Absence of the ductus venosus: report of 10 new cases and review of the literature.

OBJECTIVE: To assess the clinical significance of the absence of the ductus venosus. DESIGN: A retrospective study with a review of the literature. METHODS: The archives of our ultrasound laboratory and the English literature were searched for cases with a prenatal diagnosis of absence of the fetal ductus venosus. RESULTS: Between 1985 and 2000, 10 fetuses were diagnosed in our center as having absence of the ductus venosus. The review of the literature revealed 23 cases. Three main patterns of abnormal venous circulation were documented: (1) umbilical vein bypassing the liver and connecting directly to the right atrium (46%); (2) umbilical vein bypassing the liver and connecting to the inferior vena cava mostly through one of the iliac veins (25%); (3) umbilical vein connecting to the portal circulation without giving rise to the ductus venosus (21%). Major anomalies, including chromosomal aberrations, were found in 8/33 (24%) cases. Hydrops developed in 11/33 (33%) cases. Twenty fetuses with isolated absence of the ductus venosus were delivered, and 5 (20%) died. The portal vein was found to be absent in half of the infants examined after birth. CONCLUSIONS: Our results and the review of literature suggest that absence of the ductus venosus is associated with a high incidence of fetal anomalies and adverse outcomes, including associated malformations, chromosomal aberrations, in utero heart failure and absence of the portal vein. Heart failure and absence of the portal vein seem particularly frequent when absence of the ductus venosus is associated with a connection of the umbilical vein to either the inferior vena cava or the right atrium.     

Ultrasound-Guided Umbilical Venous Catheter Insertion With Alignment of the Umbilical Vein and Ductus Venosus

Previous studies have highlighted the importance of confirming the position of an umbilical venous catheter (UVC) tip by an ultrasound (US) examination. However, methods for preventing insertion into the portal circulation under US guidance have not yet been established. We report 15 cases in which a UVC was successfully passed through the ductus venosus by compressing the upper abdomen near the portal sinus of the liver to align the umbilical vein and ductus venosus under US guidance. The UVC was inserted into the correct position in 14 of the 15 neonates (93%) without complications.     

Aberrant Drainage of the Umbilical Vein Into the Coronary Sinus Without Ductus Venosus Agenesis

We describe a case series of 4 fetuses with ectopic connections of the ductus venosus to the coronary sinus detected prospectively between August 2011 and February 2012 in 2 congenital cardiologic centers. An enlarged coronary sinus alerted the sonographer. Fetal echocardiography showed ectopic connection of the ductus venosus in an enlarged coronary sinus in all 4 cases. To our knowledge, this anatomic form of ectopic umbilical vein drainage has not previously been reported. The infants were doing well. This venous variant should be considered in cases of isolated coronary sinus dilatation after elimination of a left superior vena cava and a totally anomalous pulmonary vein connection.     

静脉导管缺如并脐静脉异常连接产前超声心动图表现

目的 观察静脉导管缺如(ADV)并脐静脉肝内、肝外异常连接的产前超声心动图表现。方法 回顾性分析14胎ADV胎儿的超声心动图表现,观察心脏大小、功能变化,并随访临床预后。结果 ADV的检出率为0.12%(14/11 205),14胎中,5胎脐静脉与门静脉左支、1胎与门静脉右支相连;8胎脐静脉未与门静脉相连,而与肝外静脉系统相连,5胎直接连接于右心房,1胎直接连接于下腔静脉,1胎连接于肝右静脉,1胎连接于冠状静脉窦引流入右心房。结论 产前超声心动图能够明确诊断静脉导管缺如,且可以观察脐静脉肝内、肝外异常连接途径和管道内径。     

Diagnosis of absent ductus venosus in a population referred for fetal echocardiography: association with a persistent portosystemic shunt requiring postnatal device occlusion.

