Uterine Artery Notching Research Articles

OP01.05: A notch in the uterine artery during pregnancy is a sign of increased placental vascular resistance and not a reflection of increased peripheral vascular impedance

Total vascular resistance (dyne s/cm5) 1623 (1287–3125) 1163 (944–1785) 0.008 Stroke volume (mL) 69 (36–81) 67 (57–86) 0.95 Cardiac output (L/min) 5.40 (4.4–7.0) 6.1 (4.0–8.1) 0.08 Ejection fraction (%) 69 (64–83) 71 (65–79) 0.59 Midwall fractional shortening (% of predicted value) 118 (94–126) 122 (106–140) 0.04 Isovolumetric relaxation time (ms) 78 (50–90) 60 (45–75) 0.006 24 h ambulatory heart rate (bpm) 74 (61–82) 79 (76–92) 0.003 24 h ambulatory systolic blood pressure (mmHg) 117 (104–136) 106 (101–121) 0.031 24 h ambulatory diastolic blood pressure (mmHg) 75 (65–88) 66 (56–73) 0.012 24 h ambulatory mean arterial pressure (mmHg) 87 (79–104) 79 (72–87) 0.016

Estado nutricional materno, ganho de peso gestacional e peso ao nascer

INTRODUÇÃO: Tanto o estado nutricional materno como o ganho de peso gestacional vem sendo estudado em relação ao papel determinante que desempenham sobre o crescimento fetal e o peso ao nascer. O peso inadequado ao nascer é uma das grandes preocupações da saúde pública devido ao aumento da morbimortalidade no primeiro ano de vida e ao maior risco de desenvolver doenças na vida adulta, tais como a síndrome metabólica, nos casos de baixo peso, e diabetes e obesidade, nos casos de macrossomia. O objetivo deste trabalho foi descrever uma coorte de gestantes, classificando-as de acordo com o estado nutricional inicial, o ganho ponderal gestacional, a resistência nas artérias uterinas e o peso dos recém-nascidos. MÉTODOS: foi acompanhada, a cada quatro semanas gestacionais, uma coorte de 115 gestantes atendidas pelo Programa de Saúde da Família do município de Campina Grande, PB. O estado nutricional inicial foi determinado através do índice de massa corporal (kg/m²) para a idade gestacional, e as gestantes classificadas de acordo com os critérios de Atalah. Na 20ª semana, foi estudada a resistência das artérias uterinas, através da dopplervelocimetria. RESULTADOS: o estado nutricional inicial mostrou uma alta prevalência de sobrepeso e obesidade (27%), e uma prevalência significante de desnutrição (23%). Um alto percentual de gestantes ganhou peso excessivo tanto no segundo (44%) como no terceiro trimestre (45%). A distribuição do peso ao nascer, indicou uma incidência de 10% de baixo peso e de 9% de macrossomia. Observou-se ainda, uma alta prevalência de incisuras nas artérias uterinas.

Increased Apoptosis in First Trimester Extravillous Trophoblasts from Pregnancies at Higher Risk of Developing Preeclampsia

Preeclampsia complicates 5 to 10% of pregnancies and is a leading cause of maternal and fetal mortality and morbidity. Although the cause is unknown, inadequate invasion and remodeling of maternal uterine arteries by extravillous trophoblasts (EVTs) in the first trimester is a common feature. Uterine spiral artery resistance as detected by Doppler ultrasound is commonly used in the second trimester to identify pregnancies destined to develop preeclampsia. Correlation between high uterine resistance and the failure of trophoblast invasion has been reported as early as 12 weeks. However, the reason for this failure has not been established. Understanding the processes involved would significantly improve our diagnostic potential. In this study, we correlated increased first trimester uterine artery resistance with a biological abnormality in trophoblast function. EVTs derived from high-resistance pregnancies were more sensitive to apoptotic stimuli than those from normal-resistance pregnancies. Survival of EVTs from high-resistance pregnancies could be increased by nitric oxide, whereas inhibition of nitric oxide in cells from normal-resistance pregnancies increased apoptotic sensitivity. This predates the onset of symptoms by several weeks and provides evidence for a mechanism responsible for the incomplete uterine vessel remodeling and the differences in artery resistance between preeclamptic and normal pregnancies.

