Dye found in the top swab in a three swab test is indicative of?
A. Uretero-vaginal fistula
B. Vesico-vaginal fistula
C. Urethro-vaginal fistula
D. Rectovaginal fistula
Correct answer : A. Ureterovaginal fistula
Three swab test
- Three swab test is used to differentiate between ureterovaginal fistula, vesicovaginal fistula and urethrovaginal fistula.
- Three cotton swabs are placed in the vagina – at the vault, in the middle and just above the introitus.
- Methylene blue is introduced into the bladder using a rubber catheter.
- The patient is then asked to walk about for 5 minutes.
- The swabs are then retrieved for inspection.
Interpretation of three swab test
- Top swab soaked in urine, unstained – Uretero-vaginal fistula
- Middle swab stained with dye – Vesico-vaginal fistula
- Bottom swab stained with dye – Urethro-vaginal fistula
Image credits: Author: VHenryArt. Licensed under the Creative Commons Attribution-Share Alike 4.0 International license. http://en.wikipedia.org/wiki/File:Obstetric_Fistula_Locations_Diagram.png