Diverticulosis and Diverticular Disease
The colon wall is made up of several layers, including the mucosa, submucosa, and a muscular outer wall. The muscular layer itself has an inner and outer layer (Maykel 2004).
In the most common type of diverticula, the mucosa and submucosa are forced through weak areas in the muscular layer (Strate, Modi 2012; von Rahden 2012). Between 65% and 90% of colonic diverticula occur in the sigmoid colon, which is on the left side and close to the end of the digestive tract, with the remainder located in other regions (Maykel 2004; Bugiantella 2015).
Diverticula form as a result of a complex interaction of age, diet, and structural and functional changes in the nerves and muscles of the colon wall. These factors may contribute to weakness of and increased pressure on the colon wall (Strate, Modi 2012; von Rahden 2012; Bugiantella 2015; Humes 2014).
In 1‒4% of cases, diverticula become inflamed; this is known as diverticulitis (Shahedi 2013). It used to be thought that mechanical obstruction of diverticula by fecal matter or undigested food particles caused diverticular disease, but newer research suggests that changes in the microbial composition of the intestinal tract (which can create a pro-inflammatory environment) and changes in colon motility are important contributors (von Rahden 2012; Tursi 2012; Strate, Modi 2012; Peery 2013).