Yasser Y. El-Sayed

Non-invasive prenatal measurement of the fetal genome

The vast majority of prenatal genetic testing requires invasive sampling. However, this poses a risk to the fetus, so one must make a decision that weighs the desire for genetic information against the risk of an adverse outcome due to hazards of the testing process. These issues are not required to be coupled, and it would be desirable to discover genetic information about the fetus without incurring a health risk. Here we demonstrate that it is possible to non-invasively sequence the entire prenatal genome. Our results show that molecular counting of parental haplotypes in maternal plasma by shotgun sequencing of maternal plasma DNA allows the inherited fetal genome to be deciphered non-invasively. We also applied the counting principle directly to each allele in the fetal exome by performing exome capture on maternal plasma DNA before shotgun sequencing. This approach enables non-invasive exome screening of clinically relevant and deleterious alleles that were paternally inherited or had arisen as de novo germline mutations, and complements the haplotype counting approach to provide a comprehensive view of the fetal genome. Non-invasive determination of the fetal genome may ultimately facilitate the diagnosis of all inherited and de novo genetic disease.

Pelvic arterial embolization for control of obstetric hemorrhage: A five-year experience☆☆☆

OBJECTIVE Obstetric hemorrhage is a significant cause of maternal morbidity and death. Postpartum hemorrhage that cannot be controlled by local measures has traditionally been managed by bilateral uterine artery or hypogastric artery ligation. These techniques have a high failure rate, often resulting in hysterectomy. In contrast, endovascular embolization techniques have a success rate of >90%. An additional benefit of the latter procedure is that fertility is maintained. We report our experience at Stanford University Medical Center in which this technique was used in 6 cases within the past 5 years. STUDY DESIGN Six women between the ages of 18 and 41 years underwent placement of arterial catheters for emergency (n = 3) or prophylactic (n = 3) control of postpartum bleeding. Specific diagnoses included cervical pregnancy (n = 1), uterine atony (n = 3), and placenta previa and accreta (n = 2). RESULTS Control of severe or anticipated postpartum hemorrhage was obtained with transcatheter embolization in 4 patients. A fifth patient had balloon occlusion of the uterine artery performed prophylactically, but embolization was not necessary. In a sixth case, bleeding could not be controlled in time, and hysterectomy was performed. The only complication observed with this technique was postpartum fever in 1 patient, which was treated with antibiotics and resolved within 7 days. CONCLUSIONS Uterine artery embolization is a superior first-line alternative to surgery for control of obstetric hemorrhage. Use of transcatheter occlusion balloons before embolization allows timely control of bleeding and permits complete embolization of the uterine arteries and hemostasis. Given the improved ultrasonography techniques, diagnosis of some potential high-risk conditions for postpartum hemorrhage, such as placenta previa or accreta, can be made prenatally. The patient can then be prepared with prophylactic placement of arterial catheters, and rapid occlusion of these vessels can be achieved if necessary.

Bacterial flora-typing with targeted, chip-based Pyrosequencing

BackgroundThe metagenomic analysis of microbial communities holds the potential to improve our understanding of the role of microbes in clinical conditions. Recent, dramatic improvements in DNA sequencing throughput and cost will enable such analyses on individuals. However, such advances in throughput generally come at the cost of shorter read-lengths, limiting the discriminatory power of each read. In particular, classifying the microbial content of samples by sequencing the < 1,600 bp 16S rRNA gene will be affected by such limitations.ResultsWe describe a method for identifying the phylogenetic content of bacterial samples using high-throughput Pyrosequencing targeted at the 16S rRNA gene. Our analysis is adapted to the shorter read-lengths of such technology and uses a database of 16S rDNA to determine the most specific phylogenetic classification for reads, resulting in a weighted phylogenetic tree characterizing the content of the sample. We present results for six samples obtained from the human vagina during pregnancy that corroborates previous studies using conventional techniques.Next, we analyze the power of our method to classify reads at each level of the phylogeny using simulation experiments. We assess the impacts of read-length and database completeness on our method, and predict how we do as technology improves and more bacteria are sequenced. Finally, we study the utility of targeting specific 16S variable regions and show that such an approach considerably improves results for certain types of microbial samples. Using simulation, our method can be used to determine the most informative variable region.ConclusionThis study provides positive validation of the effectiveness of targeting 16S metagenomes using short-read sequencing technology. Our methodology allows us to infer the most specific assignment of the sequence reads within the phylogeny, and to identify the most discriminative variable region to target. The analysis of high-throughput Pyrosequencing on human flora samples will accelerate the study of the relationship between the microbial world and ourselves.

