i. Coeliac disease
Coeliac disease is a chronic small intestine disease precipitated by dietary gluten in genetically predisposed individuals. The disease is caused by an immune reaction triggered by exposure to gluten. This should not be confused with “gluten sensitivity” or gluten allergy. The disease may present with the “classic” features of malabsorption, but “atypical” coeliac disease is becoming more common.
Classical celiac disease
- Steatorrhoea (fatty stools)
- Weight loss
- Nutritional deficiencies
Atypical celiac disease
- Iron deficiency anaemia
- Abdominal bloating and discomfort
The diagnosis of coeliac disease depends on a combination of blood tests (serology) and histological findings (obtained by Gastroscopy). The diagnosis may be complicated by the removal of gluten from the diet prior to assessment by a physician.
The treatment of celiac disease is a gluten free diet (GFD). Gluten is the protein component of wheat. There may be cross-reactivity with the protein components in rye and barley as well, and elimination of these from the diet is also important. Effective management requires consultation with a dietician, as many foods and other products contain gluten.
ii. Inflammatory bowel disease
Inflammatory bowel disease (IBD) is an immune-mediated group of diseases affecting the bowels. The causes are complex and not fully established, but include genetic predisposition, infectious agents, environmental factors (e.g. medications, smoking) and the composition of gut micro-organisms (microbiota).
IBD typically affects the bowel, but may have manifestations outside of this system, including liver, eye, skin and joint problems.
There are no specific tests to diagnose ulcerative colitis and Crohn’s disease. Diagnosis relies on a combination of clinical, endoscopic and histological pictures.
The diagnosis and management of inflammatory bowel disease should be handled by a gastroenterologist.
iii. Ulcerative colitis
Ulcerative colitis is a chronic inflammatory disorder affecting the colon. The disease will almost always affect the last part of the colon, with the extent of involvement of the colon being variable but always continuous. The whole colon may be involved. The severity of UC also varies – from mild disease requiring minimal medication to severe disease requiring surgical removal of the colon. Severe UC, if not managed promptly, can be life-threatening.
- Diarrhoea – typically bloody.
- Rectal bleeding
- Weight loss
- Abdominal pain – usually not severe
The diagnosis of ulcerative colitis can be suspected based on the history and clinical picture. However, diagnosis requires colonoscopy with mucosal biopsies and exclusion of other conditions that may mimic it. Such conditions include Crohn’s disease and various infective causes of colitis.
Because ulcerative colitis is an inflammatory condition, agents which suppress inflammation are used in its treatment. The most commonly used class of anti-inflammatory agents are called 5-ASA agents (after their chemical structure). These agents do not suppress the immune system.
If 5-ASA agents are ineffective, or expected to be, then immunosuppressant agents are used. These medications weaken the immune system in order to dampen the immune-mediated inflammation in the bowel. Because of this, patients using them may be susceptible to certain infections. They are powerful agents and should only be used by doctors experienced in their use.
In certain situations it is necessary to remove the colon surgically. This may be in life-threatening acute severe ulcerative colitis or in patients where all therapeutic options have been exhausted. Fortunately, due to the constant development of new and effective therapies, this is becoming rare. Surgical resection of the colon can be considered as a curative procedure, but the consequences of surgery often negatively impact on quality of life.
Patients with ulcerative colitis have an increased risk of developing colorectal cancer. It is important that patients that have had ulcerative colitis for more than ten years be assessed for risk of cancer and be surveyed appropriately.
iv. Crohn’s disease
Crohn’s disease (CD) is a chronic inflammatory condition that can affect any part of the gastro-intestinal tract – from the mouth to the anus. It most commonly affects the last part of the small bowel and first part of the colon (large bowel). It may vary in severity – from not requiring specific treatment to treatment-refractory disease. Early effective therapy is vital in preventing long-term complications.
- Abdominal pain
- Blood in the stools
- Weight loss
- Growth retardation in children
- Oral ulcers
- Peri-anal disease e.g. fissures, fistulas
As with ulcerative colitis, the diagnosis of Crohn’s disease is suspected based on the history and clinical picture. It is then confirmed by colonoscopy or radiological investigations (e.g. CT scan or MRI) and excluding conditions that mimic it. Tuberculosis is the condition most commonly confused with Crohn’s disease, as the two may be virtually indistuishable. This is of special concern as the treatment of Crohn’s disease will make infection with tuberculosis much worse.
The treatment for Crohn’s disease is not curative. It usually consists of immunosuppressive medications, but sometimes surgery is required in severe cases. Medication use is usually lifelong and should be managed by a gastroenterologist. 5-ASA agents used in ulcerative colitis are rarely very effective and immunosuppression is recommended in all but mild cases of Crohn’s disease.
Immunosuppressant agents weaken the immune system and so reduce the immune-mediated inflammation in the bowel. Because of this, they also make the body susceptible to certain infections. Immunosuppressant therapy should prescribed by a doctor trained in their use.
In severe or untreated cases of Crohn’s disease complications may develop that require surgery to correct. These include fistulas, strictures or abscesses.
Patients with Crohn’s disease involving the colon which is present for more than ten years are at increased risk of developing colorectal cancer. Their risk should be assessed and they should be surveyed appropriately.
v. Irritable bowel syndrome
Irritable bowel syndrome is a disorder characterized by chronic abdominal pain and altered bowel habits in the absence of an identifiable organic cause. It is very common, affecting 10-15% of the population in first world countries. Many factors are thought to contribute to the development of IBS, but the exact mechanism has not been determined.
