Differential Diagnosis for Abdominal Pain

The differential diagnosis for abdominal pain is extensive and can be categorized based on the likelihood and potential impact of missing a diagnosis. Here's a structured approach:

• Single Most Likely Diagnosis

  • Gastroenteritis: This is often the most common cause of abdominal pain, especially if the pain is accompanied by symptoms like diarrhea, vomiting, and fever. The justification for this being the single most likely diagnosis lies in its high prevalence and the broad range of pathogens that can cause it, including viral, bacterial, and parasitic agents.

• Other Likely Diagnoses

  • Irritable Bowel Syndrome (IBS): Characterized by chronic abdominal pain, bloating, and alteration of bowel habits in the absence of any mechanical, inflammatory, or biochemical abnormalities. IBS is a common condition that can cause significant discomfort and is often considered in the differential for chronic or recurrent abdominal pain.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause abdominal pain, diarrhea, weight loss, and sometimes blood in the stool. The chronic nature of these diseases and their potential for complications make them important considerations.
  • Peptic Ulcer Disease: Gastric and duodenal ulcers can cause epigastric pain that may radiate to the back, worsen with food intake, and improve with antacids or food. The presence of Helicobacter pylori infection or the use of NSAIDs are common risk factors.
  • Constipation: Although often overlooked, constipation can cause significant abdominal pain and discomfort, especially if it leads to fecal impaction.

• Do Not Miss Diagnoses

  • Appendicitis: Although not the most common cause, appendicitis is a surgical emergency that requires prompt diagnosis and treatment to prevent perforation and peritonitis. Classic symptoms include initial diffuse or epigastric pain that localizes to the right lower quadrant, fever, and leukocytosis.
  • Ectopic Pregnancy: In women of childbearing age, ectopic pregnancy is a life-threatening condition that can present with abdominal pain, vaginal bleeding, and missed periods. A high index of suspicion is necessary, especially in patients with risk factors like previous pelvic surgery or tubal ligation.
  • Mesenteric Ischemia: This condition involves insufficient blood flow to the intestines and can lead to severe abdominal pain out of proportion to physical findings, especially in older patients or those with cardiovascular disease. Early diagnosis is crucial to prevent bowel infarction.
  • Ruptured Aortic Aneurysm: Presents with severe, tearing abdominal or back pain and is a medical emergency. Risk factors include hypertension, smoking, and atherosclerosis.

• Rare Diagnoses

  • Porphyrias: A group of disorders that can cause acute intermittent porphyria, leading to severe abdominal pain, neurological symptoms, and sometimes psychiatric disturbances. These conditions are rare but can be diagnosed with specific tests.
  • Lead Poisoning: Can cause abdominal pain, constipation, and neurological symptoms. It's more common in children exposed to lead-based paint or in adults with occupational exposure.
  • Intussusception: A condition where a part of the intestine telescopes into another part, causing bowel obstruction and potentially severe abdominal pain. It's rare in adults but more common in children.
  • Abdominal Migraine: A condition that causes recurrent episodes of severe abdominal pain, often accompanied by other migraine symptoms like headache or nausea. It's more commonly diagnosed in children.