A Low-Cost, High-Fidelity Simulator for Transabdominal Chorionic Villus Sampling

INTRODUCTION

Chorionic villus sampling (CVS) remains essential for first-trimester genetic diagnosis, yet clinical volume may be insufficient to train new clinicians in the technique. Available simulation models are expensive, require animal parts or specialized resins, and cannot be stored for repeated use.

METHODS

We present a model for trans-abdominal CVS (TA-CVS) which is constructed from readily available materials costing less than $10 and can be refrigerated and re-used to train maternal-fetal medicine fellows in CVS.

RESULTS

All three attending physicians performing TA-CVS at our institution described the model as an accurate visual and tactile simulation, prompting its integration into our fellowship curriculum. To date, two senior fellows have achieved competency on the simulator and begun to perform clinical CVS under supervision, one of whom is an author on this paper. Both fellows and attendings indicated that the simulator provided a valuable tool for repeated practice prior to clinical CVS. Simulators are now maintained on the unit and have been re-used for 3 months and dozens of simulated procedures each without any apparent qualitative degradation in performance.

DISCUSSION/CONCLUSION

We describe a low-cost easily constructed, durable, high-fidelity simulator for TA-CVS.

Postnatal Myelomeningocele Repair in the United States: Rates and Disparities Before and After the Management of Myelomeningocele Study Trial

BACKGROUND AND OBJECTIVES

Evolving technologies have influenced the practice of myelomeningocele repair (MMCr), including mandatory folic acid fortification, advances in prenatal diagnosis, and the 2011 Management of Myelomeningocele Study (MOMS) trial demonstrating benefits of fetal over postnatal MMCr in select individuals. Postnatal MMCr continues to be performed, especially for those with limitations in prenatal diagnosis, health care access, anatomy, or personal preference. A comprehensive, updated national perspective on the trajectory of postnatal MMCr volumes and patient disparities is absent. We characterize national trends in postnatal MMCr rates before and after the MOMS trial publication (2000-2010 vs 2011-2019) and examine whether historical disparities persist.

METHODS

This retrospective, cross-sectional analysis queried Nationwide Inpatient Sample data for postnatal MMCr admissions. Annual and race/ethnicity-specific rates were calculated using national birth registry data. Time series analysis assessed for trends relative to the year 2011. Patient, admission, and outcome characteristics were compared between pre-MOMS and post-MOMS cohorts.

RESULTS

Between 2000 and 2019, 12 426 postnatal MMCr operations were estimated nationwide. After 2011, there was a gradual, incremental decline in the annual rate of postnatal MMCr. Post-MOMS admissions were increasingly associated with Medicaid insurance and the lowest income quartiles, as well as increased risk indices, length of stay, and hospital charges. By 2019, race/ethnicity-adjusted rates seemed to converge. The mortality rate remained low in both eras, and there was a lower rate of same-admission shunting post-MOMS.

CONCLUSION

National rates of postnatal MMCr gradually declined in the post-MOMS era. Medicaid and low-income patients comprise an increasing majority of MMCr patients post-MOMS, whereas historical race/ethnicity-specific disparities are improving. Now more than ever, we must address disparities in the care of MMC patients before and after birth.

Minimizing Individual Learning Curves in a Mature Endoscopic Fetal Surgery Program

INTRODUCTION

Twin-to-twin transfusion syndrome affects monochorionic twin pregnancies and can result in fetal death. Endoscopic laser treatment remains a relatively infrequent procedure for this condition. This presents difficulties for maintaining proficiency and for training new personnel.

OBJECTIVE

The dual mentoring program at our institution allows for continuous mentoring of new providers. We hypothesize that this approach stabilizes program proficiency despite the addition of new practitioners.

METHODS

Query of the fetal treatment program database returned 146 cases of laser ablation between 2000 and 2019. Patient and pregnancy characteristics as well as operative time and outcomes were recorded. The learning curve-cumulative summation method and rolling averages were used to analyze outcomes.

RESULTS

Overall survival was 69%, and survival of at least 1 twin was 89%. Mean operative time was 53.6 ± 20.9 min. Overall twin survival stabilized after the first 40 cases. Rolling averages for operative time decreased from 71 to 49 min for the most recent cases. These results were not affected by the introduction of new surgeons.

CONCLUSIONS

Creative mentoring can maintain stable overall program outcomes despite changes in team composition. This training approach may be applicable to other rare procedures in fetal surgery.

Iatrogenic Preterm Premature Rupture of Membranes after Fetoscopic Laser Ablative Surgery

Introduction: To describe the incidence and risk factors for iatrogenic premature preterm rupture of membranes (iPPROM) after fetoscopic laser surgery for the twin-to-twin-transfusion syndrome. Materials and Methods: This is a retrospective review of all patients who have undergone fetoscopic laser surgery at a single fetal treatment center since 2000. We defined iPPROM as spontaneous rupture of membranes before the onset of labor prior to 34 weeks of gestation. The iPPROM cohort was compared to the cohort without iPPROM for several preoperative, operative, and delivery characteristics. Results: Ninety-two consecutive patients were reviewed. The overall rate of iPPROM was 18.5% (n = 17). The rates of iPPROM within 1 and 4 weeks were 5.4 and 10.9%, respectively. The median interval from surgery to delivery was significantly shorter in the iPPROM group (21 vs. 62 days, p = 0.01). The mean gestational age at delivery (27.0 vs. 31.1 weeks, p = 0.02) was lower in the iPPROM group. No other characteristics studied differed significantly between the groups. Discussion: The incidence of iPPROM was substantially lower than in recent multicenter reports; however, no risk factors of iPPROM could be identified. Whether this is related to variations in surgical or anesthetic management will require further investigation.

Long-term morbidity after fetal endoscopic surgery for severe twin-to-twin transfusion syndrome

BACKGROUND/PURPOSE

Severe twin-to-twin transfusion syndrome (TTTS) leads to 80% to 100% dual mortality. Endoscopic laser coagulation of connecting vessels improves outcome to 80% survival of at least 1 twin. There is limited long-term follow-up of surviving TTTS patients. The aim of this study was to analyze gestational age-stratified, long-term morbidity in these patients.

METHODS

A retrospective case-control study of TTTS surviving patients (38 patients, 72% follow-up rate) from one center. Perinatal and pediatric records were reviewed, and outcomes were compared with published reports and gestational age-matched controls.

RESULTS

Forty percent (15/38) had at least 1 major sequela, all but 6 of which were fully resolved at a median follow-up of 4.4 years. There were no permanent cardiac, genitourinary, renal, or respiratory sequelae. All major complications were in patients born <29 weeks. There were no significant differences in complications between this cohort of patients and gestational age (GA)-matched control patients.

CONCLUSIONS

The long-term morbidity of monochorionic twins after fetal laser surgery for severe TTTS is 13%. At a median follow-up of more than 4 years, these children fare no worse than gestational age-matched, non-operated twins and singletons. The degree of prematurity at birth is the best predictor of temporary or permanent sequela in this group of patients.

Reflectance spectrometry for real-time hemoglobin determination of placental vessels during endoscopic laser surgery for twin-to-twin transfusion syndrome

OBJECTIVE

The objective of the study was to develop a noninvasive technique to determine hemoglobin (Hb) content through spectral analysis of diffusely reflected broadband visible illumination from individual blood vessels during endoscopic fetal surgery for twin-to-twin transfusion syndrome (TTTS).

METHODS

The reflection of an incoming xenon endoscopic light source was captured through a 630-mum-diameter optic fiber coupled to a fixed grating spectrometer (2-nm resolution). A 450- to 700-nm wavelength range was used for analysis. Three data-capturing methods were studied: (1) fixed-image spectrum capture with fiber aimed at (but not touching) center of a vessel, (2) no-touch scanning perpendicular to the vessel and dynamic spectral capture, and (3) dynamic spectral capture and analysis of the reflectance spectra during brief vessel touch.

RESULTS

Eight controls (elective laparoscopic and thoracoscopic operations in children aged 1-17 years) were enrolled. Four vessels were analyzed in each case. The brief-touch technique with intensity peak analysis yielded the most reproducible results between multiple vessels in the same patient. Spectrometry was also applied to 2 TTTS patients. The (anemic) donor and (polycythemic) recipient twin fetuses could be differentiated with good correlation between vessels (arteries and vein) of the same fetus.

CONCLUSIONS

It is possible to differentiate donor from recipient placental vessels by spectral analysis of the reflected light through the endoscope using a noninvasive and real-time method. This may improve the accuracy of endoscopic laser ablation of placental vessels in TTTS and may allow instant endoscopic Hb determination for laparoscopic procedures as well.

Experience with a multidisciplinary antenatal diagnosis and management model in fetal medicine

BACKGROUND

Fetal medicine is a new and evolving specialty. Complex fetal conditions may require the multidisciplinary input of clinicians from many different specialties.

METHODS

Referral of fetal patients was made to a multidisciplinary antenatal diagnosis and management (MADAM) board if more than one specialty (in addition to maternal-fetal medicine) needed to be intimately involved in the evaluation or care of the fetus; consultation would probably lead to alterations in fetal or perinatal management; or development or revision of management guidelines was anticipated. The case log of the MADAM conferences was reviewed retrospectively for number and type of fetal anomalies, and outcome of the presentation to the MADAM board.

RESULTS

During a 5-year period, 1% of 25654 pregnant women who were evaluated required consultations with individual pediatric and pediatric surgical specialists. Of these, 114 patients were referred to one of 77 MADAM conferences for consensus recommendation. Of these 77 discussions, 32 (42%) led to an alteration in prenatal management, 14 (18%) led to co-ordination of postnatal management and 12 (16%) led to the establishment of a new treatment guideline, or the modification of an existing one. In all, perinatal management was altered in 75% of cases.

CONCLUSION

The MADAM model functions as a forum for exchange of up-to-date scientific information, development of evidence-based treatment protocols and continuity of care through the pre-, peri- and postnatal periods.

Preconceptional folate supplementation and the risk of spontaneous preterm birth: a cohort study

BACKGROUND

Low plasma folate concentrations in pregnancy are associated with preterm birth. Here we show an association between preconceptional folate supplementation and the risk of spontaneous preterm birth.

METHODS AND FINDINGS

In a cohort of 34,480 low-risk singleton pregnancies enrolled in a study of aneuploidy risk, preconceptional folate supplementation was prospectively recorded in the first trimester of pregnancy. Duration of pregnancy was estimated based on first trimester ultrasound examination. Natural length of pregnancy was defined as gestational age at delivery in pregnancies with no medical or obstetrical complications that may have constituted an indication for delivery. Spontaneous preterm birth was defined as duration of pregnancy between 20 and 37 wk without those complications. The association between preconceptional folate supplementation and the risk of spontaneous preterm birth was evaluated using survival analysis. Comparing to no supplementation, preconceptional folate supplementation for 1 y or longer was associated with a 70% decrease in the risk of spontaneous preterm delivery between 20 and 28 wk (41 [0.27%] versus 4 [0.04%] spontaneous preterm births, respectively; HR 0.22, 95% confidence interval [CI] 0.08-0.61, p = 0.004) and a 50% decrease in the risk of spontaneous preterm delivery between 28 and 32 wk (58 [0.38%] versus 12 [0.18%] preterm birth, respectively; HR 0.45, 95% CI 0.24-0.83, p = 0.010). Adjustment for maternal characteristics age, race, body mass index, education, marital status, smoking, parity, and history of prior preterm birth did not have a material effect on the association between folate supplementation for 1 y or longer and spontaneous preterm birth between 20 and 28, and 28 to 32 wk (adjusted HR 0.31, 95% CI 0.11-0.90, p = 0.031 and 0.53, 0.28-0.99, p = 0.046, respectively). Preconceptional folate supplementation was not significantly associated with the risk of spontaneous preterm birth beyond 32 wk. The association between shorter duration (<1 y) of preconceptional folate supplementation and the risk of spontaneous preterm birth was not significant after adjustment for maternal characteristics. However, the risk of spontaneous preterm birth decreased with the duration of preconceptional folate supplementation (test for trend of survivor functions, p = 0.01) and was the lowest in women who used folate supplementation for 1 y or longer. There was also no significant association with other complications of pregnancy studied after adjustment for maternal characteristics.

CONCLUSIONS

Preconceptional folate supplementation is associated with a 50%-70% reduction in the incidence of early spontaneous preterm birth. The risk of early spontaneous preterm birth is inversely proportional to the duration of preconceptional folate supplementation. Preconceptional folate supplementation was specifically related to early spontaneous preterm birth and not associated with other complications of pregnancy.

Down syndrome serum screening also identifies an increased risk for multicystic dysplastic kidney, two-vessel cord, and hydrocele

OBJECTIVE

The FASTER trial compared first and second trimester screening methods for aneuploidy. We examined relationships between maternal serum markers and common congenital anomalies in the pediatric outcome data set of 36 837 subjects.

METHODS

We used nested case-control studies, with cases defined by the most common anomalies in our follow-up database, and up to four controls matched by enrollment site, maternal age and race, enrollment gestational age, and infant gender. Serum markers were dichotomized to > or = 2 or < 0.5 multiples of the median (MoM). Odds ratios (ORs) and 95% confidence intervals (CI) were estimated.

RESULTS

Statistically significant (p < 0.05) associations were found between inhibin A > or = 2 MoM with fetal multicystic dysplastic kidney (MCDK) (OR = 27.5, 95% CI: 2.8-267.7) and two-vessel cord (OR = 4.22, 95% CI:1.6-10.9); hCG of > or = 2 MoM with MCDK (OR = 19.56, 95% CI: 1.9-196.2) and hydrocele (OR = 2.48, 95% CI: 1.3-4.6); and PAPP-A > or = 2.0 MoM with hydrocele (OR = 1.88, 95% CI:1.1-3.3).

CONCLUSION

In this large prospective study, significant associations were found between several maternal serum markers and congenital anomalies. This suggests potential additional benefits to screening programs that are primarily designed to detect aneuploidy.

Maintaining quality assurance for sonographic nuchal translucency measurement: lessons from the FASTER Trial

OBJECTIVE

To evaluate nuchal translucency measurement quality assurance techniques in a large-scale study.

METHODS

From 1999 to 2001, unselected patients with singleton gestations between 10 + 3 weeks and 13 + 6 weeks were recruited from 15 centers. Sonographic nuchal translucency measurement was performed by trained technicians. Four levels of quality assurance were employed: (1) a standardized protocol utilized by each sonographer; (2) local-image review by a second sonographer; (3) central-image scoring by a single physician; and (4) epidemiological monitoring of all accepted nuchal translucency measurements cross-sectionally and over time.

RESULTS

Detailed quality assessment was available for 37 018 patients. Nuchal translucency measurement was successful in 96.3% of women. Local reviewers rejected 0.8% of images, and the single central physician reviewer rejected a further 2.9%. Multivariate analysis indicated that higher body mass index, earlier gestational age and transvaginal probe use were predictors of failure of nuchal translucency measurement and central image rejection (P = 0.001). Epidemiological monitoring identified a drift in measurements over time.

CONCLUSION

Despite initial training and continuous image review, changes in nuchal translucency measurements occur over time. To maintain screening accuracy, ongoing quality assessment is needed.

Survival after laser surgery for twin-to-twin transfusion syndrome: when are they out of the woods?

PURPOSE

Severe, progressive twin-to-twin transfusion syndrome (TTTS) is associated with near-100% mortality if left untreated. Endoscopic laser ablation of placental vessels (ELA) is associated with 75% to 80% survival of at least one twin. The actuarial risk of fetal demise after ELA has not yet been described.

STUDY DESIGN

A retrospective cohort study from 2 centers on a consecutive series of 163 sets of monochorionic twins with severe TTTS (18 Quintero stage I, 55 stage II, 71 stage III, 19 stage IV) who underwent ELA. Actuarial survival was calculated and stratified for donor vs recipient and according to stage.

RESULTS

Median gestational age at diagnosis was 20.1 weeks; median operative time was 60 minutes. Overall survival was 63%, and survival of at least one twin was seen in 76% of pregnancies. Of fetal demises, 10% occurred within 48 hours after ELA, and 90% of all fetal demises occurred within 1 month. There was a 10% survival advantage of recipients over donors. Survival was similar for stages I, II, and IV (75%-80%), compared with 55% for stage III.

CONCLUSIONS

Actuarial survival curves for TTTS confirms a greater burden on donor than on recipient but not at a previously reported 2:1 ratio. The current staging system does not accurately reflect post-ELA mortality risk. The unexpected higher mortality in stage III may reflect a more acute progression of the disorder in this group, an adverse effect of LA on an as yet unknown subgroup with stage III or, alternatively, preoperative demise of fulminant stage IV patients, leaving a stage IV subgroup with a more benign course and better outcome.

Minimally invasive esophagectomy. An update on the options available

Minimally invasive techniques have been successfully applied to esophageal surgery. Initially, they were used for benign disease, but as experience has increased, so have the indications for minimally invasive esophageal surgery. Today, minimally invasive esophagectomy has been reported in all types of patients with a variety of esophageal diseases and different stages of esophageal cancer. Currently, the biggest limitation for proceeding with minimally invasive esophagectomy is experience in performing the procedure. This article provides an update on the myriad of options for performing minimally invasive esophagectomy including advantages and disadvantages of each option and outlines the surgical technique for each. It highlights the current debate on open versus minimally invasive esophagectomy. Since there is no consensus on the operative approach to open esophagectomy, it is not surprising that a number of debates over the best operative approach to minimally invasive esophagectomy exist today.

Contingent screening for Down syndrome--results from the FaSTER trial

OBJECTIVE

Comparison of contingent, step-wise and integrated screening policies.

METHODS

Mid-trimester Down syndrome risks were retrospectively calculated from FaSTER trial data. For contingent screening, initial risk was calculated from ultrasound measurement of nuchal translucency (NT), maternal serum pregnancy-associated plasma protein (PAPP)-A and free beta-human chorionic gonadotrophin (hCG) at 11-13 weeks, and classified positive (>1 in 30), borderline (1 in 30-1500) or negative. Borderline risks were recalculated using alpha-fetoprotein, hCG, unconjugated estriol (uE3) and inhibin at 15-18 weeks, and reclassified as positive (>1 in 270) or negative. For step-wise screening, initial negative risks were also recalculated. For integrated screening, a single risk was calculated from NT, PAPP-A and the second trimester markers.

RESULTS

There were 86 Down syndrome and 32,269 unaffected pregancies. The detection rate for contingent screening was 91% and false-positive rate was 4.5%; initial detection rate was 60%, initial false-positive rate was 1.2% and borderline risk was 23%. Step-wise screening had 92% detection rate and 5.1% false-positive rate; integrated screening had 88% and 4.9% respectively.

CONCLUSION

As predicted by modelling, the contingent screening detection rate for a fixed false-positive rate is comparable with step-wise and integrated screening, but substantially reduces the number needing to return for second trimester testing.

The effect of low body mass index on the development of gestational hypertension and preeclampsia

OBJECTIVES

To evaluate the relationship between low maternal body mass index (BMI) as calculated in the first trimester and the risk of preeclampsia and gestational hypertension.

METHODS

Patients enrolled in the First And Second Trimester Evaluation of Risk for aneuploidy (FASTER) trial were grouped into three weight categories: low BMI (BMI <19.8 kg/m2), normal BMI (BMI 19.8 - 26 kg/m2), and overweight BMI (26.1 - 29 kg/m2). The incidences of gestational hypertension and preeclampsia were ascertained for each group. Tests for differences in crude incidence proportions were performed using Chi-square tests. Multiple logistic regression was used to adjust for maternal age, race, parity, obesity, use of assisted reproductive technology (ART), in vitro fertilization (IVF), gestational diabetes, pre-gestational diabetes, cocaine use, and smoking.

