Transillumination is the shining of a light through a body area or organ to check for abnormalities.
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 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 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 a good test for any of the disorders above. Further tests, such as an x-ray or ultrasound, are needed to confirm the diagnosis.
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:
Internal areas will be dark to black if there is a lesion and bleeding has occurred (because blood does not transilluminate).
Gerber GS, Brendler CB. Evaluation of the urologic patient: history, physical examination, and urinalysis. In: Wein AJ, Kavoussi LR, Novick AC, et al., eds. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 3.
Haddad GG, Green TP. Diagnostic approach to respiratory disease. In: Kliegman RM, Stanton BF, St. Geme JW III, et al., eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 366.
Katz VL, Dotters D. Breast diseases: diagnosis and treatment of benign and malignant disease. In: Lentz GM, Lobo RA, Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, Pa: Elsevier Mosby; 2012:chap 15.
Poenaru D. Abdominal wall problems. In: Gleason CA, Devaskar SU, eds. Avery's Diseases of the Newborn. 9th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 71.
George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.