Which principle explains the path of fluids in fistula formation?

• A. Body fluids follow the path of least resistance
• B. Fluids always flow toward gravity
• C. Fistulas are formed only by infection
• D. They form exclusively at surgical sites

Answer: (A)

Fluids tend to move along the path of least resistance. In fistula formation, tissue damage from inflammation, infection, or surgical injury creates channels and planes that offer less opposition than surrounding, healthy tissue. As a result, inflammatory exudate and secretions dissect through these easier routes, gradually forming a tract that connects two surfaces or organs. Gravity doesn’t solely dictate flow; pressure gradients and the anatomy of tissue planes determine the direction fluids travel. Fistulas aren’t caused only by infection, nor do they occur only at surgical sites—they arise when tissue integrity is compromised and fluids can follow the easiest path.