Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android. Learn more here!


(skō-tŏm′ĕ-trē) The locating and measurement of scotomata.

scout film

In radiology, an x-ray film, esp. of the abdomen, for evaluating the condition of the body before beginning an invasive or potentially hazardous examination.




(skrāp) To remove from the surface with a scalpel or other edged instrument.


(skrā′pĭng) Removal of cells, as from diseased tissue, with an edged instrument for cytologic examination.


(skrăch) [ME. cracchen, to scratch] 1. A mark or superficial injury produced by scraping with the nails on a rough surface. 2. To make a thin, shallow cut with a sharp instrument. 3. To rub the skin, esp. with the fingernails, to relieve itching. Scratching temporarily relieves itching by soothing the cutaneous nerves, but in the long run, it may worsen the condition that caused the itching. SEE: pruritus.

scratch test

Placement of an appropriate dilution of a test material suspected of being an allergen in a lightly scratched area of the skin. If the material is an allergen, a wheal will develop within 15 min. The scratch test is used to detect mmunoglobulin E antibody responses, e.g., in patients allergic to penicillin. SEE: skin test.


(skrēn) [Fr. escren] 1. To determine the presence of a disease or its characteristics in a broad community or a selected group. 2. A structure or substance used to protect, guard, or shield from a damaging influence such as x-rays, ultraviolet light, or insects. 3. A system used to select or reject personnel. 4. In psychiatry, the blocking of one memory with another.

intensifying s. In radiography, a paired sheet of fluorescent) phosphors layered onto a plastic sheet above and below the x-ray film, used to translate into light an incoming image carried by x-ray photons.

tangent s. A simple device used in perimetry to test the central portion of the visual field. SYN: Bjerrum screen.


(skrēn′ing) 1. Evaluation of patients for diseases such as cancer, heart disease, or substance abuse before these conditions become clinically obvious. Screening can play an important part in the early diagnosis and management of selected illnesses and in some instances may prolong lives. SYN: screening test. 2. In psychiatry, the initial examination to determine the mental status of a person and the appropriate initial therapy.

aneuploidy s. The testing of embryos for evidence of sex-linked diseases and structural chromosomal defects before their implantation in the uterus during assisted reproduction. Aneuploidy screening is used to detect trisomies 12, 18, and 21, ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.