Chapter 6: The Breadth and Limits of Life on Earth.

Scientific ideas about the potential existence of life elsewhere in the universe are predominantly informed by knowledge about life on Earth. Over the past ∼4 billion years, life on Earth has evolved into millions of unique species. Life now inhabits nearly every environmental niche on Earth that has been explored. Despite the wide variety of species and diverse biochemistry of modern life, many features, such as energy production mechanisms and nutrient requirements, are conserved across the Tree of Life. Such conserved features help define the operational parameters required by life and therefore help direct the exploration and evaluation of habitability in extraterrestrial environments. As new diversity in the Tree of Life continues to expand, so do the known limits of life on Earth and the range of environments considered habitable elsewhere. The metabolic processes used by organisms living on the edge of habitability provide insights into the types of environments that would be most suitable to hosting extraterrestrial life, crucial for planning and developing future astrobiology missions. This chapter will introduce readers to the breadth and limits of life on Earth and show how the study of life at the extremes can inform the broader field of astrobiology.

Prediction of dual survival following fetoscopic laser photocoagulation for twin-twin transfusion syndrome.

OBJECTIVE: To develop a model based on factors available at the time of diagnosis of twin-twin transfusion syndrome (TTTS) for predicting the probability of dual twin survival following fetoscopic laser photocoagulation (FLP) using a machine-learning algorithm. METHODS: This was a retrospective study of data collected at two university-affiliated tertiary fetal centers between 2012 and 2021. The cohort included monochorionic diamniotic twin pregnancies complicated by TTTS that underwent FLP. Data were stratified based on survival 30 days after delivery, and cases with dual survival were compared to those without dual survival. A random forest machine-learning algorithm was used to construct a prediction model, and the relative importance value was calculated for each parameter that presented a statistically significant difference between the two study groups and was included in the model. The holdout method was applied to check overfitting of the random forest algorithm. A prediction model for dual twin survival 30 days after delivery was presented based on the test set. RESULTS: The study included 537 women with monochorionic diamniotic twin pregnancy, of whom 346 (64.4%) had dual twin survival at 30 days after delivery and were compared with 191 (35.6%) cases that had one or no survivors. Univariate analysis demonstrated no differences in demographic parameters between the groups. At the time of diagnosis, the dual-survival group had lower rates of estimated fetal weight (EFW) < 10th centile for gestational age in the donor twin (56.4% vs 69.4%; P = 0.004), intertwin EFW discordance > 25% (40.8% vs 56.5%; P = 0.001) and anterior placenta (40.5% vs 50.0%; P = 0.034). Comparison of Doppler findings between the two groups demonstrated significant differences in the donor twin, with a lower rate of pulsatility index (PI) > 95th centile in the umbilical artery and ductus venosus and a lower rate of PI < 5th centile in the fetal middle cerebral artery in the dual-survival group. Relative importance values for each of these six parameters were calculated, allowing the construction of a prediction model with an area under the receiver-operating-characteristics curve of 0.916 (95% CI, 0.887-0.946). CONCLUSIONS: We developed a predictive model for dual survival in monochorionic twin pregnancies following FLP for TTTS, which incorporates six variables obtained at the time of diagnosis of TTTS, including donor EFW < 10th centile, intertwin EFW discordance > 25%, anterior placenta and abnormal PI in the umbilical artery, ductus venosus and middle cerebral artery of the donor twin. This clinically applicable tool may improve treatment planning and patient counseling. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Perinatal outcomes of fetoscopic laser surgery for twin-twin transfusion syndrome in triplet pregnancy: cohort study, systematic review and meta-analysis.

