Gynaecology & Obstetrics Methylene blue 3 swab test is done for urinary fistulae. Source of leakage if the lowermost swab gets stained: March 2010 A Ureter B Urinary bladder C Urethra D None of the above 💡 Explanation Methylene blue 3 swab test is done for urinary fistulae. Source of leakage if the lowermost swab gets stained: March 2010 ✓ Correct Answer: C. Urethra