What is the appropriate workup and differential diagnosis for a patient with a history of gallbladder tumor resection and partial gastrectomy (partial stomach removal), now presenting with sharp, intermittent left-sided midgastric abdominal pain, back pain, and arm pain, with limited oral intake (PO) since surgery?

Workup and Differential Diagnosis

Immediate Assessment

This patient requires urgent contrast-enhanced CT abdomen/pelvis with oral contrast as the first-line diagnostic test, combined with comprehensive laboratory evaluation including CBC, liver function tests, lipase, lactate, and blood gas analysis to rule out life-threatening surgical complications. 1, 2, 3

Critical Initial Steps

Vital signs assessment is mandatory to identify alarm signs including:

• Tachycardia (≥110 beats/min) - a critical warning sign in post-surgical patients 2, 3
• Fever (≥38°C), hypotension, tachypnea, or hypoxia 3
• The combination of fever, tachycardia, and tachypnea strongly suggests anastomotic leak or surgical complication 3

Physical examination must focus on:

• Peritoneal signs (rebound tenderness, guarding, rigidity) indicating perforation or bowel necrosis 2
• Abdominal distension with diminished bowel sounds suggesting obstruction 2
• Pain out of proportion to physical findings, which suggests mesenteric ischemia until proven otherwise 2

Laboratory Workup

Essential laboratory tests include 1, 2, 3:

• Complete blood count (leukocytosis predicts abdominal emergencies) 1, 3
• Comprehensive metabolic panel with liver function tests (AST, ALT, alkaline phosphatase, GGT, bilirubin) 1
• Serum lipase (to evaluate for pancreatitis)
• C-reactive protein and procalcitonin (elevated CRP predicts postoperative complications) 1, 3
• Serum lactate and blood gas analysis are essential - elevated lactate may indicate bowel ischemia, though normal lactate does NOT exclude internal herniation or early ischemia 1, 2, 3
• Serum albumin and nutritional markers (vitamin D, folate, B12, B6, B1) given limited PO intake and risk of malnutrition after gastrectomy 1, 3

Critical caveat: Normal CRP alone does not rule out postoperative complications, and lactate may rise late in bowel ischemia. 1

Imaging Studies

Contrast-enhanced CT with oral contrast is the definitive diagnostic test 1, 3:

• Identifies obstruction, transition points, bowel ischemia, fluid collections, and surgical complications 1, 2
• Both oral and intravenous contrast are essential for accurate interpretation 1, 3
• Helps distinguish mechanical obstruction from functional issues 2

Plain abdominal radiographs have limited value but can detect bowel distension or fluid levels when CT is unavailable - negative films do NOT exclude mesenteric ischemia or early obstruction. 1, 2

Point-of-care ultrasound can evaluate for cholecystitis, biliary disease, and free intraperitoneal fluid. 1

Differential Diagnosis

High-Priority Surgical Emergencies

Anastomotic leak or staple line dehiscence:

• Most concerning given recent surgery, limited PO intake, and pain 3
• Presents with fever, tachycardia, tachypnea, and abdominal pain 3

Internal hernia or bowel obstruction:

• Prior abdominal surgery has 85% sensitivity for adhesive small bowel obstruction 2
• Persistent vomiting and nausea raise suspicion 3
• Requires serial abdominal exams every 4-6 hours to detect peritonitis 2

Mesenteric ischemia:

• Pain out of proportion to physical findings is the hallmark 2
• Requires immediate CT angiography and surgical consultation without delay 2

Bile duct injury or biloma:

• Can present with persistent abdominal pain, distension, nausea, fever 1
• May develop biliary peritonitis or abscess if undiagnosed 1
• Cholestatic jaundice suggests biliary stricture 1

Gallbladder-Related Complications

Acute acalculous cholecystitis:

• Occurs in 3.1% of patients after radical gastrectomy with lymphadenectomy 4
• Can develop postoperatively due to gallbladder dysfunction 5, 6

Cholelithiasis:

• Develops in 30% of patients after radical gastrectomy, typically within 31 months 4
• Impaired gallbladder function after gastrectomy increases risk 5, 6

Oncologic Considerations

Residual or recurrent gallbladder cancer:

• 74% of patients with incidentally discovered gallbladder cancer have residual disease requiring re-exploration 7
• Gallbladder cancer is discovered incidentally in 47% of cases during/after cholecystectomy 7
• Without pathology results, cancer cannot be excluded 1, 7
• Adenosquamous carcinoma can recur early with rapid growth 8, 9
• Five-year survival is stage-dependent: 60% (stage 0) to 1% (stage IV) 1

Peritoneal carcinomatosis or metastatic disease:

• Can cause abdominal pain and limited PO intake 1

Other Considerations

Marginal ulcer (at gastric anastomosis):

• Common after partial gastrectomy 3
• Presents with epigastric pain, may radiate to back 3

Gastroparesis or gastric outlet obstruction:

• Limited PO intake suggests impaired gastric emptying 2

Pancreatitis:

• Left-sided abdominal pain radiating to back is classic 2

Referred pain from cardiac or pulmonary pathology:

• Left arm pain warrants consideration of cardiac ischemia
• Pulmonary embolism must be ruled out if respiratory distress present 3

Management Algorithm

If clinical suspicion is high with alarm signs, do NOT delay laparoscopic exploration even if radiological evaluation is negative - diagnostic laparoscopy has higher sensitivity and specificity than any radiological assessment. 1, 3

Immediate surgical consultation is mandatory if signs of shock, peritonitis, or suspected bowel ischemia are present. 2, 3

Obtain pathology results from gallbladder and gastric specimens urgently - if gallbladder cancer is confirmed, staging with CT/MRI, chest imaging, and consideration for re-exploration is required, as extended resection may be necessary. 1, 7