OBJECTIVES: The aims of this study were to investigate the perinatal outcome of dichorionic triamniotic (DCTA) and monochorionic triamniotic (MCTA) triplet pregnancies complicated by twin-twin transfusion syndrome (TTTS) treated with fetoscopic laser photocoagulation (FLP) in two academic fetal centers, and to conduct a systematic review of previously published data to investigate perinatal survival in this targeted population. METHODS: The first part of the study was a retrospective cohort study of prospectively collected data of consecutive triplet pregnancies with TTTS that underwent FLP at two fetal treatment centers between 2012 and 2020. Demographic, preoperative and operative variables and postoperative outcome were collected. Perinatal outcomes were investigated. The second part of the study was a systematic review and meta-analysis of studies evaluating the outcome of DCTA and/or MCTA triplet pregnancies, including our cohort study. PubMed, Web of Science and Scopus were searched from inception to September 2020. Primary outcomes were fetal survival (survival to birth), neonatal survival (survival to 28 days of age) and gestational age (GA) at birth. RESULTS: A total of 31 sets of triplets with TTTS managed with FLP were included in the cohort study. Of these, 24 were DCTA and seven were MCTA. There were no significant differences in preoperative and operative variables between the two groups. There were also no significant differences between groups in GA at delivery or perinatal survival rate, including fetal and neonatal survival of at least one triplet, at least two triplets and all three triplets. Nine studies, including our cohort study, were included in the systematic review (156 DCTA and 37 MCTA triplet pregnancies treated with FLP). The overall fetal and neonatal survival was 79% (95% CI, 75-83%) and 75% (95% CI, 71-79%), respectively, in DCTA cases and 74% (95% CI, 52-92%) and 71% (95% CI, 49-89%), respectively, in MCTA cases. The rate of preterm birth before 28 weeks and before 32 weeks' gestation was 14% (95% CI, 4-29%) and 61% (95% CI, 50-72%), respectively, in DCTA triplets and 21% (95% CI, 3-45%) and 82% (95% CI, 62-96%), respectively, in MCTA triplets. CONCLUSIONS: Triplet pregnancies with TTTS are at high risk of adverse perinatal outcome and preterm birth, regardless of chorionicity. The rate of survival after FLP in MCTA triplets was higher in our study than that reported in previous studies and is currently comparable with survival in DCTA triplets, which could be due to improved surgical skills. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

B-flow/spatiotemporal image correlation M-mode: novel ultrasound method that detects decrease in spiral artery luminal diameter in first trimester in primate model of impaired spiral artery remodeling.

OBJECTIVE: To determine if B-flow/spatiotemporal image correlation (STIC) M-mode ultrasonography detects a decrease in spiral artery luminal diameter and volume flow during the first trimester in a non-human primate model of impaired spiral artery remodeling (SAR). METHODS: Pregnant baboons were treated daily with estradiol benzoate on days 25-59 of the first trimester (term, 184 days), or remained untreated. On day 60 of gestation, spiral artery luminal diameter (in seven untreated and 12 estradiol-treated baboons) and volume flow (in four untreated and eight estradiol-treated baboons) were quantified by B-flow/STIC M-mode ultrasonography. In addition, in 15 untreated and 18 estradiol-treated baboons, the percent of spiral arteries remodeled by extravillous trophoblasts was quantified ex vivo by immunohistochemical image analysis on placental basal plate tissue collected via Cesarean section on day 60. Findings were compared between treated and untreated animals. The correlation between spiral artery luminal diameter and percent of SAR was assessed in three untreated and six estradiol-treated baboons which underwent both B-flow/STIC M-mode ultrasound and quantification of SAR. RESULTS: The proportion of spiral arteries greater than 50 µm in diameter remodeled by extravillous trophoblasts was 70% lower in estradiol-treated baboons than in untreated animals (P = 0.000001). Spiral artery luminal diameter in systole and diastole, as quantified by B-flow/STIC M-mode in the first trimester of pregnancy, was 31% (P = 0.014) and 50% (P = 0.005) lower, respectively, and volume flow was 85% lower (P = 0.014), in SAR-suppressed baboons compared with untreated animals. There was a significant correlation between spiral artery luminal diameter as quantified by B-flow/STIC M-mode ultrasonography and the percent of SAR (P < 0.05). CONCLUSION: B-flow/STIC M-mode ultrasonography provides a novel real-time non-invasive method to detect a decrease in uterine spiral artery luminal diameter and volume flow during the cardiac cycle, reflecting decreased distensibility of the vessel wall, in the first trimester in a non-human primate model of defective SAR. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Iatrogenic chorioamniotic separation and septostomy following fetoscopic laser photocoagulation for twin-twin transfusion syndrome.

