trephine

{{short description|Bladed surgical instrument}}

Image:Ancientgreek surgical.jpg

File:Dr John Clarke trepanning a skull operation.jpg trepanning a skull, ca. 1664, in one of the earliest American portraits. Clarke has a trephine in his right hand. The painting is in Harvard Medical School.Holmes, Oliver Wendell (September 18, 2008). [http://www.gutenberg.org/ebooks/2700 Medical Essays].]]

A trephine ({{IPAc-en|t|r|ᵻ|ˈ|f|aɪ|n}}; from Greek τρύπανον, trypanon 'instrument for boring'){{LSJ|tru/panon|τρύπανον|ref}}. is a surgical instrument with a cylindrical blade. It can be of one of several dimensions and designs depending on what it is meant to be used for. They may be specially designed for obtaining a cylindrically shaped core of bone that can be used for tests and bone studies, cutting holes in bones (e.g., the skull) or for cutting out a round piece of the cornea for eye surgery.

A cylindrically shaped core of bone (or bone biopsy) obtained with a bone marrow trephine is usually examined in the histopathology department of a hospital under a microscope. It shows the pattern and cellularity of the bone marrow as it lay in the bone and is a useful diagnostic tool in certain circumstances such as bone marrow cancer and leukemia.{{citation needed|date=April 2014}}