Reliability and validity of an instrument to measure tissue hardness in breasts.

The author investigated the effectiveness of the Roberts Durometer, an instrument developed to measure human tissue hardness for a study on breast engorgement. The instrument is a small portable pressure gauge comprising a probe attached to a spring and contained in a tubular housing, connected to a dial gauge. The instrument was first trialed using foam rubber of differing hardness and football bladders of differing hardness. It was then used to measure the hardness of a non-pregnant, non-lactating human breast, followed by trials on postpartum women comparing breast tissue hardness on the day of birth with that of subsequent days. The instrument detected significant differences in hardness of foams, football bladders and human breast tissue. It was therefore considered suitable for measuring, in both research and clinical applications, hardness of breast tissue, which is a major physical feature of breast engorgement. Other clinical applications could include the hardness of abdominal and other skin tissues in conditions such as ascites, peritonitis and cellulitis.