Three-dimensional color power imaging of the fetal hepatic circulation

OBJECTIVE: The purpose of this study was to describe the use of three-dimensional power Doppler ultrasonography to identify vascular congenital anomalies of fetal portosystemic and umbilical venous systems. STUDY DESIGN: In a prospective study, the hepatic and umbilical venous systems were examined in 390 fetuses with two-dimensional ultrasonography, color, and spectral Doppler imaging. Fetuses suspected to have anomalies of the portal system and ductus venosus were additionally examined with three-dimensional power Doppler ultrasonography. RESULTS: Vascular anomalies were identified in 8 fetuses (absent ductus venosus, n=4; direct connection between the umbilical vein and the right atrium, n=2; and direct connection between the umbilical vein and the inferior vena cava, n=2) out of the 310 in which the venous system could be adequately imaged (prevalence=2.6%). Three-dimensional power Doppler imaging showed the course of the umbilical vein, its relationship to the portosystemic circulation, and whether a ductus venosus was present. CONCLUSION: Three-dimensional power Doppler ultrasonography can be used to image normal fetal hepatic and portal circulation, as well as identify anomalies of the fetal portosystemic and umbilical venous systems.     

An anatomic investigation of radical resection of tumor in the hepatic duct confluence

The fetal umbilical vein in the ligamentum teres can be reopened to provide a 10 centimeter long vein, as wide as the left portal vein or the central splenic vein, that gives access to the left portal vein in the umbilical fissure of the liver. By cutting the ligamentum teres, this potential autologous venous graft is lost and, therefore, the ligamentum teres should never be sacrificed without reason. The umbilical side of the reopened umbilical vein can be anastomosed with the splenic vein to form a portal vein bypassing conduit that enters the liver in the umbilical fissure and take over function of the portal vein. From the results of this postmortem investigation, it can be concluded that radical block resection of the area consisting of the hepatic duct confluence, classic right hepatic lobe and complete hepatoduodenal ligament, preceded by construction of a complete separate afferent blood supply of the classic left hepatic lobe, is possible both anatomically and technically. There is no indication denying the supposition that the result of such a procedure is functionally analogous to standard extended right lobectomy with bilioenteric reconstruction.     

The effect of an elevated maternal lysine concentration on placental lysine transport in pregnant sheep

OBJECTIVES: In a previous study, the coinfusion into the maternal circulation of lysine and several other amino acids failed to increase significantly lysine umbilical uptake. The purpose of this study was to determine whether umbilical lysine uptake can be increased by infusing a lysine solution that does not contain any other amino acid. STUDY DESIGN: Six late-gestation ewes were studied on 2 consecutive days. Samples were collected in both the control (first day) and experimental (second day) periods simultaneously from the maternal artery, uterine vein, fetal artery, and umbilical vein. In the control period, L-[1-(13)C] lysine was infused into the maternal circulation. During the experimental period, both L-[1-(13)C] lysine and L-(12)C lysine were infused to increase maternal lysine concentration. Uterine and umbilical blood flows were measured by the steady state diffusion technique. Uterine and umbilical uptake of lysine and of alpha-aminoaminoadipic acid (AAD, a biproduct of lysine oxidation) were calculated. RESULTS: In response to a 2.7-fold increase in maternal lysine concentration (P<.001), fetal lysine concentration increased approximately 70% (P<.05) and umbilical uptake 50% (P<.05). In the experimental period, there was a significant (P<.05) placental uptake of fetal AAD, and the fetal/maternal plasma (13)C-lysine-specific activity ratio increased from 0.221+/-0.026 to 0.294+/-0.029 (P<.05). In response to the increase in maternal lysine concentration, the maternal and fetal concentrations of several other amino acids were significantly decreased. CONCLUSION: This study establishes that the umbilical uptake of lysine can be increased by infusing lysine in the maternal circulation. However, the lysine infusion is associated with a decrease in the maternal concentration and umbilical uptake of other essential amino acids. These data, compared with the results of previous studies, indicate that attempts to increase the fetal uptake of an amino acid via maternal infusion may decrease the uptake of other amino acids by decreasing their maternal concentration and by inhibition of placental transport.     

