Fetal and maternal Doppler velocimetry and cytokines in high-risk pregnancy

OBJECTIVE: Fetal hypoxia and preterm delivery are reported to be strongly associated with brain damage and neurodevelopmental delay. Doppler signs of fetal brain sparing have been described during chronic hypoxia, but whether they are related to brain damage is unknown. The aim of this study was to evaluate if markers of tissue injury, i.e., tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) are related to signs of increased perinatal vascular impedance and/or fetal brain sparing in high-risk pregnancies. STUDY DESIGN: TNF-alpha and IL-6 levels were evaluated in maternal blood serum of 67 high-risk pregnancies. Serum samples were taken at the time of umbilical, middle cerebral artery and uterine artery Doppler velocimetry examination. The values for TNF-a and IL-6 were correlated with reference median values obtained with gestational age in the form of a Z-score. RESULTS: TNF-alpha levels showed values within the normal range in only four cases. IL-6 values were found normal in 14 cases. The Z-score for mean middle cerebral artery pulsatility index (PI) showed a significant correlation to TNF-alpha and IL-6 levels, P < 0.0001 and P < 0.003, respectively. This might suggest a strong correlation between signs of fetal brain sparing and increased maternal serum TNF-alpha and IL-6 levels. Abnormal uterine artery PI and the presence of a "notch" were also highly significantly related to TNF-alpha and IL-6 levels, which were nearly two-fold higher compared to normal uterine artery blood flow and the absence of a "notch". Abnormal cerebro/placental ratios showed significant correlations to TNF-alpha and IL-6 levels. CONCLUSION: The present results suggest a strong correlation between levels of TNF-alpha and IL-6 not only for signs of fetal brain sparing, but also for uteroplacental blood flow. This finding supports the role of tissue injury in cases of fetal brain sparing, but whether this is a reflection of brain damage or secondary to placental pathology needs further evaluation.     

Fetal umbilical artery flow velocimetry in postdate pregnancies

This study prospectively examined the use of umbilical artery flow velocimetry for monitoring fetal health in postdate pregnancies. Forty-six patients with well-established dates were evaluated with semiweekly biophysical profiles and umbilical artery flow velocimetry (characterized by the ratio of the peak systolic to end-diastolic velocity). Their labor records were reviewed, and neonates were examined for signs of postmaturity. Twenty neonates had an abnormal test result or outcome (identified as an abnormal nonstress test, oligohydramnios, meconium, intrapartum fetal distress, or a 5-minute Apgar score less than 7). Nine neonates had a physical examination consistent with the postmaturity syndrome. Twenty-one neonates were entirely normal. Comparisons of the mean systolic/diastolic ratios for neonates with and without the complications associated with postdatism showed no significant differences. In addition, all systolic/diastolic ratios were within the normal range. Therefore, umbilical artery flow velocimetry is unlikely to be useful for the routine antenatal assessment of the postdate fetus.     

Effect of caffeine on superior mesenteric artery blood flow velocities in preterm neonates

Objective: To investigate the effect of caffeine infusion on superior mesenteric artery (SMA) blood flow velocities (BFV) in preterm infants.

Methods: Prospective observational study on 38 preterm neonates 28–33⁺⁶ weeks gestation, who developed apnea on their first day of life, and caffeine citrate infusion was initiated at a loading dose of 20?mg/kg, followed by a maintenance dose of 5–10?mg/kg/day. Duplex ultrasound measurements of SMA BFV were recorded: peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI), at 15?min before, 1-, 2- and 6-h after caffeine loading dose, and 2?h after two maintenance doses.

Results: There was a significant reduction in PSV 1-h (p?=?.008), a significant decrease in EDV 1- and 2-h (p?=?.000 and p?=?.005, respectively) and a significant increase in RI 1- and 2-h (p?=?.003 and p?=?.005, respectively) following caffeine loading dose, as compared to values before caffeine infusion. No significant effect of caffeine maintenance doses on SMA BFV was observed (p?>?.05).

Conclusion: Blood flow in SMA is significantly reduced after caffeine citrate infusion at a loading dose of 20?mg/kg. This effect continues for at least 2?h. Meanwhile, SMA BFV seems not affected by maintenance doses.     

Fetal blood flow in diabetic pregnancy

Forty pregnant diabetic women were examined with combined Doppler and real-time ultrasound. The volume blood flow in the fetal aorta and umbilical vein was higher and the pulsatility index (PI) in the aorta lower in the early third trimester, as compared with a reference group. Near term, the umbilical artery PI was higher in diabetic than in non-diabetic pregnancies, indicating a higher placental vascular resistance in the former group. The high umbilical artery PI occurred in fetuses who later developed distress in labor. Therefore, a high umbilical artery PI cannot be considered characteristic of diabetic pregnancy, although fetal distress might be more common in diabetic pregnancy. In addition, a high aortic volume flow was found in those fetuses who later develop distress in labor. This might be an expression of an early compensatory mechanism for increased placental vascular resistance. No specific flow variation was observed for any White class, or in association with hypertension or non-optimally regulated diabetes. The blood flow variables in growth-accelerated fetuses were comparable to those found in fetuses with normal weight. Since fetal distress might be more common in diabetic pregnancy, ultrasonic fetal blood flow measurements are recommended for antenatal fetal surveillance.     