OBJECTIVE: The purpose of this series was to assess the incidence, anatomic variants, and implications of an absent ductus venosus (ADV) in patients referred for fetal echocardiography. METHODS: We searched our fetal cardiology database for diagnoses of ADV from May 2003 to December 2006. RESULTS: During the study period, we performed 1328 fetal echocardiographic examinations in 990 fetuses. We found 6 cases of ADV (6/1000). Indications for fetal echocardiography were cardiomegaly, dilated umbilical or systemic veins, and extracardiac abnormalities. We identified 5 anatomic variants of ADV. In 2 patients, the umbilical vein connected to the systemic venous circulation by way of the portal sinus: via an abnormal venous channel from the portal sinus to the right atrium (case 1) and presumably via hepatic sinusoids to the hepatic veins (case 2). In the remaining 4 patients, the umbilical vein bypassed the portal sinus and the liver and connected to the systemic venous circulation via an abnormal venous channel: from the umbilical vein to the right atrium (case 3), from the umbilical vein to the inferior vena cava (cases 4 and 5), and from the umbilical vein to the right iliac vein (case 6). All patients survived; 2 required cardiovascular intervention. No intervention was required in 3 patients. CONCLUSIONS: An ADV should be ruled out in a fetus with unexplained cardiomegaly or dilatation of the umbilical vein, systemic veins, or portal sinus. To our knowledge, prenatal diagnosis of an ADV with an abnormal communication between the portal sinus and the right atrium has not been reported previously. The portosystemic communication persisted after birth and required device occlusion.     

The anatomy of the umbilical, portal and hepatic venous systems in the human fetus at 14-19 weeks of gestation.

BACKGROUND: Ultrasound imaging of the fetal ductus venosus is becoming increasingly commonplace in clinical practice. The true anatomical relationships of the fetal umbilical and portal venous systems have not been clearly defined due to paucity of published data on the relevant anatomy. This has led to confusing terminology when describing the fetal umbilical, portal and hepatic circulations. The aim of the present study was to examine and document the anatomy of the umbilical, portal and hepatic venous systems and to propose a standardized nomenclature. METHODS: This was a prospective study on 11 fetuses obtained from medical termination of pregnancies between 14 and 19 weeks of gestation. The liver was microdissected to expose the branching pattern and anatomical relations of the umbilical, portal and hepatic venous systems. RESULTS: A wide L-shaped venous confluence at the terminal end of the umbilical vein, termed the portal sinus, was identified. The portal sinus was connected to the right and left hepatic lobes, by the right and left intrahepatic portal veins, respectively. The extrahepatic portal vein drained into the portal sinus just before the origin of the right intrahepatic portal vein. The ductus venosus, a branchless straight vessel, originated from the portal sinus and ascended steeply in the direction of the diaphragm. Numerous small vessels draining the liver converged into three main hepatic veins, which open into the subdiaphragmatic vestibulum. CONCLUSION: Based on detailed sequential anatomical dissection and clear illustrations, the present study documents the anatomy of the umbilical, portal and hepatic venous systems. Taking into account the embryological origin of the vessels, a new anatomically appropriate and simplified nomenclature of these venous systems is proposed. In clinical practice, the consistent use of the suggested terminology would allow collection of comparable data between units and enable operators to be confident of which vessels they are sampling by Doppler ultrasound.     

胎儿脐静脉-门静脉系统正常解剖与异常分流的超声特征分析

目的探讨胎儿脐静脉-门静脉系统的正常超声图像以及异常分流的超声诊断特征。 方法回顾性选取2018年1月至2020年12月在郑州大学第三附属医院行产前超声筛查和诊断的正常胎儿85例,观察脐静脉-门静脉系统的超声图像特征。另收集产前超声诊断为脐静脉-门静脉系统异常分流的26例胎儿的资料,对其产前超声图像及合并异常进行分析。 结果正常胎儿脐静脉-门静脉系统中门静脉主干与门静脉窦连接方式分为3种：“T”形连接60例;“X”形连接11例;“H”形连接14例。脐静脉-门静脉系统异常分流的26例胎儿中,脐静脉-体静脉分流6例,其中脐静脉回流入右心房4例,回流入下腔静脉1例,肝静脉异常分流1例,6例均合并静脉导管缺失,3例合并畸形,3例合并心脏增大;静脉导管-体静脉分流4例,其中静脉导管下腔静脉入口位置下移2例,经冠状静脉窦回流入右心房1例,直接回流至肝静脉1例,2例合并心内、心外多发畸形;肝内门静脉-体静脉分流16例,Ⅰ型1例、Ⅱ型6例、Ⅲ型3例、Ⅳ型6例。其中4例合并胎儿生长受限,2例合并心脏畸形,2例合并单脐动脉。 结论正确识别正常脐静脉-门静脉系统超声图像有助于发现和诊断异常分流;各类型异常分流有不同的超声图像特征;评估肝内门静脉系统发育、心功能及各系统发育可为临床咨询和处理提供信息和依据。     

Ductus venosus blood velocity and the umbilical circulation in the seriously growth-retarded fetus.