Effect of epidural anesthesia for cesarean delivery on maternal femoral arterial and venous, uteroplacental, and umbilical blood flow velocities and waveforms

The effect of epidural anesthesia on the maternal femoral arterial and venous, uteroplacental, and umbilical circulations was studied by the pulsed Doppler technique in 13 women undergoing elective cesarean delivery. Resistance and pulsatility indices of umbilical arterial velocity waveforms did not change with the use of epidural anesthesia. In the uteroplacental circulation, these indices increased in 11 patients, suggesting an increase in resistance. Reduction of sympathetic tone in resistance and capacitance vessels was reflected in the femoral artery by an increase in systolic and end-diastolic velocities, a reversal of the post-systolic backward flow, and an increase in mean velocity. The latter also occurred in the femoral vein. The diameters of these large maternal vessels did not change. This study suggests an impairment in uteroplacental circulation associated with a drop in peripheral vascular resistance and an increase in leg blood flow after epidural anesthesia.     

Prenatally diagnosed portocaval shunt and postnatal outcome: a case report

Congenital absence of the portal vein (CAPV) is a rare anomaly in the form of a portocaval shunt, whereby the intestinal and splenic venous drainage bypasses the liver and drains directly into the systemic circulation. We report a case of CAPV diagnosed prenatally after the recognition of a dilated umbilical vein draining directly into a large inferior vena cava (IVC). The IVC then drained into the right atrium of a dilated, hyperdynamic heart. The ductus venosus could not be identified. Repeated postnatal scans showed a gradual disappearance of venous lakes in the region of the porta hepatis and a clear drainage of the splenic vein to the left renal vein and the superior mesenteric vein to the IVC. From birth up to twelve months follow-up there was no evidence of liver dysfunction, encephalopathy or liver lesions.     

Simultaneous measurement of hepatic arterial and portal venous flows by transit time ultrasonic volume flowmetry

Simultaneous measurement of the hepatic artery and the portal vein was performed successfully upon 15 anesthetized patients during abdominal operations with the use of transit time ultrasonic volume flowmeter. The hepatic arterial flow, portal venous flow and total hepatic flow were 267.3 +/- 21.2, 746.4 +/- 41.3 and 1,010.7 +/- 52.7 milliliters per minute, respectively. The ratio of hepatic arterial flow to portal venous flow was 0.36 +/- 0.03. Temporary occlusion of the portal vein resulted in a significant increase in hepatic arterial flow (23.6 +/- 4.3 per cent, p less than 0.01), whereas temporary occlusion of the hepatic artery did not alter portal venous flow significantly. Occlusion of the common hepatic artery induced a significant decrease in hepatic arterial flow (p less than 0.05), but did not alter portal venous flow significantly. The results of this approach had useful clinical meanings in one patient in whom the Appleby's operation was performed in which sufficient hepatic arterial flow was needed after the common hepatic artery was ligated. Data are presented for hepatic circulation measured by transit time ultrasonic volume flowmeter, which is a good device to use to assess portal venous flow as well as hepatic arterial flow with reproducibility and stability.     