Uterine Artery Velocity Waveforms as Predictors of Pregnancy Outcome in Patients with Antiphospholipid Syndrome

In pregnant women, antiphospholipid syndrome (APS) is associated with an increased risk for preeclampsia, fetal intrauterine growth restriction, and other complications related to uteroplacental insufficiency. In normal pregnancy, impedance to flow in the uterine arteries decreases with gestation, as the likely consequence of the physiologic change of spiral arteries into low-resistance vessels. The presence of antiphospholipid antibodies can impair this vascular adaptation, resulting in a reduced placental perfusion. Doppler investigation provides a noninvasive method for the study of uteroplacental blood flow. Several studies were performed to detect the predictive role of uterine artery Doppler velocimetry in relation to pregnancy outcome in APS patients. In some studies, a high resistance index in the uterine arteries strongly predicted the subsequent development of obstetric complications. In other studies, persistent bilateral uterine artery notches identified the risk of preeclampsia and fetal intrauterine growth restriction. To date, the uterine artery Doppler velocimetry resulted to be a useful tool for identifying APS pregnancies at risk for adverse pregnancy outcome. These findings might have important implications for the management of these patients.

Identification of patients at risk for early onset and/or severe preeclampsia with the use of uterine artery Doppler velocimetry and placental growth factor

Preeclampsia has been proposed to be an antiangiogenic state that may be detected by the determination of the concentrations of the soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and placental growth factor (PlGF) in maternal blood even before the clinical development of the disease. The purpose of this study was to determine the role of the combined use of uterine artery Doppler velocimetry (UADV) and maternal plasma PlGF and sVEGFR-1 concentrations in the second trimester for the identification of patients at risk for severe and/or early onset preeclampsia. A prospective cohort study was designed to examine the relationship between abnormal UADV and plasma concentrations of PlGF and sVEGFR-1 in 3348 pregnant women. Plasma samples were obtained between 22 and 26 weeks of gestation at the time of ultrasound examination. Abnormal UADV was defined as the presence of bilateral uterine artery notches and/or a mean pulsatility index above the 95th percentile for the gestational age. Maternal plasma PlGF and sVEGFR-1 concentrations were determined with the use of sensitive and specific immunoassays. The primary outcome was the development of early onset preeclampsia (< or = 34 weeks of gestation) and/or severe preeclampsia. Secondary outcomes included preeclampsia, the delivery of a small for gestational age (SGA) neonate without preeclampsia, spontaneous preterm birth at < or = 32 and < or = 35 weeks of gestation, and a composite of severe neonatal morbidity. Contingency tables, chi-square test, receiver operating characteristic curve, and multivariate logistic regression were used for statistical analyses. A probability value of < .05 was considered significant. (1) The prevalence of preeclampsia, severe preeclampsia, and early onset preeclampsia were 3.4% (113/3296), 1.0% (33/3296), and 0.8% (25/3208), respectively. UADV was performed in 95.4% (3146/3296) and maternal plasma PlGF concentrations were determined in 93.5% (3081/3296) of the study population. (2) Abnormal UADV and a maternal plasma PlGF of < 280 pg/mL were independent risk factors for the occurrence of preeclampsia, severe preeclampsia, early onset preeclampsia, and SGA without preeclampsia. (3) Among patients with abnormal UADV, maternal plasma PlGF concentration contributed significantly in the identification of patients destined to develop early onset preeclampsia (area under the curve, 0.80; P < .001) and severe preeclampsia (area under the curve, 0.77; P < .001). (4) In contrast, maternal plasma sVEGFR-1 concentration was of limited use in the prediction of early onset and/or severe preeclampsia. (5) The combination of abnormal UADV and maternal plasma PlGF of < 280 pg/mL was associated with an odds ratio (OR) of 43.8 (95% CI, 18.48-103.89) for the development of early onset preeclampsia, an OR of 37.4 (95% CI, 17.64-79.07) for the development of severe preeclampsia, an OR of 8.6 (95% CI, 5.35-13.74) for the development of preeclampsia, and an OR of 2.7 (95% CI, 1.73-4.26) for the delivery of a SGA neonate in the absence of preeclampsia. The combination of abnormal UADV and maternal plasma PlGF concentration of < 280 pg/mL in the second trimester is associated with a high risk for preeclampsia and early onset and/or severe preeclampsia in a low-risk population. Among those with abnormal UADV, a maternal plasma concentration of PlGF of < 280 pg/mL identifies most patients who will experience early onset and/or severe preeclampsia.

