What are the next steps for a patient with abdominal swelling, intermittent abdominal pain, and tenderness to pressure?

Immediate Assessment and Diagnostic Workup for Abdominal Swelling with Pain and Tenderness

This patient requires urgent imaging with CT angiography to rule out life-threatening causes, particularly acute mesenteric ischemia, bowel perforation, or intra-abdominal infection, followed by immediate surgical consultation if any of these are identified. 1, 2

Initial Clinical Assessment

The combination of abdominal swelling (distension), intermittent pain, and aversion to pressure raises concern for several surgical emergencies that must be excluded immediately:

• Check vital signs immediately for fever, tachycardia, tachypnea, hypotension, or altered mental status—any of these indicate potential sepsis, bowel ischemia, or perforation requiring immediate resuscitation 2
• Establish IV access and initiate fluid resuscitation if any hemodynamic instability is present 2
• Perform focused physical examination looking specifically for:
  • Peritoneal signs (guarding, rebound tenderness, rigidity) which suggest perforation or ischemia and mandate immediate surgical consultation 1, 2
  • Absent bowel sounds indicating ileus or complete obstruction 2
  • Tympany on percussion suggesting bowel obstruction 2

Critical Laboratory Testing

Order the following immediately while arranging imaging:

• Complete blood count to assess for leukocytosis or anemia 2
• Serum lactate level—elevated lactate strongly suggests bowel ischemia or sepsis and is a critical early marker 1, 2
• C-reactive protein—more sensitive than WBC alone for surgical abdominal disease 2
• D-dimer and lactate may assist in identifying acute mesenteric ischemia, though neither is sufficiently accurate alone 1

Imaging Strategy

Obtain CT angiography (CTA) of the abdomen and pelvis with IV contrast as soon as possible 1, 2:

• CTA is the gold standard for detecting acute mesenteric ischemia, bowel perforation, intra-abdominal fluid, and other surgical emergencies 1
• Do not delay CT for oral contrast—it delays diagnosis without improving accuracy 2
• If mesenteric ischemia is suspected based on clinical presentation (severe pain out of proportion to exam findings), CTA should be performed immediately 1
• Look for free intraperitoneal fluid, extraluminal gas (perforation), bowel wall thickening, transition points (obstruction), or vascular occlusion 1

Ultrasound can be used initially if CT is not immediately available, particularly to detect free intraperitoneal fluid, though it has lower sensitivity than CT for many surgical emergencies 1

Life-Threatening Diagnoses to Exclude

Acute Mesenteric Ischemia

• Severe abdominal pain out of proportion to physical examination findings should be assumed to be acute mesenteric ischemia until disproven 1
• If CTA confirms vascular occlusion or bowel ischemia with peritonitis, prompt laparotomy is mandatory 1
• Begin fluid resuscitation immediately, correct electrolyte abnormalities, and place nasogastric tube for decompression 1
• Administer broad-spectrum antibiotics immediately and anticoagulate with IV unfractionated heparin unless contraindicated 1

Bowel Perforation

• Look for extraluminal gas, intra-abdominal fluid, and thick reactive intestinal wall on imaging 1
• If peritonitis is present, prompt laparotomy is required 1
• Begin broad-spectrum antibiotics immediately covering gram-negative bacteria and anaerobes 1

Intra-Abdominal Infection/Abscess

• If imaging reveals intra-abdominal fluid collection or abscess, percutaneous drainage should be performed if safely possible 1
• Broad-spectrum antibiotics should be administered immediately 1

When to Involve Surgery Immediately

Surgical consultation is mandatory if any of the following are present 2:

• Signs of peritonitis (guarding, rebound, rigidity)
• Free air on imaging indicating perforation
• Complete mechanical bowel obstruction on CT
• Hemodynamic instability despite resuscitation
• Bowel ischemia or mesenteric vascular occlusion on CTA
• Intra-abdominal abscess requiring drainage

Management Pending Imaging

While awaiting imaging results:

• Provide early analgesia—pain control does not compromise diagnostic accuracy 2
• Avoid opioids if possible as they worsen bowel function and can mask evolving peritonitis 2
• Keep patient NPO (nothing by mouth) until surgical emergencies are excluded
• Administer VTE prophylaxis with low-molecular-weight heparin as acute abdominal conditions carry high thrombotic risk 2

Common Pitfalls to Avoid

• Do not dismiss "soft" abdomen as reassuring—acute mesenteric ischemia classically presents with severe pain but minimal physical findings early in the course 1
• Do not delay imaging for laboratory results—CT should be obtained urgently based on clinical presentation 1, 2
• Do not withhold antibiotics if sepsis is suspected—early antibiotic administration improves outcomes in intra-abdominal infections 1
• Do not assume benign etiology in elderly patients or those with vascular risk factors—these populations are at highest risk for mesenteric ischemia 1