Chronic Hypertension and Pregnancy.

Chronic hypertension is frequently encountered during pregnancy and needs to be distinguished from other hypertensive complications of pregnancy, such as preeclampsia and gestational hypertension. The prevalence of this pregnancy complication is attributable to the increased prevalence of obesity and maternal age at childbearing. Women with chronic arterial hypertension are at increased risk for several pregnancy complications, including superimposed preeclampsia, caesarean delivery, preterm delivery <37 weeks gestation, birth weight <2500 g, neonatal unit admission, and perinatal death. Therefore, specialized attention should be given to these women as part of family planning before conception to provide counseling about the pregnancy risks, to inform about surveillance of fetal well-being, to determine the timing of delivery, and to optimize BP control before, during, and after birth.

Superimposed Preeclampsia.

Superimposed preeclampsia refers to women with chronic arterial hypertension (primary or secondary) who develop preeclampsia (PE). Because hypertension affects 5-15 % of pregnancies, it is itself a matter of concern. However, this concern should be permanent, given the increased risk of the hypertension worsening and, particularly, the appearance of superimposed PE. The search for factors that underlie or promote the development of this disorder has been the subject of intense research. However, despite the wealth of knowledge, the cause or causes remain to be determined.

Relationship between body mass index and mean arterial pressure in normotensive and chronic hypertensive pregnant women: a prospective, longitudinal study.

BACKGROUND: Being overweight is associated with both higher systolic blood pressure (SBP) and diastolic blood pressure (DBP) during pregnancy and increased risk of gestational hypertensive disorders. The objective of this study was to determine and quantify the effect of body mass index (BMI) on mean arterial pressure (MAP) at several time points throughout pregnancy in normotensive (NT) and chronic hypertensive pregnant (HT) women. METHODS: A prospective longitudinal study was carried out in 461 singleton pregnancies (429 low-risk and 32 with chronic arterial hypertension), with measurements taken at the 1(st), 2(nd), and 3(rd) trimesters and at delivery. Linear mixed-effects regression models were used to evaluate the time-progression of BMI, SBP, DBP and MAP during pregnancy (NT vs. HT). The longitudinal effect of BMI on MAP, adjusted for the hypertensive status, was investigated by the same methodology. RESULTS: BMI consistently increased with time in both NT and HT women. In contrast, MAP decreased during the first half of pregnancy, after which it increased until the moment of delivery in both groups. A 5-unit increase in BMI was predicted to produce an increase of approximately 1 mmHg in population MAP values. This effect is independent from the time period and from hypertensive status. CONCLUSIONS: In both NT and HT pregnant women, MAP is strongly (and significantly) influenced by increases in BMI.

Uterine artery Doppler in the management of early pregnancy loss: a prospective, longitudinal study.

BACKGROUND: The pharmacological management of early pregnancy loss reduced substantially the need for dilation and curettage. However, prognostic markers of successful outcome were not established. Thus the major purpose of this study was to determine the sensitivity and specificity of the uterine artery pulsatility (PI) and resistance (RI) indices to detect early pregnancy loss patients requiring dilation and curettage after unsuccessful management. METHODS: A cohort prospective observational study was undertaken to include women with early pregnancy loss, ≤ 12 weeks of gestation, managed with mifepristone (200 mg) and misoprostol (1600 µg) followed by PI and RI evaluation of both uterine arteries 2 weeks after. At this time, in 173/315 patients, incomplete miscarriage was diagnosed. Among them, 32 underwent uterine dilatation and curettage at 8 weeks of follow-up. RESULTS: The cut-off points for the uterine artery PI and RI, leading to the maximum values of sensitivity (69.5%, CI95%: 61.5%-76.5% and 75.0%, CI95%: 57.9%-86.8%, respectively) and specificity (75.0%, CI95%: 57.9%-86.8% and 65.6%, CI95%: 48.3%-79.6%, respectively), for the discrimination between the women who needed curettage from those who resolved spontaneously were 2.8 and 1, respectively. CONCLUSIONS: The potential usefulness of uterine artery Doppler evaluation to predict the need for uterine curettage in patients submitted to medical treatment for early pregnancy loss was demonstrated.

Uterine artery impedance during puerperium in normotensive and chronic hypertensive pregnant women.

