Predictive value of serial middle cerebral and renal artery pulsatility indices in fetuses with oligohydramnios

OBJECTIVE: To determine if unexplained changes in the amniotic fluid index or pulsatility indices of the fetal renal, middle cerebral, or umbilical artery are predictive of perinatal outcome in pregnancies complicated by oligohydramnios. METHODS: Changes in amniotic fluid measurements and fetal vessel velocimetry in patients with oligohydramnios were evaluated for correlation with fetal outcome. Fourteen fetuses with oligohydramnios underwent serial sonography evaluating the amniotic fluid index and fetal middle cerebral, renal, and umbilical velocimetry. Matched controls and neonatal outcomes were obtained. RESULTS: Change in amniotic fluid index and in renal artery pulsatility index were inversely correlated. Change in the middle cerebral artery pulsatility index was different in infants with normal outcome compared to infants with adverse outcome CONCLUSIONS: Serial velocimetry of the middle cerebral artery may identify fetuses with oligohydramnios at risk for adverse outcomes.     

Doppler assessment of fetal blood flow velocity waveforms during acute maternal oxygen administration as predictor of fetal outcome in post-term pregnancy

The changes in fetal blood flow velocity waveforms during maternal administration of 60% humidified oxygen were assessed by Doppler ultrasonography in 45 post-term fetuses. During oxygen treatment, nine fetuses exhibited temporary increases (24.3 +/- 2.0% [1 standard deviation] above pretreatment values) in the pulsatility index at the level of internal carotid artery. Although no significant changes (2.9 +/- 5.1%) were found in the remaining 36 fetuses. In this former group a higher incidence of emergency cesarean delivery due to fetal distress and more neonatal complications were observed. Also, meconium staining of the amniotic fluid and low 1- and 5-minute Apgar scores occurred more frequently in the group of fetuses who responded to maternal oxygen administration. An increase of at least 20% in the pulsatility index of internal carotid artery during maternal hyperoxygenation may be a useful marker of adverse outcome in post-term fetuses.     

Adrenomedullin is increased in the fetoplacental circulation in intrauterine growth restriction with abnormal umbilical artery waveforms

OBJECTIVE: To examine whether adrenomedullin, a novel vasoactive peptide produced by the placenta, participates in the uteroplacental hemodynamic alterations in intrauterine growth restriction, we studied the correlation between adrenomedullin levels and fetoplacental blood flow. STUDY DESIGN: Maternal and umbilical blood samples were collected in pregnancies complicated by intrauterine growth restriction with abnormal umbilical artery Doppler findings and in control pregnancies. Adrenomedullin levels were measured by means of a specific radioimmunoassay, and flow velocimetry waveforms were recorded from uterine, umbilical, and fetal middle cerebral arteries. RESULTS: Mean adrenomedullin values in umbilical plasma were higher (P <.05) in patients with intrauterine growth restriction (63.7 +/- 34.2 pg/mL; n = 16) than in control subjects (38.1 +/- 14.8 pg/mL; n = 16). A significant correlation was found between maternal adrenomedullin levels and umbilical artery pulsatility index. Moreover, fetal adrenomedullin concentrations correlated negatively with middle cerebral artery pulsatility index and positively with umbilical artery pulsatility index/middle cerebral artery pulsatility index ratio. CONCLUSION: This study provides evidence that adrenomedullin is increased in fetuses with intrauterine growth restriction in response to reduced uteroplacental blood flow and suggests that it may participate in the fetal hemodynamic modifications.     

