Differential Diagnosis for Sudden Severe Abdominal Pain

The patient's presentation of sudden severe continuous abdominal pain, particularly in the epigastric area, accompanied by nausea and tenderness with rigidity upon examination, suggests a serious gastrointestinal condition. The use of NSAIDs is a significant risk factor for certain gastrointestinal issues.

• Single Most Likely Diagnosis

  • Perforated Peptic Ulcer: This condition is highly likely given the patient's symptoms and history of NSAID use. NSAIDs are known to increase the risk of peptic ulcers and their complications, including perforation. The sudden onset of severe abdominal pain, tenderness, and rigidity (indicative of peritonitis) are classic signs of a perforated peptic ulcer.

• Other Likely Diagnoses

  • Acute Gastritis: While less severe than a perforated ulcer, acute gastritis can cause significant pain and is also associated with NSAID use. However, the presence of rigidity and the severity of pain might suggest a more serious condition.
  • Esophagitis: This could be considered, especially if the pain is more retrosternal and associated with difficulty swallowing or chest pain, but the epigastric location and severity of symptoms make it less likely.

• Do Not Miss Diagnoses

  • Boerhaave Syndrome: This is a rupture of the esophagus, which is a medical emergency. Although the patient denies vomiting, which is a common precursor to Boerhaave syndrome, any condition that could lead to severe chest or abdominal pain and potential mediastinitis or peritonitis should be considered, especially if there's any suspicion of esophageal involvement.

• Rare Diagnoses

  • Other rare conditions such as gastric volvulus, gastric cancer, or other less common causes of acute abdomen could be considered but are less likely given the information provided. These would typically require additional specific symptoms or findings to be high on the differential list.