Estimating the effect of gestational age on test performance of combined first-trimester screening for Down syndrome: a preliminary study.

OBJECTIVE: To establish how different methods of estimating gestational age (GA) affect reliability of first-trimester screening for Down syndrome. METHODS: Retrospective single-center study of 100 women with a viable singleton pregnancy, who had first-trimester screening. We calculated multiples of the median (MoM) for maternal-serum free beta human chorionic gonadotropin (free beta-hCG) and pregnancy associated plasma protein-A (PAPP-A), derived from either last menstrual period (LMP) or ultrasound-dating scans. RESULTS: In women with a regular cycle, LMP-derived estimates of GA were two days longer (range -11 to 18), than crown-rump length (CRL)-derived estimates of GA whereas this discrepancy was more pronounced in women who reported to have an irregular cycle, i.e., six days (range -7 to 32). Except for PAPP-A in the regular-cycle group, all differences were significant. Consequently, risk estimates are affected by the mode of estimating GA. In fact, LMP-based estimates revealed ten "screen-positive" cases compared to five "screen-positive" cases where GA was derived from dating-scans. CONCLUSION: Provided fixed values for nuchal translucency are applied, dating-scans reduce the number of screen-positive findings on the basis of biochemical screening. We recommend implementation of guidelines for Down syndrome screening based on CRL-dependent rather than LMP-dependent parameters of GA.

Embryonic delay in growth and development related to confined placental trisomy 16 mosaicism, diagnosed by I-Space Virtual Reality.

OBJECTIVE: To demonstrate the use of a novel three-dimensional (3D) virtual reality (VR) system in the visualization of first trimester growth and development in a case of confined placental trisomy 16 mosaicism (CPM+16). DESIGN: Case report. SETTING: Prospective study on first trimester growth using a 3D VR system. PATIENT(S): A 34-year-old gravida 1, para 0 was seen weekly in the first trimester for 3D ultrasound examinations. INTERVENTION(S): Chorionic villus sampling was performed because of an enlarged nuchal translucency (NT) measurement and low pregnancy-associated plasma protein-A levels, followed by amniocentesis. RESULT(S): Amniocentesis revealed a CPM+16. On two-dimensional (2D) and 3D ultrasound no structural anomalies were found with normal fetal Dopplers. Growth remained below the 2.3 percentile. At 37 weeks, a female child of 2010 g (<2.5 percentile) was born. After birth, growth climbed to the 50th percentile in the first 2 months. CONCLUSION(S): The I-Space VR system provided information about phenotypes not obtainable by standard 2D ultrasound. In this case, the delay in growth and development could be observed very early in pregnancy. Since first trimester screening programs are still improving and becoming even more important, systems such as the I-Space open a new era for in vivo studies on the physiologic and pathologic processes involved in embryogenesis.

Jugular lymphatic sacs in the first trimester of pregnancy: the prevalence and the potential value in screening for chromosomal abnormalities.

OBJECTIVE: To investigate the prevalence of detectable jugular lymphatic sacs in a setting for first trimester screening for Down syndrome, and to evaluate the influence of jugular lymphatic sacs on the screening performance for chromosomal abnormalities. METHODS: A prospective single center study (Erasmus University Medical Center, Rotterdam, The Netherlands) over a period of one year (January 2003-February 2004). First trimester nuchal translucency measurement was performed in a study population of 415 fetuses. Additionally, the transversal plane with the spine and mandible was visualized to verify the presence of jugular lymphatic sacs. The jugular lymphatic sacs were measured anterior-posterior. The association between nuchal translucency and jugular lymphatic sacs was tested. RESULTS: Follow-up was complete in 406 cases (97.8%). Jugular lymphatic sacs could be visualized in 98 out of 415 (23.5%). The nuchal translucency thickness and the mean of the left and right jugular lymphatic sac were significantly correlated. CONCLUSION: The sonographic visualization of jugular lymphatic sacs significantly predicts chromosomal abnormalities, although nuchal translucency is a better predictor. Nuchal translucency and jugular lymphatic sacs are strongly correlated and therefore not applicable in a combination test.

Combined first trimester screening for trisomy 21: lack of agreement between risk calculation methods.

OBJECTIVE: To call attention to differences in first trimester risk estimates for trisomy 21, as calculated by two different software packages. METHODS: A total of ninety-four pregnant women who had a first trimester risk assessment for trisomy 21 that was based on maternal age, biochemical analysis and a nuchal translucency (NT) measurement. Two commonly used software packages were used for the estimation of individual risks (i.e. Wallac-Perkin-Elmer software and Fetal Medicine Foundation software). RESULTS: Risk estimates derived from each software programme were strikingly different. In each case the discrepancy in reported magnitude of risk resulted from disparities between the two calculation methods for the assessment of the individual risk for trisomy 21. The disparities in risk estimates can be explained by significant differences in reported likelihood ratios for biochemical analyses (P = 0.01), NT measurements (P < 0.0001) and both screening parameters combined P = 0.003). CONCLUSION: It is illustrated that the lack of agreement between these risk calculation methods could give rise to major counselling problems. In order to avoid confusion, there is a need for estimating individual risks of trisomy 21 in a standardized way. It is proposed to select a set of parameters that have a proven track record as judged by detection and false positive rates and then use that set exclusively, while simultaneously monitoring its performance.

Dutch community midwives' views on preconception care.

OBJECTIVE: to explore the opinions of midwives on the desirability of preconception care for all couples contemplating pregnancy, their willingness to introduce preconception care to midwifery practice and, if it were to be implemented, the necessary conditions, including knowledge, postgraduate education and referral possibilities for successful implementation in the community. PARTICIPANTS: all community midwives (n = 129) working in 49 midwifery practices that refer their high-risk clients to the Erasmus University Medical Centre, Rotterdam (the Netherlands). SETTING: Rotterdam and its immediate surrounding communities. DESIGN: midwives working at the midwifery practices were recruited by telephone. All agreed to participate, and subsequently received a questionnaire by post. FINDINGS: 102 (79%) questionnaires were returned. Ninety-five (93%) of the 102 midwives were familiar with the concept of preconception care, and 71 (70%) of them already provided it to some extent. Of the 102 respondents, 84 (83%) seemed to be willing to provide such care in the future, and 56 (55%) felt that preconception care should be part of their professional domain. Midwives, however, lack time and knowledge to do so. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: community midwives already provide counselling, although not on a structural basis, and usually not earlier than in the first trimester of pregnancy. Midwives seem willing to play an active role in the provision of preconception care in the future. There is, however, great need for postgraduate training.