OBJECTIVE: To compare the perinatal outcomes of pregnancies complicated by chorioamniotic separation (CAS) vs septostomy following fetoscopic laser photocoagulation (FLP) for twin-twin transfusion syndrome (TTTS). METHODS: This was a retrospective cohort analysis of monochorionic diamniotic twin pregnancies with TTTS that underwent FLP at one of two university-affiliated tertiary medical centers between January 2012 and December 2020. CAS and septostomy were diagnosed either during the procedure or by ultrasonography within 24-48 h after FLP. Data on procedure and postprocedure parameters, pregnancy outcomes and survival were collected from the patients' electronic medical records. Pregnancies were stratified according to the presence of CAS, septostomy or neither. Patients diagnosed with both CAS and septostomy were analyzed separately. RESULTS: Of the 522 women included in the cohort, 38 (7.3%) were diagnosed with CAS, 68 (13.0%) with septostomy and 23 (4.4%) with both CAS and septostomy. The remaining 393 (75.3%) women comprised the control group. Groups did not differ in demographic characteristics. The septostomy group had a lower rate of selective fetal growth restriction than did the CAS and control groups (24.2% vs 36.8% vs 42.7%, respectively; P = 0.017). Moreover, intertwin size discordance was lower in the septostomy group (15.1% vs 23.4% in the CAS group and 25.5% in the control group; P = 0.001). Median gestational age at FLP was significantly lower in the CAS group (19.3 weeks vs 20.4 weeks in controls and 20.9 weeks in the septostomy group; P = 0.049). The rate of delivery prior to 34 weeks was significantly higher in the CAS group (89.2%), followed by the septostomy group (80.9%), compared with the control group (69.0%) (P = 0.006). A secondary analysis demonstrated that patients with both CAS and septostomy presented the highest rates of delivery prior to 34 weeks (100%) and 32 weeks (68.2%). CONCLUSIONS: CAS and septostomy following laser surgery for TTTS are independently associated with higher rates of preterm delivery. The presence of these two findings in the same patient enhances the risk of prematurity. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Efficacy of long-term indomethacin therapy in prolonging pregnancy after fetoscopic laser surgery for twin-to-twin transfusion syndrome: a collaborative cohort study.

OBJECTIVE: To evaluate the efficacy of long-term indomethacin therapy (LIT) in prolonging pregnancy and reducing spontaneous preterm birth (PTB) in patients undergoing fetoscopic laser surgery (FLS) for the management of twin-to-twin transfusion syndrome (TTTS). DESIGN: Retrospective cohort study of prospectively collected data. SETTING: Collaborative multicentre study. POPULATION: Five hundred and fifty-seven consecutive TTTS cases that underwent FLS. METHODS: Long-term indomethacin therapy was defined as indomethacin use for at least 48 hours. Log-binomial regression was used to estimate the relative risk of PTB in the LIT group compared with a non-LIT group. Cox regression was used to evaluate the association between LIT use and FLS-to-delivery survival. MAIN OUTCOME MEASURES: Gestational age (GA) at delivery. RESULTS: Among the 411 pregnancies included, a total of 180 patients (43.8%) received LIT after FLS and 231 patients (56.2%) did not. Median GA at fetal intervention did not differ between groups (20.4 weeks). Median GA at delivery was significantly higher in the LIT group (33.6 weeks) compared with the non-LIT group (31.1 weeks; P < 0.001). FLS-to-delivery interval was significantly longer in the LIT group (P < 0.001). The risks of PTB before 34, 32, 28 and 26 weeks of gestation were all significantly lower in the LIT group compared with the non-LIT group (relative risks 0.69, 0.51, 0.37 and 0.18, respectively). The number needed to treat with LIT to prevent one PTB before 32 weeks of gestation was four, and to prevent one PTB before 34 weeks was five. CONCLUSION: Long-term indomethacin after FLS for TTTS was found to be associated with prolongation of pregnancy and reduced risk for PTB. TWEETABLE ABSTRACT: Long-term indomethacin used after fetoscopic laser surgery for twin-to-twin transfusion syndrome is effective in prolonging pregnancy and reducing the risk for preterm birth; especially extreme preterm birth.

