Photoacoustic assessment of the fetal brain and placenta as a method of non-invasive antepartum and intrapartum monitoring

A noninvasive monitor for concurrent evaluation of placental and fetal sagittal sinus sO 2 for both antepartum surveillance at the late 2nd and 3rd trimesters and intrapartum monitoring would be a great advantage over current methods. A PA fetal brain and placental monitor has potential value to rapidly identify the fetus at risk for developing hypoxia and ischemia of a sufficient degree that brain injury or death may develop, which may be prevented by intervention with delivery and other follow-up treatments.

Prediction of adverse perinatal outcome by cerebroplacental ratio in women undergoing induction of labor

OBJECTIVE

To investigate the performance of screening for adverse perinatal outcome by the cerebroplacental ratio (CPR) measured within 24 h prior to induction of labor.

METHODS

This was a prospective observational study of 1902 singleton pregnancies undergoing induction of labor at ≥ 37 weeks' gestation. Doppler ultrasound was used to measure the pulsatility index (PI) in the umbilical artery (UA) and fetal middle cerebral artery (MCA) within 24 h before induction of labor. The measured UA-PI and MCA-PI and their ratio were converted to multiples of the median after adjustment for gestational age. Univariable and multivariable logistic regression analysis was used to determine whether CPR improved the prediction of adverse perinatal outcome provided by maternal characteristics, medical history and obstetric factors. The detection rate (DR) and false-positive rate (FPR) of screening by CPR were estimated for Cesarean section for presumed fetal distress and adverse neonatal outcome, which included umbilical arterial or venous cord blood pH ≤ 7 and ≤ 7.1, respectively, 5-min Apgar score < 7, admission to the neonatal intensive care unit for > 24 h or hypoxic ischemic encephalopathy.

RESULTS

A combination of maternal and pregnancy characteristics, including age, weight, racial origin, previous obstetric history, pre-eclampsia, gestational age at delivery and amniotic fluid volume, identified 39% of pregnancies requiring Cesarean section for fetal distress at a FPR of 10%; addition of CPR did not improve the performance of screening. In screening for adverse neonatal outcome by a combination of parity and CPR, the DR was 17% at a FPR of 10%.

CONCLUSION

Low CPR, measured within 24 h prior to induction of labor, is associated with increased risk of Cesarean section for fetal distress and adverse neonatal outcome, but the performance of CPR for such surrogate measures of fetal hypoxic morbidity is poor. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

In Vivo Neurochemical Characterization of Developing Guinea Pigs and the Effect of Chronic Fetal Hypoxia

The guinea pig is a frequently used animal model for human pregnancy complications, such as oxygen deprivation or hypoxia, which result in altered brain development. To investigate the impact of in utero chronic hypoxia on brain development, pregnant guinea pigs underwent either normoxic or hypoxic conditions at about 70 % of 65-day term gestation. After delivery, neurochemical profiles consisting of 19 metabolites and macromolecules were obtained from the neonatal cortex, hippocampus, and striatum from birth to 12 weeks postpartum using in vivo (1)H MR spectroscopy at 9.4 T. The effects of chronic fetal hypoxia on the neurochemical profiles were particularly significant at birth. However, the overall developmental trends of neurochemical concentration changes were similar between normoxic and hypoxic animals. Alterations of neurochemicals including N-acetylaspartate (NAA), phosphorylethanolamine, creatine, phosphocreatine, and myo-inositol indicate neuronal loss, delayed myelination, and altered brain energetics due to chronic fetal hypoxia. These observed neurochemical alterations in the developing brain may provide insights into hypoxia-induced brain pathology, neurodevelopmental compromise, and potential neuroprotective measures.

[The asphyxia of the fetus--cardiotocography and ultrasound methods of diagnosis]

The asphyxia of the fetus remains a main cause for neonatal morbility and mortality. And the possibility of it developing antenatal or intrapartal. The main objective of the antenatal fetus examination tests is the timely diagnosis of the signs of the asphyxia of the fetus.

The cardiac state diagram as a novel approach for the evaluation of pre- and post-ejection phases of the cardiac cycle in asphyxiated fetal lambs

The aim of this study was to investigate myocardial wall motion using echocardiography and color-coded tissue velocity imaging and to generate a cardiac state diagram for evaluation of the duration of the pre- and post-ejection phases in asphyxiated fetal lambs. Six near-term lambs were partly exteriorized and brought to cardiac arrest through asphyxia. Echocardiography measurements were recorded simultaneously with arterial blood sampling for lactate and blood gases. All fetal lambs exhibited prolongation of the pre- and post-ejection phases at the time when the most pronounced changes in lactate concentration and pH occurred. The mean change in duration of the pre- and post-ejection phases for all fetal lambs was 36 ± 7 ms (p < 0.002) and 77 ± 17 ms (p < 0.019), respectively, and the percentage change was 50% (p < 0.001) and 38% (p < 0.049), respectively. As asphyxia progressed in fetal lambs, the duration of the pre- and post-ejection phases increased. The cardiac state diagram has the potential to be a comprehensible tool for detecting fetal asphyxia.

