Mean Uterine Pulsatility Index Research Articles

A Second Trimester Prediction Algorithm for Early-Onset Hypertensive Disorders of Pregnancy Occurrence and Severity Based on Soluble fms-like Tyrosine Kinase 1 (sFlt-1)/Placental Growth Factor (PlGF) Ratio and Uterine Doppler Ultrasound in Women at Risk.

Hypertensive disorders of pregnancy (HDPs) represent a significant source of severe maternal and fetal morbidity. Screening strategies relying on traditional medical history and clinical risk factors have traditionally shown relatively modest performance, mainly in the prediction of preeclampsia, displaying a sensitivity of 37% for the early-onset form and 29% for the late-onset form. The development of more accurate predictive and diagnostic models of preeclampsia in the early stages of pregnancy represents a matter of high priority. The aim of the present paper is to create an effective second trimester prediction algorithm of early-onset HDP occurrence and severity, by combining the following two biochemical markers: a soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio and uterine artery Doppler ultrasound parameters, namely the pulsatility index (PI) and the resistivity index (RI), in a population of high-risk pregnant women, initially assessed through traditional risk factors. A prospective single-center observational longitudinal study was conducted, in which 100 women with singleton pregnancy and traditional clinical and medical history risk factors for preeclampsia were enrolled at 24 weeks of gestation. Shortly after study enrollment, all women had their sFlt-1 and PlGF levels and mean uterine artery PI and RI determined. All pregnancies were followed up until delivery. Receiver operating characteristic (ROC) analysis established algorithms based on cutoffs for the prediction of the later development of preeclampsia: PI 1.25 (96.15% sensitivity, 86.49% specificity), RI 0.62 (84.6% sensitivity, 89.2% specificity) and sFlt-1/PlGF ratio 59.55 (100% sensitivity, 89.2% specificity). The sFlt-1/PlGF ratio was the best predictor for preeclampsia, as it displayed the highest area under the curve (AUC) of 0.973. The prediction algorithm for the severe form of preeclampsia, complicated by fetal growth restriction leading to preterm birth, antepartum fetal demise or acute fetal distress with a cerebro-placental ratio of <one consisted of the following cutoffs: PI 1.44 (93.75% sensitivity, 95.24% specificity), RI 0.69 (87.5% sensitivity, 100% specificity) and sFlt-1/PlGF ratio 102.74 (93.75% sensitivity, 95.2% specificity). These algorithms may significantly enhance the prediction accuracy of preeclampsia compared to traditional risk factors. The combination of the sFlt-1/PlGF ratio with mean uterine PI and RI in particular displayed an improved performance in the prediction of severe preeclampsia with the above-mentioned complications, compared to the biochemical markers or uterine Doppler parameters used alone. Therefore, HDP screening strategies should increasingly focus on implementing such algorithms for women who are initially regarded as high risk based on traditional risk factors, in order to properly diagnose HDP and properly limit or manage the later maternal and fetal complications.

The prediction of hypertensive disorders by maternal hemodynamic assessment in the first trimester of pregnancy

Background Hypertensive disorders of pregnancy and fetal growth restriction share common etiopathological origins and could be caused by maternal hemodynamic maladaptation to pregnancy. Objective The aim of our study is to evaluate if there is a correlation between maternal hemodynamic detected by UltraSonic Cardiac Output Monitor (USCOM®) during the first trimester and the pregnancy outcome. Study design We recruited a nonconsecutive series of women in the first trimester of pregnancy with no previous history of hypertensive disorders. We measured the pulsatility index uterine arteries and performed a hemodynamic evaluation by USCOM® device. After delivery, we reported the development of hypertensive disorders or intrauterine fetal growth restriction later during gestation. Results A total of 187 women were enrolled during the first trimester; 17 (9%) developed gestational hypertension or preeclampsia while 11 (6%) delivered a restricted growth fetus. Mean uterine artery pulsatility index above the 95th percentile was significantly more frequent in both women who developed hypertension and those with fetal growth restriction compared to controls. Hemodynamic parameters (reduced cardiac output and increased total vascular resistance) were significantly different in the group that developed hypertensive disorders, compared to uncomplicated pregnancy. ROC curves demonstrated the usefulness of uterine artery pulsatility index in the prediction of fetal growth restriction, while hemodynamic parameters were significantly associated to the development of hypertensive disorders. Conclusions Hemodynamic maladaptation to pregnancy may predispose to the development of hypertension, while we demonstrated a significative relationship between growth restriction and mean uterine pulsatility index. Further studies are needed to assess the value of hemodynamics evaluation in screening protocols of preeclampsia.

