Screening for Down's syndrome and neural tube defect in Croatia - A regional prospective study

Objective: The purpose of this study was to investigate the efficiency of s econd-trimester maternal serum screening for Down's syndrome and open neura l tube defects using alpha-fetoprotein and free beta-human chorionic gonado tropin as serum markers. Methods: 3,188 women underwent testing between 14t h and 22nd week of pregnancy. Of all tested patients, 25.4% were greater th an or equal to 35 years old. A cut-off risk of greater than or equal to 1:2 50 for Down's syndrome and MS-AFP greater than or equal to 2.0 MoM for open neural tube defect were considered screen-positive. Results: The detection rate for Down's syndrome was 77.8% (7/9) with 8.2% screen-positive rate (7 .9 % false-positive rate). When evaluated separately, in patients younger t han 35 and in those greater than or equal to 35 years old, the screen-posit ive rates were 3.1 and 23.3%, respectively. A total of 52 (1.6%) were found screen-positive for open neural tube defect; 2 cases of encephalocela and 1 case of gastroschisis were confirmed prenatally. Conclusion: The respecta ble number of cases with trisomy 21 identified in this study confirms that routine mid-trimester screening for Down's syndrome including MS-AFP, free beta-hCG and maternal age is useful in identifying pregnancies at increased risk.