RESULTS

The proportion of patients having gestational hypertension in the low BMI group was 2.0% compared to 3.2% for normal BMI and 6.0% for overweight BMI (p < 0.0001). Women with low BMI were also less likely to develop preeclampsia, 1.1% vs. 1.9% for normal BMI and 2.8% for overweight BMI (p < 0.0001).

CONCLUSIONS

We found that women with low BMI in the first trimester were significantly less likely to develop gestational hypertension or preeclampsia than women with a normal BMI.

First- and second-trimester screening: detection of aneuploidies other than Down syndrome

OBJECTIVE

To evaluate the performance of first- and second-trimester screening methods for the detection of aneuploidies other than Down syndrome.

METHODS

Patients with singleton pregnancies at 10 weeks 3 days through 13 weeks 6 days of gestation were recruited at 15 U.S. centers. All patients had a first-trimester nuchal translucency scan, and those without cystic hygroma had a combined test (nuchal translucency, pregnancy-associated plasma protein A, and free beta-hCG) and returned at 15-18 weeks for a second-trimester quadruple screen (serum alpha-fetoprotein, total hCG, unconjugated estriol, and inhibin-A). Risk cutoff levels of 1:300 for Down syndrome and 1:100 for trisomy 18 were selected.

RESULTS

Thirty-six thousand one hundred seventy-one patients completed first-trimester screening, and 35,236 completed second-trimester screening. There were 77 cases of non-Down syndrome aneuploidies identified in this population; 41 were positive for a cystic hygroma in the first trimester, and a further 36 had a combined test, of whom 29 proceeded to quadruple screening. First-trimester screening, by cystic hygroma determination or combined screening had a 78% detection rate for all non-Down syndrome aneuploidies, with an overall false-positive rate of 6.0%. Sixty-nine percent of non-Down syndrome aneuploidies were identified as screen-positive by the second-trimester quadruple screen, at a false-positive rate of 8.9%. In the combined test, the use of trisomy 18 risks did not detect any additional non-Down syndrome aneuploidies compared with the Down syndrome risk alone. In second-trimester quadruple screening, a trisomy 18-specific algorithm detected an additional 41% non-Down syndrome aneuploidies not detected using the Down syndrome algorithm.

CONCLUSION

First-trimester Down syndrome screening protocols can detect the majority of cases of non-Down aneuploidies. Addition of a trisomy 18-specific risk algorithm in the second trimester achieves high detection rates for aneuploidies other than Down syndrome.

LEVEL OF EVIDENCE

II.

The contribution of birth defects to preterm birth and low birth weight

OBJECTIVE

To assess the impact of birth defects on preterm birth and low birth weight.

METHODS

Data from a large, prospective multi-center trial, the First and Second Trimester Evaluation of Risk (FASTER) Trial, were examined. All live births at more than 24 weeks of gestation with data on outcome and confounders were divided into two comparison groups: 1) those with a chromosomal or structural abnormality (birth defect) and 2) those with no abnormality detected in chromosomes or anatomy. Propensity scores were used to balance the groups, account for confounding, and reduce the bias of a large number of potential confounding factors in the assessment of the impact of a birth defect on outcome. Multiple logistic regression analysis was applied.

RESULTS

A singleton liveborn infant with a birth defect was 2.7 times more likely to be delivered preterm before 37 weeks of gestation (95% confidence interval [CI] 2.3-3.2), 7.0 times more likely to be delivered preterm before 34 weeks (95% CI 5.5-8.9), and 11.5 times more likely to be delivered very preterm before 32 weeks (95% CI 8.7-15.2). A singleton liveborn with a birth defect was 3.6 times more likely to have low birth weight at less than 2,500 g (95% CI 3.0-4.3) and 11.3 times more likely to be very low birth weight at less than 1,500 g (95% CI 8.5-15.1).

CONCLUSION

Birth defects are associated with preterm birth and low birth weight after controlling for multiple confounding factors, including shared risk factors and pregnancy complications, using propensity scoring adjustment in multivariable regression analysis. The independent effects of risk factors on perinatal outcomes such as preterm birth and low birth weight, usually complicated by numerous confounding factors, may benefit from the application of this methodology, which can be used to minimize bias and account for confounding. Furthermore, this suggests that clinical and public health interventions aimed at preventing birth defects may have added benefits in preventing preterm birth and low birth weight.

LEVEL OF EVIDENCE

II.

First- and Second-Trimester Evaluation of Risk for Down Syndrome

OBJECTIVE

To investigate the differences in costs and outcomes of Down syndrome screening using data from the First and Second Trimester Evaluation of Risk (FASTER) Trial.

METHODS

Seven possible screening options for Down syndrome were compared: 1) Triple Screen-maternal serum alpha fetoprotein, estriol, and hCG; 2) Quad-maternal serum alpha fetoprotein, estriol, hCG, and Inhibin A; 3) Combined First-nuchal translucency, pregnancy-associated plasma protein A (PAPP-A), free beta-hCG; 4) Integrated-nuchal translucency, PAPP-A, plus Quad; 5) Serum Integrated-PAPP-A, plus Quad; 6) Stepwise Sequential-Combined First plus Quad with results given after each test; and 7) Contingent Sequential-Combined First and only those with risk between 1:30 and 1:1,500 have Quad screen. The detection rates for each option were used given a 5% false-positive rate except for Contingent Sequential with a 4.3% false-positive rate. Outcomes included societal costs of each screening regimen (screening tests, amniocentesis, management of complications, and cost of care of Down syndrome live births), Down syndrome fetuses identified and born, the associated quality-adjusted life years, and the incremental cost-utility ratio.

RESULTS

Based on the screening results derived from the 38,033 women evaluated in the FASTER trial, the Contingent Sequential screen dominated (lower costs with better outcomes) all other screens. For example, the Contingent Sequential cost 32.3 million dollars whereas the other screens ranged from 32.8 to 37.5 million dollars. The Sequential strategy led to the identification of the most Down syndrome fetuses of all of the screens, but at a higher cost per Down syndrome case diagnosed ($719,675 compared with $690,427) as compared with the Contingent Sequential. Because of the lower overall false-positive rate leading to fewer procedure-related miscarriages, the Contingent Sequential resulted in the highest quality-adjusted life years as well. The Contingent Sequential remained the most cost-effective option throughout sensitivity analysis of inputs, including amniocentesis rate after positive screen, rate of therapeutic abortion after Down syndrome diagnosis, and rate of procedure-related miscarriages.