PURPOSE: The present study compared the Doppler flow pulsatility indices (PI) in the uterine arteries (UtA) during the puerperium between healthy women and those with stage-1 essential hypertension who had uncomplicated pregnancies and delivered by elective caesarean section. The change in the mean arterial pressure (MAP) and body mass index (BMI) over time was also assessed. METHODS: A longitudinal and prospective study was performed in singleton pregnancies of 28 normotensive (NT) and 24 hypertensive (HT) women. The UtA-PI was measured immediately before caesarean section (time 0) and at 1 week (time 1) and 4 weeks (time 2) postpartum. The presence or absence of early diastolic notches was recorded. The change in the MAP, BMI, and UtA-PI over time and between the two populations was modelled through multivariate linear regression using the generalised least squares. RESULTS: In both groups, the UtA-PI significantly increased from time 0 to time 1 (p < 0.05) and time 2 (p < 0.05). Stage-1 hypertension did not change the trend but did increase the UtA-PI magnitude (p < 0.05). The presence of uterine artery notching increased over time, from 6 to 98%, in both groups (p < 0.001); however, in the HT group, at time 1, the majority of women exhibited positive notching [92% (HT) vs 57% (NT), p = 0.013]. CONCLUSIONS: Chronic stage-1 hypertensive women with normal pregnancy outcomes exhibited a progressively increasing postpartum UtA impedance. This trend also occurred in normotensive women, albeit at a significantly lower magnitude.

Uterine artery impedance at very early clinical pregnancy.

OBJECTIVE: The aim of the study was to construct gestational age-based reference ranges for the uterine artery (UtA) mean pulsatility (PI) and resistance (RI) indices from 6 to 10 weeks of pregnancy. METHOD: A prospective, cross-sectional, observational study was carried out in 312 singleton pregnancies with gestational age ranging from 6 to 10 weeks. UtAs were examined transvaginally by color and pulsed Doppler imaging, and the mean of the right and left values of PI and RI, as well as the presence or absence of a bilateral protodiastolic notch, was recorded. UtA-PI and UtA-RI reference percentiles were derived through time-conditional quantile regression. RESULTS: The authors derived the 10th, 50th, and 90th reference percentile curves and correspondent 95% confidence intervals, for the evolution of the UtA mean PI and RI from week 6 to week 10 of gestation. The prevalence of bilateral notching absence was 8.1% (6/74) at 6 weeks and 28.8% (15/52) at 10 weeks. CONCLUSION: The authors present evidence of progressive reduction of uterine vascular impedance in a very early stage of pregnancy and provide new, averaged UtA-PI and UtA-RI charts between 6 and 10 weeks of gestation.

The effects of spinal anaesthesia for elective caesarean section on uterine and umbilical arterial pulsatility indexes in normotensive and chronic hypertensive pregnant women: a prospective, longitudinal study.

BACKGROUND: Despite the known effects of neuraxial blockade on major vessel function and the rapid decrease in uterine vascular impedance, it is unclear how the blockade affects the utero-placental circulation in the near-term. We hypothesize that among women with chronic hypertension, a loss of sympathetic tonus consequent to spinal block may cause significant changes in the utero-placental haemodynamics than the changes typical in normal pregnant women. Therefore, the main study objective was to analyse the effect of spinal anaesthesia for caesarean section on uterine and umbilical arterial impedance in pregnant women at term diagnosed with stage-1 chronic hypertension. METHODS: A prospective, longitudinal study was performed in singleton pregnant women (203 low-risk and 33 with hypertension) scheduled to undergo elective caesarean section. The mean arterial blood pressure and pulsatility indexes for the uterine and umbilical arteries were recorded before and after spinal anaesthesia was performed using 8-9 mg hyperbaric bupivacaine (5 mg/mL) and 2-2.5 µg sufentanil (5 µg/mL). Multiple linear regression models with errors capable of correlation or with unequal variances were fitted using the generalized least squares. RESULTS: In normotensive women, the mean arterial blood pressure decreased after administering spinal anaesthesia (p < 0.05). The pulsatility index of the uterine and umbilical arteries did not change after spinal anaesthesia. In the hypertensive women, the mean arterial blood pressure (p < 0.05) and uterine artery pulsatility index (p < 0.05) decreased. In both groups, the umbilical artery pulsatility index did not change after spinal anaesthesia. CONCLUSIONS: In stage-1 chronic hypertensive pregnant women at term, spinal anaesthesia for caesarean section reduces uterine artery impedance but not umbilical artery impedance.

Foetal aortic flow velocity waveforms in healthy and hypertensive pregnant women.

