Definition of Transillumination:

Transillumination is the shining of a light through a body cavity or organ.

How the test is performed:

The room lights are dimmed or turned off so that the appropriate part of the body may be seen more easily. A bright light is then pointed at a location on the body, typically the head, scrotum, chest of a premature or newborn infant, or breast of an adult female.

Transillumination is also sometimes used to find blood vessels.

How to prepare for the test:

No preparation is necessary for this test.

How the test will feel:

There is no discomfort associated with this test.

Why the test is performed:

This test may be done along with other tests to diagnose:

• Hydrocephalus in newborns or infants
• Hydrocele in males
• Breast lesions or cysts in adult females

In newborns, a bright halogen light may be used to transilluminate the chest cavity if there are signs of a collapsed lung. (Transillumination through the chest is only possible on small newborns.)