Based on the assumption that the ductus venosus is regulator of oxygenated blood in the fetus, the present study investigated the blood flow velocity of the ductus venosus in relation to the umbilical circulation in the that seriously growth-retarded fetus. The study group of 38 fetuses (gestational week 17-39) had no chromosomal aberrations or structural malformations and had an ultrasonographic biometry of < 2.5th centile and birth weight of 相似文献   

Doppler ultrasound measurements in the central circulation of anesthetized fetal sheep during obstruction of umbilical-placental blood flow.

OBJECTIVE: To establish by Doppler ultrasound the effects of acute blockage of umbilical cord vessels on the fetal central circulation. DESIGN: Experimental study in anesthetized pregnant sheep. METHODS: In 11 anesthetized pregnant sheep (0.66 of gestation), Doppler velocity profiles and/or venous flow rates were recorded in the ductus venosus, the fetal aorta, the umbilical arteries and the umbilical vein. This involved three phases. In Phase 1, the abdominal wall was closed (n = 9); Phase 2 was during fetoscopy after laparotomy (n = 8); Phase 3 was after coagulation of one of the umbilical arteries (n = 10). As an additional intervention in six fetuses, the umbilical cord was clamped for 5-15 s while blood flow velocity changes in the ductus venosus were observed. RESULTS: There were no significant differences between Doppler recordings in Phases 1 and 2. During Phase 3, the pulsatility index of the aorta and of the coagulated umbilical artery increased significantly. The umbilical vein blood flow rate was significantly reduced from a median of 408 (range, 243-575) mL/min/kg in Phase 1 to a median of 173 (range, 107-426) mL/min/kg in Phase 3, but the blood flow rate in the ductus venosus (median, 94; range, 56-148 mL/min/kg vs. median, 92; range, 33-237 mL/min/kg) remained unchanged. The ductus venosus/umbilical vein ratio increased from a median of 0.22 (range, 0.13-0.41) to 0.56 (range, 0.17-0.97) (P < 0.05). Compression of the cord (5-15 s) immediately reduced the time averaged maximum velocity in the ductus venosus from a mean of 51 (standard deviation, 11) cm/s to 20 (standard deviation, 6) cm/s (P < 0.001) without significant changes of the velocity profile. However, the pulsatility index increased from a mean of 0.55 (standard deviation, 0.19) to 1.89 (standard deviation, 0.73) (P < 0.001). CONCLUSION: Central venous flows in anesthetized fetal sheep are unaffected by laparotomy and hysterotomy. Obliteration of one umbilical artery increases the ductus venosus/umbilical vein volume flow (mL/min/kg) ratio. Compression of the umbilical cord shifts down blood flow velocity profiles in the ductus venosus, and the pulsatility index thus increases.     

An unusual anomalous intrahepatic connection between the left portal vein and internal mammary veins

Persistent embryonic portal vessels such as the umbilical vein or ductus venosus are occasionally encountered in the adult on ultrasound examination of the liver. These vessels must be identified and distinguished from the normal intrahepatic portal and hepatic veins. Recently, we have found another vein that, like the ductus venosus and persistent umbilical vein, is also a large intrahepatic portal vessel that is not a normal component of the hepatic vasculature. This anomalous vein originated from the left portal vein and traversed the liver parenchyma without branching to reach the anterior-superior liver margin, serving as an intrahepatic portal-systemic shunt by directly connecting the left portal vein and the internal mammary veins.     

Ductus venosus index: a method for evaluating right ventricular preload in the second-trimester fetus.

