowel Syndrome (IBS): A Colorectal Surgeon Guide

Medically reviewed by Dr. Sim Hsien Lin, Consultant General Surgeon (Colorectal Surgery)

Irritable Bowel Syndrome (IBS) is a chronic gastrointestinal or bowel disorder featuring recurrent abdominal pain with diarrhoea or constipation. IBS is mainly a disorder of gut motility and function. For people diagnosed with IBS, gut movements are sometimes faster and, at other times, slower. The symptoms of IBS varies, some people have diarrhoea as a predominant symptom, while others have constipation as a predominant symptom. There can be cases of IBS with both diarrhoea and constipation symptoms alternatively.

IBS is a fairly common condition, with prevalence rates of 10-15% worldwide. It has been found that IBS is more common in women than in men. IBS can occur at almost any age, but it typically affects adults of age group 30 to 40 years old.

It’s worth noting that IBS is a different condition from inflammatory bowel disease (IBD) which includes Crohn’s disease and ulcerative colitis. IBS is not a life-threatening condition nor does it produce any serious complications. It does not increase your risk for colon cancer, nor does it cause any structural damage or changes in the colon. Nevertheless, IBS can be distressing and may have a great impact on work and daily life.

Cause & Risk Factors

The underlying cause of IBS is not known clearly. However, multiple factors appear to play a role in causing IBS and act as triggers for the IBS symptoms. Below are some of the well-known triggers or risk factors for IBS.

  • Diet: Dairy products, caffeine, artificial sweeteners are more likely to worsen the symptoms in people having IBS.
  • Post-infection: IBS symptoms might begin following bacterial infection of the stomach and intestines i.e., gastroenteritis caused by Campylobacter, Salmonella, and Shigella.
  • Stress and Psychological factors: It’s a well-known fact that stress and lack of sleep are found to trigger IBS symptoms in many individuals. Also, several research studies suggest IBS is linked to people with depression and anxiety.
  • Genetics and environment: Although no single gene mutation has been identified to cause this condition, it could possibly be due to the mutation of many genes. IBS tends to occur in individuals with family history of the condition.


Symptoms tend to come in phases or episodes that can last for days to weeks and may relapse after a certain time. Symptom intensity ranges from mild to severe and differs between individuals, for severe cases, it can even affect their daily lives. The most frequently reported symptom is abdominal pain. Abdominal pain can be localized or generalized, which is instantly relieved with the passing of stool or gas. The stool is not too watery but most often, mucus is present. People who have IBS, generally report to the doctor with the following symptoms:

  • Abdominal pain and cramps
  • Diarrhoea and/or constipation
  • Bloating (or distension)
  • Flatulence and gas
  • Mucus in stool
  • Anxiety and depression


IBS is diagnosed based on your clinical history, past medical history and with no clinical evidence of other gastrointestinal diseases. It’s worth noting that IBS is diagnosed only if your symptoms are present for more than six months and do not have any other similar conditions. No visible changes are noted on abdominal X-ray, endoscopy or colonoscopy if you have IBS.

Based on clinical features, you might need to undergo some tests for further evaluation and diagnosis: Blood tests, Urinalysis and urine culture, Stool culture, Faecal occult blood test, Abdominal X-ray, Abdominal Ultrasound, Colonoscopy. If test results are normal and not pointing towards other conditions, it is more likely you have IBS.

Other Conditions Similar to IBS

It must be understood that several other conditions do present with similar symptoms. So it is important to elicit a detailed clinical history and rule out other diagnoses. If a person presents with rectal bleeding, significant weight loss or fever along with symptoms of IBS, it can indicate other diseases and should seek medical advice.

Following are the differential diagnosis of IBS:

  • Lactose intolerance
  • Infectious or Drug-induced diarrhoea
  • Celiac disease
  • Inflammatory bowel disease (Crohn’s disease and Ulcerative colitis)
  • Colorectal cancer

Treatment Options For IBS

There is no known cure for IBS, but it is possible to manage the symptoms through multiple approaches.

Dietary changes

If you have IBS, you might need to be cautious about certain foods you consume in your diet, as certain foods can be the triggers for IBS symptoms. You will also need to follow diet habits.

  • Fibre-rich diet: Good sources of fibre include vegetables, green leafy vegetables, fruits, whole grains.
  • Hydration: Drinking 1.5 – 2 litres of water per day is essential to maintain hydration and also aids in the digestion and absorption of food in the intestine.
  • Adopting Diet that is gluten free or low in fermentable oligosaccharides, disaccharides, monosaccharides and polygols (FODMAP). FODMAPs are found in food such as wheat, onions, some fruits and vegetables, sorbitol and some dairy.

Lifestyle Changes

  • Stress management: As we know, stress and lack of sleep can be a trigger for IBS symptoms. Knowing how to handle stressful situations and getting adequate sleep is particularly important in managing this condition.
  • Regular exercises: Physical and breathing exercises like yoga will certainly help in reducing stress and maintaining good health.
  • Stop smoking and alcohol intake: Smoking and alcohol can actually cause flare-ups in those having IBS. So, one needs to consider stopping smoking and alcohol intake in order to relieve the symptoms.


  • Antispasmodics: Antispasmodics are used to control abdominal pain and spasms. They work by decreasing gut motility.
  • Laxatives: Laxatives are particularly beneficial in IBS with constipation. Laxatives work by absorbing fluid and promoting gut movements.
  • Antidiarrheal: Loperamide and Diphenoxylate are drugs used to treat chronic diarrhoea symptoms. They work by slowing gut movements.
  • Probiotics supplements: Probiotics contain friendly bacteria, which is available in yoghurt or supplements. Taking probiotics for a period of 2-4 weeks provides relief of symptoms. Persons with IBS will more likely benefit from probiotics as they help boost gut health.


Irritable Bowel Syndrome (IBS) is a fairly common digestive disorder that can cause repeated abdominal pain and changes in bowel movements. The symptoms occur intermittently and can be a lifelong problem. IBS can significantly impact your daily life leading to frustration, anxiety, and depression. Since many conditions can mimic the symptoms of IBS it is important to seek help from a healthcare provider. There is no definitive cure for the disorder but your doctor may help find the treatment that works best for you. Dietary modification, probiotics, and medications can improve symptoms and the quality of life. Leading an active and healthy lifestyle is also beneficial.

Dr. Sim Hsien Lin’s main sub-specialty is in colorectal surgery. In addition, her sub interests include laparoscopic colorectal surgery, transanal endoscopic microsurgery (TEMS), surgical management of piles, inflammatory bowel diseases, complex anal fistulas as well as diagnostic and therapeutic endoscopic procedures.

Dr. Sim Hsien Lin

Consultant General Surgeon (Colorectal Surgery)
  • MBBS (Singapore)
  • MRCS (Edinburgh)
  • MMed (General Surgery)
  • FRCS (Edinburgh)

Dr. Sim Hsien Lin is a specialist colorectal surgeon in Singapore with over 10 years of experience in colorectal surgery. Her sub interests include laparoscopic colorectal surgery, transanal endoscopic microsurgery (TEMS), surgical management of piles, inflammatory bowel diseases and complex anal fistulas.

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