Expectant management for umbilical artery thrombosis in monochorionic diamniotic twin pregnancies: a case report.

BACKGROUND: Thrombosis of one of the umbilical arteries is a rare complication of pregnancy and is associated with adverse pregnancy outcomes, including stillbirth and intrauterine growth restriction. Although extremely rare, umbilical artery thrombosis (UAT) in monochorionic diamniotic twins is difficult to diagnose prenatally and manage. UAT has a poor prognosis and is associated with an increased perinatal mortality rate. In most previous cases, emergency cesarean section was performed or intrauterine fetal death occurred at the time of UAT diagnosis. CASE PRESENTATION: Herein, we report an extremely rare case of sequential UAT in monochorionic diamniotic twins diagnosed via ultrasound at 29+ 5 weeks of gestation in a 34-year-old woman. Following expectant management with intensive monitoring for 16 days, two healthy infants were delivered through an emergency cesarean section. UAT in both fetuses was confirmed by pathological examination. The mother and twins described in this case underwent long-term follow-up and are currently in good health without any complications. CONCLUSIONS: Based on our experience, we suggest that expectant management should be undertaken as long as the mother and infants are stable on ultrasonographic scans and are closely monitored. When UAT is suspected, we believe that the best delivery time should be determined by considering complaints of unusual fetal movements, non-stress test evidence, gestational age, amniotic fluid volume, and blood flow in the umbilical artery, middle cerebral artery, and ductus venosus. Obstetricians should ensure that the patients and their families are clearly informed about all potential risks of expectant management for UAT.

Ultrasound parameters of early pregnancy and Doppler indices of blood vessels in the placenta and umbilical cord throughout the pregnancy period in sheep.

BACKGROUND: Ultrasonography is one of the most important techniques that enable the detection and monitoring of pregnancy. One such study using this technique is the assessment of the hemodynamics of fetal and umbilical blood vessels. However, there is little data on blood flow in the placentomes, which is the basic structural unit of the sheep's placenta. Therefore, the aim of this study was to determine the Doppler parameters in the arterial vessels of the caruncles, cotyledons and the umbilical cord as well as measuring venous flow rates during the entire gestation period of the sheep. Additionally, the usefulness of various other ultrasound parameters in the early diagnosis of pregnancy in sheep was analyzed. RESULTS: Most of the Doppler parameters in umbilical, cotyledonary and caruncular arteries were significantly correlated with the day of pregnancy (p < 0.01). In the early stages of pregnancy, the peak systolic velocity (PSV), regardless of the location of the artery, was significantly lower than that in the later stages of pregnancy (p < 0.01). PSV was also found to be significantly higher in the umbilical artery than in the cotyledonary and caruncular arteries (p < 0.01). Until the 50th day of pregnancy, the end diastolic velocity (EDV) was not found in the umbilical and cotyledonary arteries. EDV was significantly higher in the caruncular arteries than in the cotyledonary and umbilical arteries (p < 0.01). The resistance index (RI) and pulsatility index (PI) in the early stages of pregnancy were found to be significantly higher than that in the later stages of pregnancy (p < 0.01). The RI and PI were significantly lower in the caruncular arteries than in the arteries of the cotyledons and umbilical cord (p < 0.01). In the umbilical vein, all Doppler parameters were observed to be significantly higher than those in the placentomal veins (p < 0.01 or p < 0.05). Using transrectal ultrasound, pregnancy was detected between 20 and 28 days after mating. The ovaries were observed to have corpora lutea, the diameter of which was fairly consistent from the 17th to the 56th day of pregnancy. CONCLUSIONS: It has been demonstrated that both the location of the arterial vessel in the placental-umbilical circulation and the gestational age have a significant impact on hemodynamic parameters. The results also provide new insights about the blood flow in caruncular and cotyledonary arteries, which could contribute to a more holistic understanding of hemodynamic changes in the placentas of sheep. Analyzing haemodynamic parameters in the umbilical and placental veins are preliminary studies in sheep, but it could inspire further research in this field. Furthermore, the research conducted confirms the practicality and convenience of transrectal ultrasonography in the early diagnosis of pregnancy in sheep and also indicates that the identification and imaging of the corpus luteum using B-mode ultrasonography can be a very early and simple method of confirming effective mating in sheep.

Comparison of pregnancy outcomes and placental characteristics between selective fetal growth restriction with and without thick arterio-arterial anastomosis in monochorionic diamniotic twins.