This study was designed to examine ventricular preload by measuring the ductus venosus index during the second trimester of pregnancy. A total of 137 women were entered into the study. Each fetus was examined with real-time, color and pulsed Doppler ultrasound. The color Doppler maximal velocity setting was adjusted so that the umbilical vein was homogeneous in color, did not demonstrate aliasing, and filled the venous lumen. The pulsed Doppler gate was placed within the ductus venosus in all subjects. Color Doppler identified a turbulent flow velocity within the ductus venosus which was not present in the umbilical vein, hepatic vein or inferior vena cava. The ductus venosus pulsed Doppler waveform demonstrated flow velocity from the umbilical vein to the heart during ventricular systole, the rapid filling phase of ventricular diastole, and atrial systole. However, flow velocity was decreased during atrial systole compared to ventricular systole and the rapid filling phase of diastole. The ductus venosus index was computed from the Doppler waveform of the ductus venosus at points consistent with ventricular and atrial systole ((ventricular systole - atrial systole)/ventricular systole). Regression analysis demonstrated a significant (p = 0.001) relationship between the ductus venosus index and gestational age (ductus venosus index = 75.5757 - 7.25484 x weeks gestation), standard error of the estimate = 7.21959; R = -0.451. One fetus with a hypoplastic left atrium and ventricle demonstrated a normal ductus venosus index. Two fetuses, one with pulmonary atresia and the second with severe cardiovascular dysfunction, demonstrated an abnormal ductus venosus index associated with absent flow velocity during atrial systole. This was associated with notching in the umbilical vein. The ductus venosus index is an angle-independent measurement from which right ventricular preload may be evaluated.     

Venous Doppler velocimetry in the surveillance of severely compromised fetuses.

OBJECTIVE: To investigate whether venous Doppler velocimetric signs of cardiac decompensation might predict fetal demise in severely compromised fetuses. MATERIAL AND METHODS: This was a prospective study involving 154 growth-restricted fetuses, 37 of which were found to have reversed flow in the umbilical artery (BFC III). Doppler velocimetry of the right hepatic vein and ductus venosus were investigated serially and the presence of umbilical venous pulsations also registered. Only the final examination prior to birth or fetal demise was accepted for analysis and related to obstetric outcome defined as gestational age at birth, birth weight and perinatal mortality. In cases of BFC III the venous velocimetry of 15 nonsurviving fetuses was compared to that of the 22 survivors. RESULTS: There was a significant correlation between venous blood velocity and placental vascular resistance. In the right hepatic vein there was a significant decrease in peak systolic and end-systolic velocities and an increase of maximum velocity during atrial contraction and pulsatility (P < 0.05). A decrease of all velocities and increase of pulsatility were noted in the ductus venosus (P < 0.05). A reversed flow in the ductus venosus was found in 9/37 fetuses and double umbilical venous pulsations in 16/37 fetuses. However, the hepatic vein seemed to be a better predictor of impending mortality than the ductus venosus. Changes in diastolic venous blood velocity and a double pulsation in the umbilical vein were closely related to perinatal mortality, although these parameters did not provide a useful threshold to optimize the timing of delivery. CONCLUSION: Diastolic venous velocimetry changes significantly in severely compromised fetuses. These changes might be of great clinical value in deciding on the timing of delivery to minimize damage to the fetus and newborn.     

Prenatal diagnosis of abnormalities of the fetal venous system.

OBJECTIVE: To present our experience in the prenatal diagnosis of anomalies of fetal veins using high-resolution color Doppler ultrasound. DESIGN: An observational study of 16 fetuses with abnormalities of the umbilical, portal, hepatic and caval venous system being diagnosed at the Division of Prenatal Diagnosis and Therapy (Bonn, Germany) over the past 5 years. The abnormality of the venous system, the underlying embryologic disorder and the outcome of the pregnancy are presented and compared with the literature. RESULTS: In group A, eight fetuses had an abnormal course of the umbilical vein with a patent (n = 3) or absent (n = 5) ductus venosus. No portal veins and absent or abnormal hepatic veins were visualized by color Doppler sonography. Six fetuses (75%) did not have an associated malformation and have survived. Two pregnancies with fetal hydrops due to a small heart and to Turner's syndrome were terminated or ended in fetal demise. In group B, seven of eight fetuses with an abnormal caval system had a situs ambiguus or an atrial isomerism. A cardiac defect was detected in six cases (86%). These six pregnancies ended in four terminations of pregnancy and two infant deaths due to the severity of the congenital cardiac defect. One child with a normal heart and a child with an isolated abnormal course of the lower inferior vena cava are developing well. CONCLUSIONS: In a targeted fetal scan the course of the umbilical vein, ductus venosus, the portal and hepatic veins and inferior vena cava should be carefully examined using color Doppler. Any suspicious finding should be followed by a detailed assessment of the specificity of this abnormality taking into consideration the embryologic development of the fetal venous system together with the associated malformations.     