Evaluating the Optimal Definition of Abnormal First-Trimester Uterine Artery Doppler Parameters to Predict Adverse Pregnancy Outcomes.

To investigate the optimal definition of abnormal first-trimester uterine artery Doppler parameters associated with adverse pregnancy outcomes. A prospective cohort of women with singleton gestations between 11 and 14 weeks consented to uterine artery Doppler measurements. Doppler parameters were measured bilaterally, and mean pulsatility index (PI) and resistive index (RI) values were calculated. The presence of notching was also determined. Each parameter was evaluated for prediction of preeclampsia, early preeclampsia (<34 weeks), preterm birth (<37 weeks), early preterm birth (<34 weeks), and small for gestational age (SGA; birth weight <10th percentile). Descriptive statistics evaluated the association between abnormal Doppler indices and outcomes. A receiver operating characteristic (ROC) analysis was used to define the best cutoff points for mean PI and RI. The sensitivity, specificity, positive predictive value, and negative predictive value (NPV) were calculated for bilateral notching and mean PI and RI percentiles. Of 1192 patients with complete outcome data, preeclampsia was seen in 8.4%, early preeclampsia in 1.8%, preterm birth in 12.9%, early preterm birth in 5.6%, and SGA in 8.5%. A mean PI above the 75th percentile (>1.91) was the best index for predicting early preeclampsia (sensitivity, 45.0%; specificity, 75.5%; NPV, 98.7%; ROC area, 0.65). A mean PI above the 75th percentile was also the best index for predictive early preterm birth (sensitivity, 40.0%; specificity, 76.0%; NPV, 95.5%; ROC area, 0.65). None of the parameters were significant for predicting SGA. A mean uterine PI above the 75th percentile is the most discriminative abnormal uterine artery Doppler parameter for predicting both early preeclampsia and early preterm birth.

Predicting small for gestational age in the first trimester of pregnancy using maternal ophthalmic artery Doppler indices

Objective: To assess the capacity of maternal ophthalmic Doppler indices for predicting small for gestational age (SGA) newborns in the first trimester of pregnancy.Methods: We performed a prospective observational cohort study involving 499 singleton pregnancies during the first trimester scan (11–14 weeks). The following maternal ophthalmic Doppler indices were assessed: pulsatility index (PI), first diastolic peak velocity (PD1) and peak ratio (PR) = PD1/peak systolic velocity. We considered SGA all newborns with weight below 10th percentile. We used chi-square test (χ2) to compare the groups. We used area under receiver operating characteristics (ROC) curves with 95% confidence intervals (CI) and detection rate of 5% of false positive of each maternal ophthalmic Doppler index and the mean uterine artery PI for prediction SGA.Results: 27 (5.4%) patients delivered SGA newborns, 12 (2.4%) patients developed preeclampsia (PE) and delivered SGA newborns, and 460 had uneventful pregnancies (controls). We observed significant difference of PI and PR between SGA (SGA and SGA+PE) and control groups, p = 0.043 and p = 0.014, respectively. To 5% of false positive, the detection rate of SGA (SGA and SGA+PE groups) using PI, PD1 and PR were 14.8, 3.7, 14.8, 16.7, 16.7 and 16.7%, respectively. Mean uterine PI was significantly higher in the SGA+PE group (p = 0.003).Conclusion: The isolated use of maternal ophthalmic Doppler indices or in combination with uterine artery Doppler, in the first trimester of pregnancy, was not efficient to predict SGA newborns.

Multicenter screening for adverse pregnancy outcomes by uterine artery Doppler in the second and third trimester of pregnancy

