Why physician or laboratory technician prefer to take blood smear from ring finger?

we suggest working with the ring finger. The ring finger

is less calloused and somewhat less sensitive. Plus, it's easy to palpitate above the puncture to produce and

increase blood flow.

The recommended site for capillary collection on adults and children over one year of age is the palmar surface of the distal (end) segment of the third (middle) or fourth (ring) finger, ideally of the non-dominant hand. Fingers on the nondominant hand are generally less calloused. The puncture should be made slightly off center from the central, fleshy portion of the fingertip and if using a blade-type puncture device, perpendicular to the fingerprint whorls. Puncturing along or parallel to the whorls may cause the blood to follow the pattern of the fingerprint, redirecting the flow and making it more difficult to collect. The index finger is often calloused and potentially more sensitive to pain due to additional nerve endings. The thumb also may be calloused and has a pulse, indicating arterial presence, and, therefore, should be avoided. The distance between the skin surface and the bone in the fifth finger also makes it unsuitable for puncture. The side and tip of the finger should be avoided, as the tissue is about half as thick as the central portion of the fingertip.