Cancer, for example, sometimes necessitates removal of all or part of the penis. In very rare instances, botched circumcisions have also resulted in full or partial penectomies, as with David Reimer. Genital surgical procedures for transsexual women undergoing sex reassignment surgery do not usually involve the complete removal of the penis. Instead, part or all of the glans is usually kept and reshaped as a clitoris, while the skin of the penile shaft may also be inverted to form the vagina. When procedures such as this are not possible, other procedures such as colovaginoplasty are used which may involve the removal of the penis.