Operator auditory perception and spectral quantification of umbilical artery Doppler ultrasound signals

OBJECTIVE

An experienced sonographer can by listening to the Doppler audio signals perceive various timbres that distinguish different types of umbilical artery flow despite an unchanged pulsatility index (PI). Our aim was to develop an objective measure of the Doppler audio signals recorded from fetoplacental circulation in a sheep model.

METHODS

Various degrees of pathological flow velocity waveforms in the umbilical artery, similar to those in human complicated pregnancies, were induced by microsphere embolization of the placental bed (embolization model, 7 lamb fetuses, 370 Doppler recordings) or by fetal hemodilution (anemia model, 4 lamb fetuses, 184 recordings). A subjective 11-step operator auditory scale (OAS) was related to conventional Doppler parameters, PI and time average mean velocity (TAM), and to sound frequency analysis of Doppler signals (sound frequency with the maximum energy content [MAXpeak] and frequency band at maximum level minus 15 dB [MAXpeak-15 dB] over several heart cycles).

RESULTS

WE FOUND A NEGATIVE CORRELATION BETWEEN THE OAS AND PI: median Rho -0.73 (range -0.35- -0.94) and -0.68 (range -0.57- -0.78) in the two lamb models, respectively. There was a positive correlation between OAS and TAM in both models: median Rho 0.80 (range 0.58-0.95) and 0.90 (range 0.78-0.95), respectively. A strong correlation was found between TAM and the results of sound spectrum analysis; in the embolization model the median r was 0.91 (range 0.88-0.97) for MAXpeak and 0.91 (range 0.82-0.98) for MAXpeak-15 dB. In the anemia model, the corresponding values were 0.92 (range 0.78-0.96) and 0.96 (range 0.89-0.98), respectively.

CONCLUSION

Audio-spectrum analysis reflects the subjective perception of Doppler sound signals in the umbilical artery and has a strong correlation to TAM-velocity. This information might be of importance for clinical management of complicated pregnancies as an addition to conventional Doppler parameters.

[Doppler blood flow velocimetry in the umbilical artery in uncomplicated pregnancy]

OBJECTIVE

To determine the resistance index (RI) and pulsatility (PI) in the umbilical artery (UA) in prediction of abnormal fetal heart rate during labor and poor fetal outcome in term pregnancy.

MATERIAL AND METHODS

The study included 148 patients at term in uncomplicated pregnancy Daily evaluation of blood flow in the UA was performed and PI and RI were calculated. The last value before delivery was taken for the analysis. In turn predictive value of Doppler parameters has been determined in the prediction of abnormal FHR during labor and abnormal newborn condition. Evaluation included fetal CTG parameters and newborn status based on the V.Apgar scale and acid-base equilibrium in the umbilical cord blood. Then selected parameters, characterizing pregnancy and the newborn status, with abnormal Doppler results were compared. The prognostic value of Doppler indices was assessed for selected parameters determining the course of pregnancy and abnormal fetal heart rate.

RESULTS

A poor predictive value of UA PI and RI in the prediction of abnormal fetal heart rate during labor and poor fetal outcome was found. The RI in the UA presented the highest predictive value.

CONCLUSION

RI in the UA shows higher predictive value than PI in the detection of abnormal fetal outcome and abnormal fetal heart rate in uncomplicated pregnancy at term. However, PI as well as RI in the UA have a low predictive value for the analyzed parameters.

[Doppler blood flow velocimetry in the middle cerebral artery in uncomplicated pregnancy]

OBJECTIVE

To determine the resistance index (RI) and pulsatility (PI) in the middle cerebral artery (MCA) in prediction of abnormal fetal heart rate during labor and poor fetal outcome in term pregnancy.

MATERIAL AND METHODS

The study included 148 patients at term in uncomplicated pregnancy Daily evaluation of blood flow in the MCA was performed and PI and RI were calculated. The last value before delivery was taken for the analysis. The predictive value of Doppler parameters has been determined in turn to predict abnormal FHR during labor and abnormal newborn condition. Evaluation included fetal CTG parameters and newborn status based on the V Apgar scale and acid-base equilibrium in the umbilical cord blood. Then selected parameters, characterizing pregnancy and the newborn status, were compared with abnormal Doppler results. The prognostic value of Doppler indices was assessed for selected parameters determining the course of pregnancy and abnormal fetal heart rate.

RESULTS

Poor predictive value of UA PI and RI in the prediction of abnormal fetal heart rate during labor and poor fetal outcome was found. The RI in the UA presented the highest predictive value.

CONCLUSION

PI in the MCA shows higher predictive value than RI in the detection of abnormal fetal outcome and abnormal fetal heart rate in uncomplicated pregnancy at term. However PI indices, particularly RI in the middle cerebral artery have low predictive value for the analyzed parameters.

Sonographic biophysical profile in detection of foetal hypoxia in 100 cases of suspected high risk pregnancy

BACKGROUND

The foetus has become increasingly accessible and visible as a patient over the last two decades. Ultrasound imaging has broadened the scope of foetal assessment. Dynamic real time B-Mode ultrasound is used to monitor cluster of biophysical variables, both dynamic and static collectively termed as biophysical profile. The purpose of this study was to determine the effect of sonographic biophysical profile score on perinatal outcome in terms of mortality and morbidity.

METHODS

This descriptive study was carried on 100 randomly selected high risk pregnant patients in Radiology Department PGMI, Government Lady Reading Hospital, Peshawar from December 2007 to June 2008. Manning biophysical profile including non-stress was employed for foetal screening, using Toshiba ultrasound machine model Nemio SSA-550A and 7.5 MHZ probe.

RESULTS

Out of 100 cases 79 (79%) had a normal biophysical profile in the last scan of 10/10 and had a normal perinatal outcome with 5 minutes Apgar score > 7/10. In 13 (13%) cases Apgar score at 5 minute was < 7/10 and babies were shifted to nursery. There were 2 (2%) false positive cases that showed abnormal biophysical profile scores of 6/10 but babies were born with an Apgar score of 8/10 at 5 minutes. There were 2 (2%) neonatal deaths in this study group. The sensitivity of biophysical profile was 79.1%, specificity 92.9%. Predictive value for a positive test was 98.55%; predictive value for a negative test was 41.93%.

CONCLUSION

Biophysical profile is highly accurate and reliable test of diagnosing foetal hypoxia.

Pulsations in the umbilical vein during labor are associated with increased risk of operative delivery for fetal distress

OBJECTIVES

Under physiological conditions the blood flow velocity waveform in the umbilical vein (UV) has an even non-pulsating pattern. Pulsations in the UV have been described in human fetuses exposed to chronic hypoxia and heart failure. Current techniques for fetal surveillance during labor and delivery involve a risk of both over- and underestimation of fetal hypoxia. We aimed to examine whether pulsations in the UV appear in the human fetus during suspected intrapartum hypoxia, and if so whether they are associated with increased risk of operative delivery for fetal distress (ODFD).

METHODS

This was a prospective double blind study including 52 normal pregnancies. A Doppler examination of the UV was performed on 26 fetuses with pathological and 26 fetuses with normal cardiotocography (CTG) during labor. Presence or absence of pulsations in the UV were noted and related to perinatal outcome.

RESULTS

Pulsations in the UV were seen in eight (30.8%) of the fetuses with pathological CTG, of which six (75%) underwent ODFD. No pulsations were seen in the other 18 (69.2%) fetuses with pathological CTG and these were all delivered without ODFD. No pulsations were seen in the UV in the fetuses with normal CTG and these were all delivered without ODFD. Among the fetuses with pathological CTG, there was an increased risk of ODFD in fetuses with vs. those without pulsations in the UV (P < 0.0001).

CONCLUSIONS

Pulsations in the UV can be observed in human fetuses during suspected intrapartum hypoxia and these pulsations are associated with an increased risk of ODFD. Doppler examination of the UV might give important additional information on fetal condition during labor and delivery.

Fetal ductus venosus, middle cerebral artery and umbilical artery flow responses to uterine contractions in growth-restricted human pregnancies

OBJECTIVE

To explore fetal ductus venosus (DV) flow velocity changes relative to umbilical artery (UA) blood flow and brain-sparing flow (BSF) during uterine contractions.

METHODS

Forty-five term fetuses suspected of having growth restriction were exposed to an oxytocin challenge test (OCT) with simultaneous Doppler velocimetry in the UA, middle cerebral artery (MCA) and DV. Basal BSF was defined as a MCA-to-UA pulsatility index (PI) ratio of < 1.08, and de novo BSF as a decrease in MCA-PI of > or = 1 SD (equivalent to a value of 0.24 units) during the OCT.

RESULTS

Basal DV flow velocities were lower in the BSF group (n = 7) than they were in the non-BSF group (n = 38). During the OCT, DV flow velocity parameters changed in neither group but MCA-PI decreased in the non-BSF group. A crude de novo BSF was not associated with DV flow velocity changes, but when UA-PI changes were considered, a serial relationship was found between decreased UA-PI, increased DV flow velocity, and decreased MCA-PI. When UA-PI increased, the MCA-PI still decreased (though not significantly) but DV flow velocity parameters remained unchanged.

CONCLUSIONS

Established fetal BSF is associated with low DV flow velocities, but in an acute sequence there might be two contrasting courses along which BSF develops: one with an increase and one with a decrease in the UA vascular flow resistance. In the former situation the DV flow velocity increases, while in the latter situation the role of the DV in the acute redistribution of fetal blood flow is unclear.

