1T Aneuploidy Screen Build info

Synonyms

• 1T ANEUPLOIDY SCREEN
• 1TANEU
• LAB14312

Procedure Name

1T ANEUPLOIDY SCREEN

Procedure Master Number

LAB14312

Procedure ID

186039

Clinical Info

1T Aneuploidy Screen is a first trimester screening test for the three most common fetal aneuploidies, trisomies 21, 18 and 13.  
The test incorporates the maternal serum markers AFP, free βhCG, Inhibin A, PAPP-A  and PlGF and the fetal ultrasound markers 
nuchal translucency (NT) and nasal bone (NB -optional)  An increased risk result means that further screening
(ultrasound, NIPT) and/or diagnostic testing (amniocentesis) may be offered.

Specimen Sources

Specimen Types

Container

Gold Top Tube

Collection Instructions

Container/Tube:  Gold Top Tube
Specimen:  3 mL serum ( 0.5 mL min)
Collection:
Specimen draw is form 10.0 to 13.6 weeks gestation and must be before CVS or amniocentesis.
NT and NB must be assessed when the CRL is 45-84mm. 
 The Sonographer
must be credentialed by the Fetal Medicine Foundation and the certification
number must be provided.
 
Special Instructions:
The following Ask on Order Entry (AOE) patient information must be provided:
1:Maternal Weight
2:Race
3:Estimated Date of Delivery (EDD)
4:Current Smoker
5:Number of Fetuses
6:Insulin Dependent Diabetes
7:Age of Egg Donor at Retrieval
8:Previous Pregnancy with Down Syndrome
9. Ultrasound Date
10. Sonographer (Name or ID)
11. Sonographer Supervisor MD (Name or ID)
12. CRL
13. NT
14. Nasal Bone
15. Chorionicity
16. CRL Twin B
17. NT Twin B
18. Nasal Bone Twin B

Complete information is necessary to interpret the test. Patient information may be
provided to the laboratory using the Maternal Prenatal Screening request form (0900).  
Specimen Rejection Criteria:  Incorrect tube type
                                                Insufficient volume
                                                Fetal/maternal blood contamination
                                                Out of gestational age range.

Specimen Volume

3 mL serum ( 0.5 mL min)

Transport Instructions

Room Temperature

Specimen Stability

6 days Room Temperature

Methodology

Time-Resolved Amplified Cryptate Emission (TRACE)

Days Performed

Monday - Friday  TAT 1-2 Days

Performing Laboratory

Northwell Health Laboratories

CPT

82105- AFP
84704 Free BhCG
86336- Inhibin A
84163- PAPP-A
83520- PIGF

PDM

Only Orderable at Locations:

Results

Result Interpretation

Risk Calculation:

Each analyte level is converted into a multiple of the GA specific median (MoM) and is then adjusted based on the patient's race, weight, diabetic status, and smoking status.  The likelihood ratio for each analyte is calculated as the ratio of the probability density function in affected pregnancies divided by the probability density function for unaffected pregnancies.  Patient specific risks for Down syndrome and trisomy18/13 are calculated using Bayes’ rule. The prior risk, based on demographic factors, is multiplied by the likelihood ratios for each maker appropriate for the condition screened.

An interpretive risk report including the patient's analyte levels, cut-off values and risks for trisomy 21 and trisomies 18/13 will be provided.

Down’s Syndrome (trisomy 21) Interpretation:

The risk cut-off is set equal to the first-trimester risk of a 35 year old (1/250).  This test may detect 98% of cases with Down’s syndrome at an approximate 2% false positive rate.

Edward Syndrome (trisomy 18)/Patau Syndrome (trisomy 13) Interpretation:

The risk cut-off is set equal to 1/100. This cut-off is chosen to balance the detection and false positive rates.  This test may detect 95% of cases with T18/13 at an approximate 0.5% false positive rate.

Test Follow Up:

If the patient's risk is less than the cut-off risk the test is considered "Within Normal Range" and no further action is required. If the patient’s risk is greater than or equal to the cut-off risk the test is considered "Increased Risk". Patients at increased risk are offered detailed ultrasound, NIPT and/or diagnostic amniocentesis.

Upon receiving maternal serum screening results, all information used in the risk calculation should be reviewed for accuracy (ie, weight, diabetic status, gestational dating). If any information is incorrect, the laboratory should be contacted for recalculation of the estimated risks. ‘Within Range’ risk results typically do not warrant further evaluation. Ultrasound is recommended to confirm dates for ‘Increased Risk’ results. If ultrasound yields new dates that differ by at least 7 days, a recalculation should be considered. The screen results are dependent on accurate information for gestation, race, IDD, and weight. Inaccurate information can lead to significant alterations in the estimated risk. In particular, erroneous assessment of gestational age can result in false-positive or false-negative screen results. Because of its increased accuracy, the determination of gestational age by ultrasound is recommended, when possible, rather than by last menstrual period.

Disclaimers

This is a screening test, not a diagnostic test. A ‘Within Range’ risk result indicates low risk for the conditions screened but does not guarantee the absence of those conditions or other abnormalities. An ‘Increased Risk’ result indicates an increased risk for the condition screened but does not infer a definitive diagnosis.

Cautions

Valid measurements of maternal serum markers cannot be made after CVS or amniocentesis. Triplet and higher order multiple pregnancies cannot be interpreted. In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. Caution should be used in interpretation of results and the laboratory should be alerted if the result does not correlate with the clinical presentation.

Each center offering maternal serum screening to patients should establish a standard screening protocol, which provides pre- and post-screening education and appropriate follow-up for ‘Increased Risk’ results.

Clinical References

1.   ACOG Practice Bulletin 226 - Screening for Fetal Chromosomal Abnormalities.  Obstet Gynecol VOL. 136, NO. 4, OCTOBER 2020.

2.   NJ Wald, C Rodeck, AK Hackshaw, J Walters, L Chitty, AM Mackinson.  First and second trimester antenatal screening for Down’s syndrome:  the results of the Serum, Urine and Ultrasound Screening Study (SURUSS). (2003) Health Technology Assessment Vol. 7: No.11.

3.   Fergal D. Malone, M.D., Jacob A. Canick, Ph.D., Robert H. Ball, M.D., David A. Nyberg, M.D., Christine H. Comstock, M.D., Radek Bukowski, M.D., Richard L. Berkowitz, M.D., Susan J. Gross, M.D., Lorraine Dugoff, M.D., Sabrina D. Craigo, M.D., Ilan E. Timor-Tritsch, M.D., Stephen R. Carr, M.D., Honor M. Wolfe, M.D., Kimberly Dukes, Ph.D., Diana W. Bianchi, M.D., Alicja R. Rudnicka, Ph.D., Allan K. Hackshaw, M.Sc., Geralyn Lambert-Messerlian, Ph.D., Nicholas J. Wald, F.R.C.P., and Mary E. D’Alton, M.D., for the First- and Second-Trimester Evaluation of Risk (FASTER) Research Consortium* (2005) First-Trimester or Second-Trimester Screening, or Both, for Down’s Syndrome.  N Engl J Med 353;19 2001-2011.

4. Carmichael JB, Liu HP, Janik D, Hallahan TW, Nicolaides KH and Krantz DA.  Expanded conventional first trimester screening.  Prenatal Diagnosis 2017, 37, 802–807.

This test was developed, and its performance characteristics determined by Northwell Health Laboratories. It has not been cleared or approved by the Food and Drug Administration. The methods and performance characteristics have been reviewed and approved by the New York State Department of Health

Forms

• Technical Bulletin: 1T Aneuploidy Screen New Test-Test Update 09-30-2024