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Uterine artery color Doppler assisted veloeimetry and perinatal outcome

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Uterine artery color Doppler assisted veloeimetry and perinatal outcome
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  Acta Obstet Gynecol Scand 1996; 7 : 612419 Printed n Denmark - all riKhts reserved Copyright Acto bsret Gyneml Scond 19Y6 Acta Obstetricia et Gynecologica Scandinavica ISSN 0001-6349 ORIGINAL ARTICLE Uterine artery color Doppler assisted velocimetry and perinatal outcome CORNELIA OFSTAETTER, ARIUSZ UBIEL, EMUNDUR UDMUNDSSON ND KAREL ARSAL From the Department of Obstetrics and Gynecology University of Lund University Hospital Malmo Sweden Acta Obstet Gynecol Scand 1996; 75: 612-619.0 Acta Obstet Gynecol Scand 1996 Background. Previously, we have found uterine artery blood velocimetry performed with Doppler ultrasound without vessel visualization to be a poor predictor of perinatal outcome. The aim of this study was to ascertain whether the combination of color Doppler imaging with the method would improve its predictive value. Methods. In a cross-sectional study of 110 uncomplicated pregnancies, uterine artery blood velocity was recorded bilaterally from 18 to 42 weeks of gestation to obtain reference values for pulsatility index (PI). Using color Doppler imaging, the main uterine artery was located as it crosses the iliac vessels and blood velocity was then recorded with pulsed Doppler ultra- sound. The uterine and umbilical blood velocity waveforms were also obtained in 421 compli- cated pregnancies, and the results related to placental site and perinatal outcome. Results. In uncomplicated pregnancies, the uterine artery PI was unrelated to gestational age using 1.20 as the upper cut-off limit for the mean PI of both vessels (mean+2 s.d.). Corres- ponding values for unilateral placental localization were 1 OO at the placental side and 1.40 at the non-placental side. Blood velocities obtained using the color Doppler combination were similar to previously presented results. In the complicated pregnancies, significant correlation was found between abnormal perinatal outcome and abnormality of the uterine artery blood velocity waveform, either increased PI n=44) or a notch in early diastole n=92). The predic- tive value of an early diastolic notch was superior to an increased PI in predicting abnormal outcome. The mean PI for both uterine arteries was a better predictor of outcome than blood velocity on the placental side. The blood velocity waveforms on the non-placental side were the poorest predictors of outcome. Conclusion. The addition of color Doppler imaging to pulsed wave Doppler ultrasound recording of uterine artery blood velocity improves the predictive value of blood velocity waveforms with regard to the perinatal outcome. Key words: Doppler ultrasound; notch; perinatal outcome; placental location; umbilical artery; uterine artery Submitted October; 1995 Accepted 18 January, 1996 Normal fetal growth and development is dependent on normal development and function of the pla- centa. During the first half of gestation, trophoblas- tic cells invade the decidual and sub-placental ves- Abbreviutions: PI: pulsatility index; IUGR: intra-uterine growth retardation; PIH: pregnancy induced hypertension; CTG: cardiotocography : SGA: small-for-gestational age; ODFD: operative deliveries for fetal distress: NICU: neonatal intensive care unit; ROC: receiver operating characteristic; SID-ratio: systolic/diastolic ratio. sels resulting in an opening of the arteries into sac- like lagoons without contractile capacity (1). Disturbances of trophoblastic invasion into sub-pla- cental arteries result in reduced blood flow to the placenta and are related