Routine urine drug screening at the first prenatal visit.

OBJECTIVE: The purpose of this study is to determine whether routine urine drug screening at the first prenatal visit will identify and permit early intervention for those at risk for poor outcome. STUDY DESIGN: Comparisons of maternal and neonatal outcomes between 166 randomly chosen patients with positive and 150 randomly chosen patients with negative drug screens identified by the enzyme multiplied immunoassay test were made by unpaired t test, chi 2 test, probit analysis, and tests of independent Poisson distributions. RESULTS: Forty percent of those identified denied drug use. Antepartum (p less than 0.01) and postpartum (p less than 0.05) complications were increased among drug users. Birth weight (p less than 0.001), gestational age (p less than 0.03), and head circumference (p less than 0.05) were decreased among neonates. CONCLUSION: Because of difficulty in identifying illicit substance--using patients, consideration should be given to the implementation of routine urine drug screening at the first prenatal visit in populations with a high rate of illicit substance use.     

Fasting plasma glucose test at the first prenatal visit as a screen for gestational diabetes

OBJECTIVE: To determine whether the fasting plasma glucose test administered at the first prenatal visit could serve as an efficient screen for gestational diabetes. METHODS: A total of 5557 women not known to have diabetes were offered a fasting plasma glucose test at their first prenatal visit. Results less than 100 mg/dL were blinded. A glucose tolerance test was requested immediately of those whose screening test result was 100-125 mg/dL and of all women not identified as having diabetes by their 23rd gestational week. RESULTS: A total of 4507 women (81%) complied with the protocol. Of the 302 women found to have gestational diabetes, 46 (15%) were detected before 24 weeks. A false-positive rate of 57% was found at a threshold fasting glucose concentration giving a sensitivity of 80% for the detection of gestational diabetes.CONCLUSION: The fasting plasma glucose screening test at the first prenatal visit has good patient compliance. However, its poor specificity (high false-positive rate) makes it an inefficient screening test for gestational diabetes.     

Voluntary HIV-screening at the first prenatal visit

The evolution of screening mechanisms, the patient outcomes, and CNM reactions to a voluntary HIV screening at the first prenatal visit are briefly reviewed.     

First trimester prenatal diagnosis

PURPOSE OF REVIEW: The recent developments in first trimester sonography promise to greatly enhance our diagnostic capabilities for detection of aneuploidies. Collateral benefits of nuchal translucency measurements include the prediction of non-chromosomal adverse outcomes. These advances will fundamentally change clinical practices. All obstetricians must therefore have a working knowledge of the expanding literature in this field. RECENT FINDINGS: The review covers developments in nuchal translucency based first trimester detection of chromosomal anomalies and discusses the recent literature on the use of fetal nasal bone measurements to further improve diagnostic accuracy. Emerging data on the relationship between nuchal fluid measurement and the risk of cardiac anomaly will also be presented. SUMMARY: It is likely that the emphasis in obstetric clinical care will shift substantially towards the first trimester. With the enhanced diagnostic capabilities, greater research emphasis will inevitably need to be placed on the first trimester treatment of fetal disorders.     

First trimester screening

Screening for aneuploidy has traditionally been reserved for women of advanced maternal age. More recent advances in serum screening and ultrasound technology have allowed women of all ages to be offered screening in the second and even first trimester. These methods and their effectiveness are discussed.     

Gestational diabetes: fasting and postprandial glucose as first prenatal screening tests in a high-risk population

OBJECTIVE: To evaluate the value of fasting (FPG) and 2-hour postprandial (PPG) plasma glucose as screening tests for gestational diabetes mellitus (GDM) in a high-risk population during early pregnancy. STUDY DESIGN: At their first prenatal visit, 708 women underwent FPG and PPG for universal screening for GDM, with the diagnosis confirmed by the 75-g oral glucose tolerance test (World Health Organization criteria). The area under the receiver operating characteristic curve (AUC) was used to analyze the performance of the 2 screening tests. RESULTS: Of 184 (25.9%) women with GDM, 79 (42.9%) were identified before 18 weeks. The AUC for FPG to predict GDM was 0.579 (95% CI 0.531-0.627). Though a threshold of 85 mg/dL achieved minimally acceptable sensitivity, 79.9%, the corresponding specificity remained poor, 27.5%, with a false positive rate (FPR) of 72.5%. The AUC for PPG was 0.717 (95% CI 0.670-0.765); a cutoff of 95 mg/dL achieved a sensitivity of 79.9% and FPR of 53.1%. CONCLUSION: Though GDM could be diagnosed in > 40% women in early pregnancy at their first prenatal visit, the poor specificity and high FPR of FPG and PPG, alone or in combination, make them unsuitable screening tests for GDM.     

