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Table 2 Summary of ultrasonic features particular to milk ejection in the lactating breast

From: The use of ultrasound to identify milk ejection in women – tips and pitfalls

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

  1. *First half of milk ejection is defined as the initiation of duct dilation until peak duct diameter is reached.
  2. **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.