to complications in late ges- tation such as pre-eclampsia and intra-uterine 8 growth retardation (IUGR) (2). A characteristic uterine artery Doppler velocity pattern with de- creased diastolic flow and an early diastolic notch in the utero-placental arteries has been described in these pregnancies (3-6). cta Obstet Gynecol Scand 75 1996)  Uterine artery velocimetiy 6 13 nancy induced hypertension (PIH) (systolic and diastolic blood pressure increased by 30 and 15 mm Hg, respectively after 20 weeks of gestation) (n=32), diabetes mellitus (n=25) (21 insulin treated), prolonged pregnancy (>42 weeks) (n=23), third trimester hemorrhage (n=44), prema- ture rupture of membranes (<37 weeks of gesta- tion) (n=22), decreased fetal movements (n=10), bad obstetric history (n=26), anemia (Hb<100 g/ L) (n=7), poly- or oligohydramnios n=8) (amni- otic fluid index >25 mm and c mm, respec- tively), fetal heart arrhythmia (n=6), abnormal cardiotocogram (CTG) n=7), or other reasons (n=28). The pregnancies were managed either in hospital or on an outpatient basis. The clinicians managing the pregnancies were only informed about the umbilical artery blood velocity. The examinations were performed with a 3.5 MHz Acuson 128 real-time sector scanner (Acu- son Comp., Mountain View, Califormia, USA) with pulsed and color Doppler options. A 125 Hz high pass filter was used to eliminate signals from slow moving tissues. The umbilical artery blood velocity signals were obtained from a free floating central part of the cord. Both main uterine arteries were located by color flow mapping in an oblique scan, and blood velocity was recorded in the art- ery just cranial to the crossing of the uterine and iliac blood vessels. Three subsequent blood veloc- ity waveforms were analyzed for pulsatility index (PI), according to Gosling et al. (13). The sign of an early diastolic notch in the uterine blood ve- locity was registered as described by Campbell et al. (3) and illustrated in Fig. 1. The placental location was noted as central, left or right sided. In the prospective study, serial examinations were performed with intervals of 3 days-2 weeks, median gestational age at the last examination be- ing 36 weeks (range 23-42). For the series as a whole, the results of the last examination before delivery were related to perinatal outcome, char- acterized by gestational age at delivery, birth- weight and birthweight deviation from the ex- pected mean for the normal population (14), oc- currence of small-for-gestational age (SGA) new- borns (birthweight<mean - 2 s.d.), placental At first, the focus of research was on the sub- placental arcuate arteries. The blood velocity ob- tained, however, was a poor predictor of perinatal outcome and manifested poor reproducibility (7- 9), which might have been expected as one arcu- ate artery only reflects 3-10 of the uteroplacen- tal circulation. Research on uteroplacental blood velocity was therefore shifted to the uterine arter- ies - each representing approximately 50 of the utero-placental blood supply. In our hands, how- ever, uterine artery blood velocimetry, obtained without vessel imaging, was an unreliable predic- tor of perinatal outcome in high-risk pregnancies. A reproducibility study on uterine artery blood velocity yielded a high coefficient of variation (lo), suggesting that blood velocities might have been recorded from different ascending branches of the vessel. The use of color flow mapping made the uterine arteries easier to locate, and im- proved the reproducibility of the recordings (1 1). The aim of the present study was to ascertain whether the use of color Doppler for location of the uterine arteries might improve the perinatal predictive capacity of uterine artery velocimetry, and to compare its potential for use in