Causes of Left Flank Pain in a 54-Year-Old Female
Left flank pain in a 54-year-old woman has a broad differential diagnosis that extends well beyond urolithiasis, with up to one-third of cases having alternative diagnoses unrelated to kidney stones. 1
Urologic Causes
Nephrolithiasis (Kidney Stones)
- Most common urologic cause, presenting with colicky, wave-like severe pain independent of body position, often radiating to the groin or genitals with abrupt onset 2
- Hematuria (even microscopic) is frequently present but absent in over 20% of confirmed stone cases 2
- Stones <5 mm typically pass spontaneously, while larger stones may require intervention 2
Pyelonephritis/Urinary Tract Infection
- Pain that worsens with external flank pressure suggests pyelonephritis rather than stones 3
- May present with fever, chills, and systemic signs of infection 2
- Requires urgent evaluation if accompanied by hemodynamic instability 2
Renal Malignancy
- Critical consideration in this age group, especially if accompanied by hematuria 4
- Classic triad of hematuria, flank mass, and flank pain suggests renal cell carcinoma 4
- Urothelial carcinoma should be considered, particularly with central renal masses 4
Other Urologic Conditions
- Hydronephrosis from obstruction (non-stone causes) 5
- Perinephric abscess (pain worsens with external pressure) 3
- Page kidney (subcapsular hematoma causing compression and secondary hypertension) 6
- Papillary necrosis 7
Gynecologic Causes
- Adnexal masses (most common gynecologic finding on imaging for flank pain) 1
- Ovarian cyst complications including torsion or rupture 7, 1
- Pelvic congestion syndrome 5
- Ectopic pregnancy must be excluded in women with delayed menses 2
Gastrointestinal Causes
Left-Sided Colonic Pathology
- Left colonic diverticulitis (common mimic of renal colic) 5, 1
- Inflammatory bowel disease 5
- Gastroenteritis and colitis 5
- Constipation 5
Other GI Conditions
Vascular Causes
- Abdominal aortic aneurysm (life-threatening emergency that must be ruled out) 8
- Renal artery or vein thrombosis 1
- Arteriovenous malformation with hemorrhage 6
Musculoskeletal Causes
- Pain after prolonged static positioning suggests paraspinal muscle strain, facet joint pathology, or referred pain from lumbar spine 2
- Pain that varies significantly with body position favors musculoskeletal origin over renal colic 2
Hepatobiliary Causes
- Hepatic or splenic pathology (less common but possible) 1
Key Diagnostic Considerations
Red Flags Requiring Urgent Evaluation
- Fever, chills, or signs of sepsis 2
- Hemodynamic instability or shock 2
- Inability to urinate or decreased urine output 2
- Visible hematuria in elderly patients (malignancy concern) 4
Imaging Approach
- Non-contrast CT abdomen/pelvis is the gold standard with 98-100% sensitivity and specificity for stones, and identifies alternative diagnoses in approximately one-third of patients 2, 8
- CT with IV contrast is preferred when malignancy is suspected (elderly patient with hematuria and flank pain) 4
- Ultrasound is appropriate for radiation concerns and can detect hydronephrosis with up to 100% sensitivity 2
Common Pitfalls to Avoid
- Do not assume all flank pain is kidney-related—the positional nature of symptoms is key to distinguishing musculoskeletal from visceral causes 2
- Normal urinalysis does not exclude significant pathology—over 20% of stone patients have negative urinalysis 2
- In women of reproductive age, always consider ectopic pregnancy before extensive imaging 2
- In elderly patients with hematuria, prioritize malignancy evaluation over assuming benign stone disease 4