Increased uterine artery pulsatility index (PI) is associated with adverse pregnancy outcomes. The aim of the study was to determine the role of uterine artery PI at 18-24 and 30-34 weeks, gestation in predicting adverse pregnancy outcomes. Color Doppler assessment of the uterine arteries was carried out in 435 consecutive women attending an antenatal clinic at 18-24 weeks and in 134 women at 30-34 weeks. The 95th percentiles of the mean uterine PI and the presence or the absence of bilateral notches was recorded. Using the reference range, performance characteristics in the prediction of pregnancy outcomes were calculated. Association of mean PI at 30-34 weeks with pregnancy outcomes also was studied. The adverse pregnancy outcomes were defined as any or the combination of pre-eclampsia, fetal growth restriction, intrauterine fetal death, preterm delivery and placental abruption. The women with adverse pregnancy outcomes had significant higher mean PI (1.27 +/- 0.55 vs. 0.99+/-0.32; p=0.003) and higher prevalence of bilateral notch (20% vs. 4.6%, p=0.001) than those with normal outcomes. The mean (+/-SD) PI in women with severe adverse outcome was 1.66+/-0.66 vs. 1.0+/-0.32 in women with normal pregnancy outcome (p=0.002). For a screen positive rate of 10.6% (mean PI>95th percentile for gestational age and/or bilateral notches), the sensitivity for predicting an adverse outcome was 33.3%. The sensitivity increased to 60% for predicting a severe adverse outcome. Increased resistance in the third trimester was also associated with an adverse pregnancy outcome. Increased uterine artery PI in second and third trimester of pregnancy is associated with an increased risk of adverse pregnancy outcomes.

Evidence for impaired physiological decrease in the uteroplacental vascular resistance in pregnant women with familial hypercholesterolemia

Abnormal hyperlipidemia characterizes pregnancy in familial hypercholesterolemia (FH), and is associated with vascular dysfunction. Hence, we compared blood flow in the feto- and uteroplacental circulation in FH and healthy reference women using Doppler velocimetry. The umbilical artery pulsatility index (PI) at gestational weeks 24 and 36, and the concomitant physiological decrease in PI, was similar in FH (n=10) and the reference group (n=143). The decrease in mean PI of both uterine arteries from week 24 to 36 was significant in the reference group, but not among the FH women. Plasma LDL-cholesterol measured between weeks 24 and 36 was not correlated with the decrease in umbilical PI in the FH group, or with the decrease in umbilical or mean uterine PI in the reference group. We conclude that pregnancy in FH might be associated with attenuated physiological decrease in mean PI of uterine arteries, possibly reflecting increased uteroplacental vascular resistance unrelated to plasma LDL-cholesterol levels.

Comparison between three‐dimensional placental volume at 12 weeks and uterine artery impedance/notching at 22 weeks in screening for pregnancy‐induced hypertension, pre‐eclampsia and fetal growth restriction in a low‐risk population

To compare the value of three-dimensional placental volume at 12 weeks and uterine artery Doppler at 22 weeks for predicting pregnancy-induced hypertension (PIH), pre-eclampsia and fetal growth restriction in a low-risk population. Over a 20-month period we calculated the placental quotient (PQ = placental volume/crown-rump length) at 11-13 weeks' gestation in all women with singleton pregnancies who booked for delivery in our hospital. At 22 weeks, in the same population, we calculated the mean pulsatility index (PI) of both uterine arteries and the presence of an early diastolic notch was noted. Logistic regression models, the PQ and Doppler parameters were used to compare the two screening methods for subgroups of pregnancy outcome. Complete outcome data were obtained in 2489 consecutive singleton pregnancies. Logistic regression models for the detection of pre-eclampsia had a sensitivity of 38.5% (PQ) vs. 44.8% (Doppler); for the detection of small-for-gestational age (SGA) the sensitivity was 27.1% (PQ) vs. 28.1% (Doppler) at a specificity of 90%. Taking a PQ of <or= 10th centile, a mean uterine PI of >or= 90th centile and a bilateral notch, the sensitivity for detection of SGA was 25.0%, 20.2% and 22.0%, respectively; for PIH it was 9.5%, 4.8% and 4.8%; for pre-eclampsia without SGA it was 20.0%, 28%, 12%; for PIH/pre-eclampsia with SGA it was 30.8%, 46.1% and 69.2%. In the group with the most severe complications, in which delivery took place before 34 weeks, the sensitivity was 50.0%, 50.0% and 38.9%, respectively. PQ at 12 weeks and uterine artery Doppler at 22 weeks have similar sensitivities for predicting pre-eclampsia and fetal growth restriction, although uterine artery Doppler is marginally more sensitive for the prediction of pre-eclampsia. While both methods are insufficient for screening in a low-risk population, the PQ method has the potential advantage of being performed in the first trimester.

