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Test Code Billings Clinic: 7610 Mayo: QUAD1 Quad Screen (Second Trimester) Maternal, Serum

Reporting Name

QUAD SCRN (2nd Tri) Maternal, S

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Prenatal screening for open neural tube defect (alpha-fetoprotein only), trisomy 21 (alpha-fetoprotein, human chorionic gonadotropin, estriol, and inhibin A) and trisomy 18 (alpha-fetoprotein, human chorionic gonadotropin, and estriol)

Method Name

Immunoenzymatic Assay

Specimen Type

Serum


Necessary Information


In order to provide the best results, either answer the order entry questions or provide the required information using the Second Trimester Maternal Screening Alpha-Fetoprotein (AFP)/QUAD Screen Patient Information (T595) (see Special Instructions).



Specimen Required


Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 1 mL

Collection Instructions:

1. Do not draw specimen after amniocentesis as this could affect results.

2. Centrifuge immediately

Additional Information:

1. For an assessment that includes neural tube defect results, gestational age must be between 15 weeks, 0 days and 22 weeks, 6 days.

2. Assessments for trisomy 21 (Down syndrome) and trisomy 18 (Edwards syndrome) only are available between 14 weeks, 0 days and 22 weeks, 6 days.

3. Initial or repeat testing is determined in the laboratory at the time of report and will be reported accordingly. To be considered a repeat test for the patient, the testing must be within the same pregnancy and trimester, with interpretable results for the same tests, and both tests are performed at Mayo Clinic.

4. Maternal Serum Screening patient education brochure (T522) is available upon request.


Specimen Minimum Volume

0.75 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
  Frozen  90 days

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Reference Values

NEURAL TUBE DEFECTS

An AFP multiple of the median (MoM) <2.5 is reported as screen negative. AFP MoMs ≥2.5 (singleton and twin pregnancies) are reported as screen positive. 

 

DOWN SYNDROME

Calculated screen risks <1/270 are reported as screen negative, risks ≥1/270 are reported as screen positive.

 

TRISOMY 18

Calculated screen risks <1/100 are reported as screen negative, risks ≥1/100 are reported as screen positive.

 

An interpretive report will be provided.

Interpretation

Neural Tube Defects (NTD)

A screen-negative result indicates that the calculated alpha-fetoprotein (AFP) multiple of the median (MoM) falls below the established cutoff of 2.50 MoM. A negative screen does not guarantee the absence of neural tube defects (NTD).

 

A screen-positive result indicates that the calculated AFP MoM is 2.50 or greater and may indicate an increased risk for open NTD. The actual risk depends on the level of AFP and the individual's pretest risk of having a child with NTD based on family history, geographical location, maternal conditions such as diabetes and epilepsy, and use of folate prior to conception. A screen-positive result does not infer a definitive diagnosis of NTD but indicates that further evaluation should be considered. Approximately 80% of pregnancies affected with NTD have elevated AFP, MoM values greater than 2.5.

 

Trisomy 21 (Down syndrome) and Trisomy 18 (Edwards syndrome):

A screen-negative result indicates that the calculated screen risk is below the established cutoff of 1/270 for trisomy 21 and 1/100 for trisomy 18. A negative screen does not guarantee the absence of trisomy 21 or trisomy 18.

 

When a trisomy 21 second-trimester risk cutoff of 1/270 is used for follow-up, the combination of maternal age, AFP, estriol, human chorionic gonadotropin (hCG), and inhibin A has an overall detection rate of approximately 77% to 81% with a false-positive rate of 6% to 7%. In practice, both the detection rate and false-positive rate increase with age. The detection rate ranges from 66% (early teens) to 99% (late 40s), with false-positive rates of between 3% and 62%, respectively.

 

The detection rate for trisomy 18 is 60% to 80% using a second trimester cutoff of 1/100.

 

Follow-up

Upon receiving maternal serum screening results, all information used in the risk calculation should be reviewed for accuracy (maternal date of birth, gestational dating, etc). If any information is incorrect, the laboratory should be contacted for a recalculation of the estimated risks.

 

Screen-negative results typically do not warrant further evaluation.

 

Ultrasound is recommended to confirm dates for NTD or trisomy 21 screen-positive results. Many pregnancies affected with trisomy 18 are small for gestational age. Recalculations that lower the gestational age may decrease the detection rate for trisomy 18. If ultrasound yields new dates that differ by at least 7 days, a recalculation should be considered. If dates are confirmed, high-resolution ultrasound and amniocentesis (including amniotic fluid AFP and acetylcholinesterase measurements for NTD) are typically offered.

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.-4:30 p.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

81511

LOINC Code Information

Test ID Test Order Name Order LOINC Value
QUAD1 QUAD SCRN (2nd Tri) Maternal, S 48800-7

 

Result ID Test Result Name Result LOINC Value
7058 Recalculated Maternal Serum Screen 32399-8
113146 Results Summary 32399-8
10334 Down syndrome screen risk estimate 43995-0
10335 Down syndrome maternal age risk 49090-4
10337 Trisomy 18 screen risk estimate 43994-3
113147 Neural tube defect risk estimate 48803-1
10351 AFP 83073-7
113148 AFP MoM 23811-3
601921 AFP MoM (14,0-14,6) 23811-3
10352 uE3 2250-9
113149 uE3 MoM 21264-7
10353 hCG, TOTAL 83086-9
113150 hCG, TOTAL MoM 23841-0
113151 INHIBIN MoM 36904-1
10354 INHIBIN 2478-6
10356 INTERPRETATION 49092-0
10357 RECOMMENDED FOLLOW UP 80615-8
10248 Additional comments 48767-8
3009 Specimen collection date 33882-2
7823 Maternal date of birth 21112-8
7834 Calculated age at EDD 43993-5
26717 Maternal Weight 29463-7
26718 Maternal Weight 29463-7
IDD Insulin dependent diabetes 44877-9
RACE1 Patient race 21484-1
SMKNG Current cigarette smoking status 64234-8
10054 EDD by U/S scan 11781-2
7203 GA on collection by U/S scan 11888-5
7753 EDD by LMP 11779-6
7204 GA on collection by dates 11885-1
7830 GA used in risk estimate 21299-3
MULTF Number of Fetuses 55281-0
CHOR_ Number of Chorions 92568-5
IVFP IVF pregnancy 47224-1
PRHIS Prev Down (T21) / Trisomy Pregnancy 53826-4
PRNTD Prev Pregnancy w/ Neural Tube Defect 53827-2
PTNTD Patient or father of baby has a NTD 53827-2
INTL Initial or repeat testing 77202-0
DRPHN Physician Phone Number 68340-9
10358 GENERAL TEST INFORMATION 62364-5

Testing Algorithm

See Prenatal Aneuploidy Screening and Diagnostic Testing Options in Special Instructions