Transillumination

• 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 females

  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.)

• 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.

• References

  Haddad GG, Green TP. Diagnostic approach to respiratory disease. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 371.

  Elder JS. Disorders and anomalies of the scrotal contents. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 545.

  Valea FA, Katz VL. Breast diseases: Diagnosis and treatment of benign and malignant disease. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 15.

Review Date: 12/7/2009

Reviewed By: David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc., and Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine.