cranioclast

from The Century Dictionary.

• noun A powerful forceps employed in the operation of craniotomy for seizing, breaking down, and withdrawing the fetal skull.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Med.) An instrument for crushing the head of a fetus, to facilitate delivery in difficult eases.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun medicine An instrument for crushing the head of a foetus, to facilitate delivery in difficult cases.