Gall bladder contractility in preterm infants.

Postnatal response of the gall bladder to feeding was studied in 28 preterm infants (gestational age 24-37 weeks) by ultrasonography immediately before feeding and one hour after feeding. Nineteen of the infants were studied once during the first week of life, and nine infants were studied weekly from a postconceptional age of 27-31 until a postprandial gall bladder contraction was seen. A contraction index was calculated as a percentage decrement of the surface area of the gall bladder from its initial value. All preterm infants of more than 33 weeks' gestation showed a gall bladder response to feeding with a contraction index of at least 50%. Very preterm infants (gestational age 27-32 weeks) showed no postprandial gall bladder contraction or the contraction index was under 50%. In a follow up study of nine very preterm infants, the contraction index exceeded 50% at a postconceptional age of 29 to 32 weeks. One infant with prolonged feeding problems had no postprandial gall bladder response before the postconceptional age of 38 weeks. The contraction index increase was dependent on gestational age at birth and on the bolus volume of feeds.