Effects of maternal dexamethasone administration on fetal Doppler flow velocity waveforms

Objective To investigate the effects of maternal dexamethasone administration on umbilical and fetal cerebral artery flow velocity waveforms.
Design Cross-sectional study.
Setting Department of Obstetrics and Gynaecology, Robert Ballanger Hospital, Aulnay-sous-Bois, France.
Sample Twenty-six pregnant women with singleton pregnancies considered at risk for preterm delivery. At baseline, all pregnancies had normal fetoplacental vascular resistance.
Methods These women were given weekly six intravenous doses of 4 mg of dexamethasone eight hours apart.
Main outcome measures Doppler studies were performed from both umbilical artery (UA) and fetal middle cerebral artery (MCA) before (day 0), during (day 2), immediately after (day 4) and shortly after (day 7) every steroid course.
Results No significant variation was noted in both umbilical artery pulsatility index (PI) and fetal heart rate through dexamethasone therapy. Compared with mean initial values, we found on day 4 a significant decrease in MCA PI of 0.28 (F = 7.17,   P < 0.001  ) and a significant increase in UA:MCA PI ratio of 0.08 (F = 3.85,   P = 0.013  ); in contrast no significant change was documented on days 2 and 7 in both MCA pulsatility index and UA:MCA PI ratio. After multiple regression analysis, only the decrease in fetal middle cerebral artery pulsatility index on day 4 remained significant (F=5.84,   P = 0.001  ).
Conclusions The current study finds in healthy fetuses a transient, significant and unexplained decrease in fetal middle cerebral artery impedance on the fourth day following maternal dexamethasone administration. Further basic research and clinical studies including larger sample sizes or pregnancies with fetoplacental dysfunction are needed.     

Maternal nitric oxide supplementation increases adrenomedullin concentrations in growth retarded fetuses.

Nitric oxide (NO) and adrenomedullin (AM) are both involved in the regulation of fetoplacental circulation in human pregnancy. The aim of this study was to investigate the effect of maternal NO supplementation in pregnancies complicated by intrauterine growth retardation (IUGR) on maternal and fetal NO and AM concentrations and their correlation with uteroplacental and fetal blood flow. We studied 20 pregnant women with IUGR and impaired uteroplacental blood flow between 27 and 35 weeks of gestation randomly selected to receive either transdermal glyceryl trinitrate or placebo. Maternal NO metabolites (NOx) and AM concentrations did not change before and after NO treatment. AM levels were significantly higher in growth retarded fetuses whose mothers received NO donors (114.1 +/- 17.6 pg/ml) than in untreated fetuses (59.8 +/- 38.6 pg/ml), whereas NO treatment did not affect significantly fetal NOx levels. Fetal AM correlated with middle cerebral artery pulsatility index in untreated IUGR but not in NO treated pregnancies.     

Maternal nitric oxide supplementation increases adrenomedullin concentrations in growth retarded fetuses

Nitric oxide (NO) and adrenomedullin (AM) are both involved in the regulation of fetoplacental circulation in human pregnancy. The aim of this study was to investigate the effect of maternal NO supplementation in pregnancies complicated by intrauterine growth retardation (IUGR) on maternal and fetal NO and AM concentrations and their correlation with uteroplacental and fetal blood flow. We studied 20 pregnant women with IUGR and impaired uteroplacental blood flow between 27 and 35 weeks of gestation randomly selected to receive either transdermal glyceryl trinitrate or placebo. Maternal NO metabolites (NOx) and AM concentrations did not change before and after NO treatment. AM levels were significantly higher in growth retarded fetuses whose mothers received NO donors (114.1 ± 17.6 pg/ml) than in untreated fetuses (59.8 ± 38.6 pg/ml), whereas NO treatment did not affect significantly fetal NOx levels. Fetal AM correlated with middle cerebral artery pulsatility index in untreated IUGR but not in NO treated pregnancies.     

The use of fetal Doppler cerebroplacental blood flow and amniotic fluid volume measurement in the surveillance of postdated pregnancies

BACKGROUND: This prospective observational study aims at determining the distribution of fetal cerebro-placental Doppler indices and amniotic fluid volume in a homogenous group of uncomplicated postdated pregnancies at 41 weeks. The correlation with incidence of passage of thick meconium-stained liquor in labor was analyzed to decide which parameter would be useful in the surveillance of postdated pregnancies. METHODS: The amniotic fluid volume, middle cerebral artery pulsatility index, umbilical artery pulsatility index, and cerebroplacental ratio were measured and distribution determined in 118 well-dated singleton pregnancies admitted for routine induction of labor at 41 weeks. The 10th centile and the 90th centile in each Doppler parameter and amniotic fluid volume were chosen to divide each parameter into three centile groups. The prevalence of thick meconium-stained liquor in labor in different Doppler and amniotic fluid volume centile groups was compared using Chi-square test for trend with P < 0.05 taken as statistically significant. RESULTS: The prevalence of thick meconium-stained liquor in labor was significantly inversely correlated with the middle cerebral artery pulsatility index (P = 0.008), with significant difference across different middle cerebral artery pulsatility index centile groups (P = 0.02). There was no significant difference in the prevalence of thick meconium-stained liquor in labor or oligohydramnios across different umbilical artery pulsatility index centile groups. Neither was there significant difference in the prevalence of thick meconium-stained liquor in labor and oligohydramnios across different cerebroplacental ratio and amniotic fluid volume centile groups. Logistic regression using the 10th centile of middle cerebral artery pulsatility index confirmed that it was a significant independent predicting factor for risk of thick meconium-stained liquor in labor with adjusted odds ratio (95th CI) of 6.14 (1.6-24.1). CONCLUSION: Middle cerebral artery pulsatility index is better than amniotic fluid volume or umbilical artery pulsatility index in predicting the risk of thick meconium-stained liquor in labor in uncomplicated postdated pregnancy at 41 weeks.     

The effect of maternal fasting on the fetal biophysical profile.

OBJECTIVES: To determine fetal biophysical profile changes in women observing Ramadan with uncomplicated singleton pregnancy. METHODS: In this cross-sectional observational study healthy women who were observing Ramadan at 30 weeks or more of gestation were recruited as well as a non-fasting control group matched for age, parity, and gestational age. Ultrasound examination included assessment of amniotic fluid volume, fetal bladder volume, fetal biophysical profile, and umbilical artery Doppler flow. RESULTS: A total of 162 pregnant women were observed. Mean umbilical artery pulsatility index, vertical amniotic pool depth, and fetal bladder volume were similar in the study and control groups. However, there was a significant difference in biophysical scores between the two groups. In the fasting group, 30 of 81 fetuses (37%) had a score of 6/8 compared with 11 of 81 fetuses (13.6%) in the control group (P=0.001). All fetuses in both groups with a biophysical score of 6/8 showed no breathing movements. CONCLUSIONS: Fetal breathing movements are reduced during maternal fasting.     

Amniotic fluid nitric oxide and uteroplacental blood flow in pregnancy complicated by intrauterine growth retardation

Objective To examine the correlation between placental nitric oxide production and uteroplacental blood flow.
Participants Thirty-one pregnant women with fetuses with intrauterine growth retardation and 27 normal pregnancies as controls.
Design Correlation between amniotic fluid measurements of nitrite metabolite in the third trimester and flow velocimetry waveforms recorded from uterine, umbilical and fetal middle cerebral arteries. Intrauterine growth retarded pregnancies were compared with controls.
Main outcome measures Concentrations of nitric oxide metabolites (NO₂^- and NO₃^-) in amniotic fluid were correlated with flow velocimetry waveforms findings by the determination of correlation coefficient.
Results Overall median nitrite values in amniotic fluid were higher (   P < 0.01  ) in intrauterine growth retarded patients (median 8.6 μmol/mg creatinine) than in controls (5.6 μmol/mg creatinine). Pathologic uterine flow velocimetry waveforms in uterine artery (-2SD) were observed in 12 women of the intrauterine growth retarded group, and the concentration of amniotic fluid nitrite was significantly lower (   P < 0.01  ) in these patients (median 4.45 μmol/mg creatinine) than in those with normal flow velocity waveforms (median 11.43 μmol/mg creatinine). A significant negative correlation was observed between nitrite concentrations and uterine artery resistance index, umbilical artery pulsatility index and umbilical artery pulsatility index:middle cerebral artery pulsatility index ratio.
Conclusions We conclude that placental nitric oxide is significantly associated with uteroplacental blood flow and may be important in maintaining adequate uteroplacental perfusion in intrauterine growth retarded pregnancies.     