BACKGROUND: Unequal placental territory in monochorionic diamniotic twins is a primary cause of selective fetal growth restriction (sFGR), and vascular anastomoses play important role in determining sFGR prognosis. This study investigated differences in placental characteristics and pregnancy outcomes in cases of sFGR with and without thick arterio-arterial anastomosis (AAA). METHODS: A total of 253 patients diagnosed with sFGR between April 2013 and April 2020 were retrospectively analyzed. An AAA greater than 2 mm in diameter was defined as a thick AAA. We compared placental characteristics and pregnancy outcomes between cases of sFGR with and without thick AAA. RESULTS: Prevalence of AAA, thick arterio-venous anastomosis (AVA), veno-venous anastomosis (VVA), and thick VVA were significantly higher in the thick AAA group relative to the non-thick AAA group (100.0 vs. 78.5%, P < 0.001; 44.3 vs. 15.4%, P < 0.001; 27.1 vs. 10.8%, P = 0.017, and 24.3 vs. 6.2%, P = 0.004, respectively). The total numbers of AVA and total anastomoses were significantly higher in thick AAA group relative to the non-thick AAA group (5 [1, 14] vs. 3 [1, 15, P = 0.016; and 6 [1, 15] vs. 5 [1, 16], P = 0.022, respectively). The total diameter of AAA, AVA, VVA, and all anastomoses in the thick AAA group was larger than in the non-thick AAA group (3.4 [2.0,7.1] vs. 1.4 [0.0, 3.3], P < 0.001; 6.3 [0.3, 12.0] vs. 2.5 [0.3, 17.8], P < 0.001; 4.2±1.8 vs. 1.9±1.2, P =0.004; and 10.7 [3.2,22.4] vs. 4.4 [0.5, 19.3], P < 0.001, respectively). Growth-restricted fetuses in the thick AAA group exhibited significantly increased birthweight relative to those in thenon-thick AAA group (1570 (530, 2460)g vs. 1230 (610, 2480)g, p = 0.002). CONCLUSIONS: In the placentas associated with sFGR, thick AAA can co-occur with thick AVA and VVA, and placental angiogenesis may differ significantly based upon whether or not thick AAA is present. The birth weights of growth-restricted fetuses in cases of sFGR with thick AAA are larger than in cases without thick AAA.

Dexamethasone on absent end-diastolic flow in umbilical artery, in growth restricted fetuses from early-onset preeclamptic pregnancies and the perinatal outcome.

BACKGROUND: Absent end-diastolic flow (AEDF) in the umbilical artery (UA) worsens the already poor prognosis of growth-restricted fetuses (GRFs) in pregnancies complicated by early-onset preeclampsia with severe features (ESP). METHOD: We assessed the correlation between the effect of maternal dexamethasone (Dex) on AEDF in the UA and perinatal outcomes, in 59 GRFs from EPS-complicated pregnancies. The maternal outcome was also evaluated. RESULTS: The mean maternal age at inclusion was 22.4 ± 5.9 years. Dex transiently restored EDF in the UA in 38 (64.4%) cases (trAEDF group), but in 21 (35.6%) patients, the flow was persistently absent (prAEDF group). The effect lasted up to the 4th day.The gestational age at diagnosis, number of days from admission until delivery, and fetal weight were significantly lower in the prAEDF group than in the trAEDF group (p < .05). The same group had a significantly increased rate of fetal proximal deterioration, low APGAR scores, neonatal hypoxia, assisted ventilation, mild intraventricular haemorrhage (I/II), and respiratory distress syndrome, as well as maternal deterioration, especially in cases of resistant hypertension (p < .05). Although the rates of fetal acidemia and perinatal mortality in the prAEDF group were respectively three times and two times higher, the differences were not significant (p > .05). CONCLUSIONS: The Dex no-effect on UA Doppler in GRFs with AEDF in the UA, in EPS-complicated pregnancies, can be a useful marker for a higher risk of proximal fetal deterioration, poor state at delivery, neonatal hypoxic complications, and worsening maternal condition, but not for perinatal mortality. The findings also highlight the alarmingly younger age of patients with EPS. Finally, all these pregnancies should be monitored in a complex multidisciplinary manner in tertiary referral units.Key messageThe effect of dexamethasone on absent end-diastolic flow in the umbilical artery in growth-restricted fetuses from pregnancies complicated by early-onset preeclampsia with severe features can be a useful prognostic factor for perinatal outcomes.

