The caecum, or cecum, is a pouch-like portion of the large intestine. It is located in the lower right side of a person’s torso and marks the intersection of the large intestine, small intestine, and appendix. This pouch’s chief function is to assist in the digestion of plant-based foods. The most common medical ailment associated with this part of the large intestine is called malrotation, which occurs when the bowels become twisted while a fetus develops in the uterus.

Traveling through the digestive tract, consumed food first meets the stomach, then the small intestine and large intestine. The end of the small intestine is called the ileum, and the beginning of the large intestine is the caecum. These two are separated by the ileocecal valve, which allows passage from the small intestine to the large, but not in the opposite direction. This valve ensures that digested material travels away from the ileum when the caecum is emptied.

The function of the caecum has been explained by examining specimens of other mammals that utilize a similar appendage. Animals that relied heavily on plants as a source of nutrition were found to have larger, more active caecums. The opposite was found in animals that were chiefly carnivorous. These findings have led to the explanation that this part of the large intestine plays an important role in extracting water and salt from plant-based foods. It prepares this material, allowing easier digestion of the complex nutrients that are found in vegetative sources.

A rare developmental problem can occur during the formation of the digestive system in embryos, resulting in complications that require medical intervention. Most commonly, an ailment known as malrotation causes the caecum’s support structure to block the flow of food waste through the small intestine. When an embryo is developing, the caecum fails to rotate into position properly. The string-like supports for the caecum, called mesentery, cross over the small bowel and pinch it either partially or completely closed. Since this condition drastically affects livelihood, it is often found at a young age after symptoms manifest, including vomiting bile, bloody stools, and abdominal pain.

An ileocecal fistula also can develop between the caecum and ileum at any age. These abnormal passageways can cause abdominal pain and diarrhea, and typically require the attention of a medical professional. Treatment generally requires surgery to remove the affected part of the intestine and antibiotics to help prevent any subsequent infection.