Transient hydropic signs in the donor fetus after fetoscopic laser coagulation in severe twin-twin transfusion syndrome: incidence and clinical relevance.

OBJECTIVE: To evaluate the incidence, characteristics, and impact on perinatal outcome of the development of hydropic signs in the donor fetus after laser coagulation for severe twin-twin transfusion syndrome in the second trimester. METHODS: Forty cases of second-trimester severe twin-twin transfusion underwent fetoscopic laser coagulation of placental anastomoses and were followed up with serial ultrasound up to 14 days after therapy. Ultrasound scans were performed just before, and on days 1, 3, 5 and 14 after therapy, and fetuses were monitored for the presence of hydropic signs (skin edema, pleural effusion, ascites and pericardial effusion). Response to therapy and perinatal outcome in terms of neonatal survival were recorded for all cases. RESULTS: Four recipients (10%) and three donors (7.5%) died over the first 72 h after therapy. During the study period, two recipients (5.5%) developed frank hydrops fetalis, and eventually died in utero. Ten donors (27.0%) developed one or more hydropic signs. In nine (90%), signs were mild or moderate and transient (mean, 3.2 days), while in one case hydrops worsened and the fetus eventually died. No donors with transient hydrops died in utero, and two died postnatally due to extreme prematurity. Gestational age at procedure and deepest amniotic fluid vertical pocket were similar between hydropic and non-hydropic donors. Discrepancy in estimated fetal weight at procedure was significantly lower in donors developing hydrops (9.6 (SD, 6.4) vs. 17.8 (14.4)%,P = 0.018). In pregnancies with hydropic donors, gestational age at delivery (33.1 (3.4) vs. 29.7 (3.5) weeks,P = 0.015) and birth weight for recipient (2392 (423) vs. 1631 (576) g, P < 0.001) and donor (1908 (774) vs. 1281 (583) g,P = 0.021) were significantly higher. The development of transient hydrops had no influence on neonatal survival at 28 days nor on the rate of clinical resolution of intertwin transfusion. CONCLUSIONS: Transient hydropic signs may develop in a proportion of donor fetuses after laser coagulation for severe twin-twin transfusion syndrome. This phenomenon is normally not associated with a poor prognosis, and possibly indicates an hemodynamic adaptation response following interruption of the transfusion process.     

Prognostic factors in severe twin-twin transfusion syndrome treated by endoscopic laser surgery.

OBJECTIVE: The aim of this study was to investigate clinical and sonographic parameters, in particular Doppler blood flow measurements, in severe second-trimester twin-twin transfusion syndrome before and after endoscopic laser coagulation of the placental vascular anastomoses, to correlate these data with fetal outcome and to determine whether fetal blood flow measurements could help to estimate the probability of fetal survival. METHODS: In 121 cases of severe twin-twin transfusion syndrome examined between 17 and 26 weeks of gestation, the following investigations were performed: fetal biometry, placental location, deepest pool of amniotic fluid, echocardiography and Doppler sonography of the umbilical arteries and the ductus venosus of both twins before and after fetoscopic laser ablation of the placental anastomoses. RESULTS: The overall survival rate was 64% (156/242). Both fetuses survived in 48% (58/121) and one fetus survived in 33% (40/121), resulting in 81% (98/121) of pregnancies with at least one survivor. Gestational age at the time of the procedure and placental location had no significant influence on fetal survival. The amniotic fluid volume drained after laser coagulation correlated significantly (p = 0.038) with the risk of miscarriage or extremely premature delivery within 4 weeks of the procedure. Intertwin discrepancy in abdominal circumference showed a significant negative correlation (p = 0.004) with the probability for survival of donor fetuses. Before the procedure, 19% (23/121) of donor twins and 5% (6/121) of recipient twins showed absent or reversed end-diastolic flow in the umbilical artery (p = 0.001). This finding had no significant influence on the survival rate of donors. An increase of waveform indices in the umbilical artery 1 day after the procedure compared to immediately after the procedure correlated significantly with a lower probability for survival of donors (p = 0.042) and recipients (p = 0.018). Before the procedure, 37% (45/121) of recipient twins and 9% (10/113) of donor twins showed absent or reversed flow during atrial contraction in the ductus venosus (p < 0.0001). This finding had a significant negative influence on the survival rate of recipient fetuses (p = 0.02). Furthermore, an increase of waveform indices in the ductus venosus 1 day after the procedure compared to immediately after the procedure correlated significantly with a lower probability of survival in recipients (p = 0.005). CONCLUSIONS: Fetoscopic laser coagulation of the placental vascular anastomoses in severe mid-trimester twin-twin transfusion is a potentially corrective and effective, minimally invasive procedure. Doppler investigation of the umbilical and fetal circulations provides important information on the fetal condition, prognosis and therapeutic effects of the intervention. Signs of congestive heart failure in the recipient may reduce the probability of survival, whereas increased placental resistance in the donor before the procedure is not necessarily associated with a reduction in the probability of survival after laser coagulation.     