Fetal middle cerebral artery Doppler waveforms in twin-twin transfusion syndrome

The aim of this study was to compare the fetal middle cerebral artery (MCA) Doppler waveforms in growth-retarded twin fetuses with (n = 11) and without (n = 24) twin-twin transfusion syndrome (TTTS). Umbilical artery (UA) and fetal MCA Doppler velocity waveforms were recorded on admission. The mean values of the UA pulsatility index (PI) of smaller twin fetuses with and without TTTS were significantly higher than those of normal singleton pregnancies. The mean values of the MCA PI of smaller twin fetuses in the TTTS group (+0.7 +/- 1 SD) were significantly higher than those of normal singleton pregnancies on admission, and these levels did not markedly change following amniocentesis. On the other hand, the values of the MCA of the growth-retarded fetuses without TTTS (-0.9 +/- 1 SD) were significantly lower than those of normal singleton pregnancies. Our findings suggest that measurement of fetal MCA PI is a useful method to assess growth-retarded fetuses in monochorionic twin pregnancies. Copyright Copyright 1999 S. Karger AG, Basel     

Equalization of amniotic fluid volumes after decompression amniocentesis for treatment of the twin oligohydramnios-polyhydramnios sequence

OBJECTIVE: To measure acute and chronic changes in the placenta and amniotic fluid associated with performance of decompression amniocentesis in pregnancies with the twin oligohydramnios-polyhydramnios sequence (TOPS). METHODS: Amniotic fluid pressures, placental thickness, placental perfusion, and amniotic fluid volumes were measured in each sac of a monochorionic diamniotic twin gestation before and after decompression amniocentesis. Indigo carmine was injected into the polyhydramnic sac after decompression, and fluid from the oligohydramnic sac was sampled after equilibration. Spectrophotometric analysis of amniotic fluid specimens was performed for dye detection. Amniotic fluid volume and placental perfusion studies were repeated 1 week later. RESULTS: Three patients with TOPS were enrolled, and decompression amniocentesis was performed in the midtrimester. After decompression, amniotic fluid volume decreased in the polyhydramnic sac, amniotic fluid pressures decreased in both sacs, placental thickness increased, and umbilical artery Doppler velocimetry was unaffected. The amniotic fluid volume increased acutely in only one oligohydramnic sac after decompression, and ultrasonographic examination, amniotic fluid spectrophotometric analysis, and placental pathologic examination all identified interfetal membrane disruption as the etiology. CONCLUSIONS: Decompression amniocentesis as a treatment for TOPS does not result in acute or chronic changes in the amniotic fluid volume of the oligohydramnic sac in the absence of interfetal membrane disruption.     

Maternal and fetal haemodynamics in hypertensive pregnancies during maternal treatment with intravenous hydralazine or labetalol

Intravenous treatment with 10 mg of hydralazine or 100 mg of labetalol was randomly allocated to 30 hypertensive pregnant women. Umbilical artery flow velocity waveforms were recorded using a pulsed Doppler duplex scanner (ATL Mk V) and umbilical artery pulsatility index (PI) and fetal heart rate (FHR) were derived from these recordings. Maternal blood pressure decreased significantly after both drugs. Maternal pulse rate increased after hydralazine but did not change significantly after labetalol. FHR did not change significantly after hydralazine but decreased after labetalol. PI decreased after hydralazine and increased after labetalol--most fetuses showed little change but a few in each group showed large changes in PI, as did two of five additional patients studied. We attributed the decrease in PI in some fetuses after hydralazine to vasodilation, and the increase in PI in some fetuses after labetalol to vasoconstriction in the fetoplacental circulation, suggesting that fetal beta-blockade may occur after maternal treatment with labetalol.     

