What is the appropriate management for a patient with fever, tachycardia, tachypnea, left-sided abdominal pain, and irregular bowel movements, who is tender in the LLQ (lower left quadrant) and LUQ (upper left quadrant) and positive for Rovsing's sign?

Acute Left-Sided Diverticulitis with Systemic Inflammatory Response

This patient most likely has acute left-sided colonic diverticulitis (ALCD) and requires immediate CT abdomen/pelvis with IV contrast for diagnosis, followed by broad-spectrum antibiotics and surgical consultation if complicated disease is identified. 1

Clinical Presentation Analysis

The constellation of findings strongly suggests ALCD rather than appendicitis despite the positive Rovsing's sign:

• Left lower quadrant pain and tenderness is the hallmark of ALCD, with pain typically localized to the left side 1
• Fever (38.9°C), tachycardia (120), and tachypnea (30) indicate systemic inflammatory response syndrome (SIRS), suggesting complicated diverticulitis with possible abscess or perforation 1
• Positive Rovsing's sign on the left (left-sided pain with right abdomen palpation) is an atypical finding that can occur with left-sided pathology when peritoneal irritation is present 2
• Irregular bowel movements (3x/week) and constipation are risk factors for diverticulitis 1
• Age 59 places this patient in the typical demographic for ALCD, with prevalence of 32.6% for diverticulosis in ages 50-59 1

Immediate Diagnostic Workup

CT abdomen/pelvis with IV contrast is the gold standard and must be obtained urgently:

• CT has 90% sensitivity and 90% specificity for diagnosing ALCD 1
• IV contrast is essential to characterize bowel wall abnormalities, detect abscesses, and identify complications 1
• CT will differentiate uncomplicated from complicated diverticulitis and guide management decisions 1

Ultrasound can be considered as initial imaging if CT is not immediately available, with 90% sensitivity and 90% specificity, though CT remains superior 1

Initial Management Algorithm

Immediate Stabilization 1

• NPO status (nothing by mouth)
• IV access and fluid resuscitation to address tachycardia and potential sepsis
• Vital sign monitoring given SIRS criteria (fever, tachycardia, tachypnea)
• Laboratory tests: CBC, CRP, lactate, comprehensive metabolic panel 1

Risk Stratification 1

This patient meets SIRS criteria (temperature >38°C, heart rate >90, respiratory rate >20), requiring assessment for sepsis:

• Check serum lactate immediately
• If lactate >2 mmol/L with hypotension requiring vasopressors, this constitutes septic shock 1

Treatment Based on CT Findings

Uncomplicated Diverticulitis (No Abscess/Perforation)

• Antibiotics are NOT routinely recommended for uncomplicated diverticulitis without systemic inflammation 1
• However, given this patient's fever and SIRS, antibiotics are indicated 1
• Oral antibiotics preferred when feasible to facilitate shorter hospital stay 1
• Broad-spectrum coverage for gram-negative and anaerobic organisms

Complicated Diverticulitis

Small abscess (<4 cm): Antibiotics alone may suffice 1

Larger abscess: CT-guided percutaneous drainage plus antibiotics 1

Diffuse peritonitis or free perforation:

• Urgent surgical consultation required 1
• Hartmann's procedure remains the standard for critically ill patients with diffuse peritonitis 1
• Damage control approach for physiologically deranged patients 1

Critical Pitfalls to Avoid

Do not dismiss left-sided pathology based on positive Rovsing's sign alone - this sign can be present with any peritoneal irritation and does not exclusively indicate appendicitis 2

Do not delay imaging in a patient with SIRS - the combination of fever, tachycardia, and tachypnea with abdominal pain requires urgent CT to identify source control needs 1

Do not use plain radiographs as primary diagnostic tool - they have only 49% sensitivity for detecting inflammatory processes 3

Consider alternative diagnoses if CT is negative for diverticulitis:

• Epiploic appendagitis (focal left-sided pain, normal WBC, no fever - less likely here given fever) 4
• Colonic malignancy with perforation
• Inflammatory bowel disease with abscess 1

Antibiotic Selection

Empiric broad-spectrum antibiotics should cover:

• Gram-negative organisms (E. coli, Klebsiella)
• Anaerobes (Bacteroides fragilis)

Common regimens include fluoroquinolone plus metronidazole, or beta-lactam/beta-lactamase inhibitor combinations 1