Persistent right umbilical vein associated with complex congenital cardiac malformation

Umbilical venous catheterization is frequently used for vascular access during neonatal resuscitation. The differentiation between umbilical artery and vein, specifically during the resuscitation procedure, is clinically neither always easy nor unambiguous. A preterm infant of 35 weeks of gestational age was born after an uneventful course of his mother's pregnancy. Severe postnatal cyanosis led to the placement of presumed arterial and venous umbilical catheters. Chest x-ray was suggestive of the presence of a persistent right umbilical vein (PRUV). Echocardiography showed a double outlet right ventricle with mitral atresia and a levo-atrial cardinal vein draining the left atrium into the azygos vein. The foramen ovale was firmly closed and conventional balloon atrioseptostomy failed. Several attempts of transseptal puncture and subsequent creation of an atrial septal defect were unsuccessful and the infant eventually died. There is an association of PRUV and congenital cardiac malformation. PRUV can be diagnosed prenatally if specifically looked for. The presence of PRUV can be the only clue prenatally alerting to the presence of congenital heart disease. Postnatal diagnosis of PRUV may justify echocardiography and cardiologic assessment even in the absence of clinical cyanosis.     

Prenatal diagnosis of ductus venosus agenesis and its association with cytogenetic/congenital anomalies

OBJECTIVES: We present an observational study of 12 cases of anomalies of the umbilical and portal vein systems associated with absence of the ductus venosus (DV) diagnosed over the past 5 years. The hemodynamic implications of each pattern of umbilico-portal system anomalies associated with absence of the DV have been investigated, as well as the frequency and types of associated anomalies and their embryological origin. METHODS: In all cases ultrasound, color Doppler, and cytogenetic investigations were performed. RESULTS: Four main patterns of abnormal venous circulation were documented: (1). the umbilical vein (UV) bypasses the liver and drains into the right atrium directly or through a dilated coronary sinus (three cases); (2). the UV bypasses the liver, with an infrahepatic or suprahepatic connection directly to the inferior vena cava (IVC) (two cases); (3). the UV bypasses the liver and drains directly into the iliac or renal veins (four cases); and (4). the UV drains directly into the portal veins (three cases). Among seven cases with other associated anomalies (58%), there were three cases of Turner's and Noonan's syndromes. Two fetuses and two neonates died and there were two terminations of pregnancy (TOP). CONCLUSIONS: In utero diagnosis of ultrasound patterns associated with DV anomalies is feasible. Fetal karyotyping should be considered, serial ultrasound examinations recommended and, in the presence of heart failure, delivery can be anticipated.     

Severe fetal hemolytic disease. Evaluation and successful treatment by means of cordocentesis

Ultrasonically guided access to the fetal umbilical circulation offers an alternative to the standard management of the severe isoimmunized pregnancy. This technique allows fetal blood sampling, direct hematocrit analysis and intravascular transfusion. A severely Rh isoimmunized pregnancy is described in which five intrauterine transfusions of blood were given directly into the umbilical vein under ultrasound visualization. Technical aspects of the procedure and complications are discussed.     

Doppler assessment of the fetal asphyxia in pregnancies complicated by gestational hypertension and intrauterine growth retardation

OBJECTIVES: Gestational hypertension is associated with a high morbidity for both mother and fetus. Doppler ultrasound has allowed the fetal circulation to be examined. Now it is possible to monitor the response of the fetal circulation to hypoxia. DESIGN: The aim of this study was to determine flow patterns in fetal circulation from pregnancies complicated by gestational hypertension and intrauterine growth restriction. MATERIALS AND METHODS: The investigation included 23 fetuses with signs of the gestational hypertension and intrauterine growth restriction. We evaluated cerebral-placental ratio (CPR) and pulsation index (PI) in the middle cerebral artery (MCA) and the umbilical artery (UA). We also evaluated flows in umbilical vein. RESULTS: We observed abnormal flow pattern in all cases of analyzing fetuses. The most common abnormal flow was vein pulsation (48%). CONCLUSIONS: All analyzing fetuses shown signs of the hypoxia. Present of the umbilical vein pulsation or decompensate of the brain sparing effect is closely related o increased perinatal mortality.     

