Yes, on the arm opposite the fistula. Never on the same arm as the fistula

closure of Gastrocolic fistula

The plural of "fistula" is "fistulas" or "fistulae."

The scientific name of amaltas is Cassia fistula.

In medicine it is an abnormal connection between cells or organs that normally do not connect
A fistula is an abnormal connection between an organ, vessel, or intestine and another structure. What happened to using google when you have questions like this?
'Fistula' has a couple of senses: 1: an abnormal passage leading from a suppurating cavity to the body surface; 2: a chronic inflammation of the withers of a horse