Critique of the Allen test for continuity of the palmar arch assessed by doppler ultrasound.

The arterial circulation of both hands of 128 adults was assessed by the Allen test, a modified Allen test emphasizing proper hand position and by Doppler ultrasound. Full extension of the fingers during the Allen test resulted incomplete capillary refilling of the hand in 73 per cent of the patients. The modified Allen test, avoiding hyperextension of the wrist and fingers, revealed interruption of the palmar arch in only one patient with absence of the left radialy artery. There was complete concordance of findings by Doppler ultrasound and the modified Allen test, emphasizing the importance of maintaining proper hand position to avoid false interpretations of incomplete circulation of the palmar arch.