Skip to main content

Obstetric

Updated

EDD Calculations

Obstetric Worksheet GA Tab

The Obstetric worksheet GA tab contains dates of previous ultrasound, last menstrual period (LMP), current ultrasound, and conception date. Estimated date of delivery (EDD) is calculated based on these values.

The highlighted EDD is considered the ‘best assessment’ by the user to calculate the EDD and fetal age most accurately. The EDD best assessment defaults is “EDD by LMP” but users can select a different EDD by clicking on the preferred EDD.  Selection of a different EDD impacts the fetal biometry percentile calculations. Percentile calculations are based on the GA indicated by the Best Assessment.

EDD by Transfer type:

Studycast provides users with ability to document and auto-calculate Conception Date and EDD by Conception Date based on IVF and FET pregnancies.

Select from the transfer type dropdown the appropriate transfer type and enter transfer date using the pop-up calendar.  Studycast automatically populates the Conception Date and EDD by Conception Date based upon the entries.  

To reset the transfer type simply select “BLANK” in the transfer type dropdown. Note:  User must enter both transfer type and transfer date for calculations to be performed.  

EDD Transfer calculations:

  • IVF with own eggs "EDD by Conception date" = Transfer date + 266 days (or 38 weeks)
  • IVF with fresh donor eggs cycle "EDD by Conception date" = Transfer date + 266 days (or 38 weeks)
  • Day-3 embryo transfer "EDD by Conception date" = Transfer date + 266 days (or 38 weeks) – 3 days
  • Day-5 embryo transfer "EDD by Conception date" = Transfer date + 266 days (or 38 weeks) – 5 days
  • Fresh donor embryos cycle "EDD by Conception date" = Transfer date + 266 days (or 38 weeks) 

Obstetric References

In the Studycast system, Obstetric and Fetal Echo studies include references, which can be used to calculate values based on a selection of reference criteria.

Types of References

Each Obstetric reference in Studycast falls into one of the following categories:

  • GA models
  • Percentile models
  • EFW models

GA Models

GA models are used to determine the estimated gestational age of the fetus and can be found in the General & GA and Fetus tabs of the worksheet.

Percentile Models

Percentile models are used to estimate the percentile of a measurement based on the gestational age.

EFW Models

EFW models are used to estimate fetal weight based on a combination of biometry measurements.

Applying References

References appear in select lists within the worksheet when the criteria they depend on is present.

For example, the GA by BPD, HC, AC, FL Hadlock 84 reference is available when the BPD, HC, AC, and FL contain values within the ranges defined by that model. If values are entered within these ranges, the reference will be available to calculate the gestational age and assign an EDD based on that gestational age:

If the measurements are modified to be outside of that range (for example, changing the FL to 8), the reference will no longer be available in the select list.

Studycast Advisor for Obstetric

In the Obstetric, Fetal Echo, and Fetal Non-Stress Test worksheets, the Studycast Advisor provides helpful recommendations if the study that you are working on should be added to a case, or used to create a new case. In Studycast, using a case allows you to group studies when the belong to a single pregnancy.

There are several benefits to creating cases. Creating a case will:

  1. populate the EDD from the previous Obstetric study in the pregnancy
  2. Plot the EFW and other relevant values from previous studies in a case
  3. Enable in-worksheet access to the Compare function for studies in a case

When the Advisor has a recommendation, the indicator in the top right corner is illuminated and the number of recommendations is displayed.

To view the recommendations, click the Advisor indicator.

A Studycast Advisor window opens.

To accept the recommendation and add the study to a case or create a new case, select the appropriate recommendation, and click Apply.

If you do not want to add the study to a case or create a new case, select Cancel. The study will not be added.

Related articles