Faculty Bibliography

OBJECTIVE:To determine whether differences in the clinical entities of HELLP syndrome and severe preeclampsia are associated with different placental lesions. STUDY DESIGN/METHODS:This was a case control study of singleton pregnancies with HELLP syndrome or severe preeclampsia. Archived pathology slides were retrieved and reviewed. Clinical and histopathological features were compared between the two groups. RESULTS:There were 31 women with HELLP syndrome and 56 with severe preeclampsia. HELLP syndrome was associated with epigastric pain and higher levels of LDH, bilirubin, liver enzymes and fibrin degradation products. Hemoglobin, hematocrit and platelet counts were lower. Abruption lesions of the placenta were less common with HELLP syndrome (Odds Ratio 0.1 95% Confidence Interval 0.01,0.8). None of the other 22 placental features examined were different between the two conditions. CONCLUSION/CONCLUSIONS:The significant overlap between HELLP syndrome and severe preeclampsia for both clinical and placental features suggests that the two conditions represent a spectrum of essentially the same pathophysiologic process.

OBJECTIVE:The purpose of this study was to determine the best available antepartum fetal testing methods according to the underlying pathophysiologic condition. STUDY DESIGN/METHODS:We reviewed the current literature and our clinical experience with respect to condition-specific antepartum fetal testing. RESULTS:The efficacy of most antepartum tests that we use today is not supported by randomized controlled clinical trials, but from observational nonrandomized studies and expert opinion (evidence levels II or III). CONCLUSION/CONCLUSIONS:Based on the available evidence, the accuracy of a test depends on the underlying pathophysiologic condition. To improve accuracy, we must use condition-specific fetal testing.

OBJECTIVE:To estimate the pattern of maternal vascular reactivity in normal and high-risk pregnancies using postocclusion brachial artery diameter. METHODS:Prospective, longitudinal study of 44 low-risk singleton pregnancies and 28 high-risk pregnancies, defined as pregestational diabetes (n = 7), chronic hypertension (n = 4), twin gestation (n = 6), and a previous history of preeclampsia, fetal growth restriction, or vascular disease (n = 11). During each trimester, the brachial artery was ultrasonographically imaged above the antecubital crease. Brachial artery diameter was measured and then occluded for 5 minutes using an inflated blood pressure cuff. Changes in brachial artery diameter at 1 minute after occlusion were expressed as percent change from baseline and were compared across trimesters for both low-risk and high-risk groups, adjusting for potential confounders. RESULTS:Brachial artery diameters were increased after occlusion in every trimester for all groups. For low-risk women, the degree of postocclusion brachial artery dilatation was similar in the first and second trimesters, but was lower in the third trimester. In the first trimester, low-risk women had significantly greater brachial artery diameter increases at 1 minute compared with high-risk singleton pregnancies (19% compared with 12%; P <.001). Compared with low-risk women, pregnancies complicated by pregestational diabetes or chronic hypertension had significantly smaller 1-minute brachial artery diameter changes in the first trimester (7.0 +/- 0.5%, P <.001), whereas twin gestations had greater brachial artery responses (22.9 +/- 6.0%, P <.001). Women with previous preeclampsia or vascular disease had responses similar to low-risk women. CONCLUSION/CONCLUSIONS:Maternal vascular reactivity as assessed by postocclusion brachial artery dilatation decreases in the third trimester in both low-risk and high-risk women. In addition, singleton pregnancies at high risk for preeclampsia display decreased brachial artery reactivity compared with low-risk women.

