A keyhole defect is a term used in medicine and in the

forensic sciences Forensic science, also known as criminalistics, is the application of science to criminal and civil laws, mainly—on the criminal side—during criminal investigation, as governed by the legal standards of admissible evidence and crimina ...

to refer to the shape of an anomolous feature or traumatic lesion caused by a

gunshot wound A gunshot wound (GSW) is a penetrating injury caused by a projectile (e.g. a bullet) from a gun (typically firearm or air gun). Damages may include bleeding, bone fractures, organ damage, wound infection, loss of the ability to move part of th ...

Forensic investigation

A keyhole defect is characteristic of a type of entrance wound caused by a bullet striking the surface of a flat bone (typically the

cranium The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

) at a shallow angle. The defect is characterized by a rounded portion with a clean margin where the bullet first perforates bone, and a wider area with external beveling on the opposite end. The keyhole entrance wound can thus indicate the trajectory of the bullet at the time of impact.

Proctology

proctology Colorectal surgery is a field in medicine dealing with disorders of the rectum, anus, and colon. The field is also known as proctology, but this term is now used infrequently within medicine and is most often employed to identify practices rela ...

, a keyhole defect may refer to a groove in the

anal canal The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional segment ...

wall, which can occur after posterior midline

fissurectomy An anal fissure is a break or tear in the skin of the anal canal. Anal fissures may be noticed by bright red anal bleeding on toilet paper and undergarments, or sometimes in the toilet. If acute they are painful after defecation, but with chronic ...

or fistulotomy (surgical operations involving the anal canal), or with lateral internal anal sphincter defects. The keyhole defect is associated with minor degrees of fecal incontinence, allowing seepage of liquid stool or mucus.

References

Colorectal surgery {{digestive-stub