Microscopic variables in a “standardized” laparotomy wound in the rat

Explanation was sought for variations which we experienced in the tensile strength values of comparable wounds. The variations could not be accounted for by the technique of measurement. Microscopic study was performed on “standardized” midline laparotomy wounds of thirty young adult male Wistar rats. We examined three groups of ten animals with wounds of seven, ten and fourteen days' duration. All wounds were made by the same operator. An additional group of ten animals was sacrificed without wounding and the midline anterior abdominal wall was studied microscopically. Microscopic variations in transverse midlevel sections which might affect healing and tensile strength were found in twenty-six of thirty wounds and in four of ten specimens from the unwounded anterior abdominal wall. Suggestions are offered to minimize these variables.