BACKGROUND: The foetal aortic Doppler frequency spectrum is influenced by cardiac output and contractility of the foetal heart as well as vascular compliance, blood viscosity and impedance of the arterial vascular system. The present study aimed at comparing Doppler flow pulsatility (PI) and resistance (RI) indexes of foetal proximal descending aorta (AoF) in the first, second and third trimesters of pregnancy, in low risk women and in those with chronic arterial hypertension, who had normal pregnancy outcomes. METHODS: A longitudinal and prospective study was carried out in 101 singleton pregnancies (71 low-risk pregnancies and 30 with essential hypertension). Multivariate regression had to be considered due to the experiment's nature: two different indexes were read on the same set of individuals, once at each trimester of the pregnancy [1st (11-14 weeks), 2nd (19-22 weeks) and 3rd (28-32 weeks) trimesters]. The response variable was denoted as index d, in a subject with hypertensive status h (hypertensive or normotensive), at continuous time t. RESULTS: In both groups, AoF-PI and AoF-RI showed a small, but significant increase from the first to the second (1.850 ± 0.339 vs 2.110 ± 0.242 for PI, and 0.829 ± 0.068 vs 0.857 ± 0.038 for RI; p < 0.001) and the first to the third (1.850 ± 0.339 vs 2.163 ± 0.282 for PI, and 0.829 ± 0.068 vs 0.864 ± 0.037 for RI; p < 0.001) trimesters of pregnancy. The global model showed that while AoF-RI trends were converging as time progressed, the AoF-PI values exhibited a divergent trend (p < 0.05). CONCLUSIONS: Chronic stable hypertension in pregnancies with normal outcome, evidences an upward regular trend of foetal descending aorta pulsatility index that is similar to the normotensive condition.

Usefulness of three vessel-trachea view and parasagittal plan for prenatal diagnosis of interrupted aortic arch.

BACKGROUND: Interrupted aortic arch (IAA) is a rare congenital heart disease characterized by loss of continuity between the ascending and the descending aorta. Prenatal diagnosis of IAA by echocardiography is challenging but nonetheless can be accomplished via a systematization of cardiac fetal evaluation. CASE PRESENTATION: We report a case of fetal IAA type A prenatally diagnosed through two-dimensional echocardiography using both a three vessel-trachea view and a sagittal view. CONCLUSION: Prenatal counseling regarding the diagnosis and prognosis about this anomaly is still challenging nowadays due to associated anomalies/chromosomal abnormalities who may impact the prognosis. Fetal autopsy in all cases of pregnancy termination after abnormal ultrasound findings is important in order to make a full diagnosis and characterize the anomaly.

First Trimester Tricuspid Regurgitation: Clinical Significance.

Tricuspid regurgitation is a cardiac valvular anomaly that consists of the return of blood to the right atrium during systole due to incomplete valve closure. This structure can be visualized on ultrasound between 11 and 14 weeks of gestation in most cases. Despite being a common finding, even in healthy fetuses, the presence of tricuspid regurgitation may be associated with chromosomal and structural abnormalities. The evaluation of tricuspid flow and the presence of regurgitation on first-trimester ultrasound has shown promising results regarding its role in the early detection of aneuploidies, congenital heart defects, and other adverse perinatal outcomes. This review article aims to demonstrate the importance of tricuspid regurgitation as a secondary marker, and consequently, significant benefits of its early detection when added to the combined first-trimester screening. Its value will be discussed, namely its sensitivity and specificity, alone and together with other current markers in the fetal assessment performed in the first-trimester ultrasound.

Twin Anemia-Polycythemia Sequence (TAPS): From Basic Research to Clinical Practice.

Twin pregnancy is associated with an increased risk of perinatal and maternal complications, and early establishment of the chorionicity type defines this risk. In monochorionic (MC) pregnancies, the fetuses share the same placental mass and exhibit vascular anastomoses crossing the intertwin membrane, and the combination and pattern of anastomoses determine the primary clinical picture and occurrence of future complications. Twin Anemia-Polycythemia Sequence (TAPS) was first described in 2006 after fetoscopic laser surgery in twin-to-twin transfusion syndrome (TTTS) twins, and in 2007, the first spontaneous cases were reported, recognizing TAPS as an individualized vascular identity in fetofetal transfusion syndromes. There are two types of TAPS: spontaneous (3-5%) and iatrogenic or postlaser (2-16%). TAPS consists of small diameter arteriovenous anastomoses (<1 mm) and low-rate, small-caliber AA anastomoses in the absence of amniotic fluid discordances. There are certain antenatal and postnatal diagnostic criteria, which have progressively evolved over time. New, additional secondary markers have been proposed, and their reliability is being studied. The best screening protocol for TAPS in MC twins is still a matter of debate. This review provides a survey of the relevant literature on the epidemiology, vascular pathophysiology, underlying hemodynamic factors that regulate mismatched vascular connections, and diagnostic criteria of this condition. The aim is to increase awareness and knowledge about this recently identified and frequently unrecognized and misdiagnosed pathology.

