II. Indication
- Congenital defect screening in low risk pregnancy
III. Components: Tests comprising Quad Screen
-
Alpha-fetoprotein (AFP)
- Increased with Neural Tube Defects
- Decreased in Trisomy 21 and Trisomy 18
- Human chorionic gonadotropin (Free bHCG)
- Increased in Trisomy 21 and decreased in Trisomy 18
-
Unconjugated Estriol (uE3)
- Decreased in Trisomy 21 and Trisomy 18
- Inhibin A
- Increased in Trisomy 21 and normal in Trisomy 18
IV. Precautions
- Does not replace Amniocentesis if age 35 years or older
- All test protocols have positive rates approaching 5% (most are false positives)
- Test Sensitivity for aneuploidy on the best test protocols still only approaches 87%
-
Trisomy 21 risk increases based on Multiple Pregnancy
- Singleton gestation: Age 35 years
- Twin Gestation: Age 33 years
V. Protocol: Integrated screening for Aneuploidy and Neural Tube Defect
- First trimester screening (Nuchal Translucency, free bHCG, PAPPA) at 9-11 weeks
- Second trimester screening (AFP, uE3, HCG, Inhibin) at 15-19 weeks
VI. Protocol: First trimester screening
- Timing
- Performed at 9-11 weeks
- First trimester screening for trisomy 18 and Trisomy 21
- Maternal age
- Free Beta human chorionic gonadotropin (bHCG)
- Pregnancy associated plasma protein A
- Fetal Ultrasound
- Nuchal Translucency
- Test Sensitivity: 77%
- High False Positive Rate: >4%
- Nasal bone absent
- Test Sensitivity: 70%
- False Positive Rate: 1.5%
- Nuchal Translucency
- Efficacy of 4 factors in predicting trisomy 18 or 21
- As accurate as second trimester screening
- References
VII. Protocol: Second trimester screening (Standard Quad Screen)
- Counsel patient before screening
- Screening for Neural Tube Defects and Trisomy 21, 18
- Protocol if screening positive and diagnostic risks
- Accuracy and limitations of tests
- Timing
- Optimal time: 16 to 18 weeks gestation
- Range of testing: 15 to 22 weeks gestation
- Shifting to first trimester is being investigated
- Components
- See 4 components of Quad Screen above (AFP, uE3, HCG, Inhibin)
- Interpretation of abnormal results
- Chromosomal abnormalities suggested
- Findings
- Trisomy 21: AFP, uE3 low, hCG,Inhibin high
- Trisomy 18: AFP, hCG and uE3 decreased
- Perform Amniocentesis for chromosomal analysis
- Findings
- Neural Tube Defects suggested (AFP increased)
- Ultrasound to confirm Gestational age
- Recalculate AFP based on ultrasound Gestational age
- Redraw Triple Screen if first test <15 weeks
- Perform diagnostics if AFP still elevated
- Repeat AFP level
- Level II Ultrasound Fetal Survey
- Consider Amniocentesis
- Amnion AFP level
- Amnion acetylcholinesterase level
- Chromosomal abnormalities suggested
VIII. Interpretation: Quad Screen results predict pregnancy outcomes
- Unexplained abnormal tests confer 2 or more fold risk
- Unexplained increased AFP confers poor outcome risk
- Preeclampsia:
- Intrauterine Growth Retardation
- Intrauterine Fetal Demise
- Preterm Labor
- Low birth weight
- Placental Abruption
- Perinatal death
- Unexplained increased hcg confers poor outcome risk
- Unexplained decreased estriol confers poor outcome risk
- Associated with specific Genetic Syndromes
- References
IX. References
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| Concepts | Laboratory Procedure (T059) |
| SnomedCT | 252149008 |
| Spanish | cribado materno para la detección de sÃndrome de Down (procedimiento), cribado materno para la detección de sÃndrome de Down, tamizaje de sÃndrome de Down en la madre, rastreo materno para la detección de sÃndrome de Down, cribado de sÃndrome de Down en la madre, detección selectiva de sÃndrome de Down en la madre (procedimiento), detección selectiva materna para sÃndrome de Down, screening materno para la detección de sÃndrome de Down, tamizaje materno para la detección de sÃndrome de Down, pesquisa de sÃndrome de Down en la madre, cribaje materno para la detección de sÃndrome de Down, pesquisa materna para la detección de sÃndrome de Down, screening de sÃndrome de Down en la madre, detección selectiva de sÃndrome de Down en la madre |
| English | Down's maternal screen, Down maternal screening, Down's maternal screening (procedure), Down's maternal screening |
Ontology: Triple test (C0554819)
| Concepts | Laboratory Procedure (T059) |
| SnomedCT | 169788000, 147018001, 275835005 |
| English | testing triple, test triple, triple test, Triple test, Triple test (procedure) |
| Spanish | ensayo de AFP/E3 no conjugado /b - hCG, ensayo de alfafetoproteÃna/estriol no conjugado/subunidad beta de gonadotrofina coriónica humana (procedimiento), ensayo de alfafetoproteÃna/estriol no conjugado/subunidad beta de gonadotrofina coriónica humana |
Ontology: Screening neural tube defect (maternal serum AFP) (C0856296)
| Concepts | Laboratory Procedure (T059) |
| Dutch | screening neurale buisdefect (maternaal serum AFP) |
| French | Dépistage d'une anomalie du tube neural (AFP sérique de la mère) |
| German | Screening auf Neuralschlauchdefekt (Mutterserum AFP) |
| Italian | Ricerca di difetti del tubo neurale (alfa-fetoproteina sierica materna) |
| Portuguese | Rastreio de defeito do tubo neural (AFP no soro materno) |
| Spanish | Estudio de defecto del tubo neural (AFP en suero materno) |
| Japanese | ç¥žçµŒç®¡æ¬ æ��スクリーニング（æ¯�親血清ＡＦＰ）, ï½¼ï¾�ｹｲｶï¾�ｹｯｿï¾�ｽｸﾘｰﾆï¾�ｸﾞﾊﾊｵﾔｹｯｾｲAFP |
| English | Screening neural tube defect (maternal serum AFP) |
| Czech | Screening defektu neurálnà trubice (AFP v mateřském séru) |
| Hungarian | Idegcső rendellenesség szűrése (anyai szérum AFP) |
Ontology: Second trimester quad maternal screen panel (C2359792)
| Concepts | Laboratory Procedure (T059) |
| LNC | LP69866-9, MTHU027708 |
| English | Second trimester quad maternal screen panel |
