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Digital Allen Test

Exams and Signs

Historical Overview

In 1929, Edgar V. Allen first explained a test to assess arterial blood flow to the hands.1

Description

  • The digital Allen test examines the arterial supply to the fingers. It can be more difficult to assess than the Allen test because of the smaller size of the fingers.2
  • The Allen test may be necessary to determine if a non-palpable ulnar artery is absent or only obscured.3

Pathophysiology

  • The digital Allen test may indicate Raynaud’s phenomenon, collagen vascular disease, or other vaso-occlusive diseases.4

Instructions

  1. Ask the patient to close the affected hand tightly.
  2. Apply pressure on both the radial and ulnar artery and compress the vessels.4
  3. Observe whether the fingers display a pallor when they are flexed.5
  4. Check if there is a return of color in 2-6 seconds. If the fingers stay pale, this may show that the distal part of the ulnar artery is occluded.6
  5. If color returns to only a portion of the fingers, assess the perfusion pattern.4
  6. Examine the fingers of the contralateral hand.

Variations

  • Occlude the radial artery while listening to the ulnar artery.7
  • Trophic changes may contribute to a diagnosis of Raynaud’s phenomenon.4

Related Signs and Tests

  • Allen test
  • Doppler exam2
  • Radial artery pulse
  • Ulnar artery pulse
  • Neurovascular exam
  • Cold stress test
  • Magnetic resonance imaging (MRI)

Diagnostic Performance Characteristics

  • To improve the reliability of the digital Allen test, use Doppler ultrasound to record arterial perfusion patterns.4 The Doppler test will help to reduce false positives and false negatives.

Additional Information

Presentation Photos and Related Diagrams
  • Allen Test for the digital arteries - The examiner's thumbs are compressing both the radial and ulnar digital arteries at the beginning of the test.
    Allen Test for the digital arteries - The examiner's thumbs are compressing both the radial and ulnar digital arteries at the beginning of the test.
Definition of Positive Result
  • A positive result occurs when the typical color of the finger does not return within 6 seconds.
Definition of Negative Result
  • A negative result occurs when the typical color of the finger returns within 6 seconds. 
Comments and Pearls
  • If Raynaud’s phenomenon is diagnosed, the patient should stop smoking and avoid long exposure to the cold. Operative treatment may include sympathectomy.4 
Diagnoses Associated with Exams and Signs
Videos
Allen Test for Radial and Ulnar Digital Arteries
References
  1. Ejrup B, Fischer B, Wright IS. Clinical evaluation of blood flow to the hand: the false positive Allen Test. Circulation 1966;33:778-80.
  2. Kenney RJ, Hammert WC. Physical Examination of the Hand. J Hand Surg Am 2014;39(11):2324-34. PMID: 25442747
  3. Loscalzo J, Creager MA, Dzau VJ eds. Vascular Medicine: A Textbook of Vascular Biology and Diseases. 2nd ed. Boston: Little, Brown and Company, 1996.
  4. Culp R, Jacoby S.  Musculoskeletal Examination of the Elbow, Wrist and Hand: Making the Complex Simple. New Jersey: SLACK Incorporated, 2012.
  5. Rayan G, Akelman E. The Hand: Anatomy, Examination and Diagnosis. Philadelphia: Lippincott Williams & Wilkins, 2012.
  6. Abramson, DI. Vascular Disorders of the Extremities. 2nd ed. New York: Harper and Row, 1974.
  7. Chloros GD, Smerlis NN, Li Z, et al. Noninvasive evaluation of upper-extremity vascular perfusion. J Hand Surg Am 2008;33(4):591-600. PMID: 18406965
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