Maternal Utero-Placental Perfusion Discordance in Monochorionic-Diamniotic Twin Pregnancies with Selective Growth Restriction Assessed by Three-Dimensional Power Doppler Ultrasound.

BACKGROUND The aim of this study was to assess the correlation between selective growth restriction (sGR) and co-twin utero-placental perfusion discordance by using three-dimensional power Doppler (3DPD). MATERIAL AND METHODS We prospectively recruited 60 sGR and 64 normal monochorionic-diamniotic (MCDA) twin pregnancies. Vascularization index (VI), flow index (FI), and vascularization flow index (VFI) were assessed by 3DPD, while umbilical artery pulsatility index (UA-PI), middle cerebral artery peak systolic velocity (MCA-PSV), pulsatility index (MCA-PI), and cerebroplacental ratio (CPR) were assessed by conventional Doppler imaging. RESULTS In sGR co-twins, the VI, FI, VFI, MCA-PI, and CPR were significantly lower, while the UA-PI and MCA-PSV were significantly greater, in the smaller fetuses compared with the larger fetuses; significant differences were also observed in the VI, FI, VFI, CPR, and UA-PI in normal co-twins. Compared with the appropriately grown twins, the discordances of the VI, FI, VFI, UA-PI, MCA-PI, and CPR were increased in the sGR cohort. The discordances of the VI, FI, VFI, UA-PI, MCA-PI, and CPR were associated with birthweight discordance, and the FI discordance and CPR discordance were independently associated with sGR. The combination of the FI and CPR discordance showed a higher predictive accuracy for sGR, with an area under the ROC curve of 0.813, and a sensitivity and specificity of 68.33% and 85.94%, respectively. CONCLUSIONS MCDA twin pregnancies with birthweight discordance presented utero-placental perfusion deterioration assessed by 3DPD prior to sGR diagnosis. Co-twin utero-placental perfusion discordance was significantly correlated with growth discordance, and this correlation was more predictive of sGR when 3DPD was combined with conventional Doppler imaging.

Clinical implications of umbilical artery Doppler changes after betamethasone administration†.

Background: Betamethasone (BMZ) is commonly administered to patients with fetal growth restriction (FGR) and abnormal umbilical artery Doppler (UAD) velocimetry due to the increased risk of preterm delivery; however, the clinical impact of UAD changes after BMZ exposure is unknown.Objective: To test the hypothesis that lack of UAD improvement after BMZ administration is associated with shorter latency and greater neonatal morbidity in patients with FGR.Study design: This was a retrospective cohort study of pregnancies complicated by FGR and abnormal UAD between 240 and 336 weeks gestation. Abnormal UAD included the following categories of increasing severity: elevated (pulsatility index >95%), absent end diastolic flow (EDF), or reversed EDF improvement was defined as any improvement in category of UAD within two weeks of BMZ. Sustained improvement was defined as improvement until the last ultrasound before delivery, whereas transient improvement was considered as unsustained. The primary outcome was latency, defined as interval from betamethasone administration to delivery. Secondary outcomes were gestational age at delivery, umbilical artery pH, and a composite of neonatal morbidity (intubation, necrotizing enterocolitis, ionotropic support, intraventricular hemorrhage, total parenteral nutrition, neonatal death). Outcomes were compared between (a) patients with and without UAD improvement and (b) patients with sustained and unsustained improvement, using univariable, multivariable and time-to-event analyses.Results: Of the 222 FGR pregnancies with abnormal UAD, 94 received BMZ and had follow-up ultrasounds. UAD improved in 48 (51.1%), with 27 (56.3%) having sustained improvement. Patients with hypertension and drug use were less likely to have UAD improvement. Patients without UAD improvement had shorter latency (21.5 days [interquartile range (IQR) 8,45] versus 35 [IQR 22,61], p = .02) and delivered at an earlier gestational age (34 weeks [IQR 31,36] versus 37 [IQR 33,37], p < .01) than those with improvement. There were no differences in umbilical artery pH between groups. Composite neonatal morbidity was higher in patients without UAD improvement, but this was not statistically significant after adjusting for confounders (aOR 2.0; 95% CI 0.08-5.1). There were no differences in outcomes between patients with sustained versus unsustained improvement.Conclusions: UAD improved in half of patients following BMZ. Lack of UAD improvement was associated with shorter latency and earlier gestational age at delivery, but no difference in composite neonatal morbidity. UAD response to BMZ may be useful to further risk stratify FGR pregnancies.

