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Gastrointestinal Disorders

Medically reviewed by Carmen Fookes, BPharm. Last updated on May 20, 2022.

Gastrointestinal disorders is the term used to refer to any condition or disease that occurs within the gastrointestinal tract.

The gastrointestinal tract (also called the GI tract) is a series of hollow organs that form a long continuous passage from our mouth to our anus. The organs that make up our GI tract are our mouth, esophagus, stomach, small intestine, large intestine, and anus.

Our GI tract, together with our liver, pancreas, and gallbladder, make up our digestive system. An extensive network of blood vessels supply blood to these organs and also transport nutrients away to other organs in the body. Nerves and hormones work together to regulate the functioning of the digestive system and bacteria that reside within our GI tract (called our gut flora or microbiome) play a role in digestion, immunity, and our overall health. A membranous sac called the peritoneum holds all the digestive system organs in place.

A number of different conditions or diseases can affect the GI tract and have an impact on digestion and/or our overall health. Some conditions have similar symptoms, and further medical investigations may be required before a doctor arrives at a diagnosis. Common gastrointestinal disorders include:

  • Celiac disease: Celiac disease is a serious autoimmune disorder where the small intestine is hypersensitive to gluten. Ingestion of gluten causes the immune system of the body to attack the small intestine, leading to damage to the villi of the small intestine, which are small fingerlike projections that promote nutrient absorption.

Celiac disease can start at any age and symptoms include bloating, changes in bowel habits (either diarrhea or constipation), rashes, weight loss, and a poor growth rate in children. Currently, the only treatment for celiac disease is lifelong adherence to a strict gluten-free diet.

  • Constipation: Constipation is the term used to describe difficulty or infrequency in passing stools (feces). Not everybody has a daily bowel movement, so the passage of time between bowel motions before constipation occurs varies from person to person.
    When somebody is constipated their stools are usually small, hard, dry, and difficult to pass. Other symptoms may include bloating or distention in the stomach and pain during a bowel movement. Hemorrhoids frequently occur with constipation.

There are many different causes of constipation, such as dehydration, a lack of fiber in the diet, pregnancy, inactivity, or certain medications (such as antidepressants, iron supplements, or opioids). Laxatives can help relieve constipation and lifestyle changes can help prevent it from recurring.

  • Crohn’s Disease: Crohn’s disease is a chronic bowel disease that causes patches of inflammation in the GI tract anywhere between the mouth and the anus, although the area where the small intestine joins the large intestine is most commonly affected. The exact cause remains unknown; however, it is more common in “Westernized” countries, tends to run in families, and diet and stress may aggravate the disease.

Symptoms may include diarrhea that persists for several weeks, abdominal pain, and weight loss. Around 50% of people with Crohn’s disease notice blood or mucus in their feces and some may report an urgent need to move their bowels or a sensation of incomplete evacuation. Drug treatments may include aminosalicylates, corticosteroids, immunomodulators, and biologics. Surgery may also be an option.

  • Diarrhea: Symptoms of diarrhea include frequent, loose, watery stools (feces) which are usually accompanied by an urgent need to go to the toilet. Abdominal pain or cramping may also occur, and sometimes nausea or vomiting. Viruses are a common cause of diarrhea, particularly noroviruses which are a common cause of diarrhea and vomiting outbreaks on cruise ships. Other common causes include bacteria, such as salmonella, campylobacter, or Escherichia coli; giardia; certain medical conditions (such as Celiac disease or Crohn’s disease); food intolerance or medicines.

Anti-diarrhea medications such as loperamide or diphenoxylate help slow down bowel movements, and electrolyte solutions are beneficial for treating dehydration, which commonly occurs with excessive diarrhea. Sometimes other medications, such as antibiotics, may also be needed.

  • Diverticular disease: Diverticular disease is a chronic condition in which small pockets or outpouchings, called diverticula, occur in the bowel. Diverticula can become inflamed when undigested food gets trapped within them, causing pain and constipation, and sometimes fever, nausea, or cramping. This is called diverticulitis. Diverticular disease is common, affecting half of all people over 60. A low fiber diet is thought to be the main cause, although some people have a genetic predisposition to the disease.

Many people with diverticular disease don't have symptoms, and the condition is often discovered during a colonoscopy to screen for colorectal cancer. Treatment is usually with a high-fiber diet and a mild pain reliever.

  • Gastroesophageal Reflux Disease (GERD): GERD is also known as heartburn or acid reflux. It occurs when the ring of muscle fibers that surrounds the entrance to our stomach (known as the lower esophageal sphincter) becomes weak, and instead of remaining tightly closed to prevent the backflow of food back up our esophagus, it remains partially open, allowing partially digested food and stomach acid to leak back up the esophagus, causing irritation.

The primary symptoms associated with GERD are regurgitation, heartburn, chest pain, and nausea. GERD is most commonly treated with antacids, H2 blockers, or Proton Pump Inhibitors.

