Cell-free DNA analysis for noninvasive examination of trisomy.

BACKGROUND: Cell-free DNA (cfDNA) testing for fetal trisomy is highly effective among high-risk women. However, there have been few direct, well-powered studies comparing cfDNA testing with standard screening during the first trimester in routine prenatal populations. METHODS: In this prospective, multicenter, blinded study conducted at 35 international centers, we assigned pregnant women presenting for aneuploidy screening at 10 to 14 weeks of gestation to undergo both standard screening (with measurement of nuchal translucency and biochemical analytes) and cfDNA testing. Participants received the results of standard screening; the results of cfDNA testing were blinded. Determination of the birth outcome was based on diagnostic genetic testing or newborn examination. The primary outcome was the area under the receiver-operating-characteristic curve (AUC) for trisomy 21 (Down's syndrome) with cfDNA testing versus standard screening. We also evaluated cfDNA testing and standard screening to assess the risk of trisomies 18 and 13. RESULTS: Of 18,955 women who were enrolled, results from 15,841 were available for analysis. The mean maternal age was 30.7 years, and the mean gestational age at testing was 12.5 weeks. The AUC for trisomy 21 was 0.999 for cfDNA testing and 0.958 for standard screening (P=0.001). Trisomy 21 was detected in 38 of 38 women (100%; 95% confidence interval [CI], 90.7 to 100) in the cfDNA-testing group, as compared with 30 of 38 women (78.9%; 95% CI, 62.7 to 90.4) in the standard-screening group (P=0.008). False positive rates were 0.06% (95% CI, 0.03 to 0.11) in the cfDNA group and 5.4% (95% CI, 5.1 to 5.8) in the standard-screening group (P<0.001). The positive predictive value for cfDNA testing was 80.9% (95% CI, 66.7 to 90.9), as compared with 3.4% (95% CI, 2.3 to 4.8) for standard screening (P<0.001). CONCLUSIONS: In this large, routine prenatal-screening population, cfDNA testing for trisomy 21 had higher sensitivity, a lower false positive rate, and higher positive predictive value than did standard screening with the measurement of nuchal translucency and biochemical analytes. (Funded by Ariosa Diagnostics and Perinatal Quality Foundation; NEXT ClinicalTrials.gov number, NCT01511458.).

The case for an electronic fetal heart rate monitoring credentialing examination.

The Perinatal Quality Foundation has created an examination containing both knowledge-based and judgment questions relating to the interpretation of electronic fetal heart rate monitoring for credentialing all medical and nursing personnel working on a labor and delivery floor. A description of the examination and the rationale for its use throughout the United States is presented.

Do clinical practitioners seeking credentialing for nuchal translucency measurement demonstrate compliance with biosafety recommendations? Experience of the Nuchal Translucency Quality Review Program.

OBJECTIVES: The purpose of this study was to evaluate compliance with the ALARA (as low as reasonably achievable) principle by practitioners seeking credentialing for nuchal translucency (NT) measurement between 11 and 14 weeks' gestation. METHODS: Nuchal Translucency Quality Review Program credentialing requires quantitative scoring of 5 NT measurements from 5 different fetuses. Images submitted by 100 consecutive practitioners were retrospectively evaluated for the output display standard (ODS). The thermal index (TI) type (bone [TIb] or soft tissue [TIs]) and numeric value of the index were recorded. The TIb was considered the correct index for this study. Compliance with the numeric value was evaluated in several ways. Collectively, a TIb lower than 0.5 was considered optimal, lower than 0.7 compliant, and 1.0 or lower satisfactory. RESULTS: An ODS was present in at least 1 image submitted by 77 practitioners. The TIb was used exclusively by 15 (19.5%), the TIs by 37 (48.1%), and 25 used a combination of the TIb and TIs. Only 4 of 77 providers (5%) used the correct TI type (TIb) at lower than 0.5 for all submitted images, 5 of 77 (6%) at lower than 0.7, and 9 of 77 (12%) at 1.0 or lower. A TI (TIb or TIs) higher than 1.0 was used by 15 of 77 providers (19.5%). Proficiency in NT measurement and educational background (physician or sonographer) did not influence compliance with ALARA. CONCLUSIONS: Clinicians seeking credentialing in NT do not demonstrate compliance with the recommended use of the TIb in monitoring acoustic output.

Trends in Reporting of Nuchal Translucency Measurements After the Clinical Introduction of Cell-Free DNA Screening.

