Allen’s test – (radio-ulnar palmar anastomosis)

Definition:

Allen’s test is an orthopaedic procedure used determine the integrity and adequate functioning of the palmar branch of the ulnar artery.

Test procedure:

The patient makes a fist and the hand is elevated for approximately thirty seconds. Adequate pressure is applied over the radial and ulnar arteries so as to occlude them both. Whilst still in an elevated position, the patient’s hand is then re-opened. Deprived of blood, the patient’s hand should appear paler than prior to the procedure. Pressure over the ulnar artery is than released and results are observed.

 

Test findings: Positive & negative

A normal finding is for the hand to recover its original colour in less than ten seconds after pressure has been released from the ulnar artery. Abnormal findings are anything outside of the aforementioned, thus indicative of a potential inadequacy of the ulnar artery.

Special considerations:

In a clinical setting this test is often performed to assess whether a patient’s radial artery can safely be pricked, as ulnar supply will compensate. Note that the hand has a dual blood supply: radial and ulnar arteries