Ostomy pouching systems collect waste that is output from a stoma. In anatomy, a stoma (plural stomata or stomas) is any opening in the body. Prolapse of bowel wall through the stoma occasionally happens and can require reoperation to repair. This occurs when there is retractable vomiting, diarrhea, or external drainage via stoma or fistulas. It avoids the need for a stoma bag on the urostomy. Minor leakage may cause irritation of the skin around the gastrostomy site or stoma. The epidermis also consists of stomata(singular&colon;stoma) which helps in transpiration. These, in turn, communicate with the exterior through an open water stoma or open pore. Patients with colostomies can have melanosis involving the stoma, which is also of no significance. The urine is drained through a small stoma that is barely visible. Over the stoma, a hyphal tip produces an infection structure called an appressorium. Any hollow organ can be manipulated into an artificial stoma as necessary. The historical practice of trepanation was also a type of stoma. Guard cells are cells surrounding each stoma. This technique is characterized by the exclusive procedure to carry out the stoma.