Maternal breath-holding and the valsalva maneuver: methods to overcome fetal breathing movements during Doppler sonography

Fetal breathing movements (FBM) hinder Doppler measurements in the fetus. The aim of the present study was to establish whether FBM are overcome by the mother holding her breath for a few seconds or performing the Valsalva maneuver (VM). This prospective study included a group of 120 consecutive patients showing FBM. In 78 patients (65%), FBM were observed only at the beginning of the examination and then stopped spontaneously. In the other 42 patients, FBM were still present during and at the end of the general examination. These patients were considered for the evaluation. In a first step, the mother was asked to hold her breath for 5 s. If FBM continued, the procedure was repeated. If this also failed, the Valsalva maneuver was performed. In the presence of fetal apnea, flow velocity measurements were taken from the umbilical artery. Nine patients (21%) halted FBM with the first attempt at maternal breath-holding, four patients (10%) with the second attempt and 22 patients (52%) on using the VM. FBM was arrested within a maximum of 94 s after breath-holding or the VM. No reaction to any of the procedures was observed in seven patients (17%). Breath-holding alone or in combination with the Valsalva maneuver has been shown to be effective in overcoming the problem of FBM during prenatal Doppler examination in most cases.

New Doppler index for prediction of perinatal brain damage in growth-restricted and hypoxic fetuses

OBJECTIVE

To evaluate the new vascular score, hypoxia index (HI), in the prediction of sonographically detected structural brain lesions in neonates within the first week after delivery of growth-restricted fetuses.

METHODS

This prospective study included 29 growth-restricted fetuses delivered between 31 and 40 gestational weeks. Doppler umbilical artery (UA) and middle cerebral artery (MCA) resistance indices (RI) were recorded at 48-h intervals for at least 2 weeks before delivery. The cerebroumbilical ratio (C/U ratio = MCA-RI/UA-RI) and the HI (the sum of the daily reductions in C/U ratio, i.e. percentage below the cut-off value of 1, over the period of observation) were calculated. After delivery, neonatal outcome was evaluated according to obstetric parameters and ultrasound examinations of the brain. Doppler indices, C/U ratio and HI, as well as neonatal clinical and biochemical parameters, were tested as potential predictors of brain lesions using the C4.5 data-mining algorithm.

RESULTS

Neonatal brain lesions were detected in 13 growth-restricted fetuses. Of all the parameters tested by the C4.5 data-mining algorithm, only HI was identified as a predictor of neonatal brain lesions. HI also showed better correlation with neonatal biochemical parameters, such as umbilical venous partial pressure of oxygen and umbilical venous pH, compared with the C/U ratio.

CONCLUSIONS

HI, which takes into account cumulative oxygen deficit, could significantly improve the prediction of a poor neurological outcome in pregnancies complicated by growth restriction and hypoxia.

Doppler waveform indices of the Middle Cerebral Artery of normal fetuses in the first half of pregnancy in the Thai population

OBJECTIVE

To establish the reference ranges of middle cerebral artery (MCA) Doppler indices including pulsatility index (PI), resistance index (RI) and peak systolic velocity (PSV) of the Thai fetuses at gestational age of 11-20 weeks.

METHODS

A descriptive cross-sectional study was conducted at Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. Normal singleton pregnancies between 11 and 20 weeks of gestation were recruited into the study for measurements of MCA Doppler indices between November 2005 and August 2006. The trans-abdominal ultrasound, Aloka Model Prosound 5000 (Tokyo) was used. The MCA Doppler data were analyzed for median, 5th, and 95th percentile for each gestational week. The best-fit mathematical model was derived.

RESULTS

A total of 300 measurements, with average of 30 +/- 7.35 per gestational week (mean +/- SD) and range 23-45 per gestational week, were obtained from 149 patients. Regression analysis yielded the best-fitted equation of quadratic function as follows: PI = 8.421 - 0.705(GA) + 0.018(GA(2)) (r (2) = 0.452), RI = 1.54 - 0.073(GA) + 0.002(GA(2)) (r (2) = 0.309), PSV = -63.456 + 9.425(GA) - 0.262(GA(2)) (r (2) = 0.504).

CONCLUSION

A nomogram for MCA Doppler indices, including PI, RI and PSV ratio for each gestational age during 11-20 weeks was constructed. This may be a useful aid in the early detection of abnormalities in fetal cerebral blood flow, especially in fetal anemia secondary to hemoglobin Bart's disease.

Fetal brain sparing is strongly related to the degree of increased placental vascular impedance

BACKGROUND

Doppler ultrasound examination has become an established method of clinical surveillance in high-risk pregnancies. Doppler indication of fetal brain sparing (BS) is an acknowledged sign of circulation redistribution during chronic hypoxia.

OBJECTIVES

To evaluate the relationship between placental vascular resistance and signs of BS in middle cerebral artery (MCA) blood flow velocity.

METHODS

The MCA, uterine artery, and umbilical artery (UA) were located by color Doppler ultrasound in 103 high-risk pregnancies at risk for intrauterine fetal hypoxia. The blood velocity spectrum was analyzed for the following parameters: pulsatility index (PI) and signs of notching in the uterine arteries. Z-score was calculated for the MCA PI.