Adverse outcome in women with thrombophilia and bilateral uterine artery notches

Discrepancies about a possible relationship between prothrombotic mutations and a decreased uteroplacental blood flow are present in literature. We prospectively evaluated a cohort of pregnant women (n = 41) with bilateral uterine artery notches and found that women with inherited thrombophilia showed a sixfold higher risk to have an adverse outcome than women without.

Gene expression profiling of human placentas from preeclamptic and normotensive pregnancies

The aim of this study was to investigate patterns of gene expression in placental samples from patients with preeclampsia (PE), persistent bilateral uterine artery notching (without PE), and normal controls. This study included placental tissue from nine women with PE, seven with uncomplicated pregnancies and five with bilateral uterine artery notching in Doppler velocimetry tracings. Human cDNA microarrays with 6500 transcripts/genes were used and the results verified with real-time PCR and in-situ hybridization. Multidimensional scaling method and random permutation technique demonstrated significant differences among the three groups examined. Within the 6.5K arrays, 6198 elements were unique cDNA clones representing 5952 unique UniGenes and 5695 unique LocusLinks. Multidimensional scaling plots showed 5000 genes that met our quality criteria; among these, 366 genes were significantly different in at least one comparison. Differences in three genes of interest were confirmed with real-time PCR and in-situ hybridization; acid phosphatase 5 was shown to be overexpressed in PE samples and calmodulin 2 and v-rel reticuloendotheliosis viral oncogene homolog A (RELA) were downregulated in PE and uterine artery notch placentas. In conclusion downregulation of RELA and calmodulin 2 might represent an attempt by the placenta to compensate for elevations in intracellular calcium, possibly caused by hypoxia and/or apoptosis, in both pregnancies with uterine artery notching and preeclampsia.

Effect of first-trimester serum from pregnant women with high-resistance uterine artery Doppler resistance on extravillous trophoblast invasion

Abnormal uterine artery Doppler indices are associated with pregnancy complications such as pre-eclampsia and intrauterine growth restriction. Poor trophoblast invasion may be a consequence of, or be associated with, abnormal Doppler indices. To evaluate in vitro trophoblast function following exposure to first-trimester serum from pregnancies with high uterine artery Doppler resistance indices. Doppler ultrasound examination of the maternal uterine arteries was performed on women at 10-14 weeks' gestation. Serum was collected from women with bilateral uterine artery notches with resistance indices above the 95th centile and from patients with normal uterine artery indices. The effect of serum on trophoblast invasion was determined using an established in vitro model from the extravillous trophoblast-derived cell line SGHPL-4. Trophoblastic invasion was significantly reduced when treated with serum from women with high-resistance compared with normal-resistance uterine artery Doppler indices (P < 0.05). Maternal serum in the first trimester of pregnancy from patients with high-resistance uterine artery Doppler indices appears to inhibit trophoblast invasion. This experimental model allows further investigation of factors responsible and the evaluation of therapeutic strategies.

Evaluation of third trimester uterine artery flow velocity indices in relationship to perinatal complications

Objective. Uterine artery Doppler is becoming a routine part of pregnancy surveillance in high-risk pregnancies. Which blood flow velocity waveform index to measure is debated and the ‘notch’ in early diastole is not widely accepted, as it is a subjective measure. The aim of the present study was to evaluate the different indices in the prediction of adverse outcome of pregnancies suspected for intrauterine fetal growth restriction (IUGR).Methods. Uterine artery blood flow was recorded in 217 pregnancies admitted for Doppler ultrasound surveillance due to suspected IUGR. The median gestational age at examination was 38 weeks (range 25–42 weeks). Only cases having bilateral uterine artery notching were included in the evaluation. The uterine artery Doppler spectrum was analyzed for different indices, including evaluation of notch and end-diastolic velocities. Umbilical artery Doppler velocimetry was also performed. The outcome variables chosen were: a small-for-gestational-age (SGA) newborn, preterm birth, and abdominal delivery. ROC-curve calculations were used to compare the different indices.Results. The uterine artery blood velocity pulsatility index (PI) and resistance indices (RI) were the best predictors of adverse outcome of pregnancy. Apart from premature birth, the systolic/end-diastolic ratio was less predictive of adverse outcome. The indices including only diastolic blood velocities were the least predictive of adverse outcome. The group with notch velocity above end-diastolic velocity was compared with those having notch velocity below the end-diastolic velocity. No difference in outcome was seen between the two groups.Conclusions. RI and PI as measures of third trimester utero-placental vascular impedance are the best predictors of adverse outcome of IUGR-suspected pregnancies.