Early laser surgery is not associated with very preterm delivery or reduced neonatal survival in TTTS.

OBJECTIVE: To evaluate the association of laser photocoagulation of placental anastomoses (LPA) prior to 18 weeks' gestation (early LPA) with very preterm delivery and neonatal survival in pregnancies with twin-twin transfusion syndrome (TTTS). METHODS: This was a retrospective cohort study of monochorionic diamniotic twin pregnancies with TTTS undergoing LPA between 2002 and 2018 at two institutions. The rates of delivery < 28, < 30 and < 32 weeks' gestation, preterm prelabor rupture of membranes (PPROM) and 30-day survival of one or both infants were compared between pregnancies undergoing early LPA and those undergoing LPA ≥ 18 weeks' gestation. Regression analysis was performed to determine the association of early LPA with very preterm delivery and 30-day survival, adjusted for Quintero stage, study phase, selective fetal growth restriction, gestational age at delivery, maternal age ≥ 35 years, body mass index > 35 kg/m2 , placental location, use of Seldinger method to place the operative trocar, size of the trocar, participating center, use of Solomon technique, cerclage and PPROM. Survival analysis using the Cox proportional hazard model was applied to examine the LPA-to-delivery interval according to the timing of surgery, adjusted for confounding variables. RESULTS: A total of 414 TTTS pregnancies were included in the study, of which 68 (16.4%) underwent early LPA. In the total cohort, the incidence of delivery at < 28, < 30 and < 32 weeks' gestation was 22.7%, 39.6% and 53.4%, respectively. Survival of both twins and survival of at least one twin at 30 days were 67.5% and 90.8%, respectively. No significant difference was noted between pregnancies that underwent early LPA and those that had LPA ≥ 18 weeks in the rate of delivery < 28 weeks (19.1% vs 23.4%; P = 0.4), < 30 weeks (38.2% vs 39.9%; P = 0.8) and < 32 weeks (44.1% vs 55.2%; P = 0.1) and PPROM (29.0% vs 24.1%; P = 0.4), or in the incidence of double-twin survival (63.9% vs 68.1%; P = 0.5) and survival of at least one infant (91.8% vs 90.6%; P = 0.7) at 30 days. Early LPA was not associated with very preterm delivery or neonatal survival in the regression analyses. Early LPA was associated with a longer LPA-to-delivery interval compared with LPA performed ≥ 18 weeks (median, 106.9 days (range, 2-164 days) vs median, 69.3 days (range, 0-146 days); P < 0.001) when adjusted for confounding variables (hazard ratio, 2.56 (95% CI, 1.76-3.73); P < 0.001). CONCLUSION: Laser surgery before 18 weeks is not associated with an increased rate of very preterm delivery and PPROM or with reduced neonatal survival when compared with LPA after 18 weeks. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Adjuvant bevacizumab for melanoma patients at high risk of recurrence: survival analysis of the AVAST-M trial.