Fetal response to maternal exercise in pregnancies with uteroplacental insufficiency

The purpose of this study was to determine the fetal response to submaximal maternal exercise at 22 to 26 weeks in pregnancies with abnormal uterine artery Doppler. This was a prospective comparison of singleton pregnancies with uteroplacental vascular insufficiency (UPVI) (mean uterine pulsatility index [PI] values >1.45 [n = 12]) and those with normal uterine artery Doppler (n = 23). Maternal and fetal cardiovascular responses to 5 minutes of steady state cycling at 10% and at 15% of predicted work rate maximum were studied. Umbilical artery Doppler deteriorated after exercise in patients with UPVI (pre PI 1.4 [0.35-2.14], post PI 1.64 [0.45-2.18]). Three (25%) had transient absent-end diastolic flow (AEDF) in umbilical artery, 2 of which developed early-onset intrauterine growth restriction (IUGR) with AEDF. Fetal cardiac output studies remained stable during the examinations. Submaximal steady state exercise had a transient deleterious effect in a subset of women with uteroplacental vascular insufficiency destined to develop early-onset IUGR.

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.

The effect of exogenous estradiol benzoate and altrenogest on uterine and ovarian blood flow during the estrous cycle in mares

In recent years, a positive relationship between genital perfusion and fertility has been established; in species other than horses, uterine and ovarian perfusion was improved by exogenous estrogen but impaired by exogenous progestin. The goal of the present study was to investigate the effect of exogenous estrogen and progestin on uterine and ovarian blood flow in cycling mares. Five Trotter mares were examined daily during three estrous cycles. Mares were given no treatment, altrenogest (0.044 mg/kg BW) orally from Day 0 (ovulation) to Day 14 and estradiol benzoate (5 mg i.m.) on Days 0, 5, and 10, in three cycles, respectively. There was no difference ( P>0.05) in the length of untreated versus estrogen-treated cycles (22.8±1.3 days and 23.2±1.5 days, respectively), but cycle length was increased ( P<0.05) in progestin-treated cycles (26.0±1.2 days). To facilitate comparisons among cycles with different lengths, data from Days 0 to 15 (diestrus) and from Days −6 to −1 (estrus) were analyzed. Transrectal Doppler sonography was used to evaluate blood flow in both uterine arteries and in the ovarian artery ipsilateral to the preovulatory follicle during estrus and ipsilateral to the corpus luteum during diestrus. Blood flow was assessed semiquantitatively using the pulsatility index (PI); high PI values indicated high resistance and a low perfusion and vice versa. An immediate effect of treatments occurred only after the administration of estradiol benzoate on Day 0; uterine PI values decreased ( P<0.05) between Days 0 and 1 and estrogen-treated mares but increased ( P<0.05) at the corresponding time in untreated cycles. Mean PI values for the uterine and ovarian arteries during both diestrus and estrus were higher ( P<0.05) in estrogen-treated versus untreated mares. Furthermore, mean uterine PI values during diestrus and estrus were higher ( P<0.05) in altrenogest-treated versus untreated mares. Neither estrogen nor altrenogest treatments had a significant immediate effect on ovarian PI values. Compared to untreated cycles, mean ovarian PI values were elevated ( P<0.05) only in the estrus following altrenogest administration. In conclusion, exogenous estrogen and progestin both decreased genital perfusion in cycling mares.

Effects of transdermal nitroglycerin on impedance to flow in the uterine, umbilical, and fetal middle cerebral arteries in pregnancies complicated by preeclampsia and intrauterine growth retardation

OBJECTIVE: We studied whether transdermal nitroglycerin, a donor of nitric oxide, affects uterine, umbilical, and fetal cerebral blood flow in pregnancies complicated by preeclampsia and impaired uteroplacental blood flow. STUDY DESIGN: Seventeen patients with preeclampsia were treated with a nitroglycerin patch, 10 mg per 24 hours, for three consecutive days between 28 and 36 weeks’ gestation. The uterine, umbilical, and fetal middle cerebral artery pulsatility index and resistance index were assessed by color Doppler ultrasonography before the start of treatment, daily during treatment, and on the first 2 days after the removal of the last patch. RESULTS: The nitroglycerin patch caused a significant fall in the mean uterine pulsatility index and resistance index that reached its maximum (18% ± 4% and 17% ± 3%, respectively, from baseline) on the last treatment day. After the removal of the last patch, uterine pulsatility index and resistance index rose to the pretreatment value within 12 hours. No significant changes in umbilical or middle cerebral artery pulsatility index and resistance index were observed during treatment. Maternal mean arterial pressure fell from 122 ± 8 to 117 ± 7 mm Hg ( P = .05). CONCLUSION: Transdermal administration of nitroglycerin may offer a potential for treatment for patients with preeclampsia who have increased uteroplacental impedance. (Am J Obstet Gynecol 1998;179:140-5.)