CONCLUSION

Analysis of this actual data from the FASTER Trial demonstrates that the Contingent Sequential test is the most cost-effective. This information can help shape future policy regarding Down syndrome screening.

Human sexual size dimorphism in early pregnancy

Sexual size dimorphism is thought to contribute to the greater mortality and morbidity of men compared with women. However, the timing of onset of sexual size dimorphism remains uncertain. The authors determined whether human fetuses exhibit sexual size dimorphism in the first trimester of pregnancy. Using a prospective cohort study, conducted in 1999-2002 in the United States, they identified 27,655 women who conceived spontaneously and 1,008 whose conception was assisted by in vitro fertilization or intrauterine insemination and for whom a first-trimester measurement of fetal crown-rump length was available. First-trimester size was expressed as the difference between the observed and expected size of the fetus, expressed as equivalence to days of gestational age. The authors evaluated the association between fetal sex, first-trimester size, and birth weight. Eight to 12 weeks after conception, males were larger than females (mean difference: assisted conception = 0.4 days, 95% confidence interval (CI): 0.1, 0.7, p = 0.008; spontaneous conception = 0.3 days, 95% CI: 0.2, 0.4, p < 0.00001). The size discrepancy remained significant at birth (mean birth weight difference: assisted conception = 90 g, 95% CI: 22, 159, p = 0.009; spontaneous conception = 120 g, 95% CI: 107, 132, p < 0.00001). These data demonstrate that human fetuses exhibit sexual size dimorphism in the first trimester of pregnancy.

Fetal growth in early pregnancy and risk of delivering low birth weight infant: prospective cohort study

OBJECTIVE

To determine if first trimester fetal growth is associated with birth weight, duration of pregnancy, and the risk of delivering a small for gestational age infant.

DESIGN

Prospective cohort study of 38 033 pregnancies between 1999 and 2003.

SETTING

15 centres representing major regions of the United States.

PARTICIPANTS

976 women from the original cohort who conceived as the result of assisted reproductive technology, had a first trimester ultrasound measurement of fetal crown-rump length, and delivered live singleton infants without evidence of chromosomal or congenital abnormalities. First trimester growth was expressed as the difference between the observed and expected size of the fetus, expressed as equivalence to days of gestational age.

MAIN OUTCOME MEASURES

Birth weight, duration of pregnancy, and risk of delivering a small for gestational age infant.

RESULTS

For each one day increase in the observed size of the fetus, birth weight increased by 28.2 (95% confidence interval 14.6 to 41.2) g. The association was substantially attenuated by adjustment for duration of pregnancy (adjusted coefficient 17.1 (6.6 to 27.5) g). Further adjustments for maternal characteristics and complications of pregnancy did not have a significant effect. The risk of delivering a small for gestational age infant decreased with increasing size in the first trimester (odds ratio for a one day increase 0.87, 0.81 to 0.94). The association was not materially affected by adjustment for maternal characteristics or complications of pregnancy.

CONCLUSION

Variation in birth weight may be determined, at least in part, by fetal growth in the first 12 weeks after conception through effects on timing of delivery and fetal growth velocity.

Nuchal Translucency and the Risk of Congenital Heart Disease

OBJECTIVE

To estimate whether nuchal translucency assessment is a useful screening tool for major congenital heart disease (CHD) in the absence of aneuploidy.

METHODS

Unselected patients with singleton pregnancies at 10(3/7) to 13(6/7) weeks of gestation were recruited at 15 U.S. centers to undergo nuchal translucency sonography. Screening characteristics of nuchal translucency in the detection of major CHD were determined using different cutoffs (2.0 or more multiples of the median [MoM], 2.5 or more MoM, 3.0 or more MoM).

RESULTS

A total of 34,266 euploid fetuses with cardiac outcome data were available for analysis. There were 224 cases of CHD (incidence 6.5 per 1,000), of which 52 (23.2%) were major (incidence 1.5 per 1,000). The incidence of major CHD increased with increasing nuchal translucency: 14.1 per 1,000, 33.5 per 1,000, and 49.5 per 1,000 at 2.0 or more MoM, 2.5 or more MoM, and 3.0 or more MoM cutoffs, respectively. Sensitivity, specificity, and positive predictive values were 15.4%, 98.4%, and 1.4% at 2.0 or more MoM; 13.5%, 99.4%, and 3.3% at 2.5 or more MoM; and 9.6%, 99.7%, and 5.0% at 3.0 or more MoM. Nuchal translucency of 2.5 or more MoM (99th percentile) had a likelihood ratio (95% confidence interval) of 22.5 (11.4-45.5) for major CHD. Based on our data, for every 100 patients referred for fetal echocardiography with a nuchal translucency of 99th percentile or more, three will have a major cardiac anomaly.

CONCLUSION

Nuchal translucency sonography in the first trimester lacks the characteristics of a good screening tool for major CHD in a large unselected population. However, nuchal translucency of 2.5 or more MoM (99th percentile or more) should be considered an indication for fetal echocardiography.

LEVEL OF EVIDENCE

II.

Pregnancy Loss Rates After Midtrimester Amniocentesis

OBJECTIVE

The purpose of this study was to quantify the contemporary procedure-related loss rate after midtrimester amniocentesis using a database generated from patients who were recruited to the First And Second Trimester Evaluation of Risk for Aneuploidy trial.

METHODS

A total of 35,003 unselected patients from the general population with viable singleton pregnancies were enrolled in the First And Second Trimester Evaluation of Risk for Aneuploidy trial between 10 3/7 and 13 6/7 weeks gestation and followed up prospectively for complete pregnancy outcome information. Patients who either did (study group, n=3,096) or did not (control group, n=31,907) undergo midtrimester amniocentesis were identified from the database. The rate of fetal loss less than 24 weeks of gestation was compared between the two groups, and multiple logistic regression analysis was used to adjust for potential confounders.

RESULTS

The spontaneous fetal loss rate less than 24 weeks of gestation in the study group was 1.0% and was not statistically different from the background 0.94% rate seen in the control group (P=.74, 95% confidence interval -0.26%, 0.49%). The procedure-related loss rate after amniocentesis was 0.06% (1.0% minus the background rate of 0.94%). Women undergoing amniocentesis were 1.1 times more likely to have a spontaneous loss (95% confidence interval 0.7-1.5).

CONCLUSION

The procedure-related fetal loss rate after midtrimester amniocentesis performed on patients in a contemporary prospective clinical trial was 0.06%. There was no significant difference in loss rates between those undergoing amniocentesis and those not undergoing amniocentesis.

LEVEL OF EVIDENCE

II-2.

