These resources and point of care tools will support sonographers in performing high quality nuchal translucency (NT) and crown-rump length (CRL) measurements, assist sonographers in properly completing patients' first trimester screening requisitions, and answer other frequently asked questions about NT ultrasound and PSO's NTQA program.

Please email PSO at BORN Ontario if you have suggestions for information that you would like to see included on this webpage.

Video Resources

The short videos below provide step-by-step instruction and useful information to support sonographers in accessing, understanding, and interpreting their NT performance data. 

NT Ultrasound 

For Ultrasound Practitioners: Helpful Hints for Completing the Multiple Marker Screening (MMS) Requisition

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            
• STS – second trimester screening
• NT + STS – nuchal translucency plus second trimester 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 or NT + STS 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:

1)      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.

 2)      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.    

ULTRASOUND PRACTITIONERS - HOW TO COMPLETE THE REQUISITION

Below are the steps required to complete the Ultrasound (U/S) Information section on the Multiple Marker Screening (MMS) requisition. This is the section that you, as ultrasound practitioners, are responsible for completing when patients request enhanced first trimester screening (eFTS) or Nuchal Translucency and Second Trimester Screening (NT + STS). It is important that you fill out ALL the information below carefully, accurately, and completely. Incorrect or missing information can negatively affect how quickly a patient receives a risk assessment and/or how this risk assessment is calculated. 

1. Please record the day that you performed the NT ultrasound.

2. Please record the crown-rump length (CRL) measurement and the nuchal translucency (NT) measurement obtained on the day that you performed the NT ultrasound. Please pay close attention to the unit of measurement that you select (mm/cm).

3. Please record the bi-parietal diameter (BPD) if the CRL measurement is >84mm. Please pay close attention to the unit of measurement that you select (mm/cm).

4. Please record your Ontario NT ID number.

5. Please record the name of the hospital/clinic where you performed the NT ultrasound. Please record a contact number including the direct extension of your department.

6. Please print your name and sign the form.

7. Scan a copy of the completed requisition into the patient file for your records.

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…

a)       …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.

b)      …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 cut-offs (between 45mm and 84mm) when determining if a patient is eligible for eFTS or NT + STS. Do not use gestational age cut-offs.

 NOTES ON MULTIPLE PREGNANCIES:

Non-Invasive Prenatal Testing (NIPT) is funded by the Ministry of Health (MOH) for all twin pregnancies, regardless of gestational age, maternal age or other factors. Concurrently, First Trimester Screening (FTS) for twin pregnancies has been discontinued in Ontario.

 A stand-alone nuchal translucency (NT) ultrasound is still recommended for twin pregnancies, where available.

                What to do in the following scenarios:

• Twin pregnancy identified prior to the NT ultrasound and the pregnant individual appropriately does not present with an MMS requisition
  • Proceed with stand-alone NT ultrasound
  • Sonographers do not need to record the NT measurement on any requisitions; no risk calculations will be performed by the MMS labs for twin pregnancies.

• Twin pregnancy identified prior to the NT ultrasound, but the pregnant individual inappropriately presents with an MMS Requisition for eFTS
  • Proceed with NT ultrasound
  • Sonographer to check the “Viable twin pregnancy identified on this U/S” check box in the Ultrasound (U/S) Information section. Checking this box will signify to the MMS lab that this is a twin pregnancy, therefore, FTS cannot be performed.
  • The pregnant individual is to proceed with blood draw, and upon receipt of the blood sample the MMS lab will notify the ordering professional that FTS for twins has been discontinued and OHIP-funded NIPT is available.

• A pregnant individual presents with an MMS Requisition with a presumed singleton pregnancy, but a viable twin pregnancy is identified on the NT ultrasound
  • Proceed with NT ultrasound
  • Sonographer to check the “Viable twin pregnancy identified on this U/S” check box in the Ultrasound (U/S) Information section. Checking this box will signify to the MMS lab that this is a twin pregnancy, therefore, FTS cannot be performed.
  • The pregnant individual is to proceed with blood draw, and upon receipt of the blood sample the MMS lab will notify the ordering professional that FTS for twins has been discontinued and OHIP-funded NIPT is available.

SUSPECTED OR CONFIRMED VANISHING TWIN/CO-TWIN DEMISE

To improve the screening process for pregnancies with a suspected or confirmed vanishing twin/co-twin demise, a new test menu option, “NT + Second Trimester Screening (NT + STS) for suspected or confirmed vanishing twins/co-twin demise only,” has been added. NT + STS includes a NT ultrasound (11w2d – 13w3d) and second trimester blood sample (14w0d-20w6d). The blood draw can be done 8 weeks after demise.  The ordering professional is to calculate the date after which the pregnant individual can have their blood drawn and record this on the requisition within the NT + STS section, where indicated.

What to do in the following scenarios:

• A pregnant individual presents with an MMS Requisition for NT + Second Trimester Screening (NT + STS)
  • Proceed with NT ultrasound
  • Sonographer to complete Ultrasound Information section of the MMS Requisition
  • Patient to proceed with blood draw after the date written on their MMS Requisition

• A pregnant individual presents with an MMS Requisition with a presumed singleton pregnancy, but a suspected or confirmed vanishing twin/co-twin demise is identified on the NT ultrasound
  • Proceed with NT ultrasound
  • Sonographer to record ultrasound information for the viable fetus in the Ultrasound Information section of the MMS Requisition
  • Sonographer to check the “Confirmed or suspected vanishing twin/co-twin demise” check box in the Ultrasound (U/S) Information section. Checking this box will signify to the MMS lab that STS + NT needs to be performed.
  • The pregnant individual is to proceed with blood draw after their NT ultrasound, and upon receipt of the blood sample the MMS lab will notify the ordering provider of the next steps, which would be to arrange an STS blood draw between 14w0d-20w6d, and 8 weeks after the estimated date of demise.