Differential Diagnosis for LLQ Pain

The patient reports a 4-month history of stabbing constant pain in the lower left quadrant (LLQ) of the abdomen. The differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Irritable Bowel Syndrome (IBS): This is a common condition characterized by chronic abdominal pain, bloating, and alteration of bowel habits. The constant stabbing pain in the LLQ could be consistent with IBS, especially if the patient experiences relief with bowel movements or has associated symptoms like changes in stool frequency or consistency.

• Other Likely Diagnoses

  • Diverticulitis: Inflammation of a diverticulum in the colon can cause persistent pain in the LLQ. While it's more common in older adults, it could be a consideration, especially if the patient has a history of diverticulosis.
  • Constipation: Chronic constipation can lead to abdominal pain, including in the LLQ, due to the accumulation of feces and gas in the colon.
  • Gastroesophageal Reflux Disease (GERD): Although GERD typically presents with upper gastrointestinal symptoms, some patients may experience referred pain in the lower abdomen, including the LLQ.

• Do Not Miss Diagnoses

  • Appendicitis: Although appendicitis typically presents with pain that initially is diffuse or around the navel and then localizes to the right lower quadrant (RLQ), atypical presentations can occur, including pain in the LLQ, especially if the appendix is retrocecal or in an unusual position.
  • Ectopic Pregnancy: In women of childbearing age, ectopic pregnancy is a critical diagnosis to consider, even if the pain is constant and in the LLQ. A missed diagnosis can be life-threatening.
  • Ovarian Torsion: This condition, where the ovary twists around its ligaments, can cause severe, constant pain, often on one side, and is a surgical emergency.
  • Intestinal Obstruction: Obstruction of the intestine can cause severe abdominal pain, vomiting, and constipation. It's a condition that requires prompt diagnosis and treatment to prevent complications.

• Rare Diagnoses

  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause chronic abdominal pain, including in the LLQ, but are less common than IBS or other causes.
  • Colonic Neoplasm: Tumors in the colon can cause chronic pain, changes in bowel habits, and other symptoms, but are less likely in younger patients without risk factors.
  • Endometriosis: This condition, where tissue similar to the lining inside the uterus grows outside of it, can cause chronic pelvic pain, including in the LLQ, especially during menstruation.