Is the Allen test reliable enough?

Objective: The Allen test is a widely used screening method of hand circulation. Our aim was to study whether the Allen test alone gives sufficient information for harvesting the radial artery in coronary artery bypass grafting.

Methods: One hundred and forty-five patients scheduled for coronary artery bypass grafting underwent the Allen test, upper arm Doppler ultrasonography and digital plethysmography. In ultrasonography both anatomical and circulatory measurements were performed. The Allen test was then compared with more objective tests and sensitivity; specificity and diagnostic accuracy were calculated.

Results: Most of the patients had a negative Allen test, but 23% were positive (abnormal). Ultrasound scanning revealed anatomical anomalies in 10 patients and circulatory deficits in 17 patients. Thirteen patients had both circulatory and anatomical abnormalities. Sensitivity of the Allen test was 73.2% and specificity 97.1% based on our findings. There were no abnormalities in the recovery of the arms with harvested radial grafts.

Conclusions: The Allen test is a good and valid screening test for the circulation of the hand. If the Allen test is negative it is safe to harvest the radial artery. If it is positive further examinations are needed to ensure safe harvesting of the radial artery.