RESULTS

Signs of BS in the MCA were correlated to increased placental vascular impedance. The degree of BS in the MCA expressed as Z-scores was correlated to increasing vascular impedance, both in the umbilical and uterine arteries, and to adverse outcome of pregnancy. The greatest deviation in MCA PI Z-scores was seen in preterm pregnancies.

CONCLUSION

A clear correlation exists between increasing placental vascular impedance and BS in the MCA. Preterm pregnancies express the greatest deviation from the mean MCA PI.

[Doppler assessment of the fetal asphyxia in pregnancies complicated by gestational hypertension and intrauterine growth retardation]

OBJECTIVES

Gestational hypertension is associated with a high morbidity for both mother and fetus. Doppler ultrasound has allowed the fetal circulation to be examined. Now it is possible to monitor the response of the fetal circulation to hypoxia.

DESIGN

The aim of this study was to determine flow patterns in fetal circulation from pregnancies complicated by gestational hypertension and intrauterine growth restriction.

MATERIALS AND METHODS

The investigation included 23 fetuses with signs of the gestational hypertension and intrauterine growth restriction. We evaluated cerebral-placental ratio (CPR) and pulsation index (PI) in the middle cerebral artery (MCA) and the umbilical artery (UA). We also evaluated flows in umbilical vein.

RESULTS

We observed abnormal flow pattern in all cases of analyzing fetuses. The most common abnormal flow was vein pulsation (48%).

CONCLUSIONS

All analyzing fetuses shown signs of the hypoxia. Present of the umbilical vein pulsation or decompensate of the brain sparing effect is closely related o increased perinatal mortality.

Does chronic prenatal Doppler pathology predict feeding difficulties in neonates?

AIM

To determine whether infants with compromised fetomaternal circulation, but not yet critically threatened by absent end-diastolic flow velocities in the umbilical arteries, are at a risk for feeding problems.

METHODS

In a retrospective case-control study, enteral feeding and clinical data were compared between infants with decreased prenatal end-diastolic umbilical flow velocity (DEDFV) or brain-sparing pathology and controls matched for gestational age (GA). In all infants, enteral feedings were advanced according to a standardized enteral feeding protocol.

RESULTS

11 (GA>34 wk) of the 87 infants with DEDFV were fully enterally fed by day 5 and excluded, leaving 76 infants (and matched controls) for final analysis. DEDFV infants were significantly smaller (1,230+/-550 g vs 1,600+/-682 g). Advancement of enteral feedings varied widely, with a significant difference between DEDFV infants and controls. There was no difference in the incidence of NEC (five in both groups). In the most severely affected subgroup of 25 infants with GA<30 wk and prenatal brain sparing, enteral feedings were significantly delayed in comparison to the controls (parenteral amino acid administration for 22 vs 15 d; significantly fewer enteral calories through day 15).

CONCLUSION

Enteral feeds were introduced more slowly to infants who had shown signs of prenatal distress with brain sparing. However, a predisposition to NEC could not be proven. Our results thus do not support the delay of enteral feedings based on prenatal Doppler pathology.

[Biparietal diameter/kidney length ratio in cases with chronic hypoxic state]

AIMS

The object of this study was to investigate the fetal biparietal diameter/kidney length ratio in normal and hyperechogenic kidneys during the third trimester of gestation.

MATERIAL AND METHODS

The selected cases were characterized by pregnancy-associated hypertension and/or proteinuria, which was associated with fetal hypoxia due to the depression of placental blood flow. Depending on the renal manifestation of intrauterine chronic hypoxia, cases were divided into two study groups. Group I was composed of 21 fetuses with pregnancy-associated hypertension and/or proteinuria and hyperechogenic renal medullae. Group II consisted of 162 fetuses with pregnancy-associated hypertension and/or proteinuria and normal echoic kidney. Both study groups included pregnant women from the third trimester.

RESULTS

Fetal renal hyperechogenicity correlated with the pathological growth of fetal kidney. The fetal biparietal diameter/kidney length ratio was significantly lower in cases of hyperechogenicity.

CONCLUSIONS

The fetal renal hyperechogenicity is a relevant indicator of diminution of fetal renal perfusion. This can lead to abnormal development of the affected kidney and can result in a pathological reduction of biparietal diameter/kidney length ratio, which may also be an in utero indicator of subsequent intrauterine and neonatal complications. Detailed ultrasound examinations of renal parenchyma and kidney length seem to be a useful method in the prenatal diagnosis of decreased renal perfusion and of intrauterine hypoxia and serve to detect pathological conditions in utero.

Quantitative studies on fetal actocardiogram

AIM

To quantitatively analyze actocardiography as a method to differentiate between active and resting fetal states.

METHODS

We established five new quantitative parameters for actocardiogram; they include duration, occupancy, and frequency of movement bursts, and fetal heart rate acceleration to movement ratio (A/B ratio) in duration and number. These parameters were analyzed and compared in 14 normal late pregnancies and in non-hypoxic sinus bradycardia due to fetal cardiac sick sinus syndrome (n=1), hypoxic non-reactive non-stress test (n=3), hypoxic fetal distress (n=1), and that ensuing in death (n=1).