Mosaic trisomy 5 in amniotic fluid in a live fetus with Ebstein anomaly and complete trisomy 5 in chorionic villus sampling.

Complete trisomy 5 is a rare and lethal abnormality. Mosaic trisomy 5 presents in various phenotypes, ranging from a clinically normal fetus to fetuses presenting uterine growth restriction, congenital heart anomalies, multiple dysmorphic features and psychomotor development abnormalities. Although rare, there are cases of a normal psychomotor development regardless of the associated low fetal growth frequently associated with mosaic trisomy 5. This is the first case report to date of a live fetus with complete trisomy 5 reported in chorionic villus sampling and mosaic trisomy 5 in amniotic fluid with a concomitant Ebstein anomaly. Diagnosis of mosaic trisomy 5 represents a challenge for the clinical team and patients, as the information regarding this syndrome is scarce and based mostly on case reports of liveborns, which may introduce a selection bias when counselling the parents.

Fetal Aortic and Umbilical Doppler Flow Velocity Waveforms in Pregnancy: The Concept of Aortoumbilical Column.

Low impedance within the uteroplacental circulation is crucial for fetal development. Flow velocity waveforms (FVW) have been established for the aortic and umbilical arteries in low-risk pregnancies during the second half of pregnancy, but data regarding early gestation is limited. Both vascular territories exhibit higher impedance patterns in pregnancies complicated by fetal growth restriction (FGR), hypertensive disorders, fetal anemia, and chromosomal abnormalities. Early identification of these complications is critical in obstetric practice, to reduce perinatal morbidity and mortality through prevention and close antenatal surveillance. Available data suggest that aortic and umbilical impedances follow the same variation pattern as pregnancy progresses. This observation implies that both vessels may be considered as a single artery, referred to as the "aortoumbilical column". Our hypothesis posits that changes in the hemodynamic pattern of this column could identify high-risk pregnancies, particularly those complicated by preeclampsia, FGR, intrauterine fetal demise, fetal aneuploidies, and fetal anemia. Understanding vascular embryogenesis and the FVWs of the aortic and umbilical arteries enables comprehension of impedance changes throughout normal pregnancies. The continuous variation in impedance along a single vessel supports our concept of the aortoumbilical column. Deviations from the regular pattern could assist in identifying compromised fetuses during early pregnancy. Further research on normal aortoumbilical column FVW and the development of reference charts is necessary to consider this arterial column as a screening tool in clinical practice.

Fetal Cardiac Function: Myocardial Performance Index.

The Myocardial Performance Index (MPI) or Tei index, presented by Tei in 1995, is the ratio of the sum of the duration of the isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) to the duration of the ejection time (ET). The Modified Myocardial Performance Index (Mod-MPI), proposed in 2005, is considered a reliable and useful tool in the study of fetal heart function in several conditions, such as growth restriction, twin-twin transfusion syndrome, maternal diabetes, preeclampsia, intrahepatic cholestasis of pregnancy, and adverse perinatal outcomes. Nevertheless, clinical translation is currently limited by poorly standardised methodology as variations in the technique, machine settings, caliper placement, and specific training required can result in significantly different MPI values. This review aims to provide a survey of the relevant literature on MPI, present a strict methodology and technical considerations, and propose future research.

Preeclampsia and Fetal Congenital Heart Defects.