Maternal and fetal haemodynamics in hypertensive pregnancies during maternal treatment with intravenous hydralazine or labetalol

Summary. Intravenous treatment with 10 mg of hydralazine or 100 mg of labetalol was randomly allocated to 30 hypertensive pregnant women. Umbilical artery flow velocity waveforms were recorded using a pulsed Doppler duplex scanner (ATL Mk V) and umbilical artery pulsatility index (PI) and fetal heart rate (FHR) were derived from these recordings. Maternal blood pressure decreased significantly after both drugs. Maternal pulse rate increased after hydralazine but did not change significantly after labetalol. FHR did not change significantly after hydralazine but decreased after labetalol. PI decreased after hydralazine and increased after labetalol-most fetuses showed little change but a few in each group showed large changes in PI, as did two of five additional patients studied. We attributed the decrease in PI in some fetuses after hydralazine to vasodilation, and the increase in PI in some fetuses after labetalol to vasoconstriction in the fetoplacental circulation, suggesting that fetal beta-blockade may occur after maternal treatment with labetalol.     

Association between maternal-fetal Doppler velocimetry and fetal lung maturity

AIMS: To correlate maternal-fetal Doppler velocimetry parameters to indices of fetal lung maturity (FLM). METHODS: Fifty-five consecutive third trimester pregnancies in which a pulsed-wave Doppler study, including uterine resistance index (Ut RI), umbilical artery pulsatility index (UA PI), middle cerebral artery pulsatility index (MCA PI) and the UA/MCA ratio was performed within 24 hours before amniocentesis and within a week from birth. FLM was determined by amniotic fluid lamellar bodies count (LBs). RESULTS: A positive correlation between MCA PI and LBs (p < 0.007, r = 0.44) was found. MCA PI showed a trend to lower values in fetuses that developed RDS at birth (1.3 +/- 0.5 vs. 1.7 +/- 0.4, NS). LBs significantly decreased as Ut RI increased (O.R.: 0.98, C.I. 0.97-0.99, p < 0.05). A mean Ut RI > 0.64 was correlated to delayed FLM (LBs < 20,000/microl; sensitivity: 90.9%, specificity: 90.3%; positive predictive value: 76.9%, negative predictive value: 96.6%). COMMENT: In third trimester pregnancies abnormal uterine artery waveforms may be associated to a delayed FLM, as expressed by decreased amniotic fluid LBs.     

Effects of cholic acid infusion in fetal lambs

The effects of prolonged intravenous infusions of cholic acid into fetal lambs are described in this study. The ewes (n = 10, 11 fetuses) were operated on at 114 days of gestation (term = 150 days) by placing plastic catheters in maternal and fetal vessels and in the amniotic cavity. Gestational ages were confirmed after delivery by radiographic examination of the ossification centers of the fetal legs. Infusions of cholic acid (1.6 mumoles/min-1) started 8 to 10 days after surgery in 5 fetuses (including one twin). The remaining 6 fetuses (also including one twin) were infused with 5% dextrose in water. Total plasma bile acids at the beginning of the experiment were similar in both groups (23.8 +/- 6.6 vs. 24.3 +/- 5.7 microM). No significant changes in fetal heart rate, blood pressure, blood gases or pH were detected during the infusion. Meconium-stained amniotic fluid was observed during the third day of infusion in all the fetuses infused with cholic acid and in one control fetus. Fetuses infused with cholic acid were delivered alive 19-26 days before term. The concentration of plasma bile acids in the experimental group at delivery was 829 +/- 305 microM, i.e. significantly higher than that of the control group (24.4 +/- 5.7 microM). Control fetuses (except one twin) were delivered at term. We concluded that cholic acid, even at the high dose infused, is neither lethal nor severely harmful for the fetus. Meconium passage of the fetuses infused with cholic acid, in our experiment, appeared to be related to the stimulatory effect of cholic acid on fetal colonic motility rather than to fetal hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler, cardiotocography, and biophysical profile changes in growth-restricted fetuses

