What is the appropriate workup for a 65-year-old patient presenting with left lower quadrant (LLQ) abdominal pain?

Workup for Left Lower Quadrant Abdominal Pain in a 65-Year-Old Patient

CT scan of the abdomen and pelvis with IV contrast is the first-line imaging modality for evaluating left lower quadrant (LLQ) pain in a 65-year-old patient. 1, 2

Initial Assessment

• Focus on key symptoms:

  • Fever, duration and severity of pain, radiation of pain
  • Associated symptoms: nausea, vomiting, changes in bowel habits, urinary symptoms
  • Previous episodes of similar pain
  • Comorbidities that may affect presentation (elderly patients often have atypical presentations)

• Physical examination findings to document:

  • Vital signs (particularly fever, tachycardia)
  • Abdominal tenderness location and severity
  • Presence of peritoneal signs (rebound tenderness, guarding)
  • Digital rectal examination to assess for masses or tenderness

• Laboratory tests:

  • Complete blood count (leukocytosis suggests inflammation/infection)
  • Basic metabolic panel
  • Urinalysis (to rule out urinary tract infection or nephrolithiasis)
  • C-reactive protein (elevated in inflammatory conditions)

Imaging Algorithm

1. CT Abdomen and Pelvis with IV contrast

   • Gold standard with 98% accuracy for diverticulitis and other common causes of LLQ pain 1, 2
   • Allows for diagnosis, staging, and identification of complications
   • Can identify alternative diagnoses that may mimic diverticulitis

2. If IV contrast is contraindicated (e.g., renal failure, contrast allergy):

   • CT without IV contrast (rated 6/9 for appropriateness) 1
   • Ultrasound may be considered but has limitations in obese patients 1

3. For female patients:

   • Consider transvaginal ultrasound if gynecologic pathology is suspected 1, 2

Special Considerations for Elderly Patients

• Be aware that elderly patients (>65 years) often present atypically:

  • Only 50% present with pain in lower quadrants
  • Only 17% have fever
  • 43% do not have leukocytosis 1

• Lower threshold for imaging in elderly patients due to:

  • Higher risk of complications
  • Atypical presentations
  • Higher mortality rates (1.6% in patients <65 years vs 9.7% in patients 65-79 years) 1

Differential Diagnosis for LLQ Pain

Common causes to consider:

• Diverticulitis (most common in this age group)
• Colitis (ischemic, infectious)
• Inflammatory bowel disease
• Colon cancer
• Urolithiasis/renal colic
• Epiploic appendagitis
• Bowel obstruction
• Abdominal wall pathology

Rare but important considerations:

• Leaking abdominal aortic aneurysm
• Situs inversus with appendicitis 3
• Perforated viscus

Management Based on Findings

• Uncomplicated diverticulitis: Characterized by colonic wall thickening and inflammation of pericolic fat

  • Consider outpatient management with oral antibiotics if no comorbidities or complications
  • Amoxicillin-clavulanate 875/125 mg orally twice daily for 4-7 days 2

• Complicated diverticulitis: Presence of abscess, perforation, fistula, or obstruction

  • Hospitalization for IV antibiotics
  • Surgical consultation
  • Percutaneous drainage for abscesses ≥3-4 cm 1, 2

• Other diagnoses: Treatment based on specific findings

Follow-up

• Reassess in 48-72 hours if outpatient management is chosen
• Consider colonoscopy 6-8 weeks after symptom resolution to rule out colon cancer 2
• Warning signs requiring immediate medical attention: worsening pain, fever, inability to tolerate oral intake, signs of peritonitis

Remember that the American College of Radiology guidelines strongly recommend CT with IV contrast as the most appropriate imaging test for elderly patients with LLQ pain, with a rating of 8/9 for appropriateness 1.