Anatomic Problems of the Colon

The colon is also called the large intestine or large bowel and plays a major role in the digestion of food. The colon is attached to the ileum in the small intestine and the ileum joins part of the colon known as the caecum. The chief roles of the colon include removing salt, water and nutrients from food, processing waste products and forming stools. The colon is lined with muscle tissue which helps to push food along during the process of digestion. In a fully grown adult the colon is around 5-6 feet long.

In addition to the caecum there are four major parts of the colon. These are:

• The ascending colon (on the right hand side of the colon).
• The transverse colon (located across the abdomen).
• The descending colon (on the left hand side of the colon).
• The sigmoid colon (the curved portion of the colon located just before the rectum).

Abnormalities and anatomic problems

The development of the colon is important for healthy digestion. If there is abnormal development of the colon this can cause problems with digestion. Anatomic abnormalities can develop in a foetus during pregnancy (identified as congenital abnormalities) or later in life. Examples of anatomic problems of the colon include:

• Malrotation: malrotation occurs when the bowel does not rotate fully during foetal development. If the bowel is not positioned correctly the caecum may obstruct the small intestine. Malrotation is a medical emergency and will usually be treated within a month of a baby being born. Surgery may be carried out to untwist the bowel, clear obstructions of the small intestine, remove the appendix or position the colon correctly. Malrotation is often associated with other digestive problems, including bowel atresia and Hirschsprung’s disease. Malrotation affects both boys and girls and the main symptom to look out for is vomiting bile.

• Volvulus: volvulus occurs when the small bowel or colon is twisted. If volvulus is not treated it can lead to gangrene. This can occur if the bowel is twisted very tightly resulting in strangulation, which causes the blood supply to be cut off and the healthy tissue to die. It is important that volvulus is treated quickly because gangrene can develop fast and is able to cause a hole to form in the wall of the colon which can be life-threatening. In most cases volvulus affects the sigmoid portion of the colon. It is possible for children and adults to have volvulus. People with Hirschsprung’s disease and an enlarged colon have a higher risk of developing volvulus and it tends to affect men more often than women. Surgery is usually carried out to treat volvulus and if there is a risk of strangulation this may be done immediately.

• Intussusception: this is a rare condition which occurs when part of the colon tunnels into another part of the colon or small intestine causing a blockage. The causes of intussusception include chronic diarrhoea, benign or cancerous growths, adhesions and scar tissue formed by surgery. In some cases no cause can be identified and this is known as idiopathic. Symptoms include changes in bowel habits, abdominal pain which may last for a long time or come and go, distension, needing to go to the toilet suddenly and bleeding from the rectum. Surgery is usually carried out to untwist or remove the affected area of the bowel.

• Fistula: a fistula is an abnormal connection between two different parts of the digestive system. Fistulas can be internal (between two parts of the intestine or the intestine and a different organ) or external (between the intestine and the exterior of the body). Symptoms of fistulas cause inflammation of the abdomen and abdominal pain. Fistulas can develop at any stage of life and are usually treated with surgery combined with a course of antibiotics to fight any associated infections.

• Atresia: colonic atresia is a congenital condition which occurs if the form of the colon is abnormal. In babies with colonic atresia the tubular portion of the colon is closed and this prevents the baby from passing bowel movements. Surgery is carried out to enable the normal function of the colon. Colonic atresia is a rare condition.

• Imperforate anus: this is rare congenital condition which occurs when the anorectal portion of the digestive system is not fully developed and as a result the baby is unable to pass stools. Symptoms of an imperforate anus include not passing a stool within the first 48 hours, misplaced anus, distension and stools passing through the vagina.