Is umbilical vein varix associated with changes in cerebroplacental ratio?

Objective: We aimed to review a single-center experience in follow-up and management of fetuses with umbilical vein varix (UVV) and to assess the effect of UVV on fetal Doppler parameters.Methods: We reviewed retrospectively maternal antenatal records, delivery records, and newborn records to identify cases of UVV. Further, we retrospectively compared 25 fetuses with isolated UVV and available cerebroplacental ratio (CPR) analysis with 75 matched controls.Results: We identified 67 cases of UVV. The median gestational age (GA) at diagnosis was 34 weeks (range: 26-41 weeks). The average diameter of UVV at diagnosis was 10.1 mm (range: 9-14 mm). The median GA at delivery was 36 + 6 (range: 33-41 weeks), with an average birth weight of 2918 g (range: 1278-4140 g). There was a single case of intrauterine death at 35 weeks. CPR was 2.13 ± 0.62 in isolated UVV group compared with 1.84 ± 0.61 in the control group (p < .05). Other Doppler parameters did not differ between fetuses with UVV compared with controls.Conclusions: CPR was significantly increased in the UVV group compared with control fetuses. This finding suggests that UVV is not associated with chronic fetal oxygen deprivation; it, therefore, may contribute to our understanding of the pathophysiology explaining abnormal pregnancy outcome in cases with UVV.

Doppler ultrasonographic assessment of fetal middle cerebral artery peak systolic velocity in gestational diabetes mellitus.

OBJECTIVE: To compare Doppler ultrasonographic measurements of the fetal middle cerebral artery peak systolic velocity (MCA PSV) among women with or without gestational diabetes mellitus (GDM). METHODS: A cross-sectional study was conducted among pregnant women who presented for prenatal care at a single hospital in Brazil between September 11, 2015, and January 6, 2017. Patients were stratified into a group with GDM and a control group without GDM. One Doppler ultrasonographic assessment was performed per participant. This measurement was made after diagnosis but before the start of treatment among women in the GDM group. Fetal ultrasonographic and biometric variables assessed included MCA PSV, MCA pulsatility index, umbilical artery pulsatility index, the MCA-to-umbilical artery ratio, abdominal circumference, and weight. RESULTS: The study included 238 women: 115 in the GDM group and 123 in the control group. The median MCA PSV was 1.02 in the GDM group and 1.08 in the control group (P=0.036). No statistically significant between-group differences were found for the other fetal ultrasonographic variables or for the fetal biometric variables assessed. None of the maternal or fetal parameters assessed displayed a linear correlation with MCA PSV. CONCLUSION: Doppler ultrasonographic measurements of MCA PSV were lowered among the fetuses of women diagnosed with GDM.

Effects of prenatal exercise on fetal heart rate, umbilical and uterine blood flow: a systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review and meta-analysis examining the influence of acute and chronic prenatal exercise on fetal heart rate (FHR) and umbilical and uterine blood flow metrics. DESIGN: Systematic review with random-effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies) if published in English, Spanish or French, and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [eg, dietary; "exercise + co-intervention"]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcomes (FHR, beats per minute (bpm); uterine and umbilical blood flow metrics (systolic:diastolic (S/D) ratio; Pulsatility Index (PI); Resistance Index (RI); blood flow, mL/min; and blood velocity, cm/s)). RESULTS: 'Very low' to 'moderate' quality evidence from 91 unique studies (n=4641 women) were included. Overall, FHR increased during (mean difference (MD)=6.35bpm; 95% CI 2.30 to 10.41, I2=95%, p=0.002) and following acute exercise (MD=4.05; 95% CI 2.98 to 5.12, I2=83%, p<0.00001). The incidence of fetal bradycardia was low at rest and unchanged with acute exercise. There were no significant changes in umbilical or uterine S/D, PI, RI, blood flow or blood velocity during or following acute exercise sessions. Chronic exercise decreased resting FHR and the umbilical artery S/D, PI and RI at rest. CONCLUSION: Acute and chronic prenatal exercise do not adversely impact FHR or uteroplacental blood flow metrics.

The risk of preterm birth associated with a low cerebroplacental ratio.