Maternal middle cerebral artery velocimetry in normal pregnancy and postpartum

Objective To study changes throughout gestation and the puerperium of middle cerebral artery flow velocity waveforms obtained by transcranial Doppler ultrasound.
Design Prospective, observational study.
Setting John Radcliffe Maternity Hospital, Oxford, UK.
Participants and Methods Middle cerebral artery velocities were measured by transcranial Doppler ultrasound in 25 nonpregnant women, 22 women longitudinally followed throughout pregnancy and 21 women serially studied from delivery until the late puerperium.
Main outcome measures Transcranial Doppler changes in pregnancy and the puerperium.
Results The transcranial Doppler ultrasound measurements showed good reproducibility. Signals from one middle cerebral artery could not be obtained in 4.6% of the examinations, but otherwise readings were similar on both sides. Women in the second half of pregnancy had lower middle cerebral artery mean velocities than nonpregnant women. Velocities decreased with advancing gestation but increased in the immediate puerperium to levels comparable to those found in nonpregnant women.
Conclusions Transcranial Doppler ultrasound is a noninvasive technique suitable for studying maternal cerebral haemodynamics in pregnancy and postpartum. Middle cerebral artery mean velocity decreased with advancing gestation and increased to nonpregnant values in the immediate puerperium. These physiological changes need to be considered when comparing data with measurements taken in abnormal pregnancy states.     

Improvement of mesenteric superior artery Doppler velocimetry by amnio-infusion in fetal gastroschisis.

This study aimed to analyse the influence of amnio-infusion on superior mesenteric Doppler velocimetry and to correlate Doppler data with outcome in fetuses presenting with gastroschisis. Umbilical and intra- and extra-abdominal superior mesenteric artery Doppler velocimetry was measured prospectively before and after amnio-infusion in fetuses with gastroschisis. Doppler index values and changes were correlated with the following outcome parameters: importance of fibrous coating, duration of hospitalization in the neonatal intensive care unit, total duration of hospitalization, duration of parenteral feeding, duration of ventilatory assistance, and the interval to initiation of oral feeding. A significant improvement of diastolic flow was observed in the extra-abdominal superior mesenteric artery with amnio-infusion. No similar change was seen in the intra-abdominal superior mesenteric or in the umbilical artery. Pre-amnioinfusion extra-abdominal mesenteric Doppler index was correlated with maximal diameter of exteriorized bowel and slightly with duration of hospitalization in the neonatal intensive care unit, but no other relation between Doppler index and outcome parameter could be ascertained. Amnio-infusion induces modifications in the vascularization of exteriorized bowel in gastroschisis. This could partly explain the beneficial effect of this procedure on fetal gut.     

The examination of superior mesenteric artery circulation in fetus during pregnancy

Objective: The aim of the study was a comprehensive examination of the circulation of superior mesenteric artery in different weeks of pregnancy using Doppler ultrasound examination.

Methods: The study was conducted at the Clinic of Obstetrics and Gynecology, Jessenius Faculty of Medicine, Comenius University, Slovakia between the years 2008 and 2012. Dynamics and changes in superior mesenteric artery circulation were studied in 856 women. Results of Doppler examination were processed and subsequently evaluated for each gestational week separately.

Results: We found that changes in resistance index of superior mesenteric artery are slower and have a tendency to decrease as a consequence of a gradual decrease in vascular resistance. The changes in pulsatility index are different in nature; there is a tendency for there are to be repeating periods of higher and then lower values, which are subject to a more pronounced dependence on flow rate, especially end diastolic velocity, and Vmean.

Conclusions: This article and its results bring a new, comprehensive view not only of physiological changes in the splanchnic circulation, but also of changes that may be subject to a certain extent, not only to the sex, but primarily to the weight of the fetus, which, of course, indirectly reflects its metabolic and respiratory demands.     

Umbilical velocimetry in normal pregnancy

Five hundred ninety-six normal pregnancies were evaluated with continuous Doppler to determine the changes in velocimetry between 17 and 42 weeks gestation. The wave-form was identified by its characteristic sharp systolic rise and slow diastolic decay; plotting the S/D ratio as a function of the gestational age reveals a progressive decline in the S/D ratio as gestation progresses. A significant drop occurred around 30 weeks when the mean S/D ratio dropped from 3 (29 weeks) to 2.6 (31 weeks) reflecting decreased placental resistance.     