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.     

Ultrasound assessment of venous blood flow before and after laser therapy: approach to understanding the pathophysiology of twin-twin transfusion syndrome.

OBJECTIVE: To estimate direction and volume of blood exchange between the donor twin and recipient twin by ultrasound assessment of blood flow in the umbilical vein before and after selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS). METHODS: Forty-one TTTS patients underwent Doppler examination of the umbilical vein before and 24 h after SLPCV. The diameter and mean time-averaged velocity of the umbilical vein were estimated. Total umbilical venous flow (TUVF) was calculated as follows: TUVF (mL/min) = mean time-averaged velocity (cm/s) x mean cross-sectional area (cm2) x 60 (s). RESULTS: TUVF was significantly higher in the recipient (111.2 mL/min) than in the donor twin (44.8 mL/min) before SLPCV (P < 0.0001). However, TUVF was no different between the recipient and the donor twin after SLPCV (93.1 vs. 70.7 mL/min, recipient and donor twin, respectively, P = 0.11). The donor twin's TUVF increased after surgery (P < 0.0001), while the recipient twin's TUVF decreased (P = 0.041). The median postoperative increase in the donor twin's TUVF of 25.9 mL/min had a corresponding decrease of TUVF in the recipient twin of 18.1 mL/min (P = 0.27). CONCLUSIONS: Our data suggest that untreated TTTS is characterized by excessive umbilical venous blood flow in the recipient twin relative to the donor twin. Laser surgery results in concordant changes in umbilical venous flow in opposite directions between the donor and recipient twins, eliminating the initial imbalance. Our results lend support to the fundamental hypothesis of unbalanced blood flow exchange (net flow from donor to recipient) between monochorionic twins as the cause for TTTS and that laser surgery eliminates the pathophysiological cause.     

Fetal arterial Doppler studies in twin-twin transfusion syndrome.

This cross-sectional study investigates the circulatory profile of the donor and recipient fetuses in pregnancies with twin-twin transfusion syndrome manifested by acute polyhydramnios during the second trimester of pregnancy. Doppler investigations of the umbilical arteries and of the fetal descending thoracic aortas and middle cerebral arteries were performed in both fetuses of 27 pregnancies with twin-twin transfusion syndrome at 18 to 25 (mean, 21.7) weeks' gestation. Significant differences from normal values were increased umbilical artery pulsatility index and decreased aortic mean velocity in both donor and recipient fetuses, decreased middle cerebral artery pulsatility index in recipients and decreased middle cerebral artery mean velocity in donors. Increased umbilical artery pulsatility index in some donor and recipient fetuses may be the consequence of abnormal placental development and polyhydramnios-related compression, respectively. Doppler findings in the fetal circulation are compatible with hypovolemia in the donor and hypervolemia with congestive heart failure in the recipient.     

Stage-dependent fetal umbilical blood flow changes induced by laser therapy and amniodrainage in twin-to-twin transfusion syndrome.