- Abdominal pain – Typically cramping in nature and varies in intensity. It may be associated with change in stool consistency, eating, emotional stress and even the menstrual cycle in females. It is usually relieved by passing stools.
- Changes in bowel habits – This may include diarrhoea, constipation or alternating diarrhoea and constipation.
- Bloating, flatus and belching.
Because IBS occurs in the absence of organic disease, it is often first necessary to exclude other medical conditions before making the diagnosis. This may include blood tests, endoscopy (gastroscopy, colonoscopy) or radiology, depending on the presenting symptoms.
Rome IV diagnostic criteria
According to the Rome IV criteria, the diagnosis of irritable bowel syndrome requires the following:
- Recurrent abdominal pain, on average 1 day per week for the past 3 months
At least two of the followiong:
- Related to defecaotion
- Associated with a change in stool frequoency
- Associated with a change in stool consistency
- Above criteria fulfilled for the past three months, with symptom onset at least six months ago
vi. Chronic constipation
Constipation is sometimes described as the passage of stools less than three times per week. However, this should be accompanied by other symptoms, including hard stools, a feeling of incomplete evacuation, abdominal discomfort, distention, bloating, and symptoms of defecatory disorders (see later).
Chronic constipation may be caused by specific diseases or medications (“secondary constipation”). However, more commonly constipation is not found to have a specific cause. This is referred to as “primary constipation”. It is important to differentiate between chronic constipation and irritable bowel syndrome with constipation (where pain is the predominant feature).
Rome IV criteria for functional constipation.
The diagnosis should be based upon the presence of the following for at least three months (with symptom onset at least six months prior to diagnosis).
Must include two or more of the following:
- Straining during more than 25 percent of defecations
- Lumpy or hard stools (Bristol Stool Scale Form 1-2) in more than 25 percent of defecations
- Sensation of incomplete evacuation for more than 25 percent of defecations
- Sensation of anorectal obstruction/blockage for more than 25 percent of defecations
- Manual manoeuvres to facilitate more than 25 percent of defecations (eg, digital evacuation, support of the pelvic floor)
- Fewer than three spontaneous bowel movements per week
- Loose stools are rarely present without the use of laxatives
- There are insufficient criteria for IBS (See Irritable bowel syndrome)
Although patients with functional constipation may have abdominal pain and/or bloating, they are not the predominant symptoms.
vii. Obstructive defecation syndrome
Sometimes constipation is caused by dysfunction in the normal rectal physiology. This can be caused by disruption of the normal pelvic anatomy but rectal or vaginal prolapse, or just poorly coordinated muscle contractions.
Typical symptoms of obstructive defecation syndrome:
- Prolonged straining on the toilet
- Feeling of incomplete voiding after defecation
- The need for evacuation of the rectum using a finger in the vagina or rectum
History-taking is important in diagnosing this form of constipation. If this condition is suspected, then a balloon expulsion test should be performed. During this investigation, a catheter is passed through the anus into the rectum and the balloon is inflated with 20-30ml of water. The patient is then asked to push the inflated balloon out into the toilet. This should normally be accomplished within one minute.
viii. Colonic polyps and colorectal cancer
Colonic polyps are growths occurring in the large bowel. They can take many forms – pedunculated (stalked), sessile (rounded), flat, or even depressed. There are many different types of polyps and their nature varies greatly with their histological characteristics (i.e. what sort of cells make up the polyp, as seen under a microscope). Some types of polyps are premalignant (have the potential to turn into cancer). These polyps are called “adenomas”. Some types of adenomas have a greater risk of turning cancerous than others.
Polyps are usually asymptomatic and can exist for years or decades before turning cancerous. As such, there is a clearly demonstrated benefit for screening for colorectal cancer in its early or premalignant stage. Even if colorectal cancer is found, if it is still in an early stage then it can be surgically removed and cured.
There are many ways to screen for colonic polyps and colorectal cancer, including:
- Testing for faecal occult blood – This technique may miss many polyps, and is better for screening for colorectal cancer. Must be followed up with a more specific investigation if positive e.g. colonoscopy.
- Colonoscopy – When the correct quality assurance procedures are followed, this technique has the highest yield for detecting polyps, especially flat or depressed polyps, which may be missed by CT colonography.
- Therapeutic intervention can be performed simultaneously.
- Double contrast barium enema – This technique is seldom used anymore as its sensitivity for detecting polyps and colorectal cancer is significantly lower than colonoscopy. Usually reserved for situations where colonoscopy is not possible.
- CT colonography – A CT scanning technique whereby a “virtual” colonoscopy can be performed. Smaller polyps and flat lesions are more likely to be missed.
- Colon capsule endoscopy – A new technology which allows visualization of the colon mucosa using a video capsule that is ingested. Guidelines on its use have not yet been established, but it is a less invasive alternative to colonoscopy.
Polyps – The management of polyps depends on the technique used to detect them. If colonoscopy is performed, then polyps are usually removed during the procedure. If a polyp is very large, it may not be removed immediately and may require surgery. If alternative screening measures detect one or more polyps, then there are guidelines that advise whether colonoscopy should be performed, based on the size and number of the detected polyps.
Colorectal cancer – Once colorectal cancer is detected (it must be confirmed histologically i.e. using endoscopy) then the next step is to stage the disease. This means that radiological examination (usually CT scan) will be performed to determine if and how far the cancer has spread. Early cancer can be cured by surgically resecting it. Advanced cancer will require chemotherapy or radiotherapy.