Two ductus venosus: a previously unreported anomaly

In early fetal life, the ductus venosus (DV) connects the umbilical vein, carrying nutrient-rich and oxygenated blood from the placenta to the inferior vena cava (IVC). We present the first ever case of a fetus with two ductus venosus. The fetus presented with a four-vessel cord and a dilated bowel at 31 weeks of gestation. Ultrasonography showed a persistent right umbilical vein. Echocardiographic investigation revealed normal cardiac anatomy with no major malformations. Two DVs with slightly different Doppler patterns were visualized anastomosing with the IVC. The baby was born uneventfully at 39 weeks of gestation with stable hemodynamics. Assuming every supernumerary umbilical vein should be connected to a DV for balanced circulation, a fetus with supernumerary umbilical veins lacking a corresponding number of DV connections is likely to be predisposed to complications such as hydrops fetalis and poor perinatal outcomes. The possibility of one or more umbilical veins lacking a DV connection warrants significant attention and regular monitoring from feto-maternal specialists, given the severity of the associated morbidity and mortality.     

Agenesis of the ductus venosus—A case with favorable outcome after early signs of cardiac failure

Absence of the ductus venosus (ADV) is a rare vascular anomaly. Its prognosis depends on the pathway of the umbilical flow to the systemic venous circulation, and the presence or absence of associated structural or chromosomal anomalies, sometimes resulting in hydrops fetalis. In cases with isolated ADV in the absence of associated anomalies, survival rates are as high as 85%, depending on the shunt situation. Here, we report a patient with ADV and extrahepatic umbilical vein drainage with favorable outcome after intrauterine reversal of early signs of cardiac failure. Diagnosis was made after the appearance of moderate cardiomegaly in the 25th gestational week. Thus, in the case of cardiomegaly with or without further signs of cardiac failure, ultrasound imaging of the venous duct should be considered. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound, 2013     

Venous pulsation in the fetal left portal branch: the effect of pulse and flow direction.

OBJECTIVE: To determine whether the waveform in the left portal branch is reciprocal to the waveform found in the ductus venosus and umbilical vein due to difference in pulse direction compared to flow. METHODS: Ten fetuses (gestational age, 18-33 weeks), six with intrauterine growth restriction, three with non-immune hydrops and one with sacrococcygeal teratoma, were examined using ultrasound imaging and pulsed Doppler. Techniques were adjusted to record simultaneously the waveform from neighboring sections of the veins, relate wave components to each other and determine degree of pulsatility. The corresponding vessel diameters were determined. ANOVA with t-test or Wilcoxon signed rank test was used to compare paired measurements. RESULTS: Pulsation in the left portal branch was noted in all fetuses. The pulsatility index was higher than in the umbilical vein (P = 0.005) and the diameter smaller (P = 0.001). In the left portal branch the atrial contraction wave appeared as a velocity peak while there was a nadir during ventricular systole. Simultaneous recordings showed that the waveform was reciprocal to that found in the ductus venosus and umbilical vein. In three cases an augmented pulsatility represented a pendulation of blood in the left portal branch with time-averaged velocity near zero. CONCLUSIONS: The velocity waveform recorded in the left portal vein is an inverse image of that in the ductus venosus, proving that pulse wave and blood flow run in the same direction in the left portal vein. Low compliance (i.e. small diameter) is probably a main reason for the high incidence of pulsation in this vein. Time-averaged velocity near zero recorded in three fetuses indicates that this area acts also as a watershed.     

Congenital absence of portal vein in the fetus: a case report.

Congenital absence of portal vein (CAPV) is a rare abnormality, which may be associated with other abnormalities. We report a case of prenatal diagnosis of absent portal vein confirmed on postnatal ultrasonography and computed tomography scan. The ultrasound features of CAPV include dilated intra-abdominal segment of umbilical vein, dilated inferior vena cava and the presence of hyperechogenic areas in the liver. Blood coming from the umbilical vein directly drains into the inferior vena cava. The dilated intra-abdominal segment of the umbilical vein shows high velocity pulsatile flow, resembling that of ductus venosus. These findings should prompt a careful search for the portal vein and any associated anomalies.     

Abnormalities of the fetal central veins and umbilico-portal system: prenatal ultrasonographic diagnosis and proposed classification.