OBJECTIVE: To estimate changes in umbilical blood flow (UBF) and Doppler indices in pregnancies complicated by twin-to-twin transfusion syndrome (TTS) treated with either laser therapy or amniodrainage, and to evaluate the influence of the presence of hemodynamic deterioration prior to therapy, as determined by the Quintero stages of severity. METHODS: Forty-eight cases of TTS were included, and further classified into severity Stages I or II (absence of critically abnormal Dopplers (CAD), n = 22) and Stages III or IV (presence of CAD or hydrops fetalis, n = 26). In Stages I-II, 14 cases were treated with laser and eight with amniodrainage, and in Stages III-IV, 17 were treated with laser and nine with amniodrainage. Differences in the UBF, umbilical artery pulstility index (UA-PI) and ductus venosus pulsatility index (DV-PI) were estimated for both groups of severity before and after both treatments. Eleven normal monochorionic pregnancies were evaluated as controls. RESULTS: In recipients, UBF was significantly higher with respect to controls regardless of the stage, while donors had a significant decrease in UBF, but only in Stages III-IV. After laser treatment no changes were observed in fetuses in Stages I-II. In Stages III-IV, recipients showed a significant reduction in the DV-PI (mean DV-PI 1.31 +/- 0.18 vs. 1.05 +/- 0.22; P = 0.005) whereas donors showed a significant increase in the UBF (mean UBF 134 +/- 36 mL/min vs. 195 +/- 25 mL/min; P < 0.001) and in the DV-PI (mean DV-PI 0.99 +/- 0.26 vs. 1.36 +/- 0.42; P = 0.002), and a reduction in the UA-PI (mean UA-PI 1.86 +/- 0.41 vs. 1.58 +/- 0.30; P = 0.01). After amniodrainage only donor fetuses in Stages III-IV showed an increase in UA-PI (mean UA-PI 1.54 +/- 0.35 vs. 1.72 +/- 0.40; P = 0.015). No other changes were observed in any of the parameters studied. CONCLUSION: Laser therapy induces consistent hemodynamic variations in TTS mainly manifested in Stages III-IV.     

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.     

超声评价双胎输血综合征"供血儿"的心功能改变

目的 探讨二维及彩色多普勒超声评价双胎输血综合征(TTTS)"供血儿"心功能的临床价值。方法 选择17例TTTS孕妇及19名正常单绒毛膜囊双羊膜囊双胎孕妇,测量脐动脉、脐静脉、静脉导管等血流频谱参数,计算胎儿心胸面积比值及心肌做功指数,重点分析"供血儿"的心功能改变。结果 TTTS"供血儿"中,7胎出现脐动脉舒张期血流缺失或反向,1胎发现心脏明显扩大并合并心包积液。"供血儿"静脉导管搏动指数明显高于正常胎儿。结论 TTTS"供血儿"已出现一定程度的心功能异常,动态监测心功能状况有助于判断TTTS严重程度,评价干预治疗的疗效。     

Intrauterine death of one twin, with rescue of the other, in twin-twin transfusion syndrome.

Single intrauterine death may occur in twin-twin transfusion syndrome. We investigated why the outcome of the surviving twin is fairly good when the donor twin dies first compared with when the recipient twin dies first. A detailed hemodynamic study was performed using Doppler ultrasound in a twin pregnancy affected by twin-twin transfusion syndrome before and after a single intrauterine death that occurred in the donor twin at 26 weeks' gestation. The recipient twin was expected to die due to severe right cardiac failure with functional stenosis of the pulmonary artery 2 days before the cotwin's death. The donor twin's death caused a prompt resolution of cardiac failure and improvement in other indices, including flow velocity waveform patterns of the umbilical vein, the middle cerebral artery and the ductus venosus. A healthy, premature female neonate weighing 1630 g with a hemoglobin concentration of 17.8 g/dL was delivered by Cesarean section following rupture of the fetal membranes 28 days after the episode. Hemorrhaging from the surviving twin to the dead twin that occurred just before or after the cotwin's death may have contributed to the decrease in volume overload in the recipient twin, leading to a prompt amelioration of the critical hemodynamic indices. The early death of the donor twin may thus have played a significant role in improving the status of the recipient twin in this case of twin-twin transfusion syndrome.     