OBJECTIVE: This paper investigated whether a cerebroplacental ratio (CPR) < 10th centile (measured between 23 + 0-36 + 0 weeks gestation) is predictive of any preterm birth, birth within 2 weeks of the ultrasound scan or spontaneous preterm birth. METHODS: This was a retrospective cohort study of 8977 women during 2014 and 2015 at a major tertiary referral hospital. Selection criteria included women who had a nonanomalous, singleton fetus and underwent an ultrasound scan between 23 + 0-36 + 6 weeks gestation. RESULTS: A low CPR increased the risk of preterm birth or birth within 2 weeks of the scan with the highest odds of birth within 2 weeks seen at 28-week gestation (odds ratio (OR) 3.78, 95%CI 1.63-8.77) - the mode of delivery was most likely emergency caesarean section for nonreassuring fetal status (aOR 2.11, 95%CI 1.69-2.64, p < .001). Neonatal outcomes were worse in the low CPR cohort particularly with higher odds of death (aOR 2.30, 95%CI 1.46-3.63) and composite adverse outcome (aOR 1.46, 95%CI 1.24-1.73). The low CPR cohort had a significantly shorter interval to delivery (Cox Proportional Hazard - aHR 1.41, 95%CI 1.33-1.51, p < .001) and earlier gestation at birth. CONCLUSIONS: A low CPR is associated with an increased risk of preterm birth and birth within 2 weeks but not spontaneous preterm birth.

Prediction of adverse pregnancy outcome in monochorionic diamniotic twin pregnancy complicated by selective fetal growth restriction.

OBJECTIVE: To identify key factors associated with adverse perinatal outcome in monochorionic diamniotic twin pregnancy complicated by selective fetal growth restriction (sFGR). METHODS: This was a retrospective cohort study of all monochorionic diamniotic twin pregnancies diagnosed with sFGR at ≥ 16 weeks' gestation, in a single tertiary referral center between March 2000 and May 2015. The presence of coexisting twin-twin transfusion syndrome (TTTS) was noted. Fetal biometry and Doppler indices, including those of the umbilical artery (UA) and ductus venosus (DV), were recorded at the time of diagnosis. The type of sFGR was diagnosed according to the pattern of end-diastolic flow in the UA of the smaller twin. DV pulsatility indices for veins (DV-PIV) were converted to Z-scores and estimated fetal weight values to centiles, to correct for gestational age (GA). Cox proportional hazards model was used to examine for independent predictors of adverse perinatal outcome, which was defined according to survival and included both intrauterine fetal demise and neonatal death of the FGR twin. RESULTS: We analyzed 104 pregnancies, of which 66 (63.5%) were diagnosed with Type-I and 38 (36.5%) with Type-II sFGR at initial presentation. In pregnancies complicated by Type-II sFGR, the diagnosis of sFGR was made earlier than in those complicated by Type-I sFGR (mediam GA, 19.6 vs 21.5 weeks; P = 0.012), and Type-II sFGR was associated with increased risk of adverse perinatal outcome (intrauterine demise of the smaller twin, 34.2% vs 10.6%; P = 0.004). Twin pregnancies complicated by sFGR resulting in perinatal demise had a significantly earlier diagnosis (P = 0.002) and lower birth-weight centile of the smaller twin (P < 0.01), those with Type-I sFGR had earlier GA at delivery (P = 0.007) and those with Type-II sFGR had higher DV-PIV Z-score of the smaller twin (P = 0.003), when compared with pregnancies resulting in live birth. Coexisting TTTS had no significant impact on the perinatal outcome of pregnancies diagnosed with either Type-I or Type-II sFGR (P > 0.05 for both). Earlier GA at diagnosis (hazard ratio (HR), 0.70 (95% CI, 0.56-0.88); P = 0.002), Type-II sFGR (HR, 3.53 (95% CI, 1.37-9.07); P = 0.008) and higher DV-PIV Z-score (HR, 1.36 (95% CI, 1.12-1.65); P = 0.001) were significantly associated with increased risk of adverse perinatal outcome of the smaller twin. CONCLUSIONS: Pregnancies complicated by Type-II sFGR are diagnosed significantly earlier and are associated with increased risk of adverse perinatal outcome compared with those with Type-I sFGR. Coexisting TTTS has no significant impact on the perinatal outcome of pregnancies diagnosed with either Type-I or Type-II sFGR. Earlier GA at diagnosis, Type-II sFGR and higher DV-PIV Z-score are associated significantly with increased risk of adverse perinatal outcome of the smaller twin. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Image-scoring system for umbilical and uterine artery pulsed-wave Doppler ultrasound measurement.

