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Objective. To examine the performance of first-trimester combined screening after adding the specific algorithms for trisomies 18 and 13 in the Down syndrome screening program for chromosomal abnormalities other than trisomy 21 and to determine the outcomes of such pregnancies. Design. A retrospective study. Setting. Oulu University Hospital, Finland. Population. Pregnant women ( n=56 076) participating voluntarily in first-trimester combined Down syndrome screening in Northern and Eastern Finland during the study period 1 June 2002 to 31 December 2008. Methods. The data of all known cases of chromosomal abnormalities other than trisomy 21 were collected. Main Outcome Measures. Risk algorithms for trisomies 21, 18 and 13 were used for the calculation of patient-specific risks for certain chromosomal abnormalities. Algorithms were based on maternal age, crown-rump length, nuchal translucency, and measurement of free β-human chorionic gonadotrophin and pregnancy-associated plasma protein-A. Detection rates and false-positive rates were calculated. Results. A total of 27 cases of trisomy 18, 11 cases of trisomy 13 and 30 cases of other chromosomal abnormalities were analyzed. The algorithm for Down syndrome detected 55.6% of trisomy 18 cases, 36.4% of trisomy 13 cases and 60.0% of other chromosomal abnormalities. When specific risk algorithms were added, the detection rates improved for trisomy 18 (74.0%) and for trisomy 13 (54.5%), with only a slight increase of the false-positive rate of 0.2%. The detection rate for other chromosomal abnormalities did not improve. Conclusions. Adding the trisomy 18 algorithm to the Down screening program resulted in the detection of five additional trisomy 18 cases. [ABSTRACT FROM AUTHOR]

Objectives We evaluated the performance of first trimester screening for Down syndrome in women less than 35 years of age (study group) and in women aged 35 years or more (control group) in an unselected low-risk population. Methods The study group comprised a total of 63 945 women who participated in the first trimester combined screening in public health care in Finland during the study period of 1 May 2002 to 31 December 2008. Women at the age of 35 or more ( n = 13 004) were controls. Prevalence of Down syndrome, detection rate, false positive rate and number of invasive procedures needed to detect a single case of Down syndrome were analyzed in both groups. Results The overall prevalence of Down syndrome ( n = 73) in the study group was 1:876. The number of detected cases was 54. The detection rate was 74.0% with a false positive rate of 2.8%. Number of invasive procedures needed to detect a single case of Down syndrome was 33. In the control group, the detection rate was 87.0% with a false positive rate of 11.9%. The number of invasive procedures needed to detect a single case of Down syndrome was 15. The differences in detection rate and false positive rate were significant, P < 0.012, P < 0.001, respectively. Conclusion The overall detection rate given for the entire population is an overestimate for a woman younger than the age of 35, which should be taken into consideration when counselling women of that age. [ABSTRACT FROM AUTHOR]

Objective: To compare the efficacy of fetal nuchal translucency screening, maternal serum screening and combined screening for Down syndrome., Design: A prospective study., Setting: University hospital and its public health care district in Northern Finland., Population: A total of 35,314 women participated in the first-trimester screening for Down syndrome within the public healthcare system in 2002-08. There were 95 pregnancies involving Down syndrome. Serum samples were obtained from 35,314 women, nuchal translucency was measured in 27,144 pregnancies and full combined screening was performed in those pregnancies, including 76 involving Down syndrome., Methods: The adjusted estimated risk for Down syndrome was calculated using the Perkin Elmer AutoDELFIA® time-resolved fluoroimmunoassay kit for the measurement of pregnancy-associated plasma protein-A and free β-human chorionic gonadotropin. Nuchal translucency was measured by trained personnel in a university or district hospital. Risk cut-off figures 1:250 and 1:300 at term were used., Main Outcome Measures: Differences in detection rate, false-positive rate, positive and negative predictive values between nuchal translucency screening, serum screening and combined screening., Results: Using the risk cut-off figure 1:250, the detection rates for serum screening, nuchal translucency screening and combined screening were 64.2, 64.5 and 72.4%, respectively and the false-positive rates were 7.8, 4.4 and 4.0%, respectively., Conclusions: Combined screening is the method of choice for Down syndrome screening in Finland., (© 2013 Nordic Federation of Societies of Obstetrics and Gynecology.)