In an 85‑year‑old with acute periumbilical pain radiating to the left lower quadrant and rigors but no fever, what is the appropriate immediate evaluation and management?

Immediate Evaluation and Management of Acute Periumbilical Pain with Left Lower Quadrant Extension and Rigors in an 85-Year-Old

Obtain CT abdomen and pelvis with IV contrast immediately—this is the gold standard imaging modality with 98% diagnostic accuracy that will identify life-threatening conditions requiring urgent intervention, particularly complicated diverticulitis, bowel ischemia, perforation, or abscess formation. 1

Critical Clinical Context in Elderly Patients

The combination of acute abdominal pain and rigors (shaking chills) in an 85-year-old patient represents a high-risk presentation even without documented fever, as elderly patients frequently fail to mount typical inflammatory responses despite serious intra-abdominal infection. 1

• Laboratory tests and physical examination alone are unreliable in elderly patients with acute abdominal pain, with misdiagnosis rates of 34-68% when imaging is not performed. 1
• Many laboratory markers may remain normal in elderly patients despite serious infection, making imaging essential rather than optional. 1
• Rigors indicate systemic inflammatory response and significantly elevate concern for intra-abdominal sepsis, abscess, or perforation requiring immediate surgical or interventional management. 1

Immediate Diagnostic Workup

Essential Laboratory Tests

• Complete blood count, C-reactive protein, lactate, basic metabolic panel, and lipase should be obtained immediately while arranging CT imaging. 2
• Blood cultures should be drawn before antibiotics if sepsis is suspected based on rigors. 3

Imaging Strategy

CT abdomen and pelvis with IV contrast is rated 8/9 (usually appropriate) by the American College of Radiology for nonlocalized abdominal pain and is the definitive study for this presentation. 1, 4

• CT provides 98-100% diagnostic accuracy for diverticulitis and can detect complications including perforation, abscess, fistula, or obstruction that require surgery or interventional drainage. 1
• CT identifies alternative diagnoses in up to 49% of cases and changes management decisions in 51% of patients, making it essential when clinical presentation is atypical. 1, 4
• IV contrast is recommended to improve detection of subtle bowel wall abnormalities, abscesses, and vascular complications, though unenhanced CT can be used if contrast is contraindicated. 1

Why Not Other Imaging Modalities?

• Plain radiography has very limited diagnostic value and should not be used as the initial imaging test, as it misses most causes of acute abdominal pain. 1, 5
• Ultrasound is operator-dependent, limited by bowel gas and obesity, and cannot adequately visualize the colon, mesentery, or retroperitoneum where pathology likely exists in this presentation. 4
• MRI has limited availability in emergency settings and insufficient evidence for acute evaluation, though it shows promise for specific scenarios. 1

Differential Diagnosis Based on Clinical Presentation

Most Likely: Complicated Diverticulitis

The periumbilical pain extending to left lower quadrant with rigors in an 85-year-old most strongly suggests sigmoid diverticulitis with complications. 1

• Only 25% of diverticulitis patients present with the classic triad of left lower quadrant pain, fever, and leukocytosis—absence of fever does not exclude serious disease. 1
• Rigors suggest abscess formation, microperforation, or developing sepsis requiring urgent identification on CT. 1
• CT will determine if uncomplicated diverticulitis (medical management), abscess ≥3 cm (percutaneous drainage), or free perforation (emergency surgery) is present. 1

Critical Alternative Diagnoses to Exclude

Mesenteric ischemia must be considered in elderly patients with acute abdominal pain, particularly if pain seems disproportionate to examination findings. 1, 2

• CT angiography (which can be performed as part of CT abdomen/pelvis with IV contrast) can identify vascular occlusion or bowel ischemia. 3
• Early diagnosis is critical as mortality approaches 60-80% if diagnosis is delayed. 1

Small bowel obstruction is common in elderly patients and presents with periumbilical pain, distension, and inability to pass gas. 1

Perforated viscus (peptic ulcer, colon cancer) can present with periumbilical pain and rigors, requiring identification of free air or peritoneal contamination on CT. 1, 3

Complicated pancreatitis should be considered if pain radiates to the back, though left lower quadrant extension is less typical. 3

Immediate Management Algorithm

Before CT Results

1. Establish IV access and begin fluid resuscitation if patient shows signs of sepsis (rigors, tachycardia, hypotension). 3
2. Make patient NPO (nothing by mouth) pending imaging results. 3
3. Obtain surgical consultation immediately if patient has peritoneal signs (rebound tenderness, guarding, rigidity) as this suggests perforation or advanced peritonitis. 3
4. Hold antibiotics until after blood cultures are drawn, then initiate broad-spectrum coverage if sepsis is suspected. 3

Based on CT Findings

If CT shows uncomplicated diverticulitis: Medical management with observation, bowel rest, and consideration of antibiotics (though recent evidence supports conservative management without antibiotics in immunocompetent patients). 4

If CT shows abscess ≥3 cm: Interventional radiology consultation for percutaneous drainage plus broad-spectrum antibiotics. 1

If CT shows free perforation or peritonitis: Emergency surgical consultation for operative management. 1

If CT shows bowel obstruction: Nasogastric decompression, surgical evaluation, and determination of need for operative versus conservative management. 1, 3

If CT shows mesenteric ischemia: Emergency vascular surgery consultation for potential revascularization or bowel resection. 3

If CT is normal or shows only mild nonspecific findings: Consider alternative diagnoses including epiploic appendagitis (self-limited, treated with NSAIDs), early inflammatory bowel disease, or functional disorders, though rigors make benign diagnosis less likely. 4, 6

Critical Pitfalls to Avoid

• Do not delay CT imaging to obtain additional laboratory results—imaging should be performed urgently given the high-risk presentation. 1, 4
• Do not assume absence of fever excludes serious infection in elderly patients, as they frequently have blunted inflammatory responses. 1
• Do not rely on clinical examination alone to exclude surgical emergencies—physical findings are unreliable in elderly patients with acute abdominal pain. 1
• Do not dismiss rigors as insignificant—they indicate systemic inflammatory response and mandate aggressive evaluation for intra-abdominal sepsis. 1
• Do not order plain radiography as the initial imaging test—it will delay definitive diagnosis and has been shown to have no role in modern evaluation of acute abdominal pain. 5, 7