Background: Bevacizumab is a recombinant humanised monoclonal antibody to vascular endothelial growth factor shown to improve survival in advanced solid cancers. We evaluated the role of adjuvant bevacizumab in melanoma patients at high risk of recurrence. Patients and methods: Patients with resected AJCC stage IIB, IIC and III cutaneous melanoma were randomised to receive either adjuvant bevacizumab (7.5 mg/kg i.v. 3 weekly for 1 year) or standard observation. The primary end point was detection of an 8% difference in 5-year overall survival (OS) rate; secondary end points included disease-free interval (DFI) and distant metastasis-free interval (DMFI). Tumour and blood were analysed for prognostic and predictive markers. Results: Patients (n=1343) recruited between 2007 and 2012 were predominantly stage III (73%), with median age 56 years (range 18-88 years). With 6.4-year median follow-up, 515 (38%) patients had died [254 (38%) bevacizumab; 261 (39%) observation]; 707 (53%) patients had disease recurrence [336 (50%) bevacizumab, 371 (55%) observation]. OS at 5 years was 64% for both groups [hazard ratio (HR) 0.98; 95% confidence interval (CI) 0.82-1.16, P = 0.78). At 5 years, 51% were disease free on bevacizumab versus 45% on observation (HR 0.85; 95% CI 0.74-0.99, P = 0.03), 58% were distant metastasis free on bevacizumab versus 54% on observation (HR 0.91; 95% CI 0.78-1.07, P = 0.25). Forty four percent of 682 melanomas assessed had a BRAFV600 mutation. In the observation arm, BRAF mutant patients had a trend towards poorer OS compared with BRAF wild-type patients (P = 0.06). BRAF mutation positivity trended towards better OS with bevacizumab (P = 0.21). Conclusions: Adjuvant bevacizumab after resection of high-risk melanoma improves DFI, but not OS. BRAF mutation status may predict for poorer OS untreated and potential benefit from bevacizumab. Clinical Trial Information: ISRCTN 81261306; EudraCT Number: 2006-005505-64.

Geophysical imaging reveals topographic stress control of bedrock weathering.

Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbations to regional stress fields explain bedrock fracture distributions, as revealed by seismic velocity and electrical resistivity surveys from three landscapes. The base of the fracture-rich zone mirrors surface topography where the ratio of horizontal compressive tectonic stresses to near-surface gravitational stresses is relatively large, and it parallels the surface topography where the ratio is relatively small. Three-dimensional stress calculations predict these results, suggesting that tectonic stresses interact with topography to influence bedrock disaggregation, groundwater flow, chemical weathering, and the depth of the "critical zone" in which many biogeochemical processes occur.

Impact of structural and metabolic variations on the toxicity and carcinogenicity of hydroxy- and alkoxy-substituted allyl- and propenylbenzenes.

The metabolic fate of a compound is determined by numerous factors including its chemical structure. Although the metabolic options for a variety of functional groups are well understood and can often provide a rationale for the comparison of toxicity based on structural analogy, at times quite minor structural variations may have major consequences for metabolic outcomes and toxicity. In this perspective, the effects of structural variations on metabolic outcomes is detailed for a group of related hydroxy- and alkoxy-substituted allyl- and propenylbenzenes. These classes of compounds are naturally occurring constituents of a variety of botanical-based food items. The classes vary from one another by the presence or absence of alkylation of their para-hydroxyl substituents and/or the position of the double bond in the alkyl side chain. We provide an overview of how these subtle structural variations alter the metabolism of these important food-borne compounds, ultimately influencing their toxicity, particularly their DNA reactivity and carcinogenic potential. The data reveal that detailed knowledge of the consequences of subtle structural variations for metabolism is essential for adequate comparison of structurally related chemicals. Taken together, it is concluded that predictions in toxicological risk assessment should not be performed on the basis of structural analogy only but should include an analogy of metabolic pathways across compounds and species.

First-trimester fetal cardiac examination using spatiotemporal image correlation, tomographic ultrasound and color Doppler imaging for the diagnosis of complex congenital heart disease in high-risk patients.

