What is the cause of fever, back pain, and left lower quadrant (LLQ) pain?

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Last updated: May 3, 2025 • View editorial policy

Differential Diagnosis for Fever, Back Pain, and LLQ Pain

  • Single Most Likely Diagnosis + Pyelonephritis or lower urinary tract infection: This diagnosis is likely due to the combination of fever, back pain (which can be referred pain from the kidneys), and LLQ pain (which can be referred pain from the ureters or bladder).
  • Other Likely Diagnoses + Diverticulitis: Inflammation of the diverticula in the colon can cause fever, back pain, and LLQ pain, especially if the diverticula are located in the sigmoid colon. + Kidney stones: Nephrolithiasis can cause severe back pain and LLQ pain, and if there is an associated infection, fever may be present. + Musculoskeletal strain: Back pain and LLQ pain can be caused by muscle strain, and if there is an associated viral illness, fever may be present.
  • Do Not Miss Diagnoses + Appendicitis: Although appendicitis typically presents with RLQ pain, it can occasionally present with LLQ pain, especially if the appendix is retrocecal. Fever and back pain can also be present. + Ectopic pregnancy: A pregnancy that implants outside the uterus can cause fever, back pain, and LLQ pain, and is a life-threatening condition if not promptly diagnosed and treated. + Ovarian torsion: Torsion of the ovary can cause severe LLQ pain, fever, and back pain, and is a life-threatening condition if not promptly diagnosed and treated.
  • Rare Diagnoses + Inflammatory bowel disease (e.g. Crohn's disease, ulcerative colitis): These conditions can cause fever, back pain, and LLQ pain, but are less common than other diagnoses on this list. + Spinal infection (e.g. osteomyelitis, discitis): Infection of the spine can cause fever, back pain, and LLQ pain, but is relatively rare. + Retroperitoneal fibrosis: A rare condition in which fibrotic tissue forms in the retroperitoneum, which can cause back pain, LLQ pain, and fever.

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.