RESULTS

Fetal hypoxic disorders differed from non-hypoxic states in the significant reductions of burst frequency (normal pregnancy mean was 0.65-/+0.22 cpm and fetal distress 0.24 cpm), occupancy (32.67% and 10.00%, respectively), and the ratio of durations of acceleration to movement burst (1.03 and 0, respectively).

CONCLUSION

Our study of quantitative actocardiogram parameters in normal pregnancy and various hypoxic fetal disorders demonstrated new characteristics of fetal movement and its relation to fetal heart rate. The results are promising for further analysis of fetal behavior and abnormalities.

[Relationship between doppler velocimetry at middle cerebral artery and umbilical artery and status of newborn after delivery]

OBJECTIVES

Aim of research was estimation of correlation between doppler parameters and fetal state after delivery.

MATERIAL AND METHODS

One hundred fifty-one pregnancies treated in Dept. of Obstetrics and Gynecology of Medical Academy in Bydgoszcz was investigated between 1998-2002. Pregnancies were estimated between 27 and 43 Hbd. Ultrasound examination using pulse and color Doppler was performed (ACUSON XP 128) and PI, RI, S/D, MCA, UA were estimated.

DESIGN

Following doppler parameters were analyzed: pulsatile index (PI), resistance index (RI) and systolic/diastolic ratio (S/D) in middle cerebral artery (MCA) and in umbilical cord artery (UA). The newborn children were estimated by Apgar score in first minute of life (AP1). Correlation between amount of amniotic fluid index (AFI) and newborn state in first minute after delivery was investigated too.

RESULTS

There were following correlations in this investigation: (1) negative between UA PI and AP1 (-0.26); (2) negative between UA RI and AP1 (-0.23); (3) negative between UAS/D and AP1 (-0.16); (4) negative between AFI and API (-0.06); (5) lack of statistical correlation between MCA PI, MCA RI, MCA S/D and AP1. We considered following covariancies: (1) negative between AFI and AP1 (-1.03); (2) negative between UA S/D and AP1 (-0.42); (3) negative between UA PI and AP1 (-0.23); (4) negative between UA RI and AP1 (-0.09).

CONCLUSIONS

We concluded that Doppler investigations by measure of parameters of blood flow in umbilical cord artery (PI, RI, S/D) can be predictive to fetal threat and useful in estimation of newborn state.

[Fetal renal ultrasound investigation in toxaemic pregnancies]

INTRODUCTION

A relationship was sought between renal hyperechogenicity and the hypoxic state of fetuses.

MATERIAL AND METHODS

120 pathological pregnancies were examined between the 28th and 36th weeks. The echogenicity of the fetal kidneys was examined with Combison 530 3D ultrasound equipment fitted with a 3-5 MHz transabdominal transducer. The serum kidney and liver functions and plasma electrolytes of the mothers were examined and blood was collected from the pulsating umbilical artery for determination of the same serum parameters. After delivery, the physical condition of the neonates was followed and their kidneys were examined with the same ultrasound equipment within the first 5 days.

RESULTS

There was a significant difference between the cases with fetal renal hyperechogenicity and without it for the pathological neonatal clinical outcome (chi-square test with Yates correction, p < 0.01). There were significantly more intrauterine retarded fetuses (6 cases, 40%) in cases with fetal renal hyperechogenicity, than in the control group (3 cases, 3%). The mode of delivery was caesarean section in 7 cases (46%) in group with fetal renal hyperechogenicity, while it were 6 cases (6%) in control group. The risk for pathological outcome is 6 times more in cases with fetal renal hyperechogenicity.

CONCLUSION

The results demonstrate that fetuses exhibiting renal hyperechogenicity in pathological pregnancies require particularly careful obstetric control and neonatological consultation. It is important that hyperechogenic cases be admitted to a perinatal intensive care unit. Fetal renal hyperechogenicity is considered to be associated with an enhanced risk of adverse perinatal outcome.

MR imaging quantification of cerebellar growth following hypoxic-ischemic injury to the neonatal brain

BACKGROUND AND PURPOSE

Cerebellar atrophy may occur as a result of a primary injury, such as infarction or hemorrhage. Impaired growth of a non-injured cerebellum may be seen as a secondary effect related to damage in other remote but connected areas of the brain, or so-called diaschisis. We sought to determine whether perinatal hypoxic-ischemic injury leads to poor cerebellar growth and whether such impairment occurs asymmetrically in infants with predominantly unilateral brain injury.

METHODS

We used a computerized quantification program to measure cerebellar size by using serial MR images. Term-born infants presenting with encephalopathy and/or seizures presumed due to a hypoxic-ischemic insult within 48 hours of delivery were included if they had two or more volume acquisition images obtained at least 3 months apart but within the first 15 months of delivery.

