Heaf test
The Heaf test is a diagnostic skin test performed in order to determine whether or not a child has been exposed to tuberculosis. Also known as the Sterneedle test,[1] it is administered by a Heaf gun (trademarked "Sterneedle")[2] which is a spring-loaded instrument with six needles arranged in a circular formation.[3]
Patients who exhibit a negative reaction to the test may be offered BCG vaccination. The test is named after F. R. G. Heaf. Until 2005, the test was used in the United Kingdom to determine if the BCG vaccine was needed; the Mantoux test is now used instead. The Heaf test was preferred in the UK, because it was felt that the Heaf test was easier to interpret, with less inter-observer variability, and that less training was required to administer and to read the test. The test was withdrawn because manufacturers could not be found for tuberculin or for Heaf guns.
The Heaf test is used to test for tuberculosis in adolescents aged around 13–14.[4]
[edit] Procedure
A Heaf gun is used to inject multiple samples of testing serum under the skin at once. The needle points are dipped in tuberculin purified protein derivative (PPD) and pricked into the skin.[5] A Heaf gun with disposable single-use heads is recommended.
The gun injects purified protein derivative equivalent to 100,000 units per ml to the skin over the flexor surface of the left forearm in a circular pattern of six. The test is read between 2 and 7 days later. The injection must not be into sites containing superficial veins.
The reading of the Heaf test is defined by a scale:
- Negative - No induration, maybe 6 minute puncture scars
- Grade 1 - 4-6 papules (also considered negative)
- Grade 2 - Confluent papules form indurated ring (positive)
- Grade 3 - Central filling to form disc (positive)
- Grade 4 - Disc >10 mm with or without blistering (strongly positive)
Grades 1 and 2 may be the result of previous BCG or avian tuberculosis.
Children who have a grade 3 or 4 reaction require X-ray and follow-up.
For interpretation of the test, see Tuberculosis diagnosis.
[edit] Other Tests
The equivalent Mantoux test positive levels done with 10 TU (0.1 mL 100 TU/mL, 1:1000) are
- 0–4 mm induration (Heaf 0-1)
- 5–14 mm induration (Heaf 2)
- >15 mm induration (Heaf 3-4)
The Mantoux test is preferred in the United States for the diagnosis of tuberculosis; multiple puncture tests, such as the Heaf test and Tine test, are not recommended.
[edit] References
- Joint Tuberculosis Committee of the British Thoracic Society, Control and prevention of tuberculosis in the United Kingdom: Code of Practice 2000 BMJ 2000:55:887-901. Table 3 Heaf Test grading, reaction, and equivalent Mantoux positive levels. doi:10.1136/thorax.55.11.887 PMID 11050256
- ^ Nolan, Thomas E. (1996). Primary care for the obstetrician and gynecologist. Wiley-IEEE. p. 285. ISBN 9780471122791. http://books.google.com/books?id=XTDzmKfWkSQC&pg=PA285. Retrieved 17 October 2010.
- ^ "Test substance for tuberculosis". United States Patent and Trademark Office. 13 July 1976. http://ip.com/pdf/patent/US3969497.pdf. Retrieved 17 October 2010. "...multiple scratch scarifications by an instrument known as the Heaf gun (also known by the Trademark "Sterneedle"), or by..."
- ^ "Heaf Test (subscription required)". Black's Medical Dictionary, 42nd Edition. London: A & C Black. 2010. http://www.credoreference.com/entry/blackmed/heaf_test. Retrieved 17 October 2010.
- ^ Shaw, Ian; Woodward, Louise (2004). "Cultures: British (subscription required)". Encyclopedia of Medical Anthropology: Health and Illness in the World's Cultures. Dordrecht: Springer Science+Business Media. http://www.credoreference.com/entry/sprmedanth/british. Retrieved 17 October 2010.
- ^ "Sterneedle test (subscription required)". Academic Press Dictionary of Science and Technology. Oxford: Elsevier Science & Technology. 1992. http://www.credoreference.com/entry.do?id=3163273. Retrieved 17 October 2010.