Is Notching in the Umbilical Artery Doppler Waveform a Benign Finding?

Adiastolic notch in the uterine artery Doppler flow velocity waveform (FVW) is associated with an increased uterine vascular impedance, impaired uterine blood flow, and adverse perinatal outcome. 1 Likewise, uterine artery notching combined with an abnormal FVW of the umbilical artery (UA) is considered a predictor of adverse neonatal outcome. 2 Unlike data regarding the uterine artery, data are rare regarding the clinical importance of notching in the UA as an isolated finding. A few case reports have described the association between umbilical cord notching (with or without an abnormal FVW) and cord entanglement in monoamniotic twins, 3 fetal gastroschisis, 4 and fetal intra-abdominal vein dilatation. 5 Recently, Abuhamad et al 6 prospectively evaluated 1857 pregnancies and found UA notching in 29 (1.6%) fetuses. They showed that UA notching is associated with both cord and placental abnormalities, including abnormal cord insertion, cord stricture, and false or true knots in the cord. 6 Furthermore, they suggested that this finding may have important clinical implications, such as cord and placental abnormalities and a high prevalence of nonreassuring fetal heart rate abnormalities during labor. We present a case in which UA notching was detected in an impaired fetus with a single umbilical artery (SUA) whose umbilical cord was wrapped around its body. On the basis of this case and our review of the literature, we recommend increased fetal surveillance whenever FVWs display a notch in the UA.

Bilateral notching of uterine arteries at 12–14 weeks of gestation for prediction of hypertensive disorders of pregnancy

To assess the value of transvaginal uterine artery Doppler ultrasound at 12--14 weeks of gestation in predicting hypertensive disorders of pregnancy in high-risk women. One hundred and twenty high-risk women were evaluated prospectively by Doppler ultrasound of uterine and umbilical arteries at 12--14 weeks of gestation. The presence of bilateral notches, resistance and pulsatility index (PI), mean and maximum flow velocities of uterine arteries, and resistance and PI of umbilical arteries were investigated. Those with bilateral notching were randomized to acetylsalicylic acid (n=43) or placebo groups (n=43) and were followed up twice during pregnancy with the same ultrasound measurements. The women without bilateral notches (n=29) served as controls. In this study, we compared 43 women in the placebo group to 29 controls without bilateral notches. The outcome measures were pregnancy-induced hypertension, pre-eclampsia and intrauterine growth restriction. The sensitivity of bilateral notching in predicting hypertensive disorders of pregnancy decreased with advancing pregnancy from 91 to 35%, and the specificity and the positive predictive values increased from 41 to 94% and from 7 to 70%, respectively. The negative predictive values ranged from 86 to 97%. Bilateral notching of uterine arteries at 12--14 weeks is a useful tool in predicting the development of hypertensive disorders in high-risk pregnancies. It is also a suitable test for surveillance of high-risk pregnancies.

Uterine artery Doppler velocimetry for the detection of adverse obstetric outcomes in patients with elevated mid‐trimester β‐human chorionic gonadotrophin

The aim of this study is to review the clinical usefulness of Doppler velocimetry of the uterine artery for the detection of adverse obstetric outcome in a population of women with elevated mid-trimester serum beta-human chorionic gonadotrophin (betahCG). Women with an unexplained elevated mid-trimester betahCG level (> or = 4.0 multiples of the median) are offered uterine artery Doppler assessment at 22-24 weeks of gestation. We have audited the clinical usefulness of this practice by reviewing the prevalence of the adverse outcomes of gestational hypertension, intrauterine growth restriction (IUGR) and preterm birth and the predictive capacity of the test when applied to this subgroup of high-risk patients. Sixty-two women had an elevated serum betahCG and underwent Doppler study of uterine artery flow velocity waveform. Notching afforded better predictive utility for any outcome than the resistance index alone or in combination with notching. For a composite adverse outcome of any or all of gestational hypertension, birthweight < or = 10th centile, and preterm delivery, the presence of a uterine notch alone had sensitivity of 30.7% and specificity of 93.8%. For the identification of severe fetal growth restriction (< 5th centile) and/or preeclampsia, the presence of a notch offered a sensitivity of 50%, specificity of 96.3%, a positive likelihood ratio of 13.5, and a negative likelihood ratio of 0.5. The identification of uterine artery notching by means of Doppler ultrasound as a component of the surveillance of women with unexplained elevated betahCG levels significantly improves the prediction of preeclampsia and/or severe IUGR, although the low prevalence of 13% of these adverse outcomes limits the usefulness of the test in routine clinical practice.