Nuchal translucency (NT) measurement in conjunction with serum analytes has been used for first-trimester aneuploidy screening in the United States since 2005. We sought to analyze the trends in reporting of NT measurements to the Nuchal Translucency Quality Review program in all pregnancies beginning after the clinical introduction of cell-free DNA (cfDNA) screening for fetal aneuploidy in 2011. Overall, reported NT measurements decreased 74.3% from 2012 to 2022. A similar decline was noted among individuals with pregnancies at increased risk for aneuploidy based on patient age and twin gestations. The decrease in reporting aligns temporally with the availability of cfDNA screening and the coronavirus disease 2019 (COVID-19) pandemic.

Assessment of Transvaginal Ultrasound Cervical Length Image Quality.

OBJECTIVE: To use data from the Cervical Length Education and Review program to evaluate the quality of transvaginal cervical length ultrasonography by trained imagers (ie, ultrasonographers, radiologists, perinatologists). METHODS: This is a retrospective observational study of data from the Cervical Length Education and Review program. Candidates underwent an online lecture series, examination, and submitted a batch of images for review. For a candidate's batch of images to pass, all images must meet at least seven of the nine criteria assessed, the overall batch score needs to be 80% or greater, correct caliper placement must be met for all images, and the same criterion cannot be consistently missed. We also examined a subset of these criteria-appropriate image acquisitions, defined as an image that demonstrated both internal and external os and visualization of the entire endocervical canal. Primary outcome was the overall initial candidate pass rate; secondary outcomes included distribution of criteria missed in images and percentage of images that was inadequately acquired. RESULTS: Six hundred eighty-seven candidates submitted 3,748 images between June 10, 2012, and August 18, 2016. Eighty-five percent of candidates were ultrasonographers. Of the 687 initial batches submitted, 105 (15%) did not pass. Eight hundred thirty-seven images (22%) of all images failed at least one criterion; the most common image deficiencies were in "anterior width of cervix equals the posterior width" (33%), "failure to visualize" the internal or external os (29%), "cervix occupies 75% of image and bladder area visible" (33%), and incorrect caliper placement (24%). Two hundred fifty-six (7%) of all images failed to meet our criteria for adequate image acquisition. CONCLUSION: Fifteen percent of trained imagers failed to obtain appropriate cervical length imaging. This highlights the importance of a standardized cervical length training and certification program.

Implementation of a national nuchal translucency education and quality monitoring program.

In 2004, leaders in first-trimester aneuploidy screening and a multidisciplinary group of experts established the Nuchal Translucency Quality Review Program, a national program to standardize education, credentialing, and quality monitoring of nuchal translucency. Since its inception, the program has credentialed more than 6,600 physician and ultrasonographer participants and collected more than 2.4 million nuchal translucency measurements. Ongoing quality monitoring is conducted through statistical analysis comparing the distribution and standard deviation of participants' nuchal translucency measurements against those obtained from a standard referent curve. Results of these analyses are distributed to participants quarterly and are used to track each participant's performance and to trigger performance improvement activities or mandatory remediation. This program could serve as a template for future education and credentialing programs that include partnerships with academic leaders, national professional organizations, and industry.

Assessment of cellular actin dynamics by measurement of fluorescence anisotropy.

To study cellular actin dynamics, a cell-free assay based on fluorescence anisotropy was developed. Using G-actin-Alexa as a probe, we found that anisotropy enhancement reflects F-actin elongation. Anisotropy enhancement varies with the concentration of magnesium and calcium cations and with ethylenediaminetetraacetate or well-known effectors of the polymerization. This assay gives the overall status of actin dynamics in cell extracts which are the closest conditions to in vivo, implying most of the regulating proteins that are missing in purified actin measurements. It can be used in a large-scale screening for chemical compounds which modulate actin polymerization.

Specific triazine resistance in bacterial reaction centers induced by a single mutation in the QA protein pocket.

We report here the first example of a reaction center mutant from Rhodobacter sphaeroides, where a single mutation (M266His --> Leu) taking place in the primary quinone protein pocket confers selective resistance to triazine-type inhibitors (terbutryn, ametryn, and atrazine), which bind in the secondary quinone protein pocket, at about 13 A from the mutation site. The M266His --> Leu mutation involves one of the iron atom ligands. Interestingly, neither the secondary quinone nor the highly specific inhibitor stigmatellin binding affinities are affected by the mutation. It is noticeable that in the M266His --> Ala mutant a nativelike behavior in observed. We suggest that the long side chain of Leu in position M266 may lack space to accommodate in the Q(A) pocket therefore transferring its hindrance to the Q(B) pocket. This may occur via the structural feature formed by the Q(A)-M219His-Fe-L190His-inhibitor (or Q(B)) connection, pushing L189Leu and/or L229Ile in closer contact to the triazine molecules, therefore decreasing their bindings. This opens the possibility to finely tune, in reaction center proteins, the affinity for herbicides by designing mutations distant from their binding sites.