high-risk pregnancies with that of umbilical artery veloci- metry. Reference values for uterine artery flow velocity waveforms were also established in a cross-sectional study of uncomplicated pregnan- cies. Material and methods Reference values for the uterine artery blood vel- ocity were established in a cross-sectional study of 138 women with uncomplicated pregnancies examined from the 18th through the 42nd weeks of gestation after giving their informed consent. The examinations being equally distributed over the gestational weeks. In all pregnancies, the ges- tational age was ascertained at early ultrasound examination and the Doppler examination was ap- proved by the hospital ethical committee. Twenty- eight women were excluded because of subse- quent complications during pregnancy e.g. pre-ec- lampsia, IUGR (birthweightcmean 2 s.d.), pla- cental abruption, signs of asphyxia during labor, or because of maternal tachycardia (heart rate>100 bpm) during Doppler examination. Uterine artery blood velocity was recorded in a prospective study of 42 1 high-risk pregnancies. Recordings of the blood velocity were performed in both uterine arteries and umbilical artery. Indi- cations for the Doppler flow examinations were: suspected IUGR (n=l17), pre-eclampsia (blood pressure2140/90 and proteinuria) (n=67), preg- Table I. Uterine artery pulsatility index (PI) in normal pregnancies inrelation to placental lie Arbitrarily chosen upper normal limit (approx. meant2 s.d.) ean PI s.d.) All measurements 0.81 (0.20) 1.20 Placental side 0.65 (0.17) 1 oo Non-placental side 0.90 (0.25) 1.40 ctn bstet Gynecol Scand 7 (1996)  614 C. Hofstaetter et al. Table II Uterine artery flow velocity waveforms and perinatal outcome in 421 complicated pregnancies. Meanks.d. and numbers Pulsatility index Notch >1.20 51.20 pvalue Present Absent pvalue Number Gestational age (weeks) Birthweight (9) B-weight deviat. Oh) SGA (mean-2 s.d.) Plac. weight (9) Apgar score 1’<7 Apgar score 5’<7 Umbilical art. pH<7.10 Umbilical ven. pHc7.20 Cesarean section ODFD NICU PIH Pre-eclampsia Perinatal mortality 44 35.7k3.4 2143.8+771 -24.8+16 19 411+122 9 1 1131 1/37 29 16 20 3 15 3 377 38.3k3.0 3061k779 -7.Ok16.8 56 566k158 30 12 181249 281338 102 71 51 29 52 6 0.0001 0.0001 0.0001 0.001 0.0001 0.01 NS NS NS 0.001 0.01 0.001 NS 0.001 NS 92 36.6k3.7 2485+837 36 499k169 14 4 4160 6/82 51 43 27 2 23 4 -1 851 8 329 38.4k2.9 31 00+773 39 565+156 25 8 161221 231294 80 44 43 30 44 5 -6.0+16 0.001 0.001 0.001 0.001 0.001 0.04 NS NS NS 0.001 0.001 0.002 0.04 0.04 NS SGA: small-for-gestational age; ODFD: operative delivery for fetal distress; NICU: neonatal intensive care unit; PIH pregnancy induced hypertension; NS: non-significant. weight, Apgar score of <7 at 1 and 5 min, umbil- ical arterial pH <7 10 and umbilical venous pH ~7.20, he number of cesarean sections, operative deliveries for fetal distress ODFD) as indicated by abnormal CTG tracing andor fetal scalp blood pH sampled resulting in emergency cesarean sec- tions, vacuum or forceps extractions, admission to the neonatal intensive care unit (NICU), occur- rence of pre-eclampsia, PIH and the rate of peri- natal mortality. Simple regression analysis, Student’s t-test, Fisher’s exact test and Chi2-test were used for statistical analysis, p values <0.05 being consid- ered significant. Results Cross-sectional study Among the 110 uncomplicated pregnancies, placen- tal lie was central or fundal in 42, left-sided in 30, Table Ill. Uterine artery flow velocity waveforms and perinatal outcome in 421 complicated pregnancies. Meanks.d. and numbers Notch Absent Unilateral gvalue Bilateral pvalue Number 329 51 41 Gest. age (weeks) 38+3 38+3 NS 36+4 0.0001 Birthweight (9) 31 OOi773 281 1+743 0.01 2079+774 0.0001 Birthweight dev. (%) -6.0+16 -1 2k17 0.02 -27+16 0.0001 SGA (s2 s.d. 39 10 NS 26 0.000 Plac. weight (9) 565+156 558i179 NS 426+123 0.0001 Apgar score 1‘<7 25 5 NS 9 0.01 Apgar score 5‘<7 9 1 NS 3 NS Umb. art. pH<7.10 151220 313 5 NS 1125 NS Umb. ven. pH<7.20 231293 3/44 NS 3/38 NS Cesarean section 80 25 0.01 26 0.001 ODFO 44 23 0.0001 20 0.0001 NICU admissions 43 10 NS 17 0.001 PIH 30 1 NS I NS Pre-eclampsia 44 14 0.03 9 NS Mortality 5 1 NS 3 0.05 SGA: small-for-gestational age; ODFD: operative delivery for fetal distress; NICU: neonatal intensive care unit; PIH: pregnancy induced hypertension; NS: non-significant. cta Obstet Gynecol Scand 75 1 996)  Uterine artery velocimetry 615 Table IV. Relation between perinatal outcome md mean uterine artery pusatility index PI) in three subgroups; PI: 51.20 (normal); PI: 1.21- 1.39 (meant2-3 s.d. ; and PI: 2 1.40 (mean+>3 s.d. Uterine art. PI Number section SGA ODFD 4.20 (normal) 377 102 56 71 1.21-1.39 (2-3 s.d.) 23 11 7 6 Cesarean 21.40 (>3 s.d ) 21 18 12 10 pco 01 p<o o1 pco.01 - -_ SGA: small-for-gestational age newborn (meant2 s.d.); ODFD: operative delivery for fetal distress. and right-sided in 38 cases. Regression analysis of the uterine artery PI versus gestational age showed a slight, but non-significant decline in the mean PI for both vessels with increasing gcstational age (y=0.805-O.00 xx, r =0.036). Constant reference values for uterine artery PI were therefore chosen, irrespective of gestational age. Scattering was great- est before 21 weeks of gestation. The values of uter- ine artery PI were found to depend on the placental location - the lowest PI values being those on the placental side and the highest PI values on the non- placental side. Upper cut-off levels for different locations were chosen at approximatcly mean P1+2 s.d. (Table I). Prospective stud\ Median gestational age at birth was 39 weeks (range 3-43), and the median examination - delivery in- terval was 8 days (range 046). An increased uterine artery mean PI (>1.20) (1744) or the presence of an early diastolic notch n=92) was associated with lower gestational age at delivery, lower birthweight, SGA newborn, low pla- cental weight, operative delivery for fetal distress and admission to the NICU (Table 11 . A uterine art- ery notch was a somewhat better predictor of peri- natal outcome than PI (Table 11). All blood velocitv waveforms with an abnormal PI had a notch in early diastole. The notch was bilateral in 41 cases. A comparison of perinatal outcome between cases , without a notch, with notch in one uterine artery, and with bilateral notches is given in Table 111. The relation between perinatal outcome and mean uter- ine artery PI grouped into three categories; below mean+2 s.d.; mean+2 and 3 s.d.; and >mean+3 s.d.is given in Table IV, showing poorer outcome with in- A diagnosis of pre-eclampsia or PIH was more frequent in pregnancies with a notch in the uterine artery (Table 11). In the pre-eclampsia subgroup, an abnormal uterine artery PI was present in only 19 of cases wheras a notch in the uterine artery creasing uteroplacental vascular resistance. Fig. I Spectrum of uterine artery blood velocity; upper panel: normal blood velocity; middle panel: presence of early diastolic notch; bottom panel: signs of increased vascular resistance with reduced blood velocities and a characteristic early diastolic notch. blood velocity waveform was present in 30 of cases. Placental lie was central in 316 pregnancies, right-sided in 35, and left-sided in 70 cases. Analyz- ing the data in relation to placental lie did not im- prove the predictive value of the waveforms - he best predictor of perinatal outcome being the aver- age PI for both uterine arteries. Perinatal outcome in relation to abnormal umbili- Acta Obstet Gynecol Scand 75 1996)  616 C Hofstaetter et al. Table