Can Polycystic Ovary Syndrome (PCOS) cause flank pain?

PCOS Does Not Directly Cause Flank Pain; Kidney Stones Should Be Suspected

Polycystic Ovary Syndrome (PCOS) does not directly cause flank pain, and when a patient with PCOS presents with flank pain, kidney stones should be strongly suspected and evaluated with appropriate imaging. 1, 2

Differential Diagnosis for Flank Pain in PCOS Patients

Flank pain in patients with PCOS is likely due to another condition requiring investigation. The most common causes include:

1. Kidney stones (urolithiasis) - Most likely cause of acute flank pain

   • PCOS itself is not directly associated with flank pain 3
   • Metabolic dysfunction in PCOS may increase risk factors for stone formation

2. Hydronephrosis - Often associated with obstructive urolithiasis

   • Presence of hydronephrosis on imaging increases likelihood of ureteral stone (PPV 88%) 1

3. Non-urological causes to consider:

   • Right colonic diverticulitis
   • Bowel obstruction
   • Musculoskeletal causes
   • Gynecological conditions
   • Renal infarction or vascular pathologies 2

Diagnostic Approach for Flank Pain

Initial Evaluation:

1. Ultrasound (first-line imaging)

   • Recommended as initial imaging modality 2
   • Sensitivity up to 100% and specificity up to 90% for ureteral obstruction
   • Advantages: no radiation exposure, lower cost, wide availability
   • Limitations: decreased sensitivity (45%) for renal calculi compared to CT

2. Non-contrast CT (if ultrasound inconclusive)

   • Gold standard for kidney stone diagnosis
   • Sensitivity up to 97% for urolithiasis detection 2
   • Provides detailed information about stone size, location, and secondary signs of obstruction
   • Low-dose regimen should be used to minimize radiation exposure 1

Important Clinical Consideration:

• Up to 10-15% of patients with confirmed urolithiasis may have a negative urinalysis 2
• Absence of hematuria does not exclude stone disease, especially with:
  • Intermittent obstruction
  • Complete obstruction
  • Dehydration

Management Approach

If kidney stones are confirmed:

1. Assess stone characteristics:

   • Size, location, and degree of obstruction 2

2. Initiate treatment:

   • Pain management with NSAIDs
   • Adequate hydration
   • Medical expulsive therapy if appropriate
   • Urological intervention for larger stones or complete obstruction

3. Follow-up:

   • Repeat urinalysis after treatment to confirm resolution of hematuria
   • Consider metabolic evaluation to identify risk factors for stone formation

Common Pitfalls to Avoid

1. Assuming PCOS directly causes flank pain - There is no evidence supporting this 3, 4

2. Relying solely on urinalysis to rule out urolithiasis 2

3. Overlooking non-urological causes of flank pain 2

4. Failing to use appropriate imaging - Ultrasound as first line, followed by non-contrast CT if needed 1, 2

5. Excessive radiation exposure - Use low-dose CT protocols when CT is necessary 1

While PCOS is associated with metabolic dysfunction that could theoretically increase risk for conditions causing flank pain, the syndrome itself does not directly cause flank pain. Any patient with PCOS presenting with flank pain should undergo appropriate evaluation for kidney stones and other potential causes.