Table 1.

The ultrasonic appearances of the structures of the lactating breast (adapted from Geddes [3])

Structures of the breast	Ultrasonic appearance of the lactating breast
Milk ducts	Hypoechoic, can contain echogenic flecks representing milk fat globules Echogenic walls may be visible when insonated at 90 degrees Easily compressible Distend at milk ejection Resting state 2 mm (range;1–10 mm)
Skin	Hyperechoic Increased thickness in the areola region
Coopers ligaments	Hyperechoic
Stromal fibrous tissue	Predominantly hyperechoic – tends to be more echogenic with more milk in the breast
Adipose tissue	Hypoechoic, variable amounts Large breasts often contain a large proportion of adipose tissue
Arteries and veins	Hypoechoic, demonstrate blood flow on colour Doppler imaging