Platelet and Blood-Cell Counts in Newborn During First Two Days of Life

Abstract

The purpose of this study was to establish a set of blood-platelet-count standards in infants, based upon an accurate method of counting. Red cell counts, white cell counts, and hemoglobin determinations were made concomitantly. McLean and Caffey, 1 Lippman, 2 Jarcho, 3 Slawik, 4 Keilmann, 5 Lucas, 6 and Farnow 7 have furnished various standards.

The counts are made with a diluting fluid consisting of 100 cc. of a 3.8% aqueous solution of sodium citrate, 0.2 cc. of 40% formaldehyde, and 0.1 gm. of brilliant cresyl blue, kept ice-cold. A red-count pipette is filled to the 1.0 mark with diluting fluid, it is rapidly inserted into the drop of blood, and blood is drawn into the pipette approximately to the 0.5 mark, and diluting fluid is then immediately drawn in to the 101 mark. The pipette is then shaken. With a second pipette, an accurate red-cell count is made, using Hayem's solution. The hemocytometer is charged with the contents of the first pipette, the platelets are counted (in the same manner as red cells are counted), and then in the same fields the red cells are counted. The hemocytometer is then charged with the contents of the second pipette and a count is made. The latter number is an accurate absolute count of the red cells. The following proportion gives the number of blood platelets:

At the same time that the blood was taken from each infant for the platelet counts (through a deep heel puncture), a white-cell count was made and hemoglobin was read with a Dare hemoglobinometer (measuring 13.88 gm. per 100 cc. as 100%).