Abdominal Pain Evaluation

Clinical Presentation

• Pain out of proportion to physical exam is classic for mesenteric ischemia, according to the World Journal of Emergency Surgery guidelines 1
• Involuntary guarding, rebound tenderness, and board-like rigidity suggest peritonitis, which almost always predicts intestinal infarction or perforation 1
• A broader differential diagnosis for diffuse pain should include bowel obstruction, mesenteric ischemia, or peritonitis, as suggested by the American College of Radiology 2
• Specific warning signs for internal hernia include persistent epigastric pain, especially in patients with a history of laparoscopic Roux-en-Y gastric bypass, and for bowel obstruction include persistent crampy/colicky abdominal pain, vomiting, and abnormal stool transit, as recommended by the World Journal of Emergency Surgery guidelines 3
• Typical signs of abdominal sepsis may be masked, increasing the risk of delayed diagnosis and higher mortality rate, as noted by the American College of Radiology 2
• Alarming clinical signs requiring immediate attention include tachycardia, fever, hypotension, respiratory distress, and decreased urine output, as recommended by the World Journal of Emergency Surgery guidelines 3

Diagnostic Evaluation

• Ultrasonography is the preferred initial imaging for suspected gallbladder pathology in the right upper quadrant, with a sensitivity of 96.7% and specificity of 85.7%, according to the American Academy of Family Physicians and the American College of Radiology 4, 2
• CT with IV contrast is the first-line imaging modality for nonlocalized abdominal pain, suspected appendicitis, and diverticulitis, and is also the best imaging modality for detecting bowel obstruction and mesenteric ischemia, as recommended by the American College of Radiology 2, 5
• MRI is the preferred imaging modality when ultrasound is inconclusive, with no ionizing radiation and high accuracy for bowel obstruction, appendicitis, and soft tissue pathology, and should be considered when ultrasound is inconclusive, with a rating of 7/9 for appropriateness 6, 4, 7
• The following table compares the sensitivity and specificity of different imaging modalities for suspected abscess:

8, 9, 10

• Laboratory tests should include complete blood count, comprehensive metabolic panel, C-reactive protein (CRP) and/or procalcitonin, serum lactate levels, blood gas analysis, urinalysis, and pregnancy test in women of childbearing age, as suggested by the World Journal of Emergency Surgery 3
• Normal white blood cell count does not exclude serious pathology, and should not be relied upon solely for diagnosis, and plain films have limited value in non-traumatic abdominal pain evaluation, as recommended by the American College of Radiology 2

Management

• Immediate fluid resuscitation and surgical consultation are required for hemodynamically unstable patients, as recommended by the World Journal of Emergency Surgery and Anaesthesia guidelines 11, 12
• Hemodynamically unstable patients with positive FAST should proceed directly to trauma laparotomy, as suggested by the World Journal of Emergency Surgery guidelines 11
• Antispasmodics are recommended as first-line treatment for crampy pain, particularly when exacerbated by meals, with a strength of evidence supported by Gastroenterology and Nature Reviews Gastroenterology and Hepatology 13, 14
• Peppermint oil can be effective for IBS-related pain, as suggested by Nature Reviews Gastroenterology and Hepatology 14
• Tricyclic antidepressants (TCAs) are more effective than SSRIs for pain management in chronic pain conditions like IBS, and should be started at low doses and titrated according to response, as recommended by Nature Reviews Gastroenterology and Hepatology 14
• Antibiotics should only be administered when infection is suspected or confirmed, and clinical improvement should be seen within 3-5 days after starting antibiotics, according to the World Journal of Emergency Surgery 15
• The Gastroenterology society recommends a 2-week course of ciprofloxacin or metronidazole as first-line treatment, with ciprofloxacin being better tolerated and possibly more effective than metronidazole 16, 17
• Correction of fluid and electrolyte abnormalities is recommended as part of the management of patients with abdominal pain, according to the World Journal of Emergency Surgery 15
• Low molecular weight heparin is recommended for thromboprophylaxis in hospitalized patients with abdominal pain, as stated by the World Journal of Emergency Surgery 15

Special Considerations

• Pregnant patients with acute abdomen require prompt diagnosis and appropriate therapy, with a low threshold for surgical intervention when clinically indicated to prevent increased morbidity and mortality for both mother and fetus, according to the World Journal of Emergency Surgery guidelines 3
• Ultrasound should be the first-line imaging test for pregnant women with abdominal pain, with a sensitivity of 96.7% and specificity of 85.7%, according to the American Academy of Family Physicians 4
• CT scan should be reserved for selected cases when benefits outweigh risks, with low-dose protocols and absolute risks to the fetus being small at doses <50 mGy, as recommended by the World Journal of Emergency Surgery guidelines 3
• Cesarean delivery should be based on obstetric indications only, not due to prior abdominal surgery, as recommended by the Gastroenterology guidelines 6
• Timing of delivery should not be altered by recent non-obstetric surgery unless complications arise, as recommended by the Gastroenterology guidelines 6
• Pregnancy increases the risk of internal hernia after bariatric surgery due to increased intra-abdominal pressure, as recommended by the World Journal of Emergency Surgery guidelines 3
• Necessary imaging should not be withheld due to unfounded radiation fears, as single CT poses minimal risk to the fetus compared to untreated surgical condition, as recommended by the World Journal of Emergency Surgery guidelines 3
• Pregnant patients should always be positioned with left lateral tilt to prevent aortocaval compression, as improper positioning can lead to maternal hypotension and decreased placental perfusion, as recommended by the Gastroenterology guidelines 6

Mesenteric Ischemia

• Nearly 50% of patients with embolic acute mesenteric ischemia have atrial fibrillation, according to the World Journal of Emergency Surgery 18
• Approximately one-third of patients have prior history of arterial embolus, as reported by the World Journal of Emergency Surgery 18
• Patients with non-occlusive mesenteric ischemia (NOMI) often have history of cardiac failure, according to the World Journal of Emergency Surgery 18
• Recent surgery increases risk for NOMI, as noted by the World Journal of Emergency Surgery 18
• CT Angiography (CTA) should be performed without delay in any patient with suspicion for mesenteric ischemia, as every 6 hours of delay in CTA doubles mortality, according to the World Journal of Emergency Surgery 18
• CTA should include arterial and venous phases to demonstrate thrombus in mesenteric vessels, as recommended by the World Journal of Emergency Surgery 18
• Oral contrast is not indicated and may be harmful, according to the World Journal of Emergency Surgery 18