Agenesis of the ductus venosus and its correlation to hydrops fetalis

Absence of the ductus venosus is a rare vascular anomaly. We report a late onset of a hydrops fetalis seen in a fetus at 34 completed weeks of gestation. A persistence of the cranial parts of the left and right umbilical veins and of the paired cranial vitelline veins with an absent ductus venosus led to a bilateral hydrothorax, ascites and skin-edema. Postnatally the hydrops resolved within 7 days most probably due to the change from the fetal to the adult circulation. The abnormal venous system was confirmed by angiography. Agenesis of the ductus venosus can manifest in two different morphologic patterns: The umbilical vein drains exclusively into the left branch of the intrahepatic portal vein or the umbilical vein drains into the inferior vena cava or directly into the right atrium by-passing the liver completely. In both patterns, the preferential direction of the flow towards the foramen ovale is not present. While the first pattern leads to hyperperfusion of the liver parenchyma, the latter would result in reduced perfusion and oxygenation. Our findings suggest that agenesis of ductus venosus might induce hydrops fetalis. We conclude, that in every case of hydrops fetalis the venous system should be evaluated by ultrasonography prenatally and/or immediately postnatally.     

Use of hypertonic solutions through umbilical cord vessels]

The authors report on a newborn with skin necroses and fibularis paresis after postnatal administration of NaHCO3 via the umbilical cord. Then some problems of postnatal buffer therapy are discussed. After a review of advantages and disadvantages of puncture or cannulation of the umbilical vein on the one hand and its catheterization on the other, the former procedures are preferred for an effective buffer therapy, provided strict indications are followed.     

Percutaneous umbilical blood sampling. A new technique for prenatal diagnosis

Direct access to fetal blood during the second and third trimesters of pregnancy opens new fields of prenatal diagnosis and in utero fetal treatment. Percutaneous umbilical blood sampling, a method that involves ultrasonographically guided needle insertion into the umbilical vein, appears to have an acceptable complication rate. This technique has tremendous potential for use in evaluating fetal status.     

Transplacental passage of digoxin in severe Rhesus immunization

Maternal and umbilical vein digoxin concentrations were determined in 16 mothers and fetuses with severe Rhesus-D disease, eight with, and eight without prior digitalization of the mother, when umbilical cord puncture was performed for diagnosis and intrauterine blood transfusion. In the eight patients without digoxin treatment, the digoxin concentrations in both the mother and the umbilical vein were below the limit of detection (less than 0.3 nmol/l). In the other eight patients digitalization of the mother was started 24-48 hours before the first umbilical cord puncture. The maternal and umbilical vein digoxin concentrations were determined on 26 occasions. Except for two instances, digoxin concentrations in the umbilical vein were always below 1 nmol/l. The mean ratio of maternal to fetal digoxin concentrations before initial transfusion was 2.51 ( +/- ISD = 1.47) and before later transfusions 1.67 ( +/- ISD = 0.61). The differences in mean ratios between initial and later transfusions are not significant (p = 0.16). The mean ratio for the total group was 1.93 ( +/- ISD = 1.01). There was no correlation between the maternal to umbilical vein digoxin ratio and either gestational age or umbilical venous hematocrit. The results of our study indicate that the therapeutic effect of transplacental digitalization in severe Rhesus disease is questionable and that a multicentre randomized trial would be necessary to evaluate whether this treatment is of benefit.     

Intra-uterine exchange transfusion under ultrasound guidance

Thirty intra-uterine exchange transfusions (I.U.E.T.) under ultrasound guidance were performed on 15 pregnancies in 14 severely Rh-sensitized women. Our technique and a new method of catheterization of the umbilical cord are described. I.U.E.T. were commenced at 19-34 gestational weeks and repeated up to 5 times at 15 to 60 days intervals. The lowest pretransfusion fetal hemoglobin was 3 milligrams at 25 weeks. All the hydrops (4 cases) reversed a few days after the first procedure. The survival rate is 50% for hydropic fetuses and 66.6% for all cases. This technique avoids fetal hypervolemia and also too repetitive procedures by quick renewal of red cells. Catheterization offers a simple and safe access to the umbilical vein even with important fetal movements.     

