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Prenatal screening in the first trimester of pregnancy
1Reproductive Biochemistry and Immunology, Royal North Shore Hospital, St Leonards, Australia.
Insights
This study shows that first-trimester prenatal screening using PAPP-A and F beta-hCG accurately detects fetal abnormalities like Down syndrome (DS) and other pregnancy complications.
Area of Science:
- Obstetrics and Gynecology
- Prenatal Diagnostics
- Biochemistry
Background:
- Prenatal screening is crucial for modern obstetric care.
- Current methods require enhanced diagnostic accuracy and earlier detection of fetal abnormalities.
- First-trimester screening offers potential for identifying a broader range of pregnancy complications.
Purpose of the Study:
- To evaluate the diagnostic efficacy of Pregnancy-Associated Plasma Protein-A (PAPP-A) and free beta-human chorionic gonadotropin (F beta-hCG) in first-trimester screening.
- To assess the detection rates of Down syndrome (DS) and other compromised pregnancies.
- To determine the feasibility of early prenatal screening at 9-12 weeks of gestation.
Main Methods:
- Analysis of PAPP-A and F beta-hCG levels in 731 pregnant volunteers from a mature age population undergoing chorionic villus sampling (CVS).
- Development and application of an algorithm combining biomarker levels with maternal age.
- Calculation of detection rates and false positive rates for DS and other abnormalities.
Main Results:
- The algorithm detected 66.6% of DS pregnancies with a 5% false positive rate.
- 72.2% of compromised pregnancies were identified with a 1-2% recall rate.
- The study identified 17 DS cases and 11 other compromised pregnancies (including numerical aneuploidies and spontaneous failures).
Conclusions:
- Prenatal screening at 9-12 weeks of gestation is achievable using PAPP-A and F beta-hCG quantitation.
- Early screening can detect aneuploidies and other pregnancy-related abnormalities, expanding beyond mid-gestational targets.
- This approach enhances diagnostic efficacy and enables earlier intervention in obstetric management.
Abstract:
Prenatal screening for fetal abnormalities in an accepted part of modern obstetric management. Improvements on current screening procedures need to address increased diagnostic efficacy and earlier diagnosis. This study evaluates diagnostic efficacy of PAPP-A and F beta-hCG in the detection of first trimester pregnancy abnormalities, including Down syndrome (DS). Of 731 pregnant volunteers, obtained from a mature age population undergoing chorionic villus sampling (CVS), 17 DS and 11 compromised (six numerical (excluding sex chromosome) aneuploidies, five spontaneously failed) pregnancies were detected. Application of an algorithm, which combines PAPP-A and F beta-hCG levels with material age, detected 66.6 per cent of DS pregnancies for a five per cent false positive rate. Similarly, for a 1-2 per cent recall rate, 72.2 per cent of compromised pregnancies were detected. This report supports the notion that prenatal screening at 9-12 weeks of pregnancy is achievable with PAPP-A and F beta hCG quantitation. Whereas mid-gestational screening targetted the detection of fetal abnormalities, screening earlier in pregnancy will detect other pregnancy-related abnormalities, in addition to aneuploidy.