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:
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.)
Normal Values: Normal findings depend on the area being evaluated, and the normal tissue of that region.
What abnormal results mean: Areas filled with abnormal air or fluid will light up when they should not. For example, in a darkened room, the head of a newborn with possible hydrocephalus will light up when this procedure is done.
When done on the breast:
- Internal areas will be dark to black if there is a lesion and bleeding has occurred (because blood does not transilluminate).
- Benign tumors tend to appear red.
- Malignant tumors are brown to black.
What the risks are: There are no risks associated with this test.
Special considerations: In general, transillumination is not a particularly good test for any of these above-mentioned disorders, and further tests, such as an x-ray or ultrasound, are needed to confirm the diagnosis.
