What is the mechanism behind the symptoms observed in a patient with diverticulitis?

In diverticulitis, the primary mechanism behind the symptoms is the infection and inflammation that occurs within the diverticula, which are small pouches that can form in the wall of the colon. When these diverticula become obstructed by fecal matter or other debris, it creates an environment conducive to bacterial overgrowth, leading to infection.

As the diverticula become inflamed, typical symptoms such as abdominal pain (often localized to the left lower quadrant), fever, and changes in bowel habits such as diarrhea or constipation can occur. The inflammatory response can also lead to complications such as perforation of the diverticulum, abscess formation, or peritonitis if left untreated. This infectious process is central to the clinical presentation of diverticulitis, making it the correct answer.

The other options, while related to the overall context of gastrointestinal health, do not directly describe the immediate cause of the symptoms associated with diverticulitis. For instance, increased colonic motility is more commonly associated with conditions like irritable bowel syndrome rather than the inflammatory processes seen in diverticulitis. Fibrous infiltration of the bowel wall may occur over time in chronic conditions but is not the initiating factor in an acute diverticulitis episode. Chronic obstruction of the colon could