OBJECTIVE: The purpose of this study was to validate prospectively a previous retrospectively established nomogram for the prediction of gestational age using transcerebellar diameter, especially in the third trimester. STUDY DESIGN: In a previous study, we retrospectively constructed a cross-sectional nomogram using transcerebellar diameter measurements in 24,026 well-dated singleton fetuses. In the present study, this nomogram was validated prospectively on the basis of patients who were seen between August 2002 and May 2003 and who were carrying non-anomalous and non-malformed singleton gestations between 14 and 42 weeks (n = 2597 gestations). The actual gestational age was then subtracted from the predicted gestational age, and the concordance between actual and predicted gestational ages was assessed based on the Pearson correlation (r). RESULTS: Concordance between the actual and predicted gestational age was high (r = 0.92; P < .0001). This agreement was superior in the second trimester (r = 0.93; P < .0001) than in the third trimester (r = 0.81; P < .001). Between 17 and 21 weeks, and between 22 and 28 weeks of gestation, the predicted gestational age ranged between 0 and 4 days, and between 0 and 2 days, respectively, of actual gestational age. Between 29 and 36 weeks of gestation, predicted gestational age was within 5 days of actual gestational age; at 37 weeks of gestation, the predicted gestational age was discrepant by 9 days. CONCLUSION: This prospective study demonstrates that transcerebellar diameter measurement is an accurate predictor of gestational age, even in the third trimester of pregnancy.

Much information has been published regarding the use of second-trimester genetic sonography for the prenatal detection of Down syndrome by examining multiple aneuploidy markers. Among high-risk mothers (advanced maternal age, abnormal triple screen, or both), while many undoubtedly will choose to have invasive testing as a first option, others will instead use the information derived from genetic sonography to obtain an adjusted risk for Down syndrome to guide their decision about genetic amniocentesis. Accordingly, it is imperative that these patients have accurate and detailed counseling regarding their degree of risk reduction when the genetic sonogram is normal. This article reviews the use of second trimester genetic sonography in reducing the need for amniocentesis in the high-risk patient. At our institution, in high-risk patients when the genetic ultrasound is normal, the amniocentesis rate has been only 3%. We have found that genetic sonography is a patient-driven service, and that the information obtained at the time of ultrasound is an important component of the patient's decision of whether or not to proceed with invasive testing.

OBJECTIVE:The purpose of this study was to compare risk factor profiles for placenta previa between singleton and twin live births. STUDY DESIGN/METHODS:This cohort study was based on United States natality data files (1989 through 1998) and comprised 37,956,020 singleton births and 961,578 twin births. Women who were diagnosed with placenta previa were included only if they were delivered by cesarean delivery. Risk factors for placenta previa that were examined included sociodemographic (age, gravidity, education, marital status, and race), behavioral (prenatal care, smoking, and alcohol use), previous preterm birth, and medical and obstetric factors. Effect modification between maternal age and gravidity and the dose-response relationship with number of cigarettes smoked/day on placenta previa risk were also evaluated. RESULTS:The rate of placenta previa was 40% higher among twin births (3.9 per 1,000 live births, n = 3,793 births) than among singleton births (2.8 per 1,000 live births, n = 104,754 births). Comparison of risk factors for placenta previa between the singleton and twin births revealed fairly similar risk factor profiles. Compared with primigravid women <20 years old, the risk for placenta previa increased by advancing age and by increasing number of pregnancies among both singleton and twin births. The number of cigarettes smoked per day also showed a dose-response trend for placenta previa risk in the two groups. CONCLUSION/CONCLUSIONS:The increased rate of placenta previa among twin births underscores the need to monitor carefully such pregnancies with heightened suspicion and awareness for the development of this condition.

OBJECTIVE:The purpose of this study was to determine the association between prenatal care and preterm births among twin gestations in the presence and absence of high-risk pregnancy conditions. STUDY DESIGN/METHODS:Twin birth data in the United States were used to determine the association between preterm birth and prenatal care with the use of logistic regression. RESULTS:Of the 779,387 twin births, 54.7% twin births were delivered preterm. The rate was higher among black women than among white women in the presence (57.0% vs 51.2%, respectively) and absence (70.3% vs 61.6%, respectively) of prenatal care. The absence of prenatal care increased the relative risk for preterm birth by 1.24-fold among black women and by 1.22-fold among white women. Lack of prenatal care was associated with increased preterm birth rates in the presence of most high-risk conditions. CONCLUSION/CONCLUSIONS:Prenatal care is associated with fewer twin preterm births in the presence and absence of high-risk conditions. Increased prenatal care participation may help decrease preterm birth rates and also narrow the black-white twin preterm birth disparity.