The role of Doppler blood flow velocimetry in multiple pregnancy

This article focuses on Doppler velocimetry in the assessment of fetal growth, placental insufficiency, management of intrauterine growth restriction, discordant growth and twin-twin transfusion syndrome. Problems specific to multiple pregnancy such as twin reversed arterial perfusion, cord entanglement and visualization of anastomoses are also reviewed. Doppler sonography seems to be superior to other tests for early detection of placental insufficiency during surveillance of multiple pregnancies. It is suggested that Doppler sonography helps to select multiple fetuses who are at higher than normal risk, and might reduce perinatal mortality and morbidity. Fetal echocardiography may provide an accurate assessment of cardiovascular adaptation to intertwin transfusion, early recognition of deterioration and evaluation of antenatal management. In the management of the twin-twin transfusion syndrome, Doppler echocardiography and Doppler ultrasound examination of the venous circulation appear to be useful tools for improved perinatal management. Doppler sonography is an important adjunct in monitoring high-risk multiple pregnancies.     

Reverse end-diastolic flow velocity on umbilical artery velocimetry in high-risk pregnancies: an ominous finding with adverse pregnancy outcome

Systolic/diastolic ratios of umbilical velocimetry have been used to assess downstream placental vascular resistance. Reverse end-diastolic flow velocity during end diastole suggests extreme abnormality in waveform and resistance. We reviewed our experience of patients showing reverse end-diastolic flow velocity over a 2 1/2-year period. Out of 550 high-risk patients studied with umbilical velocimetry over this period, 12 patients showed the finding. All patients were delivered of small for gestational age fetuses and the perinatal mortality in this group was 50%. There was also significant perinatal morbidity as judged by cesarean section performed because of fetal distress, low Apgar scores, days in neonatal intensive care, prematurity, placental infarcts, and lethal anomalies. These findings suggest that reverse end-diastolic velocity on umbilical velocimetry is associated with catastrophic perinatal outcome, and aggressive perinatal management may be advised in this group of patients.     

Evaluation of fetal right coronary artery blood flow velocimetry

OBJECTIVES: In the present study fetal right coronary artery blood flow velocimetry was assessed. DESIGN: The prognostic value of the fetal right coronary artery blood flow velocimetry was evaluated in relationship with parameters of newborn's condition after birth. MATERIAL AND METHODS: The study was performed in 102 cases of pregnancies complicated by pregnancy induced hypertension. Blood flow velocimetry was visualized from fetal right coronary artery and correlated with perinatal outcome parameters. RESULTS: Fetal coronary blood flow velocimetry was visualized only in 11 cases. Coronary blood flow velocimetry visualisation correlated with each parameter of after-birth evaluation. The method has the highest specificity (97.7%) and positive prognostic value (85%) concerning evaluation of newborn's condition. CONCLUSIONS: Fetal right coronary artery blood flow velocimetry visualisation is a late sign of chronic fetal hypoxia. This seems to be a factor which causes maximal coronary vessels dilatation and allows oxygenation of fetal heart muscle.     

The superior mesenteric artery syndrome in pregnancy: a case resulting in recurrent pregnancy loss

The Superior Mesenteric Artery (SMA) syndrome was the underlying cause of severe gastrointestinal symptoms in a patient with recurrent pregnancy loss. Following a surgical transposition of the duodenum, two normal pregnancies were carried to term. This is the first report of the SMA syndrome in pregnancy, to our knowledge.     

The hemodynamic effects of neonatal patent ductus arteriosus shunting on superior mesenteric artery blood flow.

OBJECTIVE: To determine if the ratio of the pulsatility index (PI) of the left pulmonary artery to the PI of the descending aorta, the Rp/Rs index, correlates with the degree of ductal steal from the intestine in neonates with a patent ductus arteriosus (PDA). STUDY DESIGN: Echocardiograms and Doppler studies of the superior mesenteric artery (SMA) were performed in 41 neonates less than 35 weeks gestational age with a hemodynamically significant PDA (hsPDA). RESULTS: There was a significant negative correlation between the Rp/Rs index and the SMA PI after controlling for ductal size (r=-0.476, p<0.008). CONCLUSIONS: The Rp/Rs index can be used as an indicator of ductal steal on intestinal blood flow. The Rp/Rs index may be a useful adjunct to existing and new techniques for improving early assessment and treatment of hsPDA, and for evaluating the effects of hsPDA on systemic organs.     

Umbilical artery velocimetry in diabetes and pregnancy

Doppler studies of umbilical artery velocity waveforms were performed during the third trimester of pregnancy in 43 diabetic women (18 class A and 25 insulin dependent). A mean serum glucose value of 120 mg% or more was selected to indicate poor glucose control. Systolic to diastolic ratios of umbilical artery velocity waveforms were calculated to determine the degree of placental vascular resistance. A systolic to diastolic ratio of 3 or more was selected as the cut-off value for determining placental vascular disease. A significant positive correlation between systolic to diastolic ratios and serum glucose level (r = 0.52, P less than .001) was found. Elevated systolic to diastolic ratio was associated with increased number of stillbirths and neonatal morbidity. This study suggests that the risk of adverse outcome in diabetic pregnant women correlates with umbilical artery velocity waveforms.