Table 2.

Summary of ultrasonic features particular to milk ejection in the lactating breast

Milk ejection	Ultrasonic change at milk ejection	Clinical signs
First half*	Milk duct diameter increases Milk flow (echogenic flecks) towards the nipple	Sensation of milk ejection felt Pumping – visualisation of jets of milk, rapid increase in milk flow Breastfeeding – change in sucking to slower more rhythmical pattern If flow is very fast the infant may pull off the breast
Second half**	Milk duct diameter decreases Milk flow reverses back into the breast	Sensation of milk ejection Pumping – visualisation of milk jets, slowing of milk flow Breastfeeding – slow, more rhythmical pattern Infant may discontinue feeding during milk ejection if appetite met

*First half of milk ejection is defined as the initiation of duct dilation until peak duct diameter is reached.

**Second half of milk ejection is the decrease in duct diameter from peak diameter to either baseline diameter or the beginning of another duct dilation.