A-331 Prenatal Maternal First Trimester Screening and Establishing the Multiple of Medians of Double Marker Tests in Tertiary Care Hospital in India
Authors: Das B , Pal P M , Mehtalia N S , Joshi V , Gade M P , Pawar N 
Published: September 2023

Abstract

Background
Down's syndrome, Edwards syndrome, and Patau syndrome (trisomy 21, 18, 13 respectively) in a fetus can be screened by prenatal testing using the maternal serum. Prenatal testing can provide an accurate assessment of the patient's risk of carrying an affected fetus. Double marker testing which includes the levels of free β- Human Chorionic Gonadotropin and Pregnancy Associated Plasma Protein A in the maternal serum along with the measurement of Crown Rump Length and Nuchal Translucency helps in determining the risk of Trisomy 21. Prenatal testing prevents the need for invasive methods.

Methods
This is a study conducted in Kokilaben Dhirubhai Ambani Hospital and Research Centre, Mumbai, Maharashtra, India from January 2012 to December 2018 for 628 pregnant women. The data for 1st trimester was divided into 3 groups: 11 to 11.6 weeks(86 patients), 12 to 12.6 weeks (421 patients), and 13 to 13.6 weeks (121 patients) based on their gestational age. This study included the determination of levels of double markers like free β- Human Chorionic Gonadotropin and Pregnancy Associated Plasma Protein A using maternal serum along with the ultrasound studies which included the Crown Rump Length and Nuchal Translucency measurements. Additional factors like a history of chromosomal abnormalities, smoking habits, insulin-dependent diabetes, and other dichotomous markers like the presence of nasal bone, abnormal ductal flow, and tricuspid regurgitation are also considered in calculating the risk. The concentration of biochemical parameters was expressed in Multiple of Median (MOM) with respect to maternal age. The risk assessment was analyzed using SSDW 5 and SSDW 6 software and the cut-off was set at 1:250 for age as well as trisomy 21, 18, and 13.

Results
The total number of positive patients for trisomy 21 and trisomy 13/18 were represented in percentage which turned out to be 2.86% and 1.11% respectively in association with the gestational age, dichotomous markers, double marker test, and ultrasound studies. The MOM for β-HCG, PAPPA, and NT were compared in SSDW5 and SSDW6. The mean β-HCG MOM negative and positive patients (trisomy 21) were found to be 1.34 ± 0.945 and 2.74 ± 1.685 respectively indicating the levels increase above normal. The mean PAPPA MOM negative and positive patients (trisomy 21) were found to be 1.47 ± 0.9125 and 0.77 ± 7667 respectively indicating the levels decrease below the normal. The NT mom for negative and positive patients was 0.91 ± 1879 and 1.88 ± 1.6508 respectively which suggests that the thickness of nuchal translucency increases with the increased risk for trisomy 21.

Conclusion
18 out of 628 patients tested positive for trisomy 21 which was assessed using double marker testing and ultrasound studies. The levels of free β-HCG were seen to be increased and the levels of PAPPA were decreased in the patients who showed higher risks. Prenatal testing provides an advantage for early detection of this disorder.