The role of Doppler studies in predicting individual intrauterine fetal demise after laser therapy for twin-twin transfusion syndrome.

OBJECTIVE: To investigate the role of Doppler studies in predicting individual fetal demise in patients scheduled for selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS). METHODS: Doppler studies of the umbilical artery, umbilical vein, ductus venosus, tricuspid valve regurgitation and middle cerebral artery were performed in the donor and recipient twins before and 24 hours after SLPCV. Results were analyzed cross-sectionally and longitudinally. As multiple comparisons were made, an a priori alpha rejection was set at P < 0.001. RESULTS: One hundred and ten consecutive patients were available for analysis. Overall fetal survival was 68.6% (151/220) with at least one survivor in 88.2% (97/110) of cases. Absent or reversed end-diastolic velocity in the umbilical artery of the donor twin was the only preoperative Doppler result predictive of intrauterine fetal demise (IUFD) (10/15, 66.7%, P < 0.001). Postoperatively, reversed flow during atrial contraction in the ductus venosus of the donor twin showed a trend towards prediction of IUFD of this fetus (4/5, 80%, P = 0.007). No other Doppler studies, including the longitudinal analyses, were predictive of IUFD. CONCLUSIONS: Our data suggest that preoperative absent or reversed end-diastolic velocity in the umbilical artery may be useful in predicting individual fetal demise of the donor twin in TTTS patients scheduled for SLPCV. This may reflect the role of decreased individual placental mass that may be associated with some donor twins. The inability of other Doppler studies to predict individual IUFD may be explained preoperatively by the effect of the interfetal vascular connections on the individual Doppler signals and postoperatively by the effect of surgery or the timing of the assessment. Our findings may be important in patient counseling, in furthering understanding of the disease, and perhaps in improving surgical technique.     

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.     

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.     

Fetal brain/liver volume ratio and umbilical volume flow parameters relative to normal and abnormal human development.

OBJECTIVES: To estimate fetal brain volume from head circumference and published postmortem data; to determine normal values for the fetal brain/liver volume ratio relative to gestational age; to establish the relationship between the brain/liver volume ratio and fetal circulatory parameters during normal and restricted (SGA) fetal growth. PATIENTS AND METHOD: This was a cross-sectional study involving a total of 47 uncomplicated pregnancies appropriate-for-gestational age (AGA) and 23 pregnancies resulting in the delivery of a SGA fetus. At enrollment gestational age ranged between 20 and 36 weeks in both groups. Umbilical venous cross-sectional area and time-averaged velocity for calculation of volume flow as well as velocity waveforms from the umbilical artery, middle cerebral artery and ductus venosus, were recorded. Fetal liver volume measurements were obtained using three-dimensional ultrasound. Fetal brain volume was estimated from fetal head volume following comparison with published postmortem data on fetal brain weight. RESULTS: A significant correlation was observed between prenatally estimated fetal head volume and postmortem fetal brain volume. Fetal brain volume was approximately half that of fetal head volume. The normal fetal brain/liver volume ratio demonstrated a significant reduction with gestational age (R = -0.54; P < 0.001). The normal mean +/- standard deviation (SD) fetal brain/liver volume ratio (3.4 +/- 0.7) was significantly different (P < 0.001) from the mean fetal brain/liver volume ratio in the SGA group (n = 23) (5.9 +/- 1.9). A significant difference existed for mean umbilical venous volume flow between AGA (104.7 +/- 26.9 mL/min/kg) and SGA (59.6 +/- 22.7 mL/min/kg) fetuses. In the SGA fetus, there was a significant inverse relationship (P < 0.001) between fetal weight-related umbilical venous volume flow and fetal brain/liver volume ratio. In a subset of 16 SGA and 16 AGA fetuses matched for gestational age, a significant difference existed for umbilical artery pulsatility index (2.30 +/- 1.52 vs. 0.99 +/- 0.19), fetal middle cerebral artery pulsatility index (1.3 +/- 0.4 vs. 2.1 +/- 0.3) and late diastolic flow velocity in the fetal ductus venosus (6.9 +/- 14.2 cm/s vs. 23.9 +/- 8.8 cm/s), but not for peak systolic, early diastolic and time-averaged velocity in the ductus venosus. CONCLUSION: Sonographic estimates of fetal brain volume can be obtained. The fetal brain/liver volume ratio is a predictor of fetal outcome in the growth-restricted fetus. An inverse relationship exists in SGA fetuses between brain/liver volume ratio and fetal weight-related umbilical venous blood flow.     

