This elderly patient presents to the emergency department with left lower abdominal pain, constipation, and anorexia. The exam shows fever, tachycardia, and marked left lower quadrant tenderness. Compared to younger patients, abdominal pain in an elderly patient has a higher likelihood of being due to a surgical emergency or from a diagnosis that carries higher mortality. Elderly patients may have more nonspecific associated symptoms that may make it difficult to confirm a dangerous diagnosis without advanced imaging. Additionally, elderly patients do not always have a fever or elevated white blood cells during an abdominal infection. The differential diagnosis of abdominal pain in an elderly patient should be broad and encompass conditions related to many body systems.

The most likely diagnosis for this patient is diverticulitis based on the location of the pain. Features of diverticulitis include left lower quadrant pain, nausea, vomiting, change in bowel habits (diarrhea or constipation), anorexia, fever, and leukocytosis. Right-sided diverticulitis is more common in patients of Asian descent, so these patients may alternatively present with right lower quadrant pain. Treatment for acute diverticulitis includes antibiotics, bowel rest, hydration, increased dietary fiber, and pain management.

Other potential diagnoses to consider for this patient include perforated diverticulitis, abdominal abscess, colitis, bowel obstruction, malignancy, AAA, urinary tract infection, ureterolithiasis, and soft tissue infections. The best next step in the management of this patient is to treat empirically for an abdominal infection with IV hydration, antipyretics, and antibiotics. Sepsis from a gastrointestinal source requires antibiotics that cover both gram-negative and anaerobic bacteria. IV Vancomycin (Choice A) is helpful for skin infections, soft tissue infections, MRSA (Methicillin-resistant Staph aureus) infections, or other infections from gram-positive organisms. Vancomycin would not include coverage for a gastrointestinal source. IV Metronidazole covers anaerobic bacteria, and Ciprofloxacin covers gram-negative bacteria. This makes Choice D the best antibiotic choice for this patient. Other options include IV ampicillin-sulbactam, ampicillin and metronidazole, piperacillin-tazobactam, ticarcillin-clavulanate, or imipenem. A CT scan on the abdomen and pelvis (Choice B) should be performed on this patient (ideally with PO and IV contrast). However, IV hydration and antibiotics are a more important initial step to address the patient’s sepsis. CT scanning is recommended for first-time diverticulitis episodes or if there are alternative diagnoses on the differential. Patients with a history of recurrent diverticulitis who present to the Emergency department with uncomplicated acute diverticulitis are able to be treated empirically with oral antibiotics in the outpatient setting. Ill-appearing patients, have no prior history of diverticulitis or have possible alternative diagnoses should get CT imaging. Emergent colonoscopy (Choice C) is not indicated as part of the Emergency department management of acute diverticulitis. In fact, colonic inflammation or inflamed diverticuli are contraindications to colonoscopy (increased risk of bowel rupture). Correct answer: D