In situations where a fistula is located in a tunnel or deep crevice, multiple Fistula Funnels can be stacked and combined to create a tall barrier.
1. Cut the Fistula Funnels as indicated by the dotted lines.
Form an interlock on the top funnel by cutting at the inside of the first bellows below the middle flange.
Form a skirt for sealing around the fistula on the bottom funnel by cutting at the outside of the first bellows below the middle flange.

2. Stack the Fistula Funnels by inserting the interlock created on the top device into the large opening of the bottom device. Stretch the devices to ensure the interlock seats against the inside bellows of the bottom device.

3. Trim the flanges as necessary to tailor the stacked Fistula Funnels to the tunnel or crevice opening.

4. After trimming the flanges and adding dressings, the stacked Fistula Funnels can be placed over the fistula.

This technique can be used in situations where a fistula is located in a tunnel or deep crevice and a tall barrier is needed to seal and protect the skin from effluent.