OBJECTIVE: To assess from diagnosis to delivery the Doppler studies of the umbilical artery, middle cerebral artery, umbilical vein, ductus venosus, and amniotic fluid index of fetuses with idiopathic growth restriction. METHODS: A total of 145 singleton growth-restricted fetuses with abnormal umbilical artery pulsatility indexes were studied. Cesarean delivery was performed because of abnormal biophysical profile or nonreassuring fetal heart rate pattern. RESULTS: There were 4 fetal and 50 neonatal deaths. Two growth-restricted groups were identified: Group A (n = 44) included fetuses in whom all measures became abnormal preceding an abnormal biophysical profile or nonreassuring nonstress test. Group B (n = 101) included fetuses in whom 1 or more measures were normal at the time of cesarean delivery. There was no statistically significant difference in perinatal morbidity and mortality between the 2 groups. Neonatal death was increased in fetuses with umbilical artery reversed flow (odds ratio 2.34, 95% confidence interval 1.16-4.73; P < .05) and ductus venosus reversed flow (odds ratio 4.18, 95% confidence interval 2.01-8.69; P < .05). A significant correlation was also found between low birth weight and adverse perinatal outcome. CONCLUSION: In fetuses with idiopathic growth restriction, 1) low birth weight, 2) umbilical artery reversed flow, and 3) ductus venosus absent or reversed flow are associated with an increased perinatal morbidity and mortality.     

Short-term effects of maternal oxygen administration on blood flow velocity waveforms in healthy and growth-retarded fetuses

To determine whether maternal oxygen administration affects fetal hemodynamics, we investigated 10 healthy fetuses and 10 growth-retarded fetuses near term by means of Doppler ultrasonography. The growth-retarded fetuses were characterized by abnormal blood flow velocity waveforms. Velocity waveforms were simultaneously recorded at 5-minute intervals from the fetal descending aorta and internal carotid artery before, during, and after maternal oxygen administered through a face mask that delivered 60% oxygen. The pulsatility index was calculated. During oxygen treatment growth-retarded fetuses showed significant temporary hemodynamic modifications as expressed by changes of pulsatility index values that increased in the internal carotid artery and decreased at the level of the descending aorta. On the other side no changes were found in healthy fetuses. These findings suggest that maternal oxygen administration can modify fetal hemodynamics in cases of growth retardation associated with abnormal blood flow velocity waveforms.     

Acute cerebral redistribution in response to invasive procedures in the human fetus.

OBJECTIVES: We sought to investigate the fetal hemodynamic response to the acute stress of invasive procedures. STUDY DESIGN: The middle cerebral artery pulsatility index was measured by Doppler ultrasonography before and after 136 invasive procedures (fetal blood sampling, transfusion, shunt insertion, tissue biopsy, and ovarian cyst aspiration). The response of fetuses submitted to invasive procedures involving transgression of the fetal body, such as intrahepatic vein blood sampling, was compared with that of control procedures at the placental cord insertion. RESULTS: The middle cerebral artery pulsatility index value fell with fetal blood sampling performed at the intrahepatic vein (median, -0.26; 95% confidence interval, -0.35 to -0.15) but not at the placental cord insertion (median, 0.05; 95% confidence interval, -0.04 to 0.19). With transfusions, the middle cerebral artery pulsatility index also fell with procedures at the intrahepatic vein (mean, -0.51; 95% confidence interval, -0.66 to -0.35) but not at the placental cord insertion (mean, -0.04; 95% confidence interval, -0.23 to 0.14). The magnitude of the response was greater with transfusions than with blood sampling alone. The middle cerebral artery pulsatility index value also fell with non-fetal blood sampling procedures involving transgression of the fetal body (mean, -0.32; 95% confidence interval, -0.56 to -0.09) but not with control non-fetal blood sampling procedures. The change in the middle cerebral artery pulsatility index was not related to gestational age, with the youngest fetus showing a fall in the middle cerebral artery pulsatility index value being at 16 weeks' gestation. Although the degree of response was weakly correlated with the duration of needling (y = -0.21 - 0.00014x; R (2) = 0.08; P =.02), multiple logistic regression demonstrated that this was instead a function of the type of the procedure. A response was seen within 70 seconds of fetal puncture. The fetal heart rate did not change significantly with procedures in any of the above-mentioned groups. CONCLUSIONS: The human fetus mounts a cerebral hemodynamic response to invasive procedures involving transgression of the fetal body, which is consistent with the brain-sparing effect.     

