Differential Diagnosis for Abdominal Pain

The patient presents with mild to moderate pain on the right lateral abdomen, specifically in the midaxillary line, which worsens when sitting up and is relieved when leaning forward. This presentation guides the differential diagnosis into the following categories:

• Single Most Likely Diagnosis

  • Musculoskeletal strain or costochondritis: The pain's location and the fact that it worsens with movements such as sitting up and improves with leaning forward suggest a musculoskeletal origin. Costochondritis, an inflammation of the cartilage that connects the ribs to the breastbone, could also explain the pain, especially if it's exacerbated by movement and relieved by positions that reduce strain on the chest wall.

• Other Likely Diagnoses

  • Gallbladder disease: Although the pain is not typically in the midaxillary line for gallbladder disease, it's possible, especially if the gallbladder is inflamed or if there are gallstones. The pain from gallbladder disease can sometimes radiate to the right side.
  • Hepatic flexure syndrome: This condition involves the hepatic flexure of the colon and can cause right upper quadrant or lateral abdominal pain. The pain pattern might fit, especially if the patient experiences relief with certain positions.
  • Right lower lobe pneumonia: Sometimes, pneumonia can present with abdominal pain if the diaphragm is irritated. The pain could be referred to the abdomen, especially if the pneumonia involves the lower lobes of the lung.

• Do Not Miss Diagnoses

  • Appendicitis: Although the pain is not in the typical location for appendicitis (usually starts around the navel and then moves to the lower right abdomen), atypical presentations can occur, especially in retrocecal appendicitis. Missing appendicitis can lead to severe consequences, including perforation and peritonitis.
  • Pulmonary embolism: If the patient has risk factors for pulmonary embolism, this diagnosis must be considered, as it can present with sudden onset of pain that worsens with deep breathing or movement.
  • Ectopic pregnancy: In a female patient of childbearing age, ectopic pregnancy must be ruled out, especially if there's a possibility of pregnancy. The pain can be severe and is often accompanied by other symptoms like vaginal bleeding.

• Rare Diagnoses

  • Intercostal neuralgia: This condition involves inflammation of the nerves that run between the ribs and can cause severe, sharp pain that follows the distribution of the affected nerve.
  • Tumor of the abdominal wall or retroperitoneal space: Although rare, tumors in these areas can cause localized pain that might fit the patient's description, depending on the tumor's location and size.