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Transillumination

Transillumination is the shining of a light through a body area or organ to check for abnormalities.

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Infant brain test

How the Test is Performed

The room lights are dimmed or turned off so that the area of the body may be seen more easily. A bright light is then pointed at that area. Areas where this test is used include the:

Transillumination is also sometimes used to find blood vessels.

In some locations in the stomach and intestine, the light can be seen through the skin and tissues at the time of upper endoscopy and colonoscopy.

How to Prepare for the Test

No preparation is necessary for this test.

How the Test will Feel

There is no discomfort 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 or air around the heart. (Transillumination through the chest is only possible on small newborns.)

In general, transillumination is not an accurate enough test to rely on. Further tests, such as an x-ray, CT, or ultrasound, are needed to confirm the diagnosis.

Normal Results

Normal findings depend on the area being evaluated and the normal tissue of that area.

What Abnormal Results Mean

Areas filled with abnormal air or fluid 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:

Risks

There are no risks associated with this test.

Related Information

Hydrocephalus
Hydrocele
Cyst
Collapsed lung (pneumothorax)
Chest x-ray
Benign

References

Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW. Examination techniques and equipment. In: Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW, eds. Seidel's Guide to Physical Examination. 9th ed. St Louis, MO: Elsevier; 2019:chap 3.

Lissauer T, Hansen A. Physical examination of the newborn. In: Martin RJ, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine: Diseases of the Fetus and Infant. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 28.

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Review Date: 7/11/2019  

Reviewed By: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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