RESULTS

When data were grouped by MR appearances, significant differences in total cerebellum growth were seen between infants with focal infarction and those with basal ganglia and thalamic injury (P <.001). Unilateral forebrain lesions shown on MR imaging were not predictive of asymmetric cerebellar growth.

CONCLUSION

Infants with focal infarction of the cerebral hemisphere had an apparently normal pattern of growth in both cerebellar hemispheres. However, in infants with severe basal ganglia and thalamic lesions, cerebellar growth was reduced, and the vermis showed little or no growth during the first year after birth.

[Increased signal intensity of velocity measurements in duplex sonography by using the contrast agent levovist: a prospective, randomized study in a fetal sheep model]

PURPOSE

To evaluate the potential diagnostic advantages of the contrast agent Levovist for signal enhancement of small adjoining fetal vessels and to study the effect of Levovist before and during acute fetal hypoxia on the fetal circulation and the fetal blood flow velocities.

MATERIALS AND METHODS

A prospective, randomized study was performed in 12 fetal sheep before and during acute fetal hypoxia produced by complete occlusion of the maternal common iliac artery. Two groups of animals were studied, comprising animals with (study group, n = 6) and without (control group, n = 6) Levovist. In the study group, Levovist was administered intravenously by a pump (modified IVAC P 4000, Schering, Berlin). Duration and intensity of signal enhancement were measured in the fetal aorta, the common carotid artery and the ophthalmic artery of both groups before and during hypoxia. Concurrently, fetal heart rates as well as systolic and diastolic blood flow velocities in all three vessels were recorded in both groups.

RESULTS

The increased signal intensity of up to 15 dB in the study group resulted in improved differentiation and imaging quality of adjoining small fetal vessels when compared with the control group. Neither before nor during acute hypoxia, significant differences of the fetal heart rate and the systolic and diastolic blood flow velocities were observed between the two groups (p > 0.05). In the study group, no emboli were caused by Levovist in any fetal tissue or in the placenta.

CONCLUSION

The contrast agent Levovist improves the detection and accuracy of monitoring flow velocities in small fetal vessels by increasing the intensity of the Doppler signal without affecting fetal heart rate or fetal blood flow velocities.

[Placental morphometry in pregnancies with reversed enddiastolic flow in the umbilical artery or fetal aorta]

BACKGROUND

Fetuses with a reversed enddiastolic flow in the umbilical artery and/or aorta are at risk pregnancies and show a higher incidence of perinatal morbidity and mortality. The aim of this study was to evaluate the pathological changes in the terminal villous tree in fetuses with a reverse flow in the fetal aorta or umbilical artery.

MATERIALS AND METHODS

In this retrospective study, 16 cases with a reverse flow in the fetal aorta or umbilical artery (Gr. 1) were compared with gestational age matched 16 healthy pregnant women (Gr. 2). The following morphometric parameters were evaluated in 50 sections in each placenta (1600 measurements): mean vessel diameter, volume density of the villous tissue, stem villi and terminal villi. Measurements were performed using a computerized Video Image Analysis system.

RESULTS

The mean gestational age at birth was similar in both groups (30 + 4 weeks gestation vs. 30 + 6 weeks gestation, respectively, for Gr. 1 and Gr. 2). The birth weights (985 g vs. 1780 g) and the placental weights (216 g vs. 385 g) were significantly lower in the reverse flow group. There was a significant reduction in the proportion of total villous tissue (19 % versus 45 %) and in the diameter of tissue at the terminal villi (2.1 % versus 7.6 %) in the reverse flow group. Although the mean number of vessels at the terminal villi was lower than the control group (4.1 versus 5.6), the mean and total areas of the vessels were not different.

CONCLUSION

Our observations showed a significant association between the placental morphometric parameters and reversed enddiastolic flow in the umbilical artery or fetal aorta. The reduced number of functional placental units is responsible for the diminished exchange function of the placental vessels in "reverse flow" cases. This could partially explain the adverse outcome in this clinical situation.

[Evaluation of fetal right coronary artery blood flow velocimetry]

OBJECTIVES

In the present study fetal right coronary artery blood flow velocimetry was assessed.

DESIGN

The prognostic value of the fetal right coronary artery blood flow velocimetry was evaluated in relationship with parameters of newborn's condition after birth.

MATERIAL AND METHODS

The study was performed in 102 cases of pregnancies complicated by pregnancy induced hypertension. Blood flow velocimetry was visualized from fetal right coronary artery and correlated with perinatal outcome parameters.

RESULTS

Fetal coronary blood flow velocimetry was visualized only in 11 cases. Coronary blood flow velocimetry visualisation correlated with each parameter of after-birth evaluation. The method has the highest specificity (97.7%) and positive prognostic value (85%) concerning evaluation of newborn's condition.

CONCLUSIONS

Fetal right coronary artery blood flow velocimetry visualisation is a late sign of chronic fetal hypoxia. This seems to be a factor which causes maximal coronary vessels dilatation and allows oxygenation of fetal heart muscle.

