Ultrasound Practioners-Helpful Hints

This section includes additional information on completing the ultrasound information of the Multiple Marker Screening (MMS) requisition for patients requesting enhanced first trimester screening (eFTS).

These are general guidelines to assist you in completing the requisition and should not take precedence over the informed clinical decisions that you and your physician make to best benefit your patient.

Acronyms

eFTS – enhanced first trimester screening
MSS – maternal serum screening
NIPT – non-invasive prenatal testing
MMS – multiple marker screening
FMF UK – Fetal Medicine Foundation (UK)
NT – nuchal translucency

Ontario’s Multiple Marker Screening Laboratories

MSH – Mount Sinai Hospital
THP-CVH – Trillium Health Partners-Credit Valley Hospital
NYGH – North York General Hospital

Notes on your Ontario NT ID Number

If you do not have an Ontario NT ID number, you cannot perform NT ultrasound and fill out this requisition without the supervision of an Ontario NT certified ultrasound practitioner. The Ontario MMS labs cannot process an eFTS screen without the NT ID number, name, and signature of an Ontario NT certified ultrasound practitioner.

Gold Standard

An Ontario NT certified ultrasound practitioner scans the patient to obtain NT and CRL measurements that are then recorded on the patient’s requisition under the NT ID number of the Ontario NT certified ultrasound practitioner.

Outside of assisting your colleagues in obtaining the measurements they need for NT certification, sharing your Ontario NT ID number is strictly prohibited.

Your NT ID number is for your use alone. You must protect it and you must not share it.

NT certified practitioners can supervise individuals working to obtain their Ontario NT ID numbers, and assist them in obtaining the NT and CRL measurements they need for certification in the following two ways:

The Ontario NT certified ultrasound practitioner scans the patient to obtain the NT and CRL measurements that are recorded on the patient’s requisition under the NT ID number of the Ontario NT certified ultrasound practitioner. The practitioner in training then scans the patient to obtain the NT and CRL measurements they need for certification.
The practitioner in training obtains the NT and CRL measurements they need for certification. The Ontario NT certified ultrasound practitioner reviews these images to make sure that they (a) meet the Fetal Medicine Foundation (FMF UK) criteria, and (b) represent images they would take when scanning. These NT and CRL measurements are then recorded on the patient’s requisition under the NT ID number of the Ontario NT certified ultrasound practitioner.

It is important that your patient consent to two ultrasound practitioners performing the NT ultrasound. Your patient should be informed that one practitioner is in training.

Notes on Nuchal Translucency (NT) Measurements

Please include the widest NT measurement that meets the FMF UK criteria on the requisition.

If you cannot obtain an NT measurement and…

…the CRL is <84mm, please review the case with your physician and rebook the patient according to the guidelines of your place of practice. To avoid delay in screening, if you are unable to review the case with a physician and rebook your patient, please perform a dating ultrasound, record all required information on the requisition (i.e., CRL, U/S date, all practitioner information) except for the NT measurement (write “N/A, cannot obtain NT, needs rebook”), and send the patient for bloodwork.
…the CRL is ≥84mm, please perform a dating ultrasound, record all required information on the requisition (i.e., CRL, BPD, U/S date, all practitioner information) except for the NT measurement (write “N/A, cannot obtain NT”), and send the patient for bloodwork.

Notes on Crown-Rump Length (CRL) Measurements

The best CRL measurement, or the average of several satisfactory CRL measurements, should be written on the requisition.

If the CRL <45mm

Please review the case with your physician and rebook the patient according to the guidelines of your place of practice.

To avoid delay in screening, if you are unable to review the case with a physician and rebook your patient, please perform a dating ultrasound, record all required information on the requisition (i.e., CRL, U/S date, all practitioner information) except for the NT measurement (write “N/A, patient too early for eFTS”), and send the patient for bloodwork.

If the CRL >84mm

If the CRL is >84mm, please perform a dating ultrasound, record all required information on the requisition (i.e., CRL, BPD, U/S date, all practitioner information) except for the NT measurement (write “N/A, patient too late for eFTS”), and send the patient for bloodwork.

Notes on Bi-Pariteal Diameter (BPD) Measurements

Please record the BPD measurement if the CRL measurement is >84mm.

Notes on Cutoffs

Please use the CRL cutoffs (between 45mm and 84mm) when determining if a patient is eligible for eFTS. Do not use gestational age cutoffs.

Notes on Multiple Pregnancies

Pregnant individuals carrying twins and requesting eFTS should be sent for bloodwork following their NT ultrasound. Pregnant individuals carrying higher order multiples (i.e., triplets +) and requesting eFTS should not be sent for bloodwork following their NT ultrasound. If one twin’s measurements fall outside the CRL cutoffs (between 45mm and 84mm) for eFTS, the Ontario MMS labs cannot process the eFTS bloodwork.

If one fetus is too small, (i.e., CRL <45mm), please review the case with your physician and rebook the patient according to the guidelines of your place of practice. To avoid delay in screening, if you are unable to review the case with a physician, please perform a dating ultrasound, and record all required information on the requisition for both twins (i.e., CRL, U/S date, all practitioner information) except for the NT measurements (write “N/A, patient too early for eFTS”), and send the patient for bloodwork.
If one fetus is too big (i.e., CRL >84mm), please perform a dating ultrasound, record all required information on the requisition for both twins (i.e., CRL, BPD, U/S date, all practitioner information) except for the NT measurements (write “N/A, patient too late for eFTS”), and send the patient for bloodwork.

Examples

Twin A: CRL 83mm; Twin B: CRL 85mm. Patient is too late for eFTS.
Twin A: CRL 46mm; Twin B: CRL 44mm. Patient is too early for eFTS.

Twin Demise

If your patient has experienced the early demise of one twin, please image the NT of the remaining viable twin, fill out the eFTS requisition as you would for a singleton pregnancy, record that one twin has demised (i.e., check tick box IUFD next to Twin B), and send the patient for bloodwork.