We are having an issue with estimated fetal weights on our Ultrasound Reports. We have a number of high risk patients who are followed with weekly Ultrasounds and NSTS with growth being calculated every third week. We are using the Williams chart in our Voluson units to calculate fetal weights which is the default table within the units software. We are finding babies that appear to be growth restricted when looking at the individual measurments (AC and FL less then 10th percentile) but appear normal (greater then 10th percentile) when looking at the overall estimated weight using this table. We have tried swiching tables to either Hadlock or Brenner just to see what difference is produced. The Hadlock table appears to greatly alter the fetal weight percentile, which appears to be more accurate. The Brenner table does not seem to make a great change. Below is an example of a patient to show the difference.

My question is how do you decide on a table for your practice and is there a standard table according to ACOG? Do other practice use the defualt tables or do all Ultrasound vendor software apply different defaults?

Thank you for your comments,

Kimberly Juliani, Ultrasound Supervisor

Women's Health Center Lebanon PA

Ultrasound performed 11/15/10 on patient with EDC 01-27-10 making her 29w 4d gestaional age.

BPD  28w4d = 13.1%

HC    27w6d = <2%

AC    27w4d = 3.5%

FL     27w6d = 4.3%

Estimated Fetal weights-

Williams 23.3%

Hadlock 3.2%

Brenner 20.2%