Intrathecal sufentanil for labor analgesia--sensory changes, side effects, and fetal heart rate changes.

This study was designed to evaluate intrathecal (IT) sufentanil for labor analgesia with respect to sensory changes, side effects, and fetal heart rate (FHR) changes. In Phase I of the study, data regarding duration of analgesia and hemodynamic changes were obtained retrospectively from the labor and anesthetic records of 90 patients who had received IT sufentanil, 10 micrograms in 1 mL of saline, during active labor. In Phase II, an additional 18 parturients who received similar treatment were studied prospectively to document sensory, motor, and hemodynamic changes, as well as the incidence of side effects. In Phase I, analgesia occurred rapidly and lasted 124 +/- 68 min (SD); 19% of patients required no further analgesia before delivery. In Phase II, median time to onset of analgesia was 3 min (range 1-6 min) and mean duration of analgesia was 96 +/- 36 min. Decreased sensation to pinprick and cold occurred within 6 min extending from T4 to L4 (upper and lower median levels) in the majority of patients. All subjects requested additional analgesia within approximately 30 min of recession of sensory changes. Motor strength remained normal throughout. Hypotension (systolic blood pressure [BP] < or = 90 mm Hg or > 20% decrease in systolic BP) occurred in 14% and 11% of patients in Phase I and II, respectively. Perineal itching preceded analgesia in 95% of patients and all subjects experienced mild sedation. FHR changes occurred in 15% of cases but were not associated with adverse neonatal outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Microfluidic digital PCR enables rapid prenatal diagnosis of fetal aneuploidy

OBJECTIVE The purpose of this study was to demonstrate that digital polymerase chain reaction (PCR) enables rapid, allele independent molecular detection of fetal aneuploidy. STUDY DESIGN Twenty-four amniocentesis and 16 chorionic villus samples were used for microfluidic digital PCR analysis. Three thousand and sixty PCR reactions were performed for each of the target chromosomes (X, Y, 13, 18, and 21), and the number of single molecule amplifications was compared to a reference. The difference between target and reference chromosome counts was used to determine the ploidy of each of the target chromosomes. RESULTS Digital PCR accurately identified all cases of fetal trisomy (3 cases of trisomy 21, 3 cases of trisomy 18, and 2 cases of triosmy 13) in the 40 specimens analyzed. The remaining specimens were determined to have normal ploidy for the chromosomes tested. CONCLUSION Microfluidic digital PCR allows detection of fetal chromosomal aneuploidy utilizing uncultured amniocytes and chorionic villus tissue in less than 6 hours.

Noninvasive in vivo monitoring of tissue-specific global gene expression in humans.