OBJECTIVES: To develop an objective image-scoring system for pulsed-wave Doppler measurement of maternal uterine and fetal umbilical arteries, and evaluate how this compares with subjective assessment. METHODS: As an extension to the INTERGROWTH-21st Project, we developed a scoring system based on six predefined criteria for uterine and umbilical artery pulsed-wave Doppler measurements. Objective evaluation using the scoring system was compared with subjective assessment which consisted of classifying an image as simply acceptable or unacceptable. Based on sample size estimation, a total of 120 umbilical and uterine artery Doppler images were selected randomly from the INTERGROWTH-21st image database. Two independent reviewers evaluated all images in a blinded fashion, both subjectively and using the six-point scoring system. Percentage agreement and kappa statistic were compared between the two methods. RESULTS: The overall agreement between reviewers was higher for objective assessment using the scoring system (agreement, 85%; adjusted kappa, 0.70) than for subjective assessment (agreement, 70%; adjusted kappa, 0.47). For the six components of the scoring system, the level of agreement (adjusted kappa) was 0.97 for anatomical site, 0.88 for sweep speed, 0.77 for magnification, 0.68 for velocity scale, 0.68 for image clarity and 0.65 for angle of insonation. CONCLUSION: In quality assessment of umbilical and uterine artery pulsed-wave Doppler measurements, our proposed objective six-point image-scoring system is associated with greater reproducibility than is subjective assessment. We recommend this as the preferred method for quality control, auditing and teaching. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Hemodynamics of the uterine and umbilical arteries during the perinatal period in ewes.

Examining feto-maternal blood flow is extremely important for accurate prenatal control and predicting adverse conditions during puerperium. We aimed to analyze blood flow of uterine artery (UA) and umbilical artery (UMA) from and subsequent to mid-gestation, lambing and postpartum of 15 ewes, subjected to lambing induction with aglepristone. Hemodynamic variables, diameter and blood flow of UA and UMA were determined by Doppler and B-mode ultrasonography at 60, 90 and 120 days of pregnancy, at 12 h before, 12 h after first aglepristone injection and 12 h after induction and days 1, 3, 5, 7, 15 and 30 after lambing. The UMA peak systolic:diastolic velocity (S/D), resistance index (RI) and pulsatility index (PI) decreased from mid-pregnancy until 120 d, whereas peak systolic velocity (PSV), end diastolic velocity (EDV) and time average maximum velocity (TAMAX) increased towards 120 d. The UMA RI additionally decreased at 12 h after lambing induction. The UMA diameter and volume increased from mid-gestation until 12 h before lambing induction. UA PSV and TAMAX increased from 60 until 90 days of pregnancy, while EDV, PSV and TAMAX decreased soon after parturition, with a further reduction at 7 days. The UA diameter and volume decreased during postpartum, stabilizing by 15 days after parturition. In conclusion, pregnancy is marked by progressive increase in uterine and umbilical blood flow, while lambing acutely diminishes umbilical vascular resistance, suggesting lack of progesterone influence on vasodilation. Conversely, puerperium is characterized by reduction in uterine blood supply mostly within the first 2 weeks of postpartum in sheep.

Trans-abdominal in vivo placental vessel occlusion using High Intensity Focused Ultrasound.

