Ultrasound measurement of umbilical venous flow volume at the intra-abdominal portion in normal fetuses.

PURPOSE: Umbilical venous flow volume (UVFV) measured using ultrasound can be used to assess placental circulation in a fetus. UVFV measured at the intra-abdominal portion using half the maximum flow velocity of the umbilical vein (UV) has good reproducibility with low variance. However, reference values in previous reports were based on a small number of cases with a wide reference range. In the present study, we evaluated UVFV standard values measured at the intra-abdominal portion in normal Japanese fetuses. METHODS: Measurements were performed on normal pregnant women during routine ultrasound screening at around 20 or 30 weeks of gestation. The diameter and flow velocity of the UV were measured at the fetal abdomen point between the insertion of the UV and branches of the portal vein. UVFV (ml/min) was calculated as follows: (UV diameter [cm]/2)2 × maximum velocity [cm/s] × 0.5 × 3.14 × 60). RESULTS: A total of 278 pregnant women were included in the study. UVFV increased with gestational weeks, and UVFV per estimated fetal weight (EFW) slightly decreased with increasing gestational weeks. The 50th (10th-90th) percentiles of UVFV per EFW at 20, 25, and 30 weeks of gestation were 130 (105-165), 123 (94-147), and 104 (80-131) ml/min/kg, respectively. CONCLUSION: New UVFV reference values measured at the intra-abdominal portion of fetuses using large-scale samples were established. Future studies should assess fetuses under pathologic conditions using UVFV reference values.

Association of maternal birth weight with the risk of low birth weight and small-for-gestational-age in offspring: A prospective single-center cohort study.

BACKGROUND: Although low birth weight in Japan has slightly increased over the past several decades, the association between maternal birth weight and pregnancy outcomes remains poorly understood. METHODS: In this hospital-based, prospective cohort study conducted at the National Center for Child Health and Development, we obtained information on pregnant women's birth weight via their maternal and child health handbook. We analyzed 944 women born at term after dividing them into five categories according to their birth weight: <2500 g, 2500-2999 g, 3000-3499 g, 3500-3999 g, and ≥4000 g. Multivariate logistic regression analysis and trend analysis were used to elucidate the extent to which maternal birth weight was associated with small-for-gestational-age and low birth weight in offspring, as well as with hypertensive disorders of pregnancy. RESULTS: Compared with women with a birth weight of 3000-3499 g, those born with a birth weight <2500 g had a significantly higher risk of low birth weight (adjusted odds ratio: 5.39, 95% confidence interval: 2.06-14.1) and small-for-gestational-age (adjusted odds ratio: 9.11, 95% confidence interval: 3.14-26.4) infants. No significant association was found between the incidence of hypertensive disorders of pregnancy and preterm birth. A linear relationship was observed between the lower birth weight categories and a higher risk of low birth weight and small-for-gestational-age (p-values for trends: 0.009 and <0.001, respectively), but no linear relationship was observed for the risk of preterm birth and hypertensive disorders of pregnancy (p-value for trends: 0.317 and 0.157, respectively). CONCLUSIONS: Our findings suggest that lower maternal birth weight is associated with small-for-gestational-age and low birth weight in offspring of women born at term.

Risk Profiling of the Solomon Technique versus Selective Technique of Fetoscopic Laser Surgery for Twin-Twin Transfusion Syndrome.