Abnormal Doppler velocimetry and blood flow volume in the middle cerebral artery in very severe intrauterine growth restriction: is the occurrence of reversal of compensatory flow too late?

Objectives To determine the time course of quantified volumetric flow and pulsatility index changes in the middle cerebral arteries of severe intrauterine growth restricted fetuses with absent or reversed end diastolic flow velocities (AREDFV) on umbilical artery Doppler with a view to defining the threshold for early intervention before the onset of reversal of adaptation.Setting Fetal growth clinic of a large UK teaching hospital.Sample Seventeen severe intrauterine growth restricted (AC<third centile for gestation and gender) fetuses with abnormal umbilical artery Doppler velocimetry and oligohydramnios (amniotic fluid index <third centile for gestation).Methods One to three daily Doppler velocimetry and quantified volume flow of the middle cerebral artery Doppler velocimetry of the umbilical arteries and daily cardiotocography.Results Reversal of adaptation occurred in eight fetuses, four of which ended as stillbirths and four as neonatal deaths. In two of these fetuses, this had already occurred before the diagnosis of intrauterine growth restriction. In the others, the onset was rapid and difficult to predict. Volume flow in the middle cerebral arteries decreased in those fetuses exhibiting reversal of adaptation but rose in the nine in which compensatory Doppler indices persisted. The decrease in volume flow occurred before the onset of reversal of adaptation in the pulsatility index. In the fetuses exhibiting reversal of adaptation, the rise in the pulsatility index was consistent over 48 hours compared with the physiological fluctuations in pulsatility index in some fetuses where the rise was only for 24 hours followed by a fall. Quantified volume flow fell in the fetuses before reversal of adaptation set-in. The umbilical artery Doppler indices fluctuated between absent and reversed end diastolic velocities within the same fetus irrespective of the changes in the middle cerebral artery Doppler indices.Conclusion Reversal of adaptation is of sudden onset and is associated with poor prognosis. Predicting its occurrence on Doppler indices is difficult as the changes may be very rapid. However, volume flow changes appear to be slower and of earlier onset than the pulsatility index changes. This may therefore be a more useful tool in predicting imminent reversal of adaptation and therefore early delivery.     

Subclassification of small-for-gestational-age fetus using fetal Doppler velocimetry

Our purpose was to determine whether small-for-gestational-age (SGA) fetus can be divided to subclassified groups using fetal Doppler velocimetry. Fifty-four pregnant women with SGA infant delivered after 37 weeks of gestation were studied. After 24 weeks of gestation, fetal middle cerebral artery puslatility index (MCAPI) and umbilical artery pulsatility index (UAPI) were measured at 2- to 3-week intervals using Doppler ultrasound. Perinatal outcomes [operative delivery due to fetal distress, abnormal fetal heart rate (FHR) pattern, meconium staining, low Apgar score (<7), neonatal acidosis (umbilical artery blood pH <7.15), neonatal intensive care unit (NICU) admission due to neonatal asphyxia, and decreased amniotic fluid] were compared in subclassified SGA groups using fetal Doppler velocimetry. The number of SGA fetuses with normal MCAPI and UAPI (normal SGA group) was 39, and those with significantly low MCAPI but normal UAPI (eventful SGA group) 15, respectively. Birth age and birth weights in the eventful SGA group were significantly earlier and lower than those in the normal SGA group, respectively (p < 0.05, and p < 0.005). There were significant increases in operative deliveries, abnormal FHR patterns and decreased amniotic fluid in eventful SGA group, when compared with events related to normal SGA group. However, there were no significant differences in meconium staining of amniotic fluid, low Apgar score, neonatal acidosis, and NICU admission between the two groups. These results suggest that SGA fetus with abnormally low MCAPI but normal UAPI has more poor perinatal outcomes, compared with that with normal MCAPI and UAPI.