Endothelial dysfunction, impaired implantation and placental insufficiency have been identified as mechanisms behind the development of pre-eclampsia, resulting in angiogenic factors' alteration. Angiogenic imbalance is also associated with congenital heart defects, and this common physiologic pathway may explain the association between them and pre-eclampsia. This review aims to understand the physiology shared by these two entities and whether women with pre-eclampsia have an increased risk of fetal congenital heart defects (or the opposite). The present research has highlighted multiple vasculogenic pathways associated with heart defects and preeclampsia, but also epigenetic and environmental factors, contributing both. It is also known that fetuses with a prenatal diagnosis of congenital heart disease have an increased risk of several comorbidities, including intrauterine growth restriction. Moreover, the impact of pre-eclampsia goes beyond pregnancy as it increases the risk for following pregnancies and for diseases later in life in both offspring and mothers. Given the morbidity and mortality associated with these conditions, it is of foremost importance to understand how they are related and its causative mechanisms. This knowledge may allow earlier diagnosis, an adequate surveillance or even the implementation of preventive strategies.

Uterine Compression Sutures in Controlling Postpartum Haemorrhage: A Narrative Review.

INTRODUCTION: Postpartum haemorrhage is still the main cause of maternal morbidity and mortality. Many treatments are available, but they may threaten fertility potential. As a uterine sparing procedure, we aimed to review uterine compression sutures in order to better understand when they should represent an appropriate option. MATERIAL AND METHODS: A comprehensive search in MEDLINE and PubMed databases including the terms 'postpartum haemorrhage' and 'uterine compression sutures' was performed. Results were revised and articles reviewing or presenting case reports of uterine compression sutures to treat postpartum haemorrhage were included. RESULTS: The first description of uterine compression sutures to control postpartum haemorrhage was published in 1997, by B-Lynch et al. After this publication, many others have reported successful management of postpartum haemorrhage with different suturing techniques. Most of them describe success rates above 75% and the possibility of fertility preservation, with cases of uneventful pregnancy after uterine compression sutures already published. Complications associated with each technique are rare. DISCUSSION: Reports of use of uterine compression sutures include small series of cases or even single case reports which limits the quality of existing evidence to support one technique over another. Nevertheless, uterine compression sutures are recognized as an effective surgical conservative strategy to control postpartum haemorrhage due to uterine atony and its use is recommended, if possible, prior to hysterectomy. CONCLUSION: Uterine compression sutures are effective, safe and simple to perform in an emergent situation and preserve fertility potential in cases of postpartum haemorrhage.

Introdução: A hemorragia pós-parto é a principal causa de morbimortalidade materna. Apesar dos tratamentos disponíveis, o potencial fértil da mulher pode ser colocado em causa. As suturas uterinas de compressão representam uma terapêutica conservadora do útero. Assim, revimos os tipos de suturas uterinas de compressão para compreender quando devem ser uma opção terapêutica. Material e Métodos: Foi realizada pesquisa na MEDLINE e PubMed com os termos 'postpartum haemorrhage' e 'uterine compression sutures' separados e em conjunto. Os resultados foram revistos e os artigos de revisão ou descrevendo casos clínicos de suturas uterinas de compressão foram selecionados. Resultados: Em 1997, B-Lynch et al descreveu pela primeira vez as suturas uterinas de compressão para tratamento da hemorragia pós-parto. Desde aí, publicações de diferentes tipos de suturas uterinas de compressão, com registo de casos bem-sucedidos, têm sido publicadas. A maioria reporta taxas de sucesso acima de 75%, com preservação da fertilidade, existindo vários casos de bom desfecho obstétrico posteriormente descritos. As complicações associadas são raras. Discussão: A evidência acerca do uso de suturas uterinas de compressão é limitada pela qualidade dos artigos existentes que incluem apenas pequenas séries de casos ou descrições de casos isolados. Apesar disso, tem sido reconhecido o seu potencial enquanto estratégia conservadora no controlo da hemorragia pós-parto devido a atonia uterina, sendo recomendado o seu uso, se possível, antes de realizar histerectomia. Conclusão: Em situações de hemorragia pós-parto, as suturas uterinas de compressão são eficazes, seguras e simples de realizar, preservando o potencial reprodutivo.

Doppler Ultrasound of the Umbilical Artery: Clinical Application.

OBJECTIVE: To provide a survey of relevant literature on umbilical artery Doppler ultrasound use in clinical practice, technical considerations and limitations, and future perspectives. METHODS: Literature searches were conducted in PubMed and Medline, restricted to articles written in English. Additionally, the references of all analyzed studies were searched to obtain necessary information. RESULTS: The use of this technique as a routine surveillance method is only recommended for high-risk pregnancies with impaired placentation. Meta-analyses of randomized trials have established that obstetric management guided by umbilical artery Doppler findings can improve perinatal mortality and morbidity. The values of the indices of Umbilical artery Doppler decrease with advancing gestational age; however, a lack of consensus on reference ranges prevails. CONCLUSION: Important clinical decisions are based on the information obtained with umbilical artery Doppler ultrasound. Future efforts in research are imperative to overcome the current limitations of the technique.