Pre-clinically, High Intensity Focused Ultrasound (HIFU) has been shown to safely and effectively occlude placental blood vessels in the acute setting, when applied through the uterus. However, further development of the technique to overcome the technical challenges of targeting and occluding blood vessels through intact skin remains essential to translation into human studies. So too does the assessment of fetal wellbeing following this procedure, and demonstration of the persistence of vascular occlusion. At 115 ± 10 d gestational age (term~147 days) 12 pregnant sheep were exposed to HIFU (n = 6), or to a sham (n = 6) therapy through intact abdominal skin (1.66 MHz, 5 s duration, in situ ISPTA 1.3-4.4 kW.cm-2). Treatment success was defined as undetectable colour Doppler signal in the target placental vessel following HIFU exposures. Pregnancies were monitored for 21 days using diagnostic ultrasound from one day before HIFU exposure until term, when post-mortem examination was performed. Placental vessels were examined histologically for evidence of persistent vascular occlusion. HIFU occluded 31/34 (91%) of placental vessels targeted, with persistent vascular occlusion evident on histological examination 20 days after treatment. The mean diameter of occluded vessels was 1.4 mm (range 0.3-3.3 mm). All pregnancies survived until post mortem without evidence of significant maternal or fetal iatrogenic harm, preterm labour, maternal or fetal haemorrhage or infection. Three of six ewes exposed to HIFU experienced abdominal skin burns, which healed without intervention within 21 days. Mean fetal weight, fetal growth velocity and other measures of fetal biometry were not affected by exposure to HIFU. Fetal Doppler studies indicated a transient increase in the umbilical artery pulsatility index (PI) and a decrease in middle cerebral artery PI as a result of general anaesthesia, which was not different between sham and treatment groups. We report the first successful application of fully non-invasive HIFU for occlusion of placental blood flow in a pregnant sheep model, with a low risk of significant complications. This proof of concept study demonstrates the potential of this technique for clinical translation.

Doppler evaluation of umbilical artery during normal gestation in sheep.

Throughout gestation, changes in foetal umbilical cord Doppler parameters in ewes were detected. Doppler ultrasonography of the umbilical artery was performed weekly starting at 18 weeks before parturition until birth. In the foetal umbilical artery (UA), systolic peak velocity (SPV), end diastolic velocity (EDV), increased (p for within-subjects effect <0.001) while pulsatility index (PI) resistance index (RI) decreased (p for within-subjects effect <0.001) with the progress of pregnancy. A linear trend was found on all patterns (p < 0.001). In particular, the EDV values increased significantly (p < 0.05) with respect to previous weeks, at weeks 16, 11, 10, 7, and 1 before parturition. The SPV values increased significantly (p < 0.05), with respect to previous observations, at weeks 11, 10, and 7 before parturition. Finally, the PI and RI decreased significantly (p < 0.05) only at week 7 before parturition. The increased velocities and reduced resistance index suggest a progressive increment in blood flow to the foetus towards the end of pregnancy. Foetal and utero-placental vascular parameters can be reliably evaluated using high-frequency ultrasound.

Physiological adaptation of the growth-restricted fetus.

The growth-restricted fetus in utero is exposed to a hostile environment and suffers undernutrition and hypoxia. To cope with the stress, the fetus changes its physiological functions. These adaptive changes aid intrauterine survival; however, they can lead to permanent functional and structural changes that can contribute to the development of serious chronic diseases later in life. Epigenetic mechanisms are an important part of the pathophysiological processes behind this "developmental origin of adult diseases." The dominant cardiovascular adaptive change is the redistribution of blood flow in hypoxic fetuses, with preferential supply of blood to the fetal brain, myocardium, and adrenal glands. The proportion of blood from the umbilical vein to the ductus venosus and foramen ovale increases, which increases the cardiac output of the left heart ventricle. The increased perfusion of fetal brain can be followed with Doppler ultrasound as increased diastolic velocities and decreased pulsatility index in the middle cerebral artery.

Fetal growth restriction in twins.

Twin pregnancies are more likely to be affected by fetal growth restriction (FGR), preterm birth and perinatal loss. The management of fetal growth restriction in multiple pregnancy, particularly where only one fetus is affected is complicated by the need to consider the interests of both twins. Selective growth restriction in monochorionic (MC) twins is a pathophysiological process distinct from FGR in dichorionic (DC) pregnancies and management demands an understanding of the monochorionic placental structure and interdependent fetal circulations. The introduction of fetal therapy has introduced a range of potential interventions for the antenatal management of sFGR including selective fetal reduction and laser photocoagulation of the placental communicating vessels. This review summarizes up to date evidence on diagnosis, classification and management of sFGR and considers research directions likely to be of benefit in the future.

Effect of inter-twin delivery interval on umbilical artery pH and Apgar score in the second twin.

