What is the differential diagnosis and management for a patient with abdominal pain, nausea, and dark-colored vomit?

Differential Diagnosis for Abdominal Pain with Nausea and Dark Vomit

A patient presenting with 3 days of abdominal pain, nausea, and dark-colored vomit requires urgent evaluation for life-threatening conditions, particularly upper gastrointestinal bleeding, bowel obstruction, and mesenteric ischemia, with immediate focus on hemodynamic stability and exclusion of surgical emergencies. 1, 2

Critical Differential Diagnoses

Life-Threatening Conditions (Require Immediate Exclusion)

• Upper GI bleeding with hematemesis: Dark vomit ("coffee-ground" emesis) suggests digested blood from gastric or duodenal sources including peptic ulcer disease, gastric cancer, or esophageal varices 1, 3
• Bowel obstruction: Small or large bowel obstruction presents with abdominal pain, nausea, vomiting, and inability to pass gas/stool; accounts for 15% of acute abdominal pain admissions 1
• Mesenteric ischemia: Abdominal pain with nausea/vomiting in older patients or those with cardiovascular risk factors; mortality reaches 25% if ischemia develops 1
• Boerhaave's syndrome: Esophageal rupture after excessive vomiting presents with sudden severe upper abdominal pain; high mortality if untreated 4
• Perforated viscus: Gastric or duodenal perforation can present with severe abdominal pain and vomiting 1, 5

Other Important Diagnoses

• Gastroparesis: Chronic nausea, vomiting, and postprandial fullness; common in diabetics (20-40%) and functional dyspepsia patients (25-40%) 1, 6
• Cannabinoid hyperemesis syndrome (CHS): Stereotypical episodic vomiting in chronic cannabis users (>1 year, >4 times weekly) with compulsive hot water bathing behavior 1
• Gastric outlet obstruction: From malignancy, peptic ulcer disease, or other causes; presents with nausea, vomiting, and postprandial fullness 1
• Acute gastroenteritis: Typically self-limited with watery diarrhea, but infectious colitis can cause bloody diarrhea with fever 1, 3
• Pancreatitis: Severe epigastric pain radiating to back with nausea/vomiting 1, 2

Essential History to Obtain

Vomiting Characteristics

• Color and content: Dark/coffee-ground suggests upper GI bleeding; bilious suggests obstruction distal to ampulla; feculent suggests distal obstruction or bacterial overgrowth 1, 3
• Timing: Immediate post-prandial suggests gastric outlet obstruction; delayed suggests gastroparesis 1, 6
• Volume and frequency: Excessive vomiting preceding pain suggests Boerhaave's syndrome 4

Pain Characteristics

• Location: Periumbilical migrating to right lower quadrant suggests appendicitis; epigastric suggests peptic disease or pancreatitis 1
• Quality: Crampy intermittent pain suggests obstruction; constant severe pain suggests ischemia or perforation 1
• Onset: Sudden severe pain after vomiting suggests esophageal rupture 4

Associated Symptoms

• Bowel movements: Last defecation, passage of gas, presence of blood or mucus 1
• Hematemesis or melena: Confirms upper GI bleeding 1, 3
• Fever: Suggests infection, ischemia, or perforation 1
• Weight loss: Suggests malignancy 1
• Compulsive hot water bathing: Pathognomonic for CHS 1

Medical and Surgical History

• Previous abdominal surgery: 85% sensitivity for adhesive small bowel obstruction 1
• Diabetes mellitus: Risk factor for gastroparesis 1
• Cannabis use: Duration >1 year, frequency >4 times weekly suggests CHS 1
• Cardiovascular disease: Risk factor for mesenteric ischemia 1
• NSAID/anticoagulant use: Risk for peptic ulcer bleeding 1, 3
• Alcohol use: Risk for gastritis, varices, pancreatitis 3

Red Flag Symptoms (Alarm Features)

• Hemodynamic instability (hypotension, tachycardia) 1
• Peritoneal signs (rigidity, rebound tenderness) 1
• Severe unrelenting pain 1, 2
• Age >50 with new onset symptoms 1
• Progressive symptoms despite conservative management 1, 3

Physical Examination Priorities

Vital Signs Assessment

• Hemodynamic status: Blood pressure, heart rate, orthostatic changes indicate volume depletion or ongoing bleeding 1, 2
• Temperature: Fever suggests infection, ischemia, or perforation 1
• Respiratory rate: Tachypnea may indicate sepsis or metabolic acidosis 1

Abdominal Examination

• Inspection: Distension suggests obstruction; surgical scars indicate adhesion risk 1
• Auscultation: High-pitched bowel sounds suggest obstruction; absent sounds suggest ileus or peritonitis 1
• Palpation: Localized tenderness, peritoneal signs (rigidity, rebound, guarding), palpable masses 1, 2
• Percussion: Tympany suggests obstruction; shifting dullness suggests ascites 1

Specific Examination Findings

• Rectal examination: Check for masses, blood (melena or hematochezia), stool impaction 1
• Hernia examination: Inguinal, femoral, umbilical, incisional hernias account for significant obstruction cases 1
• Cardiovascular examination: Atrial fibrillation or peripheral vascular disease suggests embolic mesenteric ischemia 1
• Skin examination: Jaundice, spider angiomata suggest chronic liver disease and variceal bleeding risk 1

Initial Diagnostic Approach

Laboratory Studies

• Complete blood count: Anemia suggests bleeding; leukocytosis suggests infection, ischemia, or inflammation 1
• Metabolic panel: Electrolyte abnormalities from vomiting; elevated BUN/creatinine ratio suggests upper GI bleeding 1, 3
• Lactic acid: Elevated in mesenteric ischemia or sepsis 1
• Lipase: Elevated in pancreatitis 1, 2

Imaging Studies

• CT abdomen/pelvis with IV contrast: First-line for suspected obstruction (sensitivity >90%) or mesenteric ischemia; no oral contrast needed in high-grade obstruction 1
• Upright chest/abdominal radiographs: Free air indicates perforation; dilated bowel loops suggest obstruction 1
• Upper endoscopy: Diagnostic and potentially therapeutic for upper GI bleeding; should be performed urgently if hemodynamic instability or active bleeding 1

Critical Management Principles

• Immediate resuscitation: IV fluids, NPO status, nasogastric decompression if obstruction suspected 1
• Hemodynamic stabilization: Blood transfusion if active bleeding with hemodynamic compromise 1
• Surgical consultation: For peritoneal signs, hemodynamic instability, complete obstruction, or suspected ischemia 1
• Avoid empiric antibiotics unless sepsis, perforation, or ischemia suspected 1