Prenatal glucose screening

Of 3,563 consecutive obstetric patients undergoing glucose screening, 517 (14.5%) were found to have plasma values of greater than or equal to 140 mg%, and 74 (14.3%) of 517 were found to be diabetic on standard oral glucose tolerance testing, for an overall incidence of 2.1%. There was no absolute value on the glucose screen that predicted an abnormal oral glucose tolerance test. Twenty-eight of the 74 diabetics demonstrated none of the classic risk factors for glucose intolerance during pregnancy. Only when combining those patients over 30 years of age and with a mean body weight greater than 120% of the ideal body weight was statistical significance reached when that group was compared to the overall group. Thus, our data support the recommendation for universal prenatal glucose screening.     

Miscarriage risk for asymptomatic women after a normal first-trimester prenatal visit

OBJECTIVE: To estimate the risk of miscarriage among asymptomatic women after a prenatal visit between 6 and 11 weeks of gestation where proof of fetal viability of a singleton was obtained by office ultrasonography at the same visit. METHODS: This was a prospective cohort study performed over 2 years (March 2004-2006) at an antenatal clinic at a large tertiary hospital in Victoria, Australia. Those recruited were 697 asymptomatic women who attended their first antenatal visit between 6 (+2 days) and 11(+6 days) weeks of gestation, where evidence of fetal cardiac activity of a singleton was obtained by office ultrasonography. The main outcome measure was rates of miscarriage, stratified by gestation at presentation. RESULTS: One case was lost to follow-up. The risk of miscarriage among the entire cohort was 11 of 696 (1.6%). The risk fell rapidly with advancing gestation; 9.4% at 6 (completed) weeks of gestation, 4.2% at 7 weeks, 1.5% at 8 weeks, 0.5% at 9 weeks and 0.7% at 10 weeks (chi(2); test for trend P=.001). Most who miscarried received their ultrasound diagnoses many weeks after their visit; five (45%) were diagnosed in the second trimester, and all but one received their ultrasound diagnoses after 10 weeks of gestation. CONCLUSION: For women without symptoms, the risk of miscarriage after attending a first antenatal visit between 6 and 11 weeks is low (1.6% or less), especially if they present at 8 weeks of gestation and beyond. Our data could be used to reassure such women that the probability of progressing to later than 20 weeks of gestation is very good.     

First trimester prenatal diagnosis: Amniocentesis

Twenty years after midtrimester genetic amniocentesis was first used, first trimester invasive prenatal procedures were introduced. Chorionic villous sampling presents some disadvantages that entitled many centers to look into an alternative for first trimester diagnosis. Early amniocentesis (EA) can be performed effectively, as shown over the years in many observational studies and partially randomized and randomized trials. Recently, a multicenter randomized trial (Canadian Early and Midtrimester Amniocentesis Trial) reported a higher total pregnancy loss, a significant increased incidence of musculoskeletal foot deformities, a significant increased culture failure rate, and an increased postamniocentesis rate of leakage in the EA group compared with midtrimester amniocentesis. These results concerning EA procedures from 11w(+0) to 12w(+6) should be included in any pre-EA counseling. However, further trials have started to evaluate EA procedures between 13w(+0) to 14w(+6).     

Counselling considerations for prenatal genetic screening

This document has been developed to aid clinicians in counselling patients about prenatal screening and to provide assistance in counselling about both positive and negative screening results.     

Incorporating newborn screening into prenatal care

Research with focus groups of parents suggests that information on newborn metabolic screening needs to be integrated into prenatal care. Such a practice change can only occur with the support of the obstetric community.     

First trimester prenatal diagnosis of Sandhoff's disease

Chorionic villus sampling was performed on two patients with a previous family history of Sandhoff's disease. Total beta-hexosaminidase (Hex) activity in case 1 was within the normal range (case 1: 6365 mumol/h/g protein; control range: 3227-24 495 mumol/h/g protein). The beta-hexosaminidase isoenzyme pattern was found to be normal. These results were confirmed on cultured amniotic fluid cells. In case 2, the total Hex activity was 672 mumol/h/g protein, i.e., 7 per cent of the control mean (10,085 mumol/h/g protein), and chromatography demonstrated that more than 50 per cent of this activity was due to the abnormal isoenzyme beta-hexosaminidase S (Hex S). The fetus was predicted to be affected by Sandhoff's disease and this was confirmed on fetal tissues after termination of pregnancy. This study demonstrates that a fetus affected by Sandhoff's disease can be reliably diagnosed during the first trimester of pregnancy.     

家系分析在产前筛查诊断中的价值

家系分析有助于临床医生了解疾病的传递方式、分析检测结果,进而为家系其他成员提供检测建议。目前遗传学检测技术不断进步并应用于临床,可能发现大量“阳性”结果,更需要重视家系分析在致病性判断中的价值。