BACKGROUND: To examine the effect of inter-twin delivery interval on umbilical artery pH and Apgar score of the second twin after vaginal delivery of the first twin. METHODS: Retrospective study conducted at a single teaching hospital. All pregnant women with twin gestation who delivered the first twin vaginally at more than 24 weeks between 1995 and 2015 were included. Major malformations and intrauterine deaths of one or both twins were excluded. Women were divided into those who had an inter-twin delivery interval of less than 30 minutes (group 1) or 30 minutes or more (group 2). Primary outcome was umbilical artery pH less than 7.1 and/or Apgar score less than 7 at 5 minutes of the second twin. Generalized linear regression with log was performed to evaluate the association with delivery interval. RESULTS: Of 88 145 deliveries during this period, 1955 (2.2%) were twins. Overall, 713 twin pregnancies, 596 (83.6%) in group 1 and 117 (16.4%) in group 2, were eligible and included. Mean inter-delivery interval was 11.0 ± 6.5 and 52.5 ± 31.5 minutes in groups 1 and 2, respectively. After adjusting for variables found significantly different between the groups in univariate analysis, inter-delivery interval of less than 30 minutes or 30 minutes or more was not a significant risk factor for pH less than 7.1 and/or Apgar less than 7 (P = .91). The cesarean rate for delivery of the second twin after vaginal delivery of the first twin was 4.3% overall, with a higher rate among group 2 compared with group 1 (18.2% and 3.2%, respectively; P = .001). CONCLUSIONS: The second twin's Apgar score and cord artery pH are probably not affected when the inter-twin delivery interval exceeds 30 minutes.

Placental insufficiency among high-risk pregnancies with a normal umbilical artery resistance index after 32weeks.

OBJECTIVE: To determine the incidence of abnormal multi-vessel Doppler values among advanced pregnancies at risk of suboptimal placentation but with a normal umbilical artery resistance index (RI), and to assess whether clinical and ultrasonography findings can identify them. METHODS: In a prospective cross-sectional study at Tygerberg Hospital, South Africa, women with high-risk pregnancies but normal umbilical artery RI after 32weeks underwent ultrasonography (fetal biometry, liquor, and placenta maturation) and Doppler assessment (uterine, umbilical, and middle cerebral arteries) between February 11 and October 21, 2013. Study data were compared among four groups: fetuses with normal uterofetoplacental Doppler values and those with any abnormal pulsatility index, each subdivided into small for gestational age (SGA) and appropriate for gestational age (AGA) by estimated fetal weight. RESULTS: Of 210 participants, 72 (36.2%) had abnormal Doppler results, and 60 (28.6%) fetuses were SGA (38 [63.3%] with abnormal Doppler results). Clinical characteristics did not differ between groups with normal or abnormal Doppler values; however, among normal Doppler results, SGA pregnancies demonstrated poorer fundal growth (P=0.006). Significant associations existed between abnormal Doppler results and asymmetric growth, inappropriately advanced placental maturation, and reduced liquor volume (all P≤0.04), but with very low sensitivities (3.9%, 4.8%, and 14.5%, respectively). CONCLUSION: Maternal characteristics and imaging variables did not reliably identify more than one-third of pregnancies with evidence of suboptimal placentation.

Intrauterine thrombosis of umbilical artery - case report / Trombose intrauterina de artéria umbilical - relato de caso

ABSTRACT: CONTEXT: Umbilical cord thrombosis is related to greater fetal and perinatal morbidity and mortality. It is usually associated with umbilical cord abnormalities that lead to mechanical compression with consequent vascular ectasia. Its correct diagnosis and clinical management remains a challenge that has not yet been resolved. CASE REPORT: This study reports a case of umbilical artery thrombosis that occurred in the second half of a pregnancy. The umbilical cord was long, thin and overly twisted and the fetus presented severe intrauterine growth restriction. The clinical and histopathological findings from this case are described. CONCLUSIONS: This case report emphasizes the difficulty in diagnosing and clinically managing abnormalities of intrauterine life with a high chance of perinatal complications.

RESUMO: CONTEXTO: A trombose do cordão umbilical está relacionada com o aumento da morbimortalidade fetal e perinatal. É geralmente associada a alterações do cordão umbilical que levam à compressão mecânica com consequente ectasia vascular. Seu correto diagnóstico e manejo clínico é um desafio que não está ainda bem esclarecido. RELATO DE CASO: Neste relato se descreve caso de trombose da artéria umbilical de ocorrência na segunda metade da gravidez associada a cordão umbilical longo, fino, excessivamente retorcido, associado a feto com restrição de crescimento intrauterino grave. São descritos seus achados clínicos e histopatológicos correlacionados. CONCLUSÃO: Este relato de caso reforça a dificuldade diagnóstica e de manejo clínico em alteração da vida intrauterina com grande possibilidade de complicações perinatais.