The reasons for inserting cotton balls into anal fistula wounds include drainage, prevention of infection, hemostasis, and reduction of pseudo-healing. 1. Drainage: if belongs to complex anal fistula, some incisions may be deeper, fill cotton balls here, can play the effect of drainage, reduce the incision site dirt gathered. 2. Prevent infection: because the anal fistula long in the anus near, fistula and anus connected, in the process of excretion, excreta may seep out through the incision, resulting in the wound site was contaminated. In the wound plug cotton balls, can prevent seepage, prevent infection. 3. Stop bleeding: after anal fistula surgery, there will be bleeding at the surgical site, you can use cotton balls or gauze stuffing, to stop bleeding by compression. 4. Reduce pseudo-healing: filling cotton balls can also control the growth direction of the incision, so that the incision grows positively upwards, reducing the probability of pseudo-healing. It is recommended that the patient actively cooperate with the doctor postoperative dressing change and the necessary filling cotton ball, if there are uncomfortable symptoms, or cotton ball out, need to inform the doctor in a timely manner, in accordance with the doctor’s instructions to give treatment.