The assessment of fetal well-being by venous Doppler velocimetry

The assessment of fetal well-being by venous Doppler velocimetry, especially in cases of intrauterine growth restriction, has been growing in importance as a number of researchers have been improving their studies^1 - 5 as well as a consequence of better technologies in ultrasound equipment. Since different authors have studied the fetal blood circulation with color Doppler, initially focusing their attention on the arterial system^6 - 12, many questions and doubts have remained without a reasonable answer, especially concerning the optimal time at which to deliver these fetuses. Among these authors, some have expressed the opinion that all biophysical methods, including the cardiotocogram, should be used before the decision of fetus delivery should be made^13,14. It is possible, nowadays, to study several venous vessels, such as the ductus venosus, inferior vena cava, umbilical vein, portal vein, hepatic veins¹⁵, and, more recently^1,2, the cerebral transverse sinus. The purpose of this review is to describe the fetal circulation, the technique and rationale behind measuring venous Dopplers and to assess the clinical applications of venous Doppler velocimetry.     

The antenatal blood gas and acid-base status of normal fetuses and hydropic fetuses with Bart hemoglobinopathy

Funipuncture offers direct access to the fetal circulation. The blood gas and acid-base status of the fetus can be studied, and fetal hypoxia and acidosis can be diagnosed directly. To establish normal ranges of fetal blood gas and acid-base status, we analyzed umbilical venous blood samples obtained by funipuncture from 62 normal fetuses (20-35 weeks). These fetuses were studied because of suspected fetal diseases and were subsequently proved to be normal by the fetal blood examinations. Umbilical vein pH and pO2 decreased whereas pCO2 and bicarbonate increased with gestational age. The umbilical vein base excess did not correlate with gestational duration, but oxygen saturation tended to decrease with gestational age. Twenty hydropic fetuses with Bart hemoglobinopathy were also studied; they were found to be more acidotic, hypoxic, and hypercarbic than normal fetuses.     

Percutaneous umbilical blood sampling

In the present day, fetal blood is sampled from the umbilical vein via a needle guided by dynamic ultrasound from the maternal abdomen (percutaneous umbilical blood sampling, PUBS). PUBS has become important in the fields of fetal physiology, diagnosis and therapy. Indications for PUBS are fetal karyotyping, prenatal diagnosis of blood disorders and congenital infection, and evaluation of fetal hypoxemia. Although risk of fetal loss following PUBS depends on the indication for the procedure and the experience of the operator, the rate of fetal loss after PUBS is assumed to be around 1%. Recent advances in molecular and cytogenetic techniques have restricted the number of reasons for using PUBS. However, since this technique offers a considerable advantage in enabling access directly to the fetal circulation, PUBS is likely to be used more frequently for fetal therapy than for prenatal diagnosis in the future.     

The left portal vein is the watershed of the fetal venous system

Critical fetal organs are preferentially supplied with oxygenated blood from the umbilical vein (UV) by way of the ductus venosus (DV). Under normal conditions a significant part of UV-blood flows steadily forward through the left portal vein (LPV). Blood flow through the LPV could reverse, however, in cases of absent or reversed endodiastolic flow in the umbilical arteries. We tested when fetal blood flow reversal occurs by studying 28 cases with pathological flow in the umbilical artery. In the LPV we observed normal nonpulsatile forward flow in 9 cases, pulsatile forward flow in 10 cases, and reversed flow in 9 cases. Reverse flow in the LPV correlated significantly with an elevated resistance index of the umbilical arteries. This reversal could have major physiological implications: Deoxygenated blood may be added via the LPV to the blood shifted through the DV and ultimately reach critical fetal organs. In extremis there could be a waterhose effect, whereby more blood flows through the DV than the UV that supplies it. The LPV is thus the watershed of the venous circulation of the fetus.