Significance Circulating cell-free RNA in the blood provides a potential window into the health, phenotype, and developmental programs of a variety of human organs. We used high-throughput methods of RNA analysis such as microarrays and next-generation sequencing to characterize the global landscape of circulating RNA in human subjects. By focusing on tissue-specific genes, we were able to identify the relative contributions of these tissues to circulating RNA and monitor changes during tissue development and neurodegenerative disease states. Circulating cell-free RNA in the blood provides a potential window into the health, phenotype, and developmental programs of a variety of human organs. We used high-throughput methods of RNA analysis such as microarrays and next-generation sequencing to characterize the global landscape circulating RNA in a cohort of human subjects. By focusing on genes whose expression is highly specific to certain tissues, we were able to identify the relative contributions of these tissues to circulating RNA and to monitor changes in tissue development and health. As one application of this approach, we performed a longitudinal study on pregnant women and analyzed their combined cell-free RNA transcriptomes across all three trimesters of pregnancy and after delivery. In addition to the analysis of mRNA, we observed and characterized noncoding species such as long noncoding RNA and circular RNA transcripts whose presence had not been previously observed in human plasma. We demonstrate that it is possible to track specific longitudinal phenotypic changes in both the mother and the fetus and that it is possible to directly measure transcripts from a variety of fetal tissues in the maternal blood sample. We also studied the role of neuron-specific transcripts in the blood of healthy adults and those suffering from the neurodegenerative disorder Alzheimer’s disease and showed that disease specific neural transcripts are present at increased levels in the blood of affected individuals. Characterization of the cell-free transcriptome in its entirety may thus provide broad insights into human health and development without the need for invasive tissue sampling.

Trends in Cesarean Delivery for Twin Births in the United States: 1995–2008

OBJECTIVE: To estimate trends and risk factors for cesarean delivery for twins in the United States. METHODS: This was a cross-sectional study in which we calculated cesarean delivery rates for twins from 1995 to 2008 using National Center for Health Statistics data. We compared cesarean delivery rates by year and for vertex compared with breech presentation. The order of presentation for a given twin pair could not be determined from the available records and therefore analysis was based on individual discrete twin data. Multivariable logistic regression was used to estimate independent risk factors, including year of birth and maternal factors, for cesarean delivery. RESULTS: Cesarean delivery rates for twin births increased steadily from 53.4% to 75.0% in 2008. Rates rose for the breech twin category (81.5%–92.1%) and the vertex twin category (45.1%–68.2%). The relative increase in the cesarean delivery rate for preterm and term neonates was similar. After risk adjustment, there was an average increase noted in cesarean delivery of 5% each year during the study period (risk ratio 1.05, 95% confidence interval 1.04–1.05). CONCLUSION: Cesarean delivery rates for twin births increased dramatically from 1995 to 2008. This increase is significantly higher than that which could be explained by an increase in cesarean delivery for breech presentation of either the presenting or second twin. LEVEL OF EVIDENCE: II

Cost-effectiveness of a trial of labor after previous cesarean.

Objective To determine the cost-effective method of delivery, from societys perspective, in patients who have had a previous cesarean. Methods We completed an incremental cost-effectiveness analysis of a trial of labor relative to cesarean using a computerized model for a hypothetical 30-year old parturient. The model incorporated data from peer-reviewed studies, actual hospital costs, and utilities to quantify health-related quality of life. A threshold of

Randomized comparison of intravenous nitroglycerin and magnesium sulfate for treatment of preterm labor

50,000 per quality-adjusted life-years was used to define cost-effective. Results The model was most sensitive to the probability of successful vaginal delivery. If the probability of successful vaginal birth after cesarean (VBAC) was less than 0.65, elective repeat cesarean was both less costly and more effective than a trial of labor. Between 0.65 and 0.74, elective repeat cesarean was cost-effective (the cost-effectiveness ratio was less than

Antibiotic prophylaxis for prevention of postpartum perineal wound complications: a randomized controlled trial.

50,000 per quality-adjusted life-years), because, although it cost more than VBAC, it was offset by improved outcomes. Between 0.74 and 0.76, trial of labor was cost-effective. If the probability of successful vaginal delivery exceeded 0.76, trial of labor became less costly and more effective. Costs associated with a moderately morbid neonatal outcome, as well as the probabilities of infant morbidity occurring, heavily impacted our results. Conclusion The cost-effectiveness of VBAC depends on the likelihood of successful trial of labor. Our modeling suggests that a trial of labor is cost-effective if the probability of successful vaginal delivery is greater than 0.74. Improved algorithms are needed to more precisely estimate the likelihood that a patient with a previous cesarean will have a successful vaginal delivery.