The blackening of the head of the turtle after circumcision may be caused by blood seepage, anesthesia, ischemic conditions and so on. 1. Blood seepage: the common blackening of the head of the foreskin is blood seepage, this is because after cutting the foreskin, there is blood seepage on the incision itself, but the blood can not come out, if the needle is sewn tightly or tied tightly, the blood can not come out, it will seep out and lead to blackening in the head of the foreskin. 2. Playing anesthetics: the anesthetics used during circumcision will play on the spongy body, and bleeding will occur during the operation, which will lead to the blackening of the head in the process of slow recovery. 3. Ischemia: because just after the circumcision then will make the foreskin area ischemia, this will lead to the head blackened, need time to recover. Note that if the circumcision head turns black, you should seek medical treatment in time, and under the advice of the doctor to deal with it correctly.