Doppler sonography of normal fetal vertebral and internal carotid arteries during pregnancy

Placental growth factor as an indicator of fetal growth restriction in late-onset small-for-gestational age pregnancies

BACKGROUND

At-risk small-for-gestational age (SGA) pregnancies in New Zealand are identified using Doppler ultrasound; fetuses with Doppler abnormalities are considered growth restricted (FGR). Low maternal placental growth factor (PlGF) has also been associated with late-onset FGR.

AIMS

To investigate whether low PlGF at diagnosis of late-onset SGA identifies the same fetuses classified FGR by detailed Doppler studies, and the association between low PlGF and adverse pregnancy outcomes.

METHODS

Among an historical database of normotensive suspected SGA pregnancies (fetal abdominal circumference <10th percentile) ≥32 weeks gestation, the ability of low PlGF (<5th percentile) to identify FGR infants was investigated. 'Initial FGR' was an abnormal umbilical artery resistance index (RI) or estimated fetal weight <3rd customised centile. 'Secondary FGR' was abnormal internal carotid RI, cerebro-placental ratio and/or mean uterine artery RI. Development of hypertensive disease and adverse perinatal outcomes were compared by PlGF status.

RESULTS

Of 136 SGA pregnancies, 56 (41.1%) had initial FGR. Of the remaining, 20 (25.0%) had secondary FGR, 17 (21.3%) low PlGF. The sensitivity of low PlGF identifying secondary FGR was 0.30 (95% CI 0.14-0.50), specificity 0.83 (0.70-0.92), positive predictive value 0.47 (0.23-0.72) and negative predictive value 0.70 (0.57-0.81). Overall, low PlGF occurred in 44/136 (32.4%) pregnancies and was associated with gestational hypertensive disease (63.6% vs 15.2%, P < 0.01), adverse perinatal outcome (34.1% vs 15.2%, P = 0.01) and very low birthweight (customised centile 2.2 vs 6.8, P < 0.01).

CONCLUSIONS

At diagnosis of late-onset SGA, low PlGF was poor at identifying Doppler-defined FGR. Low PlGF identified pregnancies at risk of hypertensive disease, adverse perinatal outcome and very low birthweight.

Role of Color Doppler Flowmetry in Prediction of Intrauterine Growth Retardation in High-Risk Pregnancy

Objective: To evaluate the usefulness of Color Doppler flowmetry in the prediction of intrauterine growth restriction (IUGR) in high-risk pregnancies.

Materials and method: A total of 62 high-risk pregnant women underwent Color Doppler flowmetric umbilical artery pulsatility index (PI), resistive index (RI) and systolic/diastolic (S/D) ratio, middle cerebral artery PI, RI and S/D ratio, Ductus venosus S-wave/isovolumetric A-wave index (SIA) and vertebral artery RI at 23-27 weeks, 28-32 weeks and 32-36 weeks of their pregnancy. Cerebral-umbilical C/U PI, RI and S/D were evaluated at the third visit. All the pregnancies were followed up till delivery. Ponderal index <10 was considered to be indicative of IUGR. Data were analyzed using IBM Statistical Package for Social Sciences (SPSS) 21.0.

Results: Thirty-nine (62.9%) deliveries were IUGR. On all the three visits, umbilical artery, mean PI, RI and SD values were significantly higher while MCA PI, RI and SD values were significantly lower in IUGR as compared to non-IUGR cases. Third visit C/U PI, RI and SD ratio values were also significantly lower in IUGR as compared to non-IUGR cases. Ductus venosus SIA values did not show a significant difference between IUGR and non-IUGR groups. The vertebral artery resistive index was significantly higher in non-IUGR as compared to IUGR on all the visits. Umbilical artery PI was the most sensitive and specific for the prediction of IUGR at all the three visits, with the maximum sensitivity and specificity at the third visit (82.1% and 87%). Third visit C/U PI was most sensitive (82.1%) and specific (96.7%) for the prediction of IUGR.

