Management of Vomiting and Generalized Abdominal Pain
Begin with immediate assessment of hemodynamic stability, obtain basic laboratory tests (CBC, electrolytes, glucose, liver function, lipase, urinalysis, lactate), and perform plain abdominal radiography to exclude bowel obstruction and other acute pathology, followed by CT abdomen/pelvis with IV contrast if clinical suspicion warrants or if initial workup is concerning. 1, 2, 3
Initial Assessment and Red Flags
Assess vital signs immediately for tachycardia, hypotension, fever, and tachypnea—these combinations predict serious complications including bowel ischemia, perforation, or sepsis. 2 Tachycardia alone is a critical warning sign and should trigger aggressive investigation. 2 Signs of shock (hypotension, altered mental status, severe tachycardia) mandate immediate surgical exploration without delay. 2, 3
Critical History Elements
Vomiting characteristics: Bilious or feculent vomiting indicates mechanical obstruction and requires immediate nasogastric decompression and NPO status. 2 Dark-colored vomit suggests upper GI bleeding from peptic ulcer disease, gastric cancer, or esophageal varices. 3
Pain characteristics: Severe abdominal pain out of proportion to physical findings suggests acute mesenteric ischemia until proven otherwise. 2 The triad of abdominal pain, constipation, and vomiting suggests sigmoid volvulus, particularly in elderly institutionalized patients. 2
Prior surgical history: This has 85% sensitivity and 78% specificity for adhesive small bowel obstruction, which causes 55-75% of all small bowel obstructions. 2
Physical Examination Priorities
Peritoneal signs (rebound tenderness, guarding, rigidity) indicate possible perforation or bowel necrosis and require urgent surgical consultation. 2 Abdominal distension with diminished bowel sounds is classic for bowel obstruction. 2 Critical caveat: Absence of peritonitis does NOT exclude bowel ischemia—lactate and blood gas are essential. 2
Laboratory Evaluation
Obtain the following tests immediately: 1, 2, 3
- Complete blood count: Assess for infection, inflammation, or blood loss (anemia suggests GI bleeding) 1, 3
- Serum electrolytes and glucose: Evaluate for metabolic derangements and dehydration 1
- Liver function tests: Rule out hepatic causes 1
- Serum lipase: Assess for pancreatitis 1, 3
- Urinalysis: Evaluate hydration status and rule out urinary causes 1
- Lactate and blood gas analysis: Essential for detecting bowel ischemia 2, 3
Elevated lactate is a critical marker for mesenteric ischemia, which has a 25% mortality rate if ischemia develops. 3
Imaging Strategy
Plain abdominal radiography is the initial test during an acute episode to exclude bowel obstruction and other abdominal pathology. 4, 2 However, negative films do NOT exclude mesenteric ischemia or early obstruction—plain films have limited sensitivity. 2
CT abdomen/pelvis with IV contrast is the definitive test and should be obtained for: 2, 3
- Identifying obstruction and transition points
- Detecting bowel ischemia
- Ruling out perforation
- Distinguishing mechanical obstruction from functional bloating
CT helps prevent unnecessary laparotomy and has higher sensitivity than ultrasound or X-ray for surgical pathology. 2
For suspected mesenteric ischemia: Obtain immediate CT angiography and surgical consultation without delay. 2
Immediate Management
Resuscitation and Supportive Care
- IV fluid resuscitation: Aggressive crystalloid administration (1 L over an hour initially) for dehydration from vomiting 2, 3
- NPO status: Mandatory for bilious vomiting or suspected obstruction 2
- Nasogastric tube decompression: Required for gastric decompression in cases of bowel obstruction or severe vomiting 1, 2
Antiemetic Therapy
First-line antiemetics (choose based on availability and patient factors): 1
- Ondansetron (5-HT3 receptor antagonist): 8 mg sublingual/oral every 4-6 hours, or 4 mg IV over 2-5 minutes 1, 5
- Promethazine: 12.5-25 mg oral/rectal every 4-6 hours (caution in elderly due to anticholinergic effects and CNS depression) 1, 2
- Prochlorperazine: 5-10 mg every 6-8 hours or 25 mg suppository every 12 hours (caution in elderly) 1, 2
Important caveat: Ondansetron requires baseline ECG due to risk of QTc prolongation. 1 For severe, refractory cases, consider haloperidol or droperidol. 1
Surgical Consultation Criteria
Obtain immediate surgical consultation for: 2, 3
- Peritoneal signs (guarding, rigidity, rebound tenderness)
- Hemodynamic instability despite resuscitation
- Complete bowel obstruction on imaging
- Suspected mesenteric ischemia
- Signs of perforation
Perform serial abdominal exams every 4-6 hours to detect evolving peritonitis in patients with suspected obstruction who are initially managed conservatively. 2
Special Considerations
Elderly Patients
Clinical presentation is often atypical in elderly patients—only 43-48% have classic findings, 36-74% have fever, and 12% present with atypical or no pain at all, making imaging critical. 2 Use antiemetics cautiously in this population due to increased risk of adverse effects. 2
Post-Surgical Patients
Vomiting with abdominal pain in post-surgical patients requires aggressive investigation for anastomotic leak, bowel ischemia, or sepsis. 2 Tachycardia alone should trigger immediate workup. 2
Prolonged Vomiting
For prolonged vomiting, assess for thiamine deficiency and consider thiamine supplementation (200-300 mg daily). 1 Consider workup for Addison's disease, hypothyroidism, and hepatic porphyria if other causes are excluded. 1
Common Pitfalls to Avoid
- Do not rely on absence of peritonitis to exclude bowel ischemia—always check lactate and blood gas 2
- Do not delay imaging in elderly patients due to atypical presentations 2
- Do not use opioid analgesics for chronic visceral abdominal pain, as they delay gastric emptying and increase risk of narcotic bowel syndrome 4
- Do not assume negative plain films exclude serious pathology—proceed to CT if clinical suspicion remains high 2