Increased uterine artery vascular impedance is related to adverse outcome of pregnancy but is present in only one‐third of late third‐trimester pre‐eclamptic women

Signs of increased uterine artery vascular impedance in mid-gestation are strongly related to pre-eclampsia later in pregnancy. Whether this is true for the late third trimester is, however, unclear. The aim of the present study was to analyze the frequency of increased uterine artery vascular impedance in the third trimester, and its relationship to abnormal umbilical artery Doppler and adverse outcome of pregnancy. This was a retrospective study of uterine and umbilical artery Doppler velocimetry in 570 pregnancies complicated by pre-eclampsia. The managing clinician was informed only about the umbilical artery flow. The Doppler recordings were related to severity of pre-eclampsia, prematurity, fetal growth restriction, and rates of Cesarean section and admission to neonatal intensive care. Increased umbilical artery vascular impedance was seen in 59 cases (10.4%), seven having absent or reversed end-diastolic flow. Uterine artery notching was seen in 145 cases (25%), 88 (15%) having bilateral notches. Either increased uterine artery pulsatility index (PI) or notching, or both, were seen in 207 women (36.3%). In 108 women with severe pre-eclampsia, 38 (35.2%) had uterine artery notching. Signs of increased uteroplacental vascular impedance were more common in severe than in mild pre-eclampsia (57.4% vs. 31.4%), in premature than in term pregnancies (70.9% vs. 28.4%), and were more prevalent than abnormality in the umbilical artery (36.3% vs. 10.4%). Only one-third of pre-eclamptic cases showed signs of increased uterine artery vascular impedance in the third trimester. However, signs of increased vascular impedance were much more frequent in the uterine than in the umbilical arteries and were strongly related to adverse outcome of pregnancy.

Reduced Maternal Plasma Urocortin Concentrations and Impaired Uterine Artery Blood Flow at Human Mid Pregnancy

Urocortin is a placental neuropeptide belonging to the family of corticotropin-releasing factors (CRFs), playing a role in the uteroplacental blood flow regulation through the binding to specific CRF receptors. Since CRF receptors are expressed in the uterine vascular bed of pregnant rats, and because urocortin has a relaxant effect on uterine vasculature, we evaluated mid-gestation plasma urocortin levels in women with impaired blood flow through uterine arteries. Maternal plasma urocortin was assayed by specific radioimmunoassay and uterine artery resistance index (RI) by Doppler evaluation at 22-24 weeks' gestation in 57 healthy pregnant women, of which 29 showed a monolateral or bilateral uterine artery notch. Statistical analysis was performed by one-way analysis of variance (ANOVA), followed by post-hoc Tukey test for multiple comparison and Pearson correlation coefficient test. The mean uterine artery RI was significantly (P <.001) higher in women with a notch than healthy controls. Mean +/- SEM maternal plasma urocortin levels were significantly (P <.001) lower in women with unilateral (52.03 +/- 3.25 pg/mL) or bilateral (47.01 +/- 4.16 pg/mL) uterine artery notch than in healthy control pregnant women (84.01 +/- 3.5 pg/mL). While no difference was found in urocortin levels between patients with unilateral or bilateral uterine artery notch, urocortin concentrations inversely correlated with the mean RI (Pearson r = -0.7318; 95% confidence interval -0.8334 to -0.5822; P <.0001). The present findings suggest that reduced levels of circulating urocortin are associated with increased uterine artery resistances and support the hypothesis that urocortin may regulate uterine artery tone at mid gestation.