Conclusion: This showed that Doppler flowmetry is a useful method for the prediction of IUGR in high-risk pregnancies.

Doppler ultrasonographic assessment of maternal and fetal arteries during normal feline gestation

The aim of this study was to describe Doppler parameters of uterine, umbilical, fetal abdominal aorta, fetal renal and fetal internal carotid arteries, as well as fetal heart rate (FHR), during normal feline gestation. Fifteen, 1-4 years of age, weighing 2.5-3.9kg, domestic short-hair pregnant queens, which were born in our institutional cat colony were included in this study. Color and pulsed-wave Doppler evaluations of uterine arteries were performed every 10 days (Day 0, 10, 20, 30, 40, 50, 60) from mating. Fetal Doppler and M-mode ultrasonography were performed to assess umbilical, fetal abdominal aorta, fetal renal, fetal internal carotid arteries and FHR. Both peak systolic velocity (PSV) and end diastolic velocity (EDV) of uterine artery increased up to parturition (P<0.01), while resistance index (RI) decreased from Day 10 onwards (P<0.01). From Day 40 onwards, RI of umbilical artery diminished, while PSV and EDV augmented (P<0.01). Fetal abdominal aorta (P<0.01), renal (P<0.01) and internal carotid (P<0.01) arteries diminished their RI from Days 40, 60 and 40 onwards, respectively. Both PSV and EDV of these three arteries increased progressively. Fetal heart rate was first registered on Day 20 when it began to increase up to Day 40 and then diminished to the end of gestation (P<0.01). It is concluded that blood flow of uterine, umbilical, fetal abdominal aorta, fetal renal and fetal internal carotid arteries progressively increased during normal feline pregnancy, while FHR rose to mid gestation and then decreased up to parturition.

Extracranial Segments of the Vertebral Artery: Insight in the Developmental Changes up to the 21st Year of Life

The vertebral artery (VA) bilaterally arises usually from the subclavian artery and courses within the bony canals of cervical vertebrae, and then it reverses directions on the first vertebra before piercing the dura to enter the cranium.The aim was to follow (ab)normal developmental changes of extracranial VA from prenatal status to age 21. This chapter included a brief description of the arterial embryology and morphofunctional specificity of the VA in prevertebral, cervical, and atlantic parts, during prenatal and postnatal period.The authors concluded that the subclavian origin of the VA was in most of fetal and adult cases. The incidences of variable VA origins and domination of one of the VAs were different from one series of human specimens to the second one. Although in most of cases, anomalous origin and/or variable course of the extracranial VA had little or did not result in clinical symptoms in infants and young adults, the true value of their discovery is in the diagnostic gain before vascular surgery of supra-aortic arteries.

The vertebral artery Doppler might be an alternative to the middle cerebral artery Doppler in the follow-up of the early onset growth-restricted fetus

OBJECTIVE

The objective of this article is to show the clinical utility of the vertebral artery Doppler as an alternative to the middle cerebral artery Doppler in the follow-up of fetuses affected with early-onset growth restriction [fetal growth restriction (FGR)].

METHODS

We present a group of fetuses with early-onset FGR in which the vertebral artery resistance index (VA RI) and pulsatility index (VA PI) were measured and plotted along with their references earlier calculated using 1980 Doppler examinations. In addition, the VA and middle cerebral artery (MCA) performance was compared using values converted into multiples of the median.

RESULTS

Similar to that of the MCA, VA RI and VA PI percentiles showed curve shapes with higher values at the beginning of the third trimester. The majority of growth-restricted fetuses showed a notorious decrease in the VA impedance, which was not statistically different to that of the MCA.

CONCLUSION

Vertebral artery Doppler values can be obtained throughout the second half of pregnancy. Preliminary data suggest a clinical application in the management of early-onset FGR.

Doppler study of the fetal vertebral and middle cerebral arteries in fetuses with normal and increased umbilical artery resistance indices

OBJECTIVE

To compare the brain sparing mechanism of the fetal vertebral artery (VA), with the one of the middle cerebral artery (MCA) in fetuses with increased umbilical artery (UA) Doppler impedance.

