diverticulum

n.; pl. diverticula

a sac or pouch formed at weak points in the walls of the alimentary tract. They may be caused by increased pressure from within (pulsion diverticula) or by pulling from without (traction diverticula). A pharyngeal diverticulum occurs in the pharynx and may cause difficulty in swallowing. Oesophageal diverticula occur in the middle or lower oesophagus (gullet); they may be associated with muscular disorders of the oesophagus but rarely cause symptoms. Gastric diverticula affect the stomach (usually the upper part) and cause no symptoms. Duodenal diverticula occur on the concave surface of the duodenal loop; they may be associated with dyspepsia and an increased risk of choledocholithiasis, but usually cause few symptoms. Jejunal diverticula affect the small intestine, are often multiple, and may give rise to abdominal discomfort and malabsorption due to growth of bacteria within them. Meckel's diverticulum occurs in the ileum, about 35 cm from its termination, as a congenital abnormality. It may become inflamed, mimicking appendicitis; if it contains embryonic remnants of stomach mucosa it may form a peptic ulcer, causing pain, bleeding, or perforation. Colonic diverticula, affecting the colon (particularly the lowest portion), become commoner with increasing age and often cause no symptoms. However they are sometimes associated with abdominal pain or altered bowel habit (see diverticular disease) or they may become inflamed (see diverticulitis).