We evaluated the outcomes and adverse events after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS) using the Solomon technique in comparison to the selective technique. A retrospective analysis of a single-center consecutive cohort of FLS-treated TTTS using the selective (January 2010 to July 2014) and Solomon (August 2014 to December 2017) techniques was performed. Among 395 cases, 227 underwent selective coagulation and 168 underwent the Solomon technique. The incidence rates of recurrent TTTS (Solomon vs. selective: 0% vs. .9%, p = .510) and twin anemia-polycythemia sequence (.6% vs. .4%, p = .670) were very low in both groups. The incidence rates of placental abruption (Solomon vs. selective: 10.7% vs. 3.5%, p = .007) and preterm premature rupture of the membranes (pPROM) with subsequent delivery before 32 weeks (20.2% vs. 7.1%, p < .001) were higher in the Solomon group. The median birth recipient weight was significantly smaller in the Solomon group (1790 g vs. 1933 g, p = .049). The rate of survival of at least one twin was significantly higher in the Solomon group (98.2% vs. 93.8%, p = .046). The Solomon technique and total laser energy were significant risk factors for pPROM (odds ratio: 2.64, 1.07, 95% CI [1.32, 5.28], [1.01, 1.13], p = .006, p = .014, respectively). These findings suggest that the Solomon technique led to superior survival outcomes but increased risks of placental abruption, pPROM and fetal growth impairment. Total laser energy was associated with the occurrence of pPROM. Close attention to adverse events is required for perinatal management after FLS to treat TTTS using the Solomon technique.

Reliability and characteristics of ultrasound measurement of fetal umbilical venous blood flow volume according to the site of measurement.

PURPOSE: This study aimed at assessing the reliability and characteristics of fetal umbilical venous blood flow volume (UVFV) measurement using ultrasound. METHODS: We conducted a prospective study at our center from November 2017 to July 2019. We performed transabdominal ultrasound examinations at 18-34 weeks' gestation in uncomplicated singleton pregnancies. UVFV was calculated using vessel diameter (D) and maximum flow velocity (V) as follows: (D/2)2 × π × V × 0.5 × 60 (Q, mL/min). Two examiners measured each value three times in the free-loop (FL) and intra-abdominal (IA) portions of the umbilical vein. Intra-rater and inter-rater reliability was evaluated by intraclass correlation coefficient (ICC) and a Bland-Altman plot. RESULTS: Two hundred and eight cases were measured by two examiners. The rate of complete measurement at FL and IA was not significantly different (88.5% vs. 79.3%, respectively; p = 0.113). The intra-rater reliability of D and V was high at FL and IA. Regarding inter-rater reliability, the ICC of D, V, and Q was 0.973, 0.582, and 0.963 at FL, and 0.994, 0.912, and 0.989 at IA, respectively. A Bland-Altman plot showed that D and V had greater standard deviation at FL than IA. Regarding Q, the standard deviation at FL was also larger than at IA, and measurement variance at FL increased as the measured value increased, but that at IA did not. CONCLUSION: UVFV measurement showed high intra-rater and inter-rater reliability at FL and IA, but the variance of measurements at FL became large as the measured value increased. Properties of different measurement sites should be considered when evaluating UVFV.

Measurement of OH radicals distribution in a microwave plasma sheet using LIF method.

Microwave plasma sources (MPSs) operating at atmospheric pressure provide plasmas in the form of a flame or cylindrical column. In contrast, this article presents an innovative MPS (patented by us) for generating a new type of plasma, i.e. in the form of a plasma sheet, which is generated in a flat cuboidal quartz box. It is based on a WR 340 waveguide, powered by microwaves of 2.45 GHz and operated in argon at atmospheric pressure. The plasma sheet contains a multitude of filaments typical of microwave argon plasmas. In the presented experiment, the spatial distribution of the OH radicals in the microwave plasma sheet was measured by means of the LIF method. Studies have shown that the relative concentration of OH radicals increases with the increase in microwave power and decreases with the increasing argon flow rate.

Percolation simulation of laser-guided electrical discharges.

A three-dimensional simulation of laser-guided discharges based on percolation is presented. The model includes both local growth of a streamer due to the enhanced electric field at the streamer's tip and propagation of a leader by remote ionization such as that caused by runaway electrons. The stochastic behavior of the discharge through a preformed plasma channel is reproduced by the calculation, which shows complex path with detouring and bifurcation. The probability of guiding is investigated with respect to the ionized, conductive fraction along the channel.