OBJECTIVE: A four-dimensional (4D) fetal echocardiographic technique utilizing spatiotemporal image correlation, tomographic ultrasound imaging display (STIC-TUI echo) and color Doppler has previously been shown to be effective in displaying the examination planes constituting the extended cardiac examination. The aim of this study was to evaluate the performance of this first-trimester STIC-TUI echo technique in identifying complex congenital heart disease (CHD) in high-risk pregnancies. METHODS: This was a prospective study of patients presenting at first-trimester screening who were at high risk for CHD owing to pregestational diabetes, in-vitro fertilization (IVF), increased nuchal translucency (NT) thickness, first-trimester tricuspid regurgitation or reversed ductus venosus (DV) a-wave, a previous child with CHD or who were on anticonvulsant medication. First-trimester STIC-TUI echo was performed, and the findings were correlated with second-trimester echocardiography and post-delivery echo findings in survivors. RESULTS: One hundred and sixty-four fetuses from 152 patients were enrolled (77 diabetics, 38 IVF, 14 with increased NT, 23 cases of tricuspid regurgitation or reversed a-wave in the DV, 22 with prior CHD and two on anticonvulsants). STIC-TUI echo was abnormal in 20 (12%), showing atrioventricular canal defect (n = 9), hypoplastic left heart (n = 2), pulmonary stenosis (n = 2), right aortic arch (n = 1), interrupted aortic arch (n = 1), tricuspid atresia (n = 1), heterotaxy (n = 1), persistent truncus arteriosus (n = 1), double outlet right ventricle and ventricular septal defect (n = 1) and double inlet ventricle with transposition of the great arteries (n = 1). 85% of these anomalies were evident in the four-chamber view plane of the TUI display, and the remainder were diagnosed in the outflow tract planes with color Doppler imaging. In 13, CHD was isolated while seven had extracardiac anomalies. Thirteen fetuses had aneuploidy and all 13 underwent first-trimester termination of pregnancy. In the remaining seven, second-trimester echocardiography and neonatal echo/postmortem examination confirmed anomalies (two stillborn neonates, one neonatal death, four live births). Two cases of CHD missed by first-trimester STIC-TUI echo were diagnosed on second-trimester echo. Accordingly, first-trimester STIC-TUI echo had 91% sensitivity and 100% specificity for the detection of CHD. CONCLUSIONS: First-trimester 4D echocardiography using a standardized application of STIC, TUI and color Doppler imaging is effective in displaying the imaging planes that are necessary for achieving the diagnosis of complex cardiac anomalies in high-risk patients. Optimal imaging of the four-chamber view with two-dimensional ultrasound is the major determinant of successful volume acquisition.

Risk factors associated with preterm delivery after fetoscopic laser ablation for twin-twin transfusion syndrome.

OBJECTIVE: Despite improved perinatal survival following fetoscopic laser ablation (FLA) for twin-twin transfusion syndrome (TTTS), prematurity remains an important contributor to perinatal mortality and morbidity. The objective of the study was to identify risk factors for complicated preterm delivery after FLA. METHODS: Retrospective cohort study of prospectively collected data on maternal/fetal demographics and pre-operative, operative and postoperative variables of 459 patients treated with FLA in three USA fetal centers. Multivariate linear regression was performed to identify significant risk factors associated with preterm delivery, which were cross-validated using the k-fold method. Multivariate logistic regression was performed to identify risk factors for early compared with late preterm delivery based on median gestational age at delivery of 32 weeks. RESULTS: There were significant differences in case selection and outcomes between the centers. After controlling for the center of surgery, multivariate analysis indicated that a lower maternal age at procedure, a history of previous prematurity, shortened cervical length, use of amnioinfusion, a cannula diameter of 12 French (Fr), lack of a collagen plug placement and iatrogenic preterm premature rupture of membranes (iPPROM) were significantly associated with a lower gestational age at delivery. CONCLUSIONS: Specific fetal/maternal and operative variables are associated with preterm delivery after FLA for the treatment of TTTS. Further studies to modify some of these variables may decrease the perinatal morbidity after laser therapy.

Hematologic profile of neonates with growth restriction is associated with rate and degree of prenatal Doppler deterioration.