Comparison of Serum Markers in First-Trimester Down Syndrome Screening

OBJECTIVE

To estimate patterns of total hCG and inhibin A levels in the late first trimester of Down syndrome pregnancies, compare them with that of free beta-hCG, and assess screening performance of these markers individually and in combination with pregnancy-associated plasma protein-A (PAPP-A) and nuchal translucency.

METHODS

Seventy-nine matched case-control sets of maternal serum samples (each Down syndrome case matched to 5 controls) from 11 through 13 completed weeks of gestation were taken from the sample bank of the First and Second Trimester Evaluation of Risk Consortium, a population-based study, and assayed for levels of free beta-hCG, total hCG, and inhibin A. Distribution characteristics and correlations of the multiples of the median values were estimated in cases and controls. Screening performance for each marker, alone and in combination with PAPP-A, nuchal translucency, and maternal age, was calculated.

RESULTS

Median multiples of the median levels of free beta-hCG, total hCG, and inhibin A in cases were more elevated as gestation increased from 11 to 13 weeks, with univariate detection rates of 31%, 23%, and 29%, respectively, at a 5% false-positive rate. At 12 weeks, the multivariate detection rates at a 5% false-positive rate for nuchal translucency and PAPP-A (with maternal age) with either free beta-hCG, total hCG, or inhibin A were 84%, 83%, and 85%, respectively. The improvement in performance from nuchal translucency and PAPP-A to any of the three-marker tests was significant, while performance of any of the three-marker combinations was not significantly different from each other.

CONCLUSION

Although levels of free beta-hCG in affected pregnancies were higher earlier than the levels of either total hCG or inhibin A, there was no significant difference in screening performance when either of the three markers was used with nuchal translucency and PAPP-A at 11-13 weeks of pregnancy.

LEVEL OF EVIDENCE

II-2.

Is there a nuchal translucency millimeter measurement above which there is no added benefit from first trimester serum screening?

OBJECTIVE

The purpose of this study was to evaluate whether there is a nuchal translucency (NT) measurement, independent of gestational age, above which immediate diagnostic testing should be offered without waiting for first trimester serum markers.

STUDY DESIGN

Thirty-six thousand one hundred twenty patients had successful measurement of simple NT at 10 3/7 to 13 6/7 weeks and had first trimester serum screening. No risks were reported until second trimester serum screening was completed.

RESULTS

Thirty-two patients (0.09%) had NT > or = 4.0 mm; the lowest combined first trimester trisomy 21 risk assessment in euploid cases was 1 in 8 and among aneuploidy cases was 7 in 8. One hundred twenty-eight patients (0.3%) had simple NT > or = 3.0 mm: the lowest combined first trimester trisomy 21 risk assessment of any patient in this group was 1 in 1479 and the lowest risk assessment among aneuploid cases was 1 in 2. Ten patients (8%) had first trimester trisomy 21 risk assessments lowered to less that 1:200 and none of these 10 cases had an abnormal outcome.

CONCLUSION

During first trimester Down syndrome screening, whenever an NT measurement of 3.0 mm or greater is obtained there is minimal benefit in waiting for serum screening results, and no benefit for NT of 4.0 mm or greater. Differentiation between cystic hygroma and enlarged simple NT (> or = 3.0 mm) is now a moot point as both are sufficiently high risk situations to warrant immediate CVS.

Perinatal management of congenital cystic lung lesions in the age of minimally invasive surgery

BACKGROUND

Most congenital cystic lung lesions (CCLLs) do not require in utero or perinatal intervention. The management of asymptomatic lesions is controversial: the theoretical risk of infection and malignancy is offset by whether thoracotomy in asymptomatic children is justified. We examined our recent experience and the role of minimally invasive surgery.

METHODS

We analyzed the pre-, peri-, and postnatal findings of all consecutive CCLLs diagnosed between 1997 and 2005. We reviewed records for pre-, and postnatal imaging, management, and outcome.

RESULTS

Thirty-five CCLL were diagnosed prenatally. Since 2000, all asymptomatic lesions were removed endoscopically at 6 to 18 months (thoracoscopy for 6 extralobar sequestrations, 3 intralobar sequestrations/congenital cystic adenomatoid malformations, 5 bronchogenic cysts, and retroperitoneal laparoscopy for 2 intraabdominal sequestrations). Congenital cystic adenomatoid malformation elements were present in more than 70%. Two abdominal lesions have regressed, and 2 patients are awaiting intervention. One symptomatic infant underwent thoracotomy for congenital lobar emphysema.

CONCLUSIONS

It has been argued that the risks associated with congenital lung lesions (infection and malignancy) justify intervention in the asymptomatic patient. In our experience, all these lesions could be safely removed using endosurgical techniques. Counseling of (future) parents should be updated to include minimally invasive surgery in the management algorithm.

Port insertion and removal techniques to minimize premature rupture of the membranes in endoscopic fetal surgery

BACKGROUND

Premature rupture of membranes (PROM) remains a significant complication of fetal surgery. Rates of 40% to 100% have been reported after both open and endoscopic fetal surgery. We describe a technique of endoscopic port insertion and removal that minimizes trauma to the membranes.

METHODS

Twenty-seven consecutive patients undergoing endoscopic laser ablation for twin-to-twin transfusion syndrome were reviewed. In each case, a minilaparotomy was performed, and the amniotic cavity was entered under direct vision of the uterus using a Seldinger technique. The entry site was carefully dilated to accommodate a 4.0-mm-diameter cannula. A gelatin sponge plug was placed at port removal. Postoperative management and outcome were evaluated.

RESULTS

Median gestational age at operation was 21.3 weeks. Median operating time was 60 minutes. One patient delivered intraoperatively because of fetal distress. Seventeen (65.4%) patients required postoperative tocolysis (median duration, 12 hours). Median postoperative gestation was 6.5 weeks (range, 1-20 weeks). Only 1 (4.2%) of 24 patients with successful gelatin sponge placement developed PROM.

CONCLUSIONS

Meticulous technique and atraumatic insertion and removal of ports help minimize the risk of postoperative amniotic leak after endoscopic fetal surgery. Our PROM rate of 4.2% contrasts sharply with previously reported rates after similar operations.

Early Access to Prenatal Care

OBJECTIVE

To investigate racial disparities in perinatal mortality in women with early access to prenatal care.

METHODS

A prospectively collected database from a large, multicenter investigation of singleton pregnancies, the FASTER trial, was queried. Patients were recruited from an unselected obstetric population between 1999 and 2002. A total of 35,529 pregnancies with early access to prenatal care were reviewed for this analysis. The timing of perinatal loss was assessed. The following intervals were evaluated: fetal demise at less than 24 weeks of gestation, fetal demise at 24 or more weeks of gestation, and neonatal demise. Perinatal mortality was defined as the sum of these three intervals.

