The large intestine, or colon, can develop small, balloon-like pouches called diverticula, a condition known as diverticulosis. These outpouchings form at weak points in the bowel wall, typically due to pressure within the colon. While diverticulosis is often symptom-free, inflammation or infection within one or more of these pouches results in the painful condition known as diverticulitis. This common gastrointestinal disease requires careful medical attention, as its severity dictates a completely different approach to diagnosis and management.
Defining the Two Classifications
Diverticulitis is classified into two main categories: uncomplicated and complicated, based on the pathological state of the colon. Uncomplicated diverticulitis is the most frequent presentation, characterized by inflammation localized to the diverticulum and the surrounding tissue. This localized inflammation often presents as pericolic fat stranding or a phlegmon, which is an inflammatory mass without a defined collection of pus.
Complicated diverticulitis is defined by the presence of severe structural changes or secondary infections extending beyond the immediate area of the colon wall. The formation of an abscess is one such complication, representing a localized collection of pus adjacent to the inflamed colon segment.
A dangerous complication is perforation, where the inflamed diverticulum ruptures, creating a hole in the colon wall. A small, contained perforation may lead to a localized abscess, but a large rupture results in peritonitis, a widespread infection of the abdominal lining. Other outcomes include the formation of a fistula, an abnormal channel connecting the colon to another organ, such as the bladder or vagina. Furthermore, repeated inflammation and subsequent scarring can narrow the colon, potentially causing an intestinal obstruction.
Identifying the Severity Through Diagnosis
Determining whether a patient has uncomplicated or complicated disease begins with assessing their clinical presentation and symptoms. Patients with uncomplicated diverticulitis typically report localized pain, most commonly in the lower left quadrant of the abdomen, accompanied by a low-grade fever. The pain is usually steady and progressively worsens over several days, but the patient does not show signs of widespread systemic illness.
Symptoms suggesting a complicated condition include diffuse, severe abdominal pain, high fever, and signs of sepsis such as rapid heart rate or low blood pressure. A physical examination may reveal muscular rigidity and rebound tenderness across a large area of the abdomen, which are classic signs of peritonitis. These clinical signs prompt the use of advanced diagnostic imaging to confirm the severity of the disease.
The computed tomography (CT) scan is the gold standard for classifying the disease, providing a detailed, cross-sectional view of the colon and surrounding structures. For uncomplicated cases, the CT scan typically shows thickening of the colon wall and inflammatory changes in the surrounding fat, known as fat stranding. For complicated cases, the CT is used to precisely identify and characterize the structural damage.
A CT scan can accurately measure the size of an abscess or detect the presence of extraluminal or “free” air outside the bowel wall, a definitive sign of perforation. Blood tests, particularly a complete blood count (CBC), play a supportive role by revealing an elevated white blood cell (WBC) count, or leukocytosis, which indicates a systemic inflammatory response. While leukocytosis is common in both classifications, significantly elevated markers can point toward a more severe, complicated course.
Tailored Treatment Strategies
The difference between uncomplicated and complicated diverticulitis dictates management strategies ranging from simple outpatient care to major surgical intervention. Treatment for uncomplicated diverticulitis focuses on conservative, supportive measures that allow the colon to rest and heal. This typically involves outpatient management with a temporary liquid diet, followed by a gradual reintroduction of low-fiber foods.
The use of oral antibiotics is now often reserved for patients who are immunocompromised or show signs of systemic infection, as many mild cases resolve spontaneously. The primary goal of this conservative approach is to manage symptoms and prevent progression to a complicated state, allowing the patient to recover at home with close monitoring. Patients are encouraged to increase their dietary fiber intake once the acute episode has resolved to help prevent future attacks.
In contrast, patients with complicated diverticulitis require immediate hospitalization and an aggressive treatment plan tailored to the specific complication present. Intravenous (IV) antibiotics are administered immediately to manage the severe bacterial infection that accompanies abscesses or perforation. For small abscesses, IV antibiotics may be sufficient to clear the infection.
Larger abscesses, often defined as those greater than four centimeters, typically require percutaneous drainage. This is a minimally invasive procedure where a catheter is guided through the skin to empty the pus collection. Surgical intervention becomes necessary for complications like generalized peritonitis, obstruction, or the presence of a fistula. This surgery often involves resecting, or removing, the diseased segment of the colon, which may be followed by a primary connection of the remaining healthy bowel ends.
In cases of severe contamination, the surgeon may perform a temporary colostomy, such as a Hartmann’s procedure. Here, the end of the colon is brought through the abdominal wall, allowing the remaining segment to heal before a second surgery reconnects the bowel.