What is the most common diagnosis for a patient presenting with fever, leukocytosis, and left lower quadrant pain?

A patient presenting with fever, leukocytosis (an elevated white blood cell count), and left lower quadrant pain is most commonly diagnosed with diverticulitis. This condition occurs when diverticula—small pouches in the colon—become inflamed or infected. The clinical presentation fits well with diverticulitis: fever indicates an inflammatory process, leukocytosis shows the body is responding to infection, and left lower quadrant pain is characteristic of pain associated with the sigmoid colon, where diverticula are most commonly located.

The acute inflammation in diverticulitis can lead to symptoms that mimic other abdominal conditions, but the combination of these specific signs points most clearly to this diagnosis. It’s important to also consider that other conditions affecting the left lower quadrant can present with similar symptoms. However, diverticulitis is the most frequently observed diagnosis in similar patient presentations. Understanding this helps in differentiating it from conditions like appendicitis, pancreatitis, or cholecystitis, which typically present with other characteristic signs and symptoms not primarily centered in the left lower quadrant.