In an 83‑year‑old female with hypertension, atrial arrhythmia on digoxin, chronic apixaban therapy, and known bilateral renal parenchymal disease, who presents with acute right‑subcostal pain that worsens with movement and after meals, what is the most likely diagnosis and appropriate next‑step management?

Assessment and Plan

This patient most likely has acute cholecystitis, and the immediate next step is right upper quadrant ultrasound followed by surgical consultation if confirmed.

Clinical Assessment

Most Likely Diagnosis: Acute Cholecystitis

The clinical presentation strongly suggests biliary pathology:

• Classic features present:

  • Right subcostal (RUQ) pain for 4 days
  • Pain worsens after eating (postprandial pattern)
  • Sharp, movement-dependent pain
  • Direct tenderness on RUQ examination
  • Age 83 (increased gallstone risk)

• Important negative findings:

  • No fever (does not exclude cholecystitis in elderly)
  • No jaundice
  • Soft, non-distended abdomen
  • No peritoneal signs

Critical Management Consideration: Anticoagulation Status

This patient is on apixaban 2.5 mg BID for atrial arrhythmia, which significantly impacts surgical planning and bleeding risk. 1

The apixaban dose appears appropriate given her characteristics (age >80, likely meets dose-reduction criteria per FDA labeling) 1. However, this creates a management dilemma if cholecystectomy is needed.

Immediate Diagnostic Workup

First-Line Imaging: Right Upper Quadrant Ultrasound

Ultrasonography is the initial imaging test of choice for patients presenting with right upper quadrant pain. 2

The ACR Appropriateness Criteria clearly establish ultrasound as the gold standard initial study for RUQ pain to evaluate for:

• Gallstones (cholelithiasis)
• Gallbladder wall thickening (>3mm)
• Pericholecystic fluid
• Sonographic Murphy's sign
• Common bile duct dilatation

If Ultrasound is Negative or Equivocal

CT abdomen/pelvis with IV contrast should be obtained next if ultrasound is non-diagnostic but clinical suspicion remains high 3. CT is superior for:

• Identifying complications (perforation, gangrene, emphysematous cholecystitis)
• Detecting alternative diagnoses
• Preoperative planning
• Visualizing gallbladder wall enhancement patterns

CT findings in acute cholecystitis include gallbladder wall thickening, pericholecystic inflammation, adjacent liver parenchymal hyperemia (requires IV contrast), and potential complications 3.

Laboratory Studies Needed

Order immediately:

• Complete blood count (leukocytosis supports infection)
• Comprehensive metabolic panel (assess renal function given known renal parenchymal disease; evaluate for electrolyte abnormalities that affect digoxin toxicity risk)
• Liver function tests (AST, ALT, alkaline phosphatase, total/direct bilirubin) - elevated alkaline phosphatase and bilirubin suggest choledocholithiasis
• Lipase (exclude pancreatitis)
• Lactate dehydrogenase (markedly elevated in visceral infarction)

Differential Diagnoses to Exclude

Renal Infarction (Critical Alternative)

Given her atrial arrhythmia on anticoagulation, renal infarction must be considered, though less likely given pain location 4, 5, 6, 7, 8:

• Recent case reports document renal infarction presenting with flank/abdominal pain in AF patients 4, 5, 6, 8
• Typically presents with markedly elevated LDH, acute kidney injury, and flank pain 4, 5
• Her recent KUB ultrasound showed renal parenchymal disease, making her kidneys potentially vulnerable
• However: Pain is subcostal (not flank), no acute kidney injury mentioned, and she's appropriately anticoagulated

If LDH is markedly elevated (>1000 U/L) or creatinine acutely rises, obtain CT angiography to evaluate renal arteries 4, 6.

Other Considerations

• Peptic ulcer disease (postprandial pain pattern fits)
• Hepatic pathology (less likely without hepatomegaly)
• Musculoskeletal pain (movement-dependent, but direct tenderness argues against)
• Diverticulitis (known diverticulosis, but wrong location for pain)

Management Plan

If Acute Cholecystitis Confirmed

1. NPO status, IV fluids, pain control

   • Avoid NSAIDs given anticoagulation
   • Acetaminophen appropriate (already taking PRN)

2. Antibiotics - Start empiric coverage:

   • Ceftriaxone 1-2g IV daily PLUS metronidazole 500mg IV q8h
   • OR piperacillin-tazobactam 3.375g IV q6h

3. Surgical consultation for cholecystectomy

4. Critical anticoagulation management 1:

   • Apixaban must be discontinued at least 48 hours prior to cholecystectomy (moderate-high bleeding risk procedure) 1
   • Given her CHA₂DS₂-VASc score is likely ≥4 (age, hypertension, likely female), stroke risk is substantial
   • Do NOT bridge with heparin - FDA labeling states bridging is "not generally required" 1
   • Restart apixaban postoperatively "as soon as adequate hemostasis has been established" 1

5. Digoxin monitoring 9:

   • Check digoxin level given acute illness
   • Monitor potassium and magnesium closely - hypokalemia/hypomagnesemia sensitizes myocardium to digoxin toxicity 9
   • Her renal parenchymal disease increases digoxin toxicity risk 9

If Imaging is Negative

Pursue alternative diagnoses systematically:

• Upper endoscopy for peptic ulcer disease
• Consider hepatobiliary scintigraphy (HIDA scan) for acalculous cholecystitis or biliary dyskinesia 3
• CT angiography if renal infarction suspected

Key Pitfalls to Avoid

1. Do not delay imaging - Ultrasound should be obtained within hours, not days
2. Do not stop apixaban prematurely - Continue until surgery is definitively scheduled
3. Do not bridge with heparin - Increases bleeding risk without proven benefit in this setting 1
4. Monitor renal function closely - Her baseline renal disease plus digoxin creates toxicity risk 9
5. Check electrolytes before any intervention - Hypokalemia with digoxin is dangerous 9
6. Consider hemopericardium risk - Rare but reported with apixaban, especially with renal impairment and amiodarone (not present here, but awareness important) 10