breast unit breast unit the breast unit is a measurement of the breasts in which the breasts are measured horizontally and vertically and then these values are multiplied to given an overall idea of breast size. it was devised by vincent j. capraro and has been used in pediatric endocrinology to quantify breast development. the method has been described as follows: at times it is desirable to know whether or not a girl's breasts are developing normally by observing their increasing size over a period of several months. in some cases it is also advantageous to determine whether or not differences in the sizes of the two breasts are of clinical significance. in order to more accurately measure breast size, one of us (v.j.c.) devised a technique for breast measurement. this technique may be used in following up the development of normal breasts as well as of breasts showing asymmetric development. with a centimeter tape measure, the breast is measured from 3 o'clock to 9 o'clock (fig. 23-4, a) and from 12 o'clock to 6 o'clock (fig. 23-4, b). these two measurements are multiplied, yielding a figure called the breast unit. table 23-3 shows the typical spread of breast units in a normal adolescent. the breast unit has also been used to quantify breast size in females with complete androgen insensitivity syndrome (cais) and other individuals with disorders of sexual development.