OBJECTIVES: Anomalies of the fetal venous system are poorly documented and their pathogenesis is not well understood. The present study was undertaken to review the spectrum of fetal central veins and umbilico-portal system anomalies, and to propose a classification system. METHODS: A 7-year restrospective survey was conducted. RESULTS: Nineteen fetuses showed abnormal connection between central veins and the fetal heart. Three fetuses showed abnormal connections of the cardinal veins, two of which had interruption of the inferior vena cava, and one had isolated persistent left superior vena cava. Anomalies of pulmonary veins were seen in four fetuses: in two with asplenia syndrome, a vertical confluent pulmonary artery was observed. In a further two cases total anomalous pulmonary venous connections were found. Abnormalities of the umbilical vein (UV) were seen in 10 cases; seven had persistent right UV, and three had a spectrum of anomalies: One had abnormal connections of the UV to the left iliac vein associated with agenesis of the ductus venosus (DV) and hydrops fetalis. One case showed in utero occlusion of the DV by echogenic foci that resulted in a persistent left proximal UV and porto-systemic shunt. One case had obliteration of the DV secondary to in utero fetal hepatic fibrosis. Abnormalities of the vitelline veins or portal system were demonstrated in two cases. One had a left porto-systemic shunt which resolved spontaneously at 3 months of age, and one had secondary partial occlusion of the left portal system with liver echogenicities and direct communication of the UV with the right atrium. None of the 19 cases had an abnormal karyotype or evidence of in utero infection. CONCLUSIONS: Detection of various fetal vein anomalies in utero is feasible. The anomalies vary according to embryologic precursors or etiology. Two major mechanisms seem to be involved in the genesis of fetal vein anomalies: in most cases primary maldevelopment of the venous system occurs, while in the minority secondary anomalies from possible thromboembolic events or systemic disease may play a role.     

Combination of fetal Doppler velocimetric resistance values predict acidemic growth-restricted neonates.

OBJECTIVE: This study was undertaken to determine the efficacy of combination Doppler velocimetric resistance values of the umbilical artery and ductus venosus in predicting growth-restricted neonates with acidemia. METHODS: This retrospective case-control study included 61 gravidas complicated by intrauterine growth restriction with acidemia and 65 control pregnancies. The Doppler velocimetric resistance values obtained from the growth-restricted and control fetuses were in turn compared with the median values derived from another 192 normal pregnancies to adjust the biometric bias due to gestational age. RESULTS: Based on the pulsatility index of the umbilical artery and pulsatility index for the vein of the ductus venosus, the areas under the receiver operating characteristic curves were 0.7992 and 0.6749, respectively, for predicting growth-restricted neonates with acidemia. With a combination of the pulsatility indices of the umbilical artery and the pulsatility indices for the vein of the ductus venosus, the predictive accuracy of the growth-restricted neonates with acidemia increased, with sensitivity of 0.79 and specificity of 0.79 and an area under the receiver operating characteristic curve of 0.8441. CONCLUSIONS: Compared with single-vessel assessment, combining the pulsatility indices of the umbilical artery and the pulsatility indices for the vein of the ductus venosus provides the greatest accuracy in predicting growth-restricted neonates with acidemia.     

Ductus venosus blood flow velocity characteristics of fetuses with single umbilical artery.

OBJECTIVES: Sonographic Doppler evaluation of the fetal ductus venosus has been proved to be useful in the evaluation of fetal cardiac function. The aim of this study was to investigate the ductus venosus blood flow profile in fetuses with single umbilical artery and to correlate it with the umbilical cord morphology. METHODS: Fetuses at >20 weeks' gestation with single umbilical artery who were otherwise healthy were consecutively enrolled into the study. The sonographic examination included evaluation of the following Doppler parameters: umbilical artery resistance index, maximum blood flow velocity of the ductus venosus during ventricular systole (S-peak) and atrial contraction (A-wave), ductus venosus time-averaged maximum velocity (TAMXV), and pulsatility index for veins (PIV). The cross-sectional area of the umbilical cord and its vessels were measured in all cases. The Doppler and morphometric values obtained were plotted on reference ranges. RESULTS: A total of 88 fetuses with single umbilical artery were scanned during the study period. Of these 52 met the inclusion criteria. The S-peak velocity, A-wave velocity, and TAMXV were below the 5th centile for gestational age in 57.7%, 59.6%, and 57.7% of cases, respectively. The PIV was within the normal range in 80.1% of cases. The umbilical vein cross-sectional area of fetuses with single umbilical artery was above the 95th centile for gestational age in 34.6% cases. CONCLUSIONS: The ductus venosus blood flow pattern is different in fetuses with single umbilical artery from that in those with a three-vessel cord. This difference may be caused in part by the particular morphology of umbilical cords with a single artery.