OBJECTIVE: To examine the relationship between hematologic parameters at birth and prenatal progression of Doppler abnormalities in fetal growth restriction (FGR). METHODS: The study was a secondary analysis of FGR patients (abdominal circumference < 5th percentile and umbilical artery pulsatility index (UA-PI) elevation) with at least three examinations prior to delivery. Prenatal progression was classified as rapid, moderate or slow based on the interval between diagnosis and delivery and the extent of UA, middle cerebral artery and ductus venosus Doppler abnormalities. Associations between diagnosis-to-delivery interval, Doppler Z-scores, progression and hematologic parameters at birth were examined. RESULTS: Of 130 patients, 54 (41.5%) had rapid, 51 (39.2%) moderate and 25 (19.2%) slow deterioration, delivering within 4, 6 and 9 weeks of diagnosis, respectively. The strongest association of moderate and rapid deterioration was with a low platelet count (r2 = 0.37 and 0.70, respectively; P < 0.0001). In patients with moderate deterioration, platelet count correlated inversely with UA-PI (ρ = -0.44, P = 0.001) and was lowest when end-diastolic velocity was absent. With rapid progression, platelet count correlated inversely with nucleated red blood cell count (ρ = -0.51, P < 0.001) but no longer with UA-PI. CONCLUSION: Our observations suggest a relationship between prenatal clinical progression of FGR and hematologic abnormalities at birth. Accelerating cardiovascular deterioration is associated with decreased platelet count, which can be explained by placental consumption or dysfunctional erythropoiesis and thrombopoiesis.

When are amniotic fluid viral PCR studies indicated in prenatal diagnosis?

OBJECTIVE: To determine which prenatal ultrasound findings indicate the need to also obtain PCR studies for viral genome in women undergoing midtrimester amniocentesis. METHODS: This was a retrospective observational study on women that underwent amniotic fluid karyotyping and viral PCR testing for history or ultrasound based indication. Amniotic fluid was tested for adenovirus, cytomegalovirus, respiratory syncytial virus, enterovirus, Epstein-Barr virus, and parvovirus B19 using multiplex PCR study with multiple appropriate controls. Ultrasound findings were coded as normal or abnormal with 34 categories of ultrasound abnormality stratified into 18 subgroups. Relationships between these subgroups and karyotype/PCR results were tested by Pearson chi-square method or Fisher's exact test and overall logistic regression analysis. RESULTS: Amniotic fluid samples from 1191 patients were obtained for the study. Abnormal karyotype was detected in 5.4% of cases (64/1191), and PCR was positive in 6.5% of cases (77/1191). Abnormal fetal ultrasonographic findings were observed in 28.4% of cases (338/1191). There was an association between intrauterine growth restriction, nonimmune hydrops fetalis, hand/foot anomalies or neural tube defects (NTDs), and PCR positivity. NTDs were associated with PCR positivity in fetuses with normal karyotype and nuchal thickening, cardiac or ventral wall defects were specifically associated with aneuploidy. CONCLUSION: Amniotic fluid viral PCR testing should be considered for fetuses with intrauterine growth restriction, nonimmune hydrops fetalis, hand/foot anomalies, or NTDs. After aneuploidy is excluded, NTDs are associated with PCR positivity.

Decreased fetal cardiac performance in the first trimester correlates with hyperglycemia in pregestational maternal diabetes.