METHOD

We retrospectively studied 1084 Doppler examinations of the VA, MCA and UA performed in 1084 fetuses between 19 and 41 week of gestation. These were divided into 3 groups according to the UA resistance index (UA RI): group 1: UA RI < 95(th) percentile (N = 965), group 2: UA RI > 95(th) percentile (N = 111) and group 3: absent UA diastolic flow (N = 8). Afterwards, values were converted into multiples of the median (MoM), and means and standard deviations were calculated. Finally, Kruskal-Wallis tests and box and whiskers charts were applied to evaluate differences.

RESULTS

For both, the VA RI and MCA RI, no differences were seen among the groups of fetuses who maintained diastolic flow in the UA. However, the VA RI and MCA RI were lower when the UA diastolic flow was absent.

CONCLUSION

The VA and MCA work in unison, decreasing impedances only when UA flow is severely affected.

Doppler study of the fetal vertebral artery in small for gestational age fetuses with intrauterine growth restriction

OBJECTIVES

The purposes of this study were to evaluate the Doppler resistive index of the fetal vertebral artery in small for gestational age (SGA) fetuses and to examine the ability of the vertebral artery resistive index in the diagnosis of intrauterine growth restriction (IUGR).

METHODS

A total of 437 Doppler examinations of the vertebral and umbilical artery resistive indices were performed in 437 fetuses between 26 and 41 weeks' gestation. According to birth weight, fetuses were classified into 5 groups: 1, above the 10th percentile; 2, between the 10th and 5th percentiles; 3, between the 5th and 3rd percentiles; 4, below the 3rd percentile; and 5, below the 3rd percentile with an umbilical artery resistive index above the 95th percentile. Subsequently, vertebral artery resistive index values were converted into multiples of the median, and box and whisker charts were generated to evaluate differences. Finally, receiver operating characteristic curves were calculated to assess the accuracy of the vertebral artery resistive index for predicting IUGR and a low Apgar score.

RESULTS

Compared to normally grown fetuses, vertebral artery resistive index values were lower in fetuses with birth weight below the 3rd percentile, and this difference was greater in fetuses with birth weight below the 3rd percentile and Doppler anomalies of the umbilical artery. The receiver operating characteristic analysis showed that the vertebral artery resistive index diagnosed SGA fetuses and low Apgar scores poorly. However, it performed better in cases of severe IUGR with high umbilical artery resistive index values.

CONCLUSIONS

Preliminary data show that the vertebral artery resistive index diminishes in growth-restricted SGA fetuses. Doppler examination of the vertebral artery seems to identify a group of fetuses with brain sparing and severe IUGR.

Doppler ultrasonographic assessment of maternal and fetal blood flow in abnormal canine pregnancy

The aim of this study was to describe the changes of uterine artery, umbilical artery and fetal abdominal aorta, renal and internal carotid arteries blood flow in abnormal canine pregnancy. Twenty-two, Brucella-negative pregnant bitches were retrospectively classified into abnormal (which had either interrupted their pregnancy between days 52 and 60 or had perinatal death >60% of the litter; n=11) and normal (which had delivered healthy puppies at term; n=11). In all the animals, color and pulsed-wave Doppler examinations of uterine artery were conducted every 10 days from Day 20 to 50 from estimated luteinizing hormone peak. Doppler ultrasonography was also conducted in the fetuses to assess umbilical artery, abdominal aorta, renal and internal carotid arteries from Day 40 to 60 of gestation. Throughout the study, resistance index (RI) of uterine, umbilical and fetal renal arteries decreased up to -15% compared to -36% (P<0.01), -11% compared to -23% (P<0.05) and 2% compared to -13% (P<0.05), respectively in the abnormal and normal bitches. Fetal abdominal aorta and internal carotid did not differ between groups (P>0.05). It is concluded that in dogs, uterine artery, umbilical artery and fetal renal artery RI differ between normal and abnormal gestation being useful for the prediction of adverse obstetric outcome.