RESULTS

The study population was 5% black, 22% Hispanic, 68% white, and 5% other. All minority races experienced higher rates of intrauterine growth restriction, preeclampsia, preterm premature rupture of membranes, gestational diabetes, placenta previa, preterm birth, very-preterm birth, cesarean delivery, light vaginal bleeding, and heavy vaginal bleeding compared with the white population. Overall perinatal mortality was 13 per 1,000 (471/35,529). The adjusted odds ratios (95% confidence intervals) for perinatal mortality (utilizing the white population as the referent race) were: black 3.5 (2.5-4.9), Hispanic 1.5 (1.2-2.1), and other 1.9 (1.3-2.8).

CONCLUSION

Racial disparities in perinatal mortality persist in contemporary obstetric practice despite early access to prenatal care.

LEVEL OF EVIDENCE

II-2.

First- and second-trimester Down syndrome screening markers in pregnancies achieved through assisted reproductive technologies (ART): a FASTER trial study

OBJECTIVE

To determine whether first- and second-trimester Down syndrome screening markers and screen-positive rates are altered in pregnancies conceived using assisted reproductive technologies (ARTs).

METHODS

ART pregnancies in the multicenter FASTER trial were identified. Marker levels were evaluated for five types of ART: in vitro fertilization with ovulation induction (IVF-OI), IVF with OI and egg donation (IVF-OI-ED), IVF with ED (IVF-ED), and intrauterine insemination with OI (IUI-OI) or without OI (IUI). Each group was compared to non-ART controls using Mann-Whitney U analysis.

RESULTS

First-trimester marker levels were not significantly different between ART and control pregnancies, with the exception of reduced PAPP-A levels in the IUI-OI group. In contrast, second-trimester inhibin A levels were increased in all ART pregnancies, estriol was reduced and human chorionic gonadotropin (hCG) was increased in IVF and IUI pregnancies without ED, and alpha-fetoprotein (AFP) was increased in ED pregnancies. Second-trimester screen-positive rates were significantly higher than expected for ART pregnancies, except when ED was used.

CONCLUSIONS

These data show that ART significantly impacts second-, but not first-, trimester markers and screen-positive rates. The type of adjustment needed in second-trimester screening depends on the particular type of ART used.

First-trimester or second-trimester screening, or both, for Down's syndrome

BACKGROUND

It is uncertain how best to screen pregnant women for the presence of fetal Down's syndrome: to perform first-trimester screening, to perform second-trimester screening, or to use strategies incorporating measurements in both trimesters.

METHODS

Women with singleton pregnancies underwent first-trimester combined screening (measurement of nuchal translucency, pregnancy-associated plasma protein A [PAPP-A], and the free beta subunit of human chorionic gonadotropin at 10 weeks 3 days through 13 weeks 6 days of gestation) and second-trimester quadruple screening (measurement of alpha-fetoprotein, total human chorionic gonadotropin, unconjugated estriol, and inhibin A at 15 through 18 weeks of gestation). We compared the results of stepwise sequential screening (risk results provided after each test), fully integrated screening (single risk result provided), and serum integrated screening (identical to fully integrated screening, but without nuchal translucency).

RESULTS

First-trimester screening was performed in 38,167 patients; 117 had a fetus with Down's syndrome. At a 5 percent false positive rate, the rates of detection of Down's syndrome were as follows: with first-trimester combined screening, 87 percent, 85 percent, and 82 percent for measurements performed at 11, 12, and 13 weeks, respectively; with second-trimester quadruple screening, 81 percent; with stepwise sequential screening, 95 percent; with serum integrated screening, 88 percent; and with fully integrated screening with first-trimester measurements performed at 11 weeks, 96 percent. Paired comparisons found significant differences between the tests, except for the comparison between serum integrated screening and combined screening.

CONCLUSIONS

First-trimester combined screening at 11 weeks of gestation is better than second-trimester quadruple screening but at 13 weeks has results similar to second-trimester quadruple screening. Both stepwise sequential screening and fully integrated screening have high rates of detection of Down's syndrome, with low false positive rates.

Assisted Reproductive Technology and Pregnancy Outcome

OBJECTIVE

To determine whether the use of assisted reproductive technology (ART) is associated with an increase in chromosomal abnormalities, fetal malformations, or adverse pregnancy outcomes.

METHODS

A prospective database from a large multicenter investigation of singleton pregnancies, the First And Second Trimester Evaluation of Risk trial, was examined. Subjects were divided into 3 groups: no ART use, use of ovulation induction (with or without intrauterine insemination), and use of in vitro fertilization (IVF). Multivariate logistic regression analysis was used to assess association between ART and adverse pregnancy outcomes (significance of differences was accepted at P < .05).

RESULTS

A total of 36,062 pregnancies were analyzed: 34,286 (95.1%) were spontaneously conceived, 1,222 (3.4%) used ovulation induction, and 554 (1.5%) used IVF. There was no association between ART and fetal growth restriction, aneuploidy, or fetal anomalies after adjustment for age, race, marital status, years of education, prior preterm delivery, prior fetal anomaly, body mass index, smoking history, and bleeding in the current pregnancy. Ovulation induction was associated with a statistically significant increase in placental abruption, fetal loss after 24 weeks, and gestational diabetes after adjustment. Use of IVF was associated with a statistically significant increase in preeclampsia, gestational hypertension, placental abruption, placenta previa, and risk of cesarean delivery.

CONCLUSION

Patients who undergo IVF are at increased risk for several adverse pregnancy outcomes. Although many of these risks are not seen in patients undergoing ovulation induction, several adverse pregnancy outcomes are still increased in this group. There was no increased incidence of fetal chromosomal or structural abnormalities in the women who used any type of ART compared with the women who conceived spontaneously.

LEVEL OF EVIDENCE

II-2.

First-Trimester Septated Cystic Hygroma

OBJECTIVE

To estimate prevalence, natural history, and outcome of septated cystic hygroma in the first trimester in the general obstetric population, and to differentiate this finding from simple increased nuchal translucency.

METHODS

Patients at 10.3-13.6 weeks of gestation underwent nuchal translucency sonography as part of a multicenter clinical trial. Septated cystic hygroma cases were offered chorionic villi sampling for karyotype, and targeted fetal anatomical and cardiac evaluations. Survivors were followed up for fetal and long-term pediatric outcome (median 25 months, range 12-50 months). Cases of septated cystic hygroma were also compared with cases of simple increased nuchal translucency.

