It is important to use a voice prosthesis that has the correct length. Although a slightly too long device is seldom a problem, a too short prosthesis is troublesome and might cause fistula problems. In most instances, the existing prosthesis can be used as its own measuring device. By gently pulling with a forceps at the tracheal flange, it can be determined easily, whether the device still is of the proper length. In case the length of the (already for some time established) TE fistula tract is not known, the Provox Sizer (figure right) can be used to determine the size of the prosthesis needed. The sizer has a disposable flange on its tip, which is inserted into the TE-fistula. After the flange is allowed to open up in the esophagus, the sliding part of the device is gently pushed against the trachea back-wall, and the fistula length can be read on the scale (figure right). After having established the right size of the prosthesis, the measure is tilted out of the TE fistula tract
Warning: the Provox sizer should not be used during surgery to establish the length of a freshly created fistula tract or in a 16 Fr TE-fistula. The disposable flange has 2 different sides: a curved one for a 22.5 Fr fistula tract and a ‘hollow’ side, which allows easier removal out of a 20 Fr fistula tract.