2T Quad Screen QUAD

Synonyms

Allscripts (AEHR) Order Name

2T Quad Screen

Sunrise Clinical Manager (SCM) Order Name

2T Quad Screen

EPIC Order Name

2T Quad Screen

Clinical Info

2T Quad Screen is a second trimester screening test for the two most common fetal aneuploidies,trisomy
21 and trisomy 18. 
The test also detects Open Neural Tube Defects (ONTD’S) such as Open Spina BifidaOSB) and Anencephaly (see 2T AFP). 2T Quad Screen incorporates the maternal serum markers AFP, free ßhCG, Inhibin A and uE3.

Specimen Type

Blood

Specimen Volume

3 mL serum ( 0.5 mL min)

Container

Gold Top Tube

Collection Instructions


Container/Tube;  Gold Top Tube
Specimen:  3 mL serum (0.5 mL min)
Special Instructions:
The following Ask on Order Entry (AOE)
patient information must be provided:
1)     Maternal Weight
2)     Race/ethnicity
3)     Estimated Date of Delivery (EDD)
4)     Method Used to Determine EDD
5)     Current Smoker
6)     Number of Fetuses
7)     Insulin Dependent Diabetes
8)     IVF
9)     Egg Donor Age at Retrieval
10)  Family History of ONTD
11)  Previous Pregnancy with Down Syndrome
12)  Valproic Acid
13)  Carbamazepine
 
Complete information is necessary to
interpret the test. Patient information may be provided to the laboratory using
the Maternal Prenatal Screening request form
(0900).
Specimens must be collected before  amniocentesis.
2T Quad Screening is offered for gestational ages 15.0 to
21.6 weeks.The optimal gestational age for 2T Quad Screening is 16.0 to
18.9 weeks.

Transport Instructions

Room Temperature

Specimen Stability

6 Days Room Temperature
14 Days Refrigerated

Methodology


Time-Resolved Amplified Cryptate Emission (TRACE)

Days Performed

Monday - Friday

Performing Laboratory

Northwell Core Lab at CFAM

CPT

82105
82677
84704
86336

PDM

241466

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, trisomy18 and Open Spina bifida 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, trisomy 18 and open spina bifida will be provided.

 

Down’s Syndrome (trisomy 21) Interpretation:

The risk cut-off is set equal to that of the mid-trimester risk of a 35 year old (1/270).  If the patient's risk is less than the cut-off risk the test is considered "Within Normal Range".

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, NIPS and/or

diagnostic amniocentesis.  This test may detect 81% of cases with Down’s syndrome at an approximate 5% false positive rate

 

Edwards Syndrome (trisomy 18) Interpretation:

The risk cut-off is set equal to 1/150. This cut-off is chosen to balance the detection and false positive rates.   If the patient's risk is less than the cut-off risk the test is considered

"Within Normal Range". 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.  This test may detect 75% of cases with Edwards syndrome at an approximate 0.3% false positive rate

 

ONTD Interpretation:

ONTD interpretation is based solely on the AFP MoM.  The baseline AFP MoM cut-off is 2.5 MoM. The patient specific cut-off varies based on various risk factors (i.e. Black – 2.80,

IDDM – 1.95, Black and IDDM – 2.21, Twins – 5.0). If the patient's MoM is less than the cut-off the test is considered "Within Normal Range". If the patient’s MoM is greater than or

equal to the cut-off the test is considered "Increased Risk". Patients at increased risk are offered detailed ultrasound and diagnostic amniocentesis (including amniotic fluid AFP and

acetylcholinesterase measurements for NTD. Approximately 80% of pregnancies affected with an ONTD have elevated AFP MoM values.

 

Test Follow Up: 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 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.Benn PA, Ying J, Beazoglou T and Egan JFX.  Estimates for the sensitivity and false-positive rates for second trimester serum screening for Down syndrome and trisomy 18  with

adjustment for cross-identification and double-positive results.  Prenat Diagn 2001;21: 46-51.

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