Bilateral notching of uterine arteries at 12-14 weeks of gestation for prediction of hypertensive disorders of pregnancy

Bilateral notching of uterine arteries at 12-14 weeks of gestation for prediction of hypertensive disorders of pregnancy

Fetal response to maternal exercise in pregnancies with uteroplacental vascular insufficiency

To determine the fetal response to sub-maximal maternal exercise at 22-26 weeks in pregnancies with abnormal uterine artery Doppler. A prospective matched cohort-control study was undertaken. Twelve singleton pregnancies with bilateral uterine artery notching and mean uterine pulsatility index (PI) values >1.45 at 22-26 weeks of gestation were evaluated. Matched controls (n = 23) were clinically normal and had normal uterine artery Doppler. Maternal and fetal cardiovascular responses to 5 minutes of steady state cycling at 10% and at 15% of maximum predicted work rate were evaluated by ultrasound/Doppler. Baseline characteristics were similar between the 2 groups. No differences in either resting or in exercise-induced maternal or fetal cardiac parameters were found between the 2 groups. There was no difference between the basline umbilical artery PI values for cases and controls but the difference became significant post exercise (P = .02 after the 10% load and P = .006 after the 15% load). Of the 12 cases, 6 subsequently developed preeclampsia, 5 had SGA fetuses, 2 of which developed absent end-diastolic flow velocity (AEDF) and early-onset intrauterine growth restriction (IUGR). Mean gestational age at delivery was 33 weeks vs. 40 weeks in the controls (P = .001). 3/12 (25%) cases developed transient (AEDF) in umbilical artery Doppler after the exercise that recovered after cessation of exercise, compared with none of the controls. 2/3 of these subsequently developed AEDF and IUGR. Sub-maximal steady state exercise may have transient deleterious effects in a subset of women with uteroplacental vascular insufficiency. These findings may impact on advice regarding physical activity in this sub-group of women. Dynamic testing such as maternal exercise may be of value in identifying pregnancies that adapt poorly to uteroplacental vascular insufficiency.

Prostacyclin, thromboxane A2 and the effect of low‐dose ASA in pregnancies at high risk for hypertensive disorders

The aim of this study was to investigate the prostanoid production in pregnancies at high risk for hypertensive disorders, and the effect of low-dose acetylsalicylic acid (ASA) on prostanoids. Ninety women with a bilateral notching in uterine arteries screened by Doppler ultrasound at 12-14 gestational weeks were randomized to the ASA (0.5 mg/kg/day) or placebo group. Forty-three women in both groups were followed up throughout the pregnancy. Urine samples were taken at baseline, and at 24-26 and 32-34 weeks of gestation to determine the urinary 11-dehydrothromboxane B(2) (u-11-dehydro-TxB(2)) and 2,3-dinor-6-keto-prostaglandin F(1alpha) (u-2,3-dinor-6-keto-PGF(1alpha)), the metabolites of thromboxane A(2) and prostacyclin, respectively. In the pregnancies with pregnancy-induced hypertension (PIH) before 37 gestational weeks, the 2,3-dinor-6-keto-PGF(1alpha)/11-dehydro-TxB(2) ratio did not increase as much as in other pregnancies (P = 0.028). In the placebo group pregnancies with preeclampsia had significantly lower 2,3-dinor-6-keto-PGF(1alpha) (P = 0.019) at 12-14 weeks of gestation compared to other pregnancies. In the placebo group the 2,3-dinor-6-keto-PGF(1alpha)/11-dehydroTxB(2) ratio remained unchanged throughout the pregnancy, with no significant difference between pregnancies with a normal or an adverse outcome. In the ASA group the 2,3-dinor-6-keto-PGF(1alpha)/11-dehydro-TxB(2) ratio increased (P < 0.001, early vs. midpregnancy). Again, the changes were similar in pregnancies with a normal or an adverse outcome. The balance of prostacyclin and thromboxane A(2) shifted in an unfavorable direction in pregnancies complicated by PIH. ASA had a favorable effect on the prostanoids.