V. A comparison of uterine and umbilical artery blood velocity in predicting perinatal outcome. Meants.d. and numbers Uterine artery: Umbilical artery PI: Normal Normal pvalue Abnormal pvalue Abnormal pvalue Number 31 2 68 17 24 Notch absent Notch present Notch absent Notch present Gestational age (weeks) 38.6k2.8 37.053.7 0.01 35.353.6 0.001 35.2k3.7 0.0001 Birthweight (9) 31 55k735 27035735 0.0002 2101k786 0.0001 1867+813 0.0001 B-weight deviat. YO) -5.0+16 -1 3517 0.003 -23.7516 0.0001 -32+15 0.0001 SGA (meant2 s.d.) 30 17 0.001 9 0.0001 19 0.0001 Plac. weight (9) 5725152 537+170 NS 421k169 0.001 396+115 0.0001 Apgar score l’t7 22 8 NS 3 NS 6 NS Apgar score Yt7 9 2 NS 0 NS 2 NS Umb. art. pHt7.10 141246 4151 NS 1117 NS 011 8 NS Umb. ven. pH<7.20 181221 4/63 NS 011 7 NS 0120 NS Cesarean section 71 33 0.0001 9 0.008 18 0.0001 ODFD 38 30 0.0001 6 0.01 13 0.0001 NICU admission 35 14 0.03 8 0.0005 13 0.0001 PIH 29 2 NS 1 NS 0 NS Pre-eclampsia 40 17 0.01 4 NS 6 NS Perinatal mortality 5 0 NS 0 NS 4 0.002 Meants.d. or numbers are given; PI: pulsatility index; SGA: small-for-gestational age; PIH: pregnancy induced hypertension; ODFD: operative delivery for fetal NICU: neonatal intensive care unit; NS: non-significant. The pvalues describe the significance of difference as compared with the subgroup with normal velocities in both arteries. cal artery PI and the presence of a uterine artery notch was similar (Table V). When blood velocity was abnormal on only one side of the placenta, blood velocity predicted lower birthweight and op- erative interventions during labor (Table V). The strongest predictor of adverse outcome was the presence of abnormal blood velocity waveform on both sides of the placenta (Table V). Analyzing the data with regard to uterine artery PI, an abnormal Abnormal UA PI and UtA PI Abnormal UA PI and UtA nolch - bnorma UlA PI ‘AbnomaUA PI andlor VIA notch / UiA notch / I 0,2 0.4 0.6 0.8 , , . False positive rate 0 Fig. 2. Receiver operating characteristic ROC) curves showing sensitivity and false positive rate of umbilical UA) and uterine artery (UtA) velocimetry in predicting a small-for-gestational age newborn. PI=pulsatility index. Abnormal UAPI and/or UtA PI implies either abnormal waveform in one or both vessels. finding on the maternal side of the placenta pre- dicted retarded fetal and placental growth, but not ODFD. There were nine perinatal deaths. The relation- ship of mortality to blood velocimetry in the umbili- cal and uterine artery is given in Tables 11, 111, V. There were five perinatal deaths that might be ex- plained by prematurity - being delivered before 30 weeks of gestation. Three had abnormal uterine and umbilical artery blood velocity - wo with reversed blood velocity in the umbilical artery and three with a notch in the uterine artery. There were four deaths in term pregnancies, all having normal uterine and umbilical artery blood velocities; three fetuses died in utero, two of unknown cause (one of them in a diabetic pregnancy), and the third fetus had trisomy 18. One fetus died during labor in a pregnancy com- plicated by gestational diabetes. The blood glucose levels were normal during labor. A continuous CTG recording was performed during labor, but did not reveal signs of fetal asphyxia until bradycardia de- veloped. An emergency cesarean section was per- formed, but the newborn could not be resuscitated. iscussion In the prospective study of complicated pregnan- cies, the Doppler recorded blood velocity obtained from the uterine artery with the assistance of color flow mapping seems to improve the perinatal pre- dictive value of the blood velocity waveform ob- tained. The clinical value of uterine artery velocity ctu Ohstet Gynecol Scand 75 1996)
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