Important points of the joint SOGC-CCMG guideline - No. 348, September 2017

Important points of the joint SOGC-CCMG guideline - No. 348, September 2017

 Society of Obstetricians and Gynecologists of Canada (SOGC)
 and
 the Canadian College of Medical Geneticists (CCMG)


No. 348

"Fairy Natal Screening News for Anoploid Disorders, Fetal Anomalies and Adverse Pregnancy Consequences"

1- Where there is the ability to perform a precise screening test in the first trimester, it is recommended to perform this test, there are many benefits such as:

- Determine the exact age of the fetus

- Determination of twins and chorionicity

- Initial diagnosis of primary structural disorders

- Screening for anoploid disorders

2. If the first trimester screening test is in a low-risk area, the presence of an echocardiogram soft spot marker for trisomy 21 and the presence of plexus cyst for trisomy 18 are of poor predictive value and do not need further investigation.

3- It is not possible to offer NIPT testing to all women as primary screening in all places. However, the Contingent NIPT proposal is recommended as a feasible proposal that could potentially improve the efficiency of the screening test and at the same time benefit from serum screening and ultrasound.

recommendations

1- Ultrasound should be performed only by sonologists or sonographers who have been accredited to do so.

2. In cases where the NT is above 3.5 mm, as a major marker of anoploid and structural disorders, genetic counseling, invasive diagnostic tests with chromosomal analysis by microarray (Array CGH) is a high-resolution technique to identify deletions. Or unbalanced additions are used throughout the genome.

This test, also called a molecular karyotype, has a higher resolution than the karyotype (scanning anomaly) in the second trimester.

3- Before performing the NIPT test, explain to the patient that there is a possibility of no result (No result available), false positive and false negative.

4- It is possible to perform NIPT test for twin pregnancies, but its diagnostic power is lower than monogamous pregnancies.

5. NIPT is not recommended for microdermabrasion.

6- The presence of an isolated soft marker in the second trimester ultrasound (except for high NF) does not require risk correction for anoploid disorders.