OBJECTIVE: In-vitro animal studies suggest that high glucose levels impair fetal cardiac function early in gestation. We aimed to study whether evidence of first-trimester myocardial dysfunction can be detected in fetuses of women with pregestational diabetes mellitus. METHODS: Women with diabetes mellitus underwent fetal echocardiography at 11-14 weeks' gestational age. In fetuses with normal anatomy, the cardiac preload, diastolic function, global myocardial performance and placental afterload were studied by Doppler of the ductus venosus (DV), mitral and tricuspid early/atrial (E/A) ratios, left and right ventricular myocardial performance index (MPI) and umbilical artery (UA) Doppler, respectively. Cases were matched for gestational age and UA and DV Doppler with controls that had no diabetes mellitus. RESULTS: Sixty-three singleton diabetic pregnancies were matched with 63 controls. Mean gestational age at enrollment was 12.6 (range, 11.1-13.6) weeks. Diabetic mothers had moderate to poor glycemic control (median (range) glycosylated hemoglobin A1 (HbA1c), 7.5 (5.1-12.7)%, and the HbA1c level was ≥ 7% in 37 (59%)). Fetuses of diabetic mothers exhibited worse measures of diastolic dysfunction: the isovolumetric relaxation time (IRT) was significantly prolonged (left ventricle: 36.9 ± 7.4 ms vs. 45.8 ± 6.8 ms; right ventricle: 35.6 ± 8 ms vs. 46.4 ± 7.3 ms, P < 0.0001 for both). The mitral E/A ratio was lower in diabetics (0.55 ± 0.06 vs. 0.51 ± 0.08, P = 0.03), and the global myocardial performance was lower in both ventricles (left ventricle MPI: 0.5 ± 0.08; right ventricle MPI: 0.52 ± 0.08, P = 0.03 and P < 0.0001, respectively). This lower global myocardial performance was caused by a prolonged myocardial relaxation time, which was most marked in diabetics with an HbA1c of ≥ 7% (P < 0.001 vs. controls for both ventricles). There were no significant correlations between cardiac Doppler parameters and DV, UA indices and fetal heart rate (P > 0.05 for all). CONCLUSIONS: Fetuses of poorly controlled diabetic mothers demonstrate significant differences in first-trimester diastolic myocardial function compared with non-diabetic controls. The decrease in myocardial performance is more marked with increasing HbA1c and appears to be independent of preload and afterload. The ability to document these cardiac functional changes this early in pregnancy opens potential new avenues to understand the consequences of maternal glycemic status.

Duration of persistent abnormal ductus venosus flow and its impact on perinatal outcome in fetal growth restriction.

OBJECTIVE: To study if the duration of individual Doppler abnormalities is an independent predictor of adverse outcome in fetal growth restriction (FGR) caused by placental dysfunction. METHODS: This was a secondary analysis of patients with FGR (abdominal circumference < 5(th) percentile and umbilical artery (UA) pulsatility index (PI) elevation) who had at least three examinations before delivery. Days of duration of absent/reversed UA end-diastolic velocity (UA-AREDV), low middle cerebral artery PI (brain sparing), ductus venosus (DV) and umbilical vein Doppler abnormalities were related to stillbirth, major neonatal morbidity and intact survival. RESULTS: One hundred and seventy-seven study participants underwent a total of 1069 examinations. The duration of an absent/reversed a-wave in the DV (DV-RAV) was significantly higher in stillbirths (median, 6 days) compared with intact survivors and those with major morbidity (median, 0 days for both; P = 0.006 and P = 0.001, respectively). Duration of brain sparing was also longer in stillbirth cases compared with intact survivors (median, 19 days vs. 9 days, P = 0.02). Stepwise multinomial logistic regression showed that gestational age at delivery was a significant codeterminant of outcome for all arterial Doppler abnormalities when the DV a-wave was antegrade. However, when present, the duration of DV-RAV was the only contributor to stillbirth (probability of stillbirth = 1/(1 + exp - (interval to delivery × 1.03 - 2.28)), r2 = 0.73). Receiver-operating characteristics curve statistics showed that a DV-RAV for > 7 days predicted stillbirth (100% sensitivity, 80% specificity, likelihood ratio = 5.0, P < 0.0001). In contrast, neither neonatal death nor neonatal morbidity was predicted by the days of persistent DV-RAV. CONCLUSIONS: The duration of absent or reversed flow during atrial systole in the DV is a strong predictor of stillbirth that is independent of gestational age. While prematurity remains the strongest predictor of neonatal risks it is unlikely that pregnancy can be prolonged by more than 1 week in this setting.