  • Hemorrhoids and anal fissures: Hemorrhoids occur when the anal cushions (which are small areas of vein-containing tissues that seal the anal opening, preventing incontinence) become engorged and swollen. They can occur either externally or internally and both types typically bleed when a bowel motion is passed. External hemorrhoids look like small bunches of grapes and can become very red, tender, and itchy when inflamed. Internal hemorrhoids can cause a feeling of pressure inside the rectum and are not usually visible. Occasionally they may prolapse (“pop”) out of the rectum following a bowel motion, which can be quite painful. Treatment is with hemorrhoid creams and/or suppositories. Other specialized therapy, such as sclerotherapy, laser treatment, or surgery may be required.

    Anal fissures are small tears in the thin tissue that lines the anus. They are common in infants and often occur when passing large bowel motions. Laxatives and improving the fiber content of the diet can make it easier to pass stools and prevent anal fissures from developing.

  • Irritable Bowel Syndrome (IBS): IBS is defined by the American College of Gastroenterology as "Abdominal discomfort associated with altered bowel habits". It usually takes most people three years and at least three different doctors before they are given a diagnosis of IBS. Part of the difficulty with diagnosis rests with the many different presentations of IBS. Some people are more likely to have constipation (constipation-predominant IBS or IBS-C), others diarrhea (diarrhea-predominant IBS or IBS-D), while a few experience both constipation and diarrhea at different times (mixed IBS).

Symptoms are also similar to countless other conditions, such as endometriosis, giardia, food allergies, or inflammatory bowel disease, and most of these conditions need to be excluded before a diagnosis of IBS can be made. Treatment depends on what type of IBS a person has (ie, either constipation or diarrhea-predominant) and usually includes medication and dietary changes.

  • Lactose intolerance: People with lactose intolerance do not produce enough of the enzyme lactase, and find it difficult to digest lactose, which is a type of sugar found in cows’, goats’, and sheep's milk. It is more common in people of Asian, Middle Eastern, Mediterranean, South American, or African descent, and can also be brought on by gut damage (such as that following gastroenteritis or surgery) or with conditions such as Celiac or Crohn’s disease.

Symptoms usually include wind, bloating, tummy pain, nausea, or diarrhea within 30 minutes to 2 hours after eating something with lactose.

  • Malabsorption syndromes: Malabsorption syndromes refers to a number of different conditions in which the small intestine is unable to absorb nutrients, such as proteins, carbohydrates, fats, vitamins, or minerals. There are numerous causes of malabsorption syndrome, such as prolonged use of antibiotics, diseases of the gallbladder, liver, or pancreas, conditions such as Crohn’s disease, celiac disease, chronic pancreatitis, and cystic fibrosis, and birth defects. Treatment depends on the underlying condition and the extent of malabsorption.
  • Polyps and colorectal cancer: Polyps are growths that occur on the inner surface of the colon. There are two main types. One type (adenomas or adenomatous polyps) has a high risk of turning into colorectal cancer and should be completely removed if found.
    Colorectal cancer is the third leading cause of cancer deaths among American men and women. Most colorectal cancers grow slowly and cause few symptoms until they reach a large size, which is why colorectal cancer screening is so important because colorectal cancer is more common in people aged 45 through to 75 years. Treatment of colorectal cancer depends upon which stage the cancer is found at and may include surgery, chemotherapy, and radiation therapy.
  • Peptic Ulcer Disease (PUD): Peptic ulcer disease is an umbrella term used to describe both gastric and duodenal ulcers, which are small holes that can occur in the lining of your stomach (gastric ulcer) or upper part of your small intestine (duodenal ulcers). Duodenal ulcers are the most common type and are more likely in men aged between 30 and 50 years. Gastric ulcers most often affect middle-aged or elderly people.
    The most common cause is an infection with a bacteria called Helicobacter pylori (H. pylori), which is usually acquired in childhood, although most people never develop ulcers.

Overuse of anti-inflammatory drugs such as aspirin, ibuprofen, or diclofenac, excessive acid production in the stomach, and smoking are also common causes. Symptoms typically include abdominal pain and heartburn. The pain of duodenal ulcers tends to be relieved by food, whereas the pain with gastric ulcers is worsened by eating. Treatment usually consists of medications to reduce acid production in the stomach or to protect the stomach, and therapy to eradicate H. pylori infection.

  • Ulcerative colitis: Ulcerative colitis affects only the innermost lining of the colon. Although the colon is the only part of the bowel affected, the whole of the colon is inflamed. Symptoms are similar to Crohn’s disease and include diarrhea and the frequent need to have a bowel movement (also called tenesmus). Pus and mucus may also occur as a result of ulcers that form in the colon. Other symptoms include rectal bleeding or bloody stools, abdominal pain, tiredness, and loss of appetite. The cause remains unknown although an abnormal immune response seems responsible for the inflammation, and diet and stress aggravate the condition. Genetics also seems to play a role. Treatment is with corticosteroids, antidiarrheal agents, immunomodulators, and biologics, depending on disease severity.
  • Vomiting: Vomiting is when the contents of the stomach are forcefully expelled through the mouth, usually involuntarily. Nausea is the term used to describe feeling sick – or like you are just about to vomit. Infection from bacteria, viruses, or other micro-organisms is one of the most common causes of vomiting. Overindulgence in alcohol, food allergies, migraines, and pregnancy may also cause vomiting. Treatment depends on the cause and may include antiemetics and rehydration solutions, depending on how suitable these are for the person with the vomiting.

Further information

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