Color Doppler ultrasonography in the identification of communicating vessels in twin-twin transfusion syndrome and acardiac twins.

This study evaluates the role of color Doppler ultrasonography in the identification of the communicating placental vessels in pregnancies with twin-twin transfusion syndrome and acardiac twins. In 18 pregnancies with twin-twin transfusion syndrome and two with an acardiac twin, color Doppler studies of the placental vasculature were performed before fetoscopy for laser coagulation of the communicating vessels. In six cases of twin-twin transfusion syndrome the placental attachment of the intertwin membrane could be visualized. Pulsatile arterial blood flow was observed from the donor to the recipient twin that disappeared after laser therapy. In both cases of acardiac twins, one communicating vessel with pulsatile and another vessel with nonpulsatile blood flow in the opposite direction could be identified. Color Doppler imaging is unlikely to play a major role in assisting endoscopic laser separation of chorioangiopagus in patients with acute polyhydramnios, but it may prove to be useful in the early identification of pregnancies at risk of developing twin-twin transfusion syndrome.     

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   

彩色多普勒超声对宫内发育迟缓胎儿动静脉的血流动力学研究

目的应用彩色多普勒超声检测宫内发育迟缓(IUGR)胎儿动静脉的血流动力学参数。方法测量胎儿静脉导管和脐静脉的血流量,计算静脉导管(DV)分流率;测量胎儿脐动脉、大脑中动脉(MCA)、肾动脉的搏动指数(PI)、阻力指数(RI)及脐动脉收缩期最大流速与舒张末期流速的比值(S/D),结果进行对比分析。结果与对照组比较,IUGR组胎儿脐动脉的PI、RI、S/D及肾动脉的RI显著增高,MCA的PI、RI及S/D显著减低,DV分流率显著增加,差异均有统计学意义(P<0.05)。结论彩色多普勒超声通过综合监测胎儿血流动力学变化,可以全面、客观地评价胎儿的供血情况,预测胎儿宫内缺氧和IUCR情况。     

Umbilical vein blood flow in growth-restricted fetuses.

OBJECTIVE: To determine whether umbilical blood flow is reduced in a subset of growth-restricted (IUGR) fetuses when expressed as flow per kilogram or flow per unit of specific sonographic fetal measurements. DESIGN: Prospective. SUBJECTS: Thirty-seven IUGR fetuses were examined by Doppler ultrasound within 4 h of the last non-stress test prior to delivery. This population was divided into three groups of varying clinical severity according to the characteristics of umbilical arterial pulsatility index (PI) and heart rate. METHODS: Absolute and weight-specific umbilical vein (UV) flow were calculated from measurements of UV diameter and UV mean velocity. Umbilical vein diameter, velocity and UV flow were calculated also per unit head (HC) or abdominal circumference (AC) and correlated with gestational age. RESULTS: Umbilical vein flow (UVf) per kilogram fetal weight was significantly lower in the more severe IUGR fetuses (abnormal umbilical arterial PI) than in normally grown comparable fetuses (P < 0.001). Umbilical vein flow per unit HC was significantly lower in the three groups (P < 0.001) than in the control population. The UV diameter/HC ratio was normal whereas UV velocity/HC ratio was significantly lower in IUGR fetuses than in comparable controls. CONCLUSIONS: The present study clearly establishes that umbilical venous blood flow is reduced in IUGR fetuses on a weight-specific basis. The sonographic growth parameter which best distinguishes umbilical flow differences of IUGR fetuses from normal fetuses is the head circumference.     