OBJETIVO: Compilar informação relevante proveniente da literatura atual sobre a ultrassonografia Doppler das artérias umbilicais (AUs) na prática clínica, considerações e limitações técnicas e perspectivas futuras. MéTODOS: A pesquisa bibliográfica foi realizada nos bancos de dados PubMed e Medline e restringiu-se a artigos escritos na língua inglesa. Recorreu-se também à bibliografia dos artigos selecionados, quando necessário, para obter informação relevante. RESULTADOS: A utilização desta técnica como método de vigilância de rotina está apenas recomendada em gravidezes de alto risco com disfunção placentar. Metanálises de estudos randomizados mostraram que o seguimento obstétrico baseado nos achados do Doppler da artéria umbilical pode melhorar a mortalidade e a morbilidade perinatal. É consensual que os valores dos índices Doppler da AU decrescem com o avanço da idade gestacional. No entanto, há ainda muita incerteza quanto aos valores de referência. CONCLUSãO: As informações obtidas através da AU Doppler US são a base para muitas decisões clínicas importantes. Trabalhos de investigação nesta área são essenciais para tentar colmatar atuais limitações da técnica.

Pregestational Diabetes and Congenital Heart Defects.

Studies have consistently shown a significant increase in the risk of congenital heart defects in the offspring of diabetic mothers compared with those of nondiabetic pregnancies. Evidence points that all types of pregestational diabetes have the capacity of generating cardiac malformations in a more accentuated manner than in gestational diabetes, and there seems to be an increased risk for all congenital heart defects phenotypes in the presence of maternal diabetes. Currently, the application of some therapies is under study in an attempt to reduce the risks inherent to diabetic pregnancies; however, it has not yet been possible to fully prove their effectiveness. The present review aims to better understand the mechanisms that govern the association between pregestational diabetes and congenital heart defects and how maternal diabetes interferes with fetal cardiac development, as there is still a long way to go in the investigation of this complex process.

Estudos têm demonstrado consistentemente um aumento significativo no risco de defeitos cardíacos congênitos em filhos de mães diabéticas em comparação com os de gestações não diabéticas. Evidências apontam que todos os tipos de diabetes pré-gestacional têm capacidade de gerar malformações cardíacas mais acentuadas do que no diabetes gestacional e parece haver um risco aumentado para todos os fenótipos de cardiopatias congênitas na presença de diabetes materno. Atualmente, está em estudo a aplicação de algumas terapias na tentativa de diminuir os riscos inerentes à gravidez diabética; no entanto, ainda não foi possível comprovar totalmente a sua eficácia. A presente revisão visa compreender melhor os mecanismos que regem a associação entre diabetes pré-gestacional e cardiopatias congênitas e como o diabetes materno interfere no desenvolvimento cardíaco fetal, pois ainda há um longo caminho a percorrer na investigação deste processo complexo.

Subcapsular hepatic haematoma in a pregnancy complicated by chronic hypertension.

Subcapsular haematoma of the liver in pregnancy is a rare complication, however life-threatening for both mother and fetus. Although it is usually associated with pre-eclampsia, a wide range of presentations can occur. Given its consequences, early diagnosis and management are essential for a successful outcome. Due to paucity of evidence, there is no current guidelines on this topic. Our aim is to add a new insight into diagnosis and management of subcapsular hepatic haematoma in pregnancy, for which new technologies in the fields of image, and minimal invasive surgery are playing an important role.

Clinical Significance of Ductus Venosus Waveform as Generated by Pressure- volume Changes in the Fetal Heart.

The ductus venosus is a vascular shunt situated within the fetal liver parenchyma, connecting the umbilical vein to the inferior vena cava. This vessel acts as a bypass of the liver microcirculation and plays a critical role in the fetal circulation. The ductus venosus allows oxygenated and nutrient-rich venous blood to flow from the placenta to the myocardium and brain. Increased impedance to flow in the fetal ductus venosus is associated with fetal aneuploidies, cardiac defects and other adverse pregnancy outcomes. This review serves to improve our understanding of the mechanisms that regulate the blood flow redistribution between the fetal liver circulation and fetal heart and the clinical significance of the ductus venosus waveform as generated by pressure-volume changes in the fetal heart.