Differential Diagnosis for Right Lower Quadrant (RLQ) Pain

The differential diagnosis for a patient presenting with right lower quadrant (RLQ) pain can be extensive, given the variety of organs and structures located in this area. The following categorization helps in systematically approaching the diagnosis:

• Single Most Likely Diagnosis

  • Appendicitis: This is often the first consideration for RLQ pain, especially if the pain is acute, starts near the umbilicus, and then localizes to the RLQ. Appendicitis is a common and potentially serious condition that requires prompt diagnosis and treatment.

• Other Likely Diagnoses

  • Ovarian Cyst or Torsion: In female patients, ovarian cysts or torsion can cause severe RLQ pain. The pain can be sudden and may be accompanied by nausea and vomiting.
  • Ectopic Pregnancy: Another consideration in female patients of childbearing age, ectopic pregnancy can present with RLQ pain, vaginal bleeding, and symptoms of early pregnancy.
  • Diverticulitis: Although more common on the left side, diverticulitis can occur on the right and cause RLQ pain, especially in individuals with right-sided diverticula.
  • Intestinal Obstruction: Obstruction of the small or large intestine can cause abdominal pain that may be localized to the RLQ, depending on the site of obstruction.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause chronic or recurrent RLQ pain, often accompanied by changes in bowel habits and weight loss.

• Do Not Miss Diagnoses

  • Ectopic Pregnancy: As mentioned, this is a critical diagnosis to consider in women of childbearing age, as it is life-threatening if not promptly treated.
  • Ruptured Ovarian Cyst: A ruptured ovarian cyst can lead to severe hemorrhage and requires immediate medical attention.
  • Appendiceal Rupture: If appendicitis is not treated promptly, the appendix can rupture, leading to peritonitis, which is a life-threatening condition.
  • Mesenteric Ischemia: This condition, involving insufficient blood flow to the intestines, can present with severe abdominal pain and is a medical emergency.
  • Pulmonary Embolism: Although less common, pulmonary embolism can refer pain to the abdomen, including the RLQ, and is a potentially life-threatening condition.

• Rare Diagnoses

  • Meckel's Diverticulitis: A congenital anomaly of the small intestine, Meckel's diverticulum can become inflamed and cause RLQ pain.
  • Lymphoma: Abdominal lymphoma can cause masses or inflammation that may present with RLQ pain.
  • Intussusception: A condition where a part of the intestine telescopes into another part, intussusception is more common in children but can occur in adults and cause abdominal pain.
  • Right-sided Inguinal Hernia: Although more common on the left, right-sided inguinal hernias can cause RLQ pain, especially if they become incarcerated or strangulated.