Differential Diagnosis for Right Abdominal and Flank Pain

Single Most Likely Diagnosis

• Appendicitis: This is often the first consideration for right lower quadrant abdominal pain, especially if the pain is severe, constant, and accompanied by fever, nausea, and vomiting. The location of the pain, which often starts near the navel and then moves to the lower right abdomen, is a classic presentation.

Other Likely Diagnoses

• Kidney Stones (Nephrolithiasis): Pain from kidney stones can radiate from the flank into the groin and is often described as severe and crampy. It may be accompanied by nausea, vomiting, and blood in the urine.
• Pyelonephritis: An infection of the kidney, which can cause flank pain, fever, and other symptoms like frequent urination and dysuria.
• Cholecystitis: Inflammation of the gallbladder, which can cause right upper quadrant pain, especially after eating fatty foods, and may be accompanied by fever and jaundice.
• Hepatitis: Inflammation of the liver, which can cause right upper quadrant pain, jaundice, and other symptoms like dark urine and pale stools.

Do Not Miss Diagnoses

• Ectopic Pregnancy: Although less common, an ectopic pregnancy can present with abdominal pain and must be considered, especially in women of childbearing age with a missed period or positive pregnancy test.
• Ruptured Aortic Aneurysm: A life-threatening condition that requires immediate medical attention, presenting with severe abdominal or back pain.
• Pulmonary Embolism: Can cause sudden onset of chest pain and shortness of breath but may also refer pain to the right flank if the embolism affects the lung's lower lobe.
• Diverticulitis: Inflammation of a diverticulum in the digestive tract, which can cause severe abdominal pain, usually on the left side but can be on the right in some cases.

Rare Diagnoses

• Intestinal Obstruction: A blockage that prevents normal flow of the products of digestion, which can cause severe abdominal pain, vomiting, and constipation.
• Pancreatitis: Inflammation of the pancreas, which can cause severe abdominal pain that radiates to the back, nausea, and vomiting.
• Right Lower Lobe Pneumonia: Can cause right flank pain due to referred pain from the diaphragm.
• Ovarian Torsion: A condition where the ovary twists around its ligaments, cutting off blood supply, and can cause severe pelvic pain that may radiate to the flank.