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.     

Angiogenic growth factor levels in maternal and fetal blood: correlation with Doppler ultrasound parameters in pregnancies complicated by pre-eclampsia and intrauterine growth restriction.

OBJECTIVES: To correlate levels of angiogenic growth factors with Doppler ultrasound parameters in pregnancies complicated by pre-eclampsia and intrauterine growth restriction (IUGR). METHODS: In 16 women with pre-eclampsia and 15 women with isolated IUGR, pulsatility indices (PI) in the umbilical and uterine arteries were measured by Doppler ultrasonography. At delivery, maternal and fetal blood (umbilical vein and artery separately) was sampled and angiogenic growth factors measured by means of enzyme linked immunosorbent assay (ELISA). RESULTS: Umbilical artery PI was significantly higher in women with IUGR than in those with pre-eclampsia, whereas uterine artery PI was not statistically significantly different. Maternal soluble fms-like tyrosine kinase-1 (sFlt-1) levels were higher in women with pre-eclampsia than in those with IUGR (P < 0.0001). Umbilical vein basic fibroblast growth factor (bFGF) levels were lower in women with pre-eclampsia than in those with IUGR (P < 0.05). Placental growth factor (PlGF) levels in the umbilical vein were below the detection limit in nearly all samples of IUGR fetuses and lower than in those with pre-eclampsia (P < 0.001). Maternal PlGF levels were inversely correlated with PI values of both vessels. In the umbilical vein sFlt-1 was positively and soluble kinase insert domain receptor (sKDR) negatively correlated with umbilical artery PI. No correlation could be found in the serum of the umbilical artery for all growth factors and for vascular endothelial growth factor (VEGF) in all compartments. CONCLUSIONS: The correlations between maternal and fetal angiogenic growth factor serum levels and Doppler ultrasound indices of uterine and umbilical arteries in pre-eclampsia and IUGR reflect the severity of the disorders especially for the fetus. A combination of both measurements may be useful in future screening for early prediction of pregnancy complications. Published by John Wiley & Sons, Ltd.     

The effect of vascular constriction on umbilical venous pulsation.

OBJECTIVES: Umbilical venous pulsation is an important sign of hemodynamic compromise, but is also found under normal physiological conditions. Mathematical modeling suggests that vascular compliance is a determinant for pulsation, and we tested this by studying velocity pulsation at three sites on the umbilical vein. METHODS: In a cross-sectional study of 279 low-risk pregnancies (20-40 weeks' gestational age) blood flow velocity in the umbilical vein was determined before, within and after the umbilical ring in the fetal abdominal wall, and the incidence and magnitude of pulsation (the difference between the maximum and minimum velocity during a pulse, and pulsatility index) were noted. Based on the fact that the vessel cross-sectional area is an important determinant of compliance, we measured the diameter and time-averaged maximum velocity to reflect variation in diameter and compliance at the three sites. RESULTS: The incidence of umbilical venous pulsation was higher at the umbilical ring in the abdominal wall (242/279, 87%, 95% CI 82-90) than in the cord (43/198, 22%, 95%CI 16-27) or intra-abdominally (84/277, 30%, 95% CI 25-36) (P < 0.001). When pulsation was observed intra-abdominally, the pulsatility was not different from that at the umbilical ring (P = 0.16). However, the lowest pulsatility was found in the cord vein (P < 0.0001), where the largest vein diameter was found. CONCLUSION: The high incidence of venous pulsation at the umbilical ring where diameter and compliance are low supports the suggestion that local compliance is an important factor influencing pulsation in fetal veins.