RESULTS

There were 134 cases of cystic hygroma (2 lost to follow-up) among 38,167 screened patients (1 in 285). Chromosomal abnormalities were diagnosed in 67 (51%), including 25 trisomy-21, 19 Turner syndrome, 13 trisomy-18, and 10 others. Major structural fetal malformations (primarily cardiac and skeletal) were diagnosed in 22 of the remaining 65 cases (34%). There were 5 cases (8%) of fetal death and 15 cases of elective pregnancy termination without evidence of abnormality. One of 23 (4%) normal survivors was diagnosed with cerebral palsy and developmental delay. Overall, survival with normal pediatric outcome was confirmed in 17% of cases (22 of 132). Compared with simple increased nuchal translucency, cystic hygroma has 5-fold, 12-fold, and 6-fold increased risk of aneuploidy, cardiac malformation, and perinatal death, respectively.

CONCLUSION

First-trimester cystic hygroma was a frequent finding in a general obstetric screening program. It has the strongest prenatal association with aneuploidy described to date, with significantly worse outcome compared with simple increased nuchal translucency. Most pregnancies with normal evaluation at the completion of the second trimester resulted in a healthy infant with a normal pediatric outcome.

Quad Screen as a Predictor of Adverse Pregnancy Outcome

OBJECTIVE

To estimate the effect of second-trimester levels of maternal serum alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), unconjugated estriol (uE3), and inhibin A (the quad screen) on obstetric complications by using a large, prospectively collected database (the FASTER database).

METHODS

The FASTER trial was a multicenter study that evaluated first- and second-trimester screening programs for aneuploidy in women with singleton pregnancies. As part of this trial, patients had a quad screen drawn at 15-18 6/7 weeks. We analyzed the data to identify associations between the quad screen markers and preterm birth, intrauterine growth restriction, preeclampsia, and fetal loss. Our analysis was performed by evaluating the performance characteristics of quad screen markers individually and in combination. Crude and adjusted effects were estimated by multivariable logistic regression analysis. Patients with fetal anomalies were excluded from the analysis.

RESULTS

We analyzed data from 33,145 pregnancies. We identified numerous associations between the markers and the adverse outcomes. There was a relatively low, but often significant, risk of having an adverse pregnancy complication if a patient had a single abnormal marker. However, the risk of having an adverse outcome increased significantly if a patient had 2 or more abnormal markers. The sensitivity and positive predictive values using combinations of markers is relatively low, although superior to using individual markers.

CONCLUSION

These data suggest that components of the quad screen may prove useful in predicting adverse obstetric outcomes. We also showed that the total number and specific combinations of abnormal markers are most useful in predicting the risk of adverse perinatal outcome.

What--and why--the pediatric surgeon should know about twin-to-twin transfusion syndrome

Abstract Endoscopic laser ablation of placental vessels is the most commonly performed fetal operation today. Herein, we review the pathophysiology of twin-to-twin transfusion syndrome and the challenges of its treatment. Pediatric surgeons, with their knowledge of fetal and congenital pathology, and their technical expertise with minimally invasive surgery, can be of great benefit to the patient and the medical team.

Impact of maternal age on obstetric outcome

OBJECTIVE

To estimate the effect of maternal age on obstetric outcomes.

METHODS

A prospective database from a multicenter investigation of singletons, the FASTER trial, was studied. Subjects were divided into 3 age groups: 1) less than 35 years, 2) 35-39 years, and 3) 40 years and older. Multivariable logistic regression analysis was used to assess the effect of age on outcomes after adjusting for race, parity, body mass index, education, marital status, smoking, medical history, use of assisted conception, and patient's study site.

RESULTS

A total of 36,056 women with complete data were available: 28,398 (79%) less than 35 years of age; 6,294 (17%) 35-39 years; and 1,364 (4%) 40 years and older. Increasing age was significantly associated with miscarriage (adjusted odds ratio [adjOR]2.0 and 2.4 for ages 35-39 years and age 40 years and older, respectively), chromosomal abnormalities (adjOR 4.0 and 9.9), congenital anomalies (adjOR 1.4 and 1.7), gestational diabetes (adjOR 1.8 and 2.4), placenta previa (adjOR 1.8 and 2.8), and cesarean delivery (adjOR 1.6 and 2.0). Patients aged 35-39 years were at increased risk for macrosomia (adjOR 1.4). Increased risk for abruption (adjOR 2.3), preterm delivery (adjOR 1.4), low birth weight (adjOR 1.6), and perinatal mortality (adjOR 2.2) was noted in women aged 40 years and older.

CONCLUSION

Increasing maternal age is independently associated with specific adverse pregnancy outcomes. Increasing age is a continuum rather than a threshold effect.

First-trimester nasal bone evaluation for aneuploidy in the general population

OBJECTIVE

To evaluate the role of fetal nasal bone imaging at 10 3/7 to 13 6/7 weeks as a screening tool for aneuploidy, in a prospective multicenter trial.

METHODS

Unselected patients from the general population with viable singleton pregnancies at 10 3/7 to 13 6/7 weeks were recruited at 15 U.S. centers. All had screening with nuchal translucency (NT) ultrasound by specially trained sonographers. In the last 8 months of this trial, first trimester nasal bone evaluation was added to the screening protocol. Nasal bones were described as present, absent, or unable to determine.

RESULTS

A total of 38,189 patients completed first trimester NT screening, of whom 6,324 also underwent nasal bone sonography. An acceptable nasal image was obtained in 4,801 cases (76%), with nasal bones described as present in 4,779 (99.5%), and absent in 22 (0.5%). There were 11 identified cases of trisomy-21 in the population of 6,324 patients. In 9 of the 11 cases (82%) the nasal bones were described as present, and 2 cases were described as unable to determine. The only other aneuploidies were 2 cases of trisomy-18, in 1 of which the nasal bones were described as absent, and in 1 present. Absence of nasal bones had sensitivity for aneuploidy of 7.7%, false-positive rate 0.3%, and positive predictive value 4.5%.

CONCLUSION

First-trimester nasal bone evaluation was not a useful test for population screening for trisomy-21 and added little to first-trimester NT screening. The difficulty in performing first-trimester nasal bone sonography consistently, in the general population setting, will significantly limit the usefulness of this aneuploidy screening technique.

Intratwin arteriovenous fistula of the placenta in a case of twin-to-twin transfusion syndrome

Arteriovenous fistulas of the placenta are extremely rare in singleton pregnancies and, to our knowledge, have not previously been reported in twin gestations. We describe a case of an arteriovenous fistula of the placenta in a diamniotic-monochorionic twin pregnancy complicated by twin-to-twin transfusion syndrome (TTTS). The arteriovenous fistula was demonstrated by color-coded vascular injection studies of the placenta. We speculate that the hemodynamic effects of the fistula may have contributed to the refractoriness of the TTTS to serial amniodrainages and laser ablation of communicating intertwin vessels.