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Obstetric Calculations

Butterfly obstetric calculations packages assist trained users in computing gestational age and amniotic fluid index from anatomic measurements.

To use the obstetrics calculations packages:

  1. From the scan screen, select the OB/GYN preset.
  2. Select the Actions button on the bottom right corner of the screen.
  3. Under the “calculations” heading, buttons to enter the Amniotic Fluid Index, Fetal Biometrics, and Crown Rump Length packages will be available. Select the one you wish to use.
  4. Any imaging mode other than M-mode can be used with these calculations. Once the region of interest is in view, tap the freeze button.
  5. Tap the measurement icon on the bottom of the screen. New measurement tools corresponding to available inputs to the calculations package will be available. 
  6. Select the desired measurement, and calipers (linear or elliptical) will appear on the scan screen.
    • In the fetal biometrics package, available measurements are biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL).
    • In the amniotic fluid index package, available measurements are Q1, Q2, Q3, and Q4.
    • In the Crown Rump Length package, available measurements are CRL1, CRL2, and CRL3.
  7. Adjust calipers as appropriate. As the calipers are adjusted, the measurement label will adjust to show the input and, if applicable, the gestational age (GA).
  8. Once satisfied with caliper placement, tap the confirm button to add the measurement to the report and capture an image. 
  9. A measurement may be deleted before confirming or unfreezing by selecting the “x” next to the measurement label or the trash can icon in the report.  
  10. Only one of each input may be added. To edit an input, delete it from the report and re-measure.
  11. While in any calculations package, a calculations report is available while the scan screen is frozen.
    • In the fetal biometrics package the report contains:
      • AUA: average ultrasound age according to the Hadlock equations
      • Hadlock - EDD: Estimating Delivery Date according to the Hadlock equations
      • Hadlock - EFW: Estimated Fetal Weight according to the Hadlock equations
      • Measurement inputs with corresponding gestational ages (GA)
      • Patient-reported dates
    • In the amniotic fluid index package, the report contains
      • AFI: amniotic fluid index
      • Measurement inputs
      • Patient-reported dates
    • In the Crown Rump Length package, the report contains:
      • Gestational age
      • Measurement inputs
      • Patient-reported dates
  12. You will exit the obstetric calculations package when you upload your study. To exit an obstetric calculations package before uploading a study, select the X on the bottom of your screen or select the Actions menu and exit by selecting the X underneath. You will be prompted to confirm exporting or deleting of captured measurements if you exit via the Actions menu or the bottom of your screen.
  13. Once the specified calculation package is exported, the output will be available in the notes field of the study. This can be retrieved and edited in the study reel prior to upload. After uploading the study, notes are available in the archive screen and in the desktop cloud.

Note: Once a calculations package is exited, the inputs may not be edited. Two calculations packages may not be used simultaneously; to run a second calculation, complete the first calculation package, exit, then select the second calculation package.

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