Chronic appendicitis, a rare and often confusing condition, involves long-term or recurring inflammation of the appendix, creating a diagnostic challenge for clinicians. The Computed Tomography (CT) scan is central to investigating abdominal pain. While the CT scan is highly effective for rapidly diagnosing the severe, sudden form of the illness, its role in detecting the more subtle, intermittent signs of chronic inflammation is complex. CT scans can show chronic appendicitis, but the findings are frequently ambiguous or non-specific, requiring careful interpretation and correlation with the patient’s clinical history.
Defining Chronic Appendicitis and Its Distinction from Acute
Appendicitis is generally understood as an acute medical emergency requiring immediate surgical intervention. It presents with severe symptoms that develop rapidly, typically over 24 to 48 hours, including intense pain migrating to the lower right abdomen, fever, and a high white blood cell count. Acute inflammation is usually the result of a complete obstruction of the appendix’s inner cavity, often by a calcified fecal mass known as an appendicolith.
Chronic appendicitis is a less common and more controversial diagnosis, defined by symptoms of inflammation that last for more than three weeks. The presentation is characterized by recurring, milder abdominal pain, which may subside only to return weeks or months later. This condition arises from a partial and transient obstruction of the appendix, leading to a low-grade, intermittent inflammatory process. Unlike the acute form, the symptoms of chronic appendicitis can be non-specific, making it easy to confuse with other conditions like irritable bowel syndrome or Crohn’s disease.
Specific CT Scan Indicators for Chronic Inflammation
A CT scan can reveal findings that suggest chronic inflammation within the appendix, even when the symptoms are mild. The radiologist looks for signs indicating prior or ongoing, low-grade inflammatory changes. One indicator is a mild thickening of the appendiceal wall, which reflects the persistent inflammatory process. Appendiceal wall thickening is defined as a single wall thickness greater than 3 millimeters, though this finding alone is not conclusive.
Another finding is the presence of an appendicolith, a calcified stone of hardened fecal material, found in both acute and chronic cases. In the chronic setting, an appendicolith may be present without the extensive swelling or surrounding fluid collection that characterizes acute appendicitis. Subtle inflammation of the fatty tissue around the appendix, known as periappendiceal fat stranding, may also be visible, although it is less pronounced than the severe fat stranding seen in acute disease. These signs, when clustered together, increase the suspicion for chronic appendicitis, especially when they correlate with a patient’s history of recurring right lower quadrant pain.
Why CT Scans Can Be Inconclusive and Other Diagnostic Tools
Despite its high accuracy in diagnosing acute appendicitis, a CT scan can be inconclusive for the chronic form due to the intermittent nature of the inflammation. If the patient is scanned when their symptoms have temporarily subsided, the appendix may appear entirely normal, leading to a false-negative result. The mildness of the chronic inflammation means that visual cues, such as wall thickening or fat stranding, are often too subtle to definitively differentiate from a normal anatomical variant. When the imaging findings are equivocal, the CT scan’s diagnostic accuracy decreases.
Diagnosis of chronic appendicitis relies heavily on clinical correlation, meaning imaging findings must be matched with the patient’s consistent and recurring history of pain. Other imaging modalities are employed to aid diagnosis or rule out other conditions. Abdominal ultrasound is a useful, non-irradiating tool, particularly in children and pregnant women, to visualize the appendix and surrounding fluid collections. When non-invasive methods fail, diagnostic laparoscopy—a minimally invasive surgical procedure—may be used to directly visualize the appendix and confirm the chronic inflammatory changes.
Treatment Approaches Following Diagnosis
Once a diagnosis of chronic appendicitis is established, the standard course of action is surgical removal of the appendix, known as an appendectomy. While chronic appendicitis is not a surgical emergency, the persistent inflammation carries a risk of progression to an acute episode, abscess formation, or perforation. Removing the appendix eliminates the source of recurring pain and prevents these complications.
The appendectomy is typically performed using a laparoscopic approach, involving small incisions and specialized instruments. Laparoscopic surgery is favored for its reduced recovery time, less post-operative pain, and smaller scars compared to traditional open surgery. However, an open appendectomy may be necessary if chronic inflammation has led to significant scarring or complications like an abscess requiring more extensive exploration. Following surgery, most patients experience a complete resolution of their chronic abdominal pain symptoms.