Heaf test

The Heaf test is a diagnosticskin test performed in order to determine whether or not a child has been exposed to tuberculosis.

It is used in the United Kingdom to determine if the BCGvaccine is needed. Patients who exhibit a negative reaction may be offered BCG vaccination.

Procedure

A Heaf gun is used to inject multiple samples of testing serum under the skin at once. A Heaf gun with disposable single-use heads is recommended.

The gun injects purified protein derivativeequivalent 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
• Grade 3 - Central filling to form disc
• Grade 4 - Disc >10 mm with or without blistering

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.

Other Tests

The equivalent Mantoux testpositive levels done with 10 TU (0.1 ml 100 TU/ml, 1:1000) are

• 0-4mm induration (Heaf 0-1)
• 5-14mm induration (Heaf 2)
• >15mm induration (Heaf 3-4)

The Mantoux testis preferred in the United States for the diagnosis of tuberculosis; multiple puncture tests, such as the Heaf Test, are not recommended.

See also

• tuberculosis
• Mantoux test
• F. R. G. Heaf

References

• Joint Tuberculosis Committee of the British Thoracic Society, Control and prevention of tuberculosis in the United Kingdom: Code of Practice 2000 BMJ2000:55:887-901. fulltext- Table 3 Heaf Testgrading, reaction, and equivalent Mantoux positive levels. PMID 11050256

• The Heaf Testfrom Bignell Surgical Instruments Ltd, manufacturer of a Heaf Test gun. Includes Reading the Testwith pictures of the different Grades and reactions.

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Heaf+test Wikipedia article Heaf test.