Prospective Evaluation of Uterine Artery Flow Velocity Waveforms at 12–14 and 22–24 Weeks of Gestation in Relation to Pregnancy Outcome and Birth Weight

Objective: Uterine artery flow velocity was prospectively assessed using Doppler ultrasound at 12–14 and 22–24 weeks of gestation in the prediction of subsequent complications related to uteroplacental insufficiency: preeclampsia, pregnancy-induced hypertension, fetal growth restriction, fetal death and placental abruption, and to elucidate its relationship with birth weight. Methods: Uterine artery Doppler assessment was obtained during routine ultrasound screening in 263 unselected women. Flow velocity waveforms were coded according to the number of notches present at each scanning, respectively: none (0, 0), uni-/bilateral notches that disappeared (1, 0) or (2, 0), uni-/bilateral notches that persisted unilaterally (1, 1) or (2, 1), and persistent bilateral notches (2, 2). Results: Complete outcome data was obtained for 243 (92.4%) women. Of these women, 55 (22.6%) and 84 (34.6%) women had uni- and bilateral notches, respectively, at 12–14 weeks’ gestation; 14 (5.8%) and 21 (8.6%) patients had uni- and bilateral notches, respectively, at 22–24 weeks’ gestation. Analysis of complication rates for the four groups showed that they increased with notch persistence (5.7, 13.5, 57.1 and 76.2%), while the corresponding mean birth weight declined (3,273, 3,180, 2,698 and 2,418 g). Conclusion: The absence or early disappearance of uterine artery notches is associated with fewer complications related to uteroplacental insufficiency and normal birth weight, whereas their late and partial disappearance or bilateral persistence tends to compromise the prognosis.

The longitudinal variation in uterine artery blood flow pattern in relation to birth weight.

To investigate the relationship between the timing of disappearance of high-resistance uterine artery waveforms between the first and second trimester of pregnancy and birth weight. Uterine artery Doppler recordings were obtained in a cohort of singleton pregnancies at 11-14 weeks of gestation and subsequently at 18-23 weeks. At each examination, the presence or absence of an early diastolic notch was recorded for each side. An abnormal pattern of blood flow was defined as the presence of bilateral notches. Cases complicated by preeclampsia or preterm delivery were excluded. Four hundred eleven pregnancies showed absent or unilateral uterine artery notches at the 11-14-week scan (group 1). All these cases maintained a low-resistance uterine blood flow pattern at the second-trimester scan. Of the 251 pregnancies with bilateral notches at the 11-14-week scan, 222 subsequently displayed a low-resistance blood flow at 18-23 weeks (group 2) whereas only 29 maintained bilateral notches (group 3). The mean birth weight was higher in group 1 (3452 g) than in groups 2 (3310 g) and 3 (3224 g). This difference was confirmed after adjusting for confounding variables. Small-for-gestational-age fetuses were more common in groups 2 (14.9%) and 3 (14%) compared with group 1 (6.8%, P <.001). During the study period, severe preterm preeclampsia was observed in 6 cases only. The longitudinal variation in uterine artery blood flow pattern has a statistically significant correlation with birth weight, likely reflecting the timing and degree of trophoblastic invasion of the maternal vessels. II-2

First-trimester uterine artery blood flow and birth weight.

To determine reference values for first-trimester uterine artery resistance index (RI) in healthy pregnant women with uncomplicated pregnancies and to investigate the relationship between uterine artery Doppler indices and birth weight. This was a cross-sectional study of 265 consecutive pregnant women attending routine ultrasound examination at 11-14 weeks' gestation. Both uterine arteries were identified using color Doppler ultrasound and the RI was measured. The presence or absence of an early diastolic notch was also noted. Pregnancy outcomes were obtained from the delivery suite database and birth weight was expressed as Z-scores. The 5(th), 50(th) and 95(th) centiles for uterine artery RI between 11 and 14 weeks' gestation were 0.53, 0.71 and 0.85, respectively. Complete pregnancy outcome data were available for 246 fetuses. There was a significant negative correlation between birth-weight Z-scores and first-trimester uterine artery mean RI (r = - 0.219, P = 0.001). The difference in birth weight between fetuses with absent and those with bilateral diastolic notches was also significant (P < 0.001). Multiple regression analysis demonstrated that both mean RI (standardized regression coefficient = - 0.14, P = 0.039) and uterine artery notching (standardized regression coefficient = - 0.17, P = 0.017) contributed independently towards the prediction of birth-weight Z-score. A significant negative correlation exists between birth weight and first-trimester uterine artery Doppler parameters, a reliable and non-invasive method of examining uteroplacental perfusion. The value of first-trimester uterine artery Doppler as a prognostic screening tool, either in isolation or in conjunction with maternal biochemistry, remains to be determined.