What is the management approach for a patient presenting with acute abdominal pain and vomiting?

Management of Acute Abdominal Pain and Vomiting

Begin with immediate hemodynamic assessment and resuscitation, followed by focused clinical evaluation to identify surgical emergencies, then proceed with CT abdomen/pelvis with IV contrast for definitive diagnosis, while initiating supportive care with IV fluids, NPO status, and nasogastric decompression for suspected obstruction. 1

Immediate Stabilization and Risk Stratification

Check vital signs immediately for tachycardia, hypotension, fever, tachypnea, and altered mental status—these combinations predict serious complications including bowel ischemia, perforation, or sepsis. 1

• Tachycardia alone is a critical warning sign and should trigger aggressive investigation 1
• Signs of shock (hypotension, oliguria, altered mental status, lactic acidosis) mandate immediate surgical exploration without delay 2, 1
• Establish IV access and initiate aggressive crystalloid resuscitation for dehydration from vomiting 1, 3
• Administer low-molecular-weight heparin for VTE prophylaxis in all patients with acute abdominal pain 3

Focused History - Key Discriminating Features

Obtain specific historical details that narrow the differential diagnosis:

• Pain migration to right lower quadrant + fever + positive psoas sign strongly suggests appendicitis 2, 1
• Vomiting BEFORE pain onset makes appendicitis unlikely 2, 4—this has 95.8% sensitivity for ruling out appendicitis when absent 4
• Bilious or feculent vomiting indicates mechanical obstruction and requires immediate nasogastric decompression 1
• Severe pain out of proportion to physical findings suggests acute mesenteric ischemia until proven otherwise 1
• Prior abdominal surgery has 85% sensitivity and 78% specificity for adhesive small bowel obstruction, which causes 55-75% of all small bowel obstructions 1, 3

Physical Examination - Critical Findings

Perform systematic examination looking for specific signs:

• Peritoneal signs (rebound tenderness, guarding, rigidity) indicate possible perforation or bowel necrosis 2, 1
• Abdominal distension with diminished bowel sounds is classic for bowel obstruction 2
• Empty rectum on digital examination supports complete obstruction 1
• Critical caveat: Absence of peritonitis does NOT exclude bowel ischemia—lactate and blood gas are essential 1

Laboratory Testing

Order the following tests immediately:

• Complete blood count, electrolytes, renal function 2, 1
• Blood gas and lactate levels are essential for detecting bowel ischemia 2, 1, 3
• C-reactive protein predicts postoperative complications 2, 1
• Liver function tests and serum albumin in appropriate contexts 1

Imaging Strategy

CT abdomen/pelvis with IV contrast is the definitive diagnostic test and should be obtained urgently to confirm or exclude appendicitis, identify bowel obstruction, detect bowel ischemia, and rule out other surgical causes. 1, 3

• Single-phase IV contrast-enhanced CT is sufficient; pre-contrast and delayed phases are unnecessary 3
• Do NOT delay CT for oral contrast—it delays diagnosis without improving accuracy 3
• Plain abdominal radiograph is the initial test but has limited sensitivity—negative films do NOT exclude mesenteric ischemia or early obstruction 2, 1
• CT helps distinguish mechanical obstruction from functional bloating and prevents unnecessary laparotomy 2

Supportive Management

Initiate the following interventions based on clinical presentation:

• NPO status and nasogastric tube decompression are mandatory for bilious vomiting or suspected obstruction 1
• Aggressive IV crystalloid resuscitation for dehydration from vomiting 1, 3
• Antiemetic therapy (ondansetron 4 mg IV) may be considered for persistent vomiting 5—ondansetron prevented postoperative vomiting in 79% of patients versus 63% with placebo 5
• Provide early analgesia without compromising diagnostic accuracy 3

Antibiotic Administration

Do NOT routinely administer antibiotics for undifferentiated abdominal pain. 3

• Antibiotics are indicated only when intra-abdominal abscess is identified, clinical signs of sepsis are present, or specific infection is confirmed 3
• Once appendicitis is suspected, start broad-spectrum antibiotics: third-generation cephalosporin plus metronidazole, or fluoroquinolone plus metronidazole 6

Specific Clinical Scenarios

Suspected Bowel Obstruction

• Obtain CT to identify transition point and assess for ischemia 1
• Perform serial abdominal exams every 4-6 hours to detect peritonitis 1, 6
• Management involves correction of physiologic and electrolyte disturbances, bowel rest, and removing the source of obstruction 7

Suspected Mesenteric Ischemia

• Immediate CT angiography and surgical consultation without delay 1
• Do not wait for laboratory confirmation—severe pain out of proportion to exam is the key clinical clue 1

Suspected Appendicitis

• CT confirms diagnosis 1, 3
• Start antibiotics once suspected 6
• Immediate surgical consultation 6

When to Involve Surgery

Surgical consultation is needed for:

• Signs of peritonitis 3
• Hemodynamic instability despite resuscitation 2, 3
• Free air on imaging 3
• Complete bowel obstruction 3
• Mesenteric ischemia 1, 3
• Ruptured abdominal aortic aneurysm 2, 3
• Failed conservative management of identified surgical pathology 3

Serial Reassessment

Perform serial abdominal examinations every 4-6 hours if initial management is conservative to detect development of peritonitis. 1, 6

• Any clinical deterioration mandates immediate surgical re-evaluation 6
• Early detection and treatment is essential to minimize complications 2

Common Pitfalls to Avoid

• Do not assume normal labs exclude serious pathology—elderly patients may have normal labs despite serious infection 3
• Do not delay imaging in unstable patients—surgery is mandatory within 12-24 hours for good outcomes 2
• Avoid opioids in chronic or functional abdominal pain—they cause narcotic bowel syndrome, dependence, and increased mortality 3