Using monopolar cautery is not advised when a child is undergoing circumcision as it may lead to coagulation of penis. The mechanism is

Channelling: Heat is produced wherever the current intensity is greatest. Normally, this would be at the tip of the active electrode, but if current passes up a narrow channel or pedicle to the active electrode, enough heat may be generated within this channel or pedicle to coagulate the tissues. This can prove disastrous, for example:coagulation of the penis in a child undergoing circumcision;coagulation of the spermatic cord when the electrode is applied to the testis.Capacitance coupling: This is a phenomenon in which a capacitor is created by having an insulator sandwiched between two metal electrodes. This can be created in situations where there is a metal laparoscopic po and the diathermy hook is passed through it.Ref: Bailey and Love 27e pg: 103