[Aqua exercise as a prophylaxis of fetal anoxia]

The paper presents the results of the action of underwater exercises and adaptational respiratory exercise under the hypoventilation mode on health of pregnant women with threatened abortion at different terms of gestation and of their babies. The exercises led to physiological development of pregnancy, diminished intrauterine fetal hypoxia, less frequent hospitalizations of the pregnant women, good pregnancy outcomes, delivery of healthy babies. Moreover, maternal morbidity decreased 1.5-fold and perinatal morbidity 2-fold.

[Bilateral hypoxic-ischaemic thalamic lesions in newborns]

Bilateral hypoxic-ischaemic thalamic lesions are a rare type of neonatal encephalopathy with characteristic but often misinterpreted clinical features. This article describes history, clinical and diagnostic findings in a preterm and a term infant with hypoxic-ischaemic thalamic lesions after severe and abrupt intrauterine hypoxia. Both neonates presented with absent suckling and swallowing whereas other cranial nerves were unaffected. Characteristic findings in both newborns were profound muscular hypotonia and weak facial expressions together with feeding difficulties and frequent episodes of aspiration pneumonias. The term infant died at the age of 14 weeks following presumed aspiration pneumonia, the preterm infant, however, has developed severe extrapyramidal cerebral palsy. Absent suckling and swallowing with otherwise normal cranial nerve function appears to be characteristic of a bilateral hypoxic-ischaemic lesion of the thalamus. Animal experiments suggest that these lesions originate from a short but total ischaemia as it can be observed in cord prolapse or total placental abruption. Specific findings may initially be absent on ultrasound examination. Hence, magnetic resonance imaging of the brain should be performed on all patients with characteristic clinical symptoms even if the ultrasound scan is unremarkable. Evidence of bilateral ischaemic lesions of the thalamus usually indicates a poor prognosis.

Fetal grasping of the umbilical cord and perinatal outcome

This study assessed perinatal outcome in pregnancies with accidentally diagnosed fetal grasping of the umbilical cord (FGUC) on ultrasonography (US) in late gestation as a possible cause of fetal hypoxia due to mechanical occlusion of umbilical circulation. In this retrospective clinical study, routine antenatal US examination revealed FGUC from 32 to 41 weeks of gestation in seven normal single pregnancies. Upon FGUC findings, fetal condition was followed up every second day by repeat US findings of FGUC, and then by Doppler parameters of fetoplacental circulation measurement of resistance index in umbilical artery (URI) and middle cerebral artery (CRI), and cardiotocography (CTG), and perinatal outcome (peripartal cardiotocography, 5-min Apgar score, umbilical arterial blood pH, occurrence of meconium amniotic fluid, need of additional treatment at neonatal intensive care unit (NICU), and mode of pregnancy termination (cesarean section, forceps or vacuum extraction-VE for hypoxia). After delivery, neonatal neurosonography and neonatal complications related to pregnancy or birth were evaluated. All URI values were increased, resulting from persistent FGUC and elevated umbilical arterial RI. CRI showed great oscillations in the values for gestational age and decreased CRI. In two cases, cerebral/umbilical ratio was less than 1, indicating initial vasocentralization as a fetal compensatory mechanism for hypoxia. In these cases, a pathological peripartal CTG and pH 7.23, indicative of preacidosis, were verified. All children were discharged from NICU as healthy, free from neurological lesions, with the exception of the latter, who had dystonia syndrome and mild motor deficit as a sign of peripartal hypoxia. Although it probably belongs to normal reflexes, intermittent FGUC should be US controlled. Persistent FGUC should be considered pathological for its possible hypoxic effect and umbilical circulation obstruction. These pregnant women should be hospitalized and closely monitored, as in part confirmed by the present study.

[Prognostic Doppler ultrasound examination of fetal arteries blood flow]

Early detection of fetal risk is one of the main issues in today obstetrics. Ultrasound diagnostics plays a significant role, as the introduction of Doppler imaging method in the evaluation of blood flow has enabled non-invasive assessment of uteroplacental circulation. Therefore, we have analysed foetal three arteries: umbilical artery, middle cerebral artery and renal artery after determining the normal range for the analysed parameters.

AIM OF WORK

1. Comparison of the obtained blood flow indices (S/D, RI, PI) in the umbilical artery, middle cerebral artery and renal artery of foetuses from normal and complicated full-term pregnancies. 2. Determination of indices: umbilical-cerebral and renal-cerebral in normal and pathological pregnancy. 3. Evaluation of feasibility of the analysed flow parameters for the detection of intrauterine foetal hypoxia.

MATERIAL AND METHODS

We have examined 151 women, who were divided into control group--101 pregnant women with normal pregnancy and study group--50 pregnant women with complicated pregnancy. All pregnant women underwent ultrasound examination using the Hitachi EUB 515 C (Japan) scanner with 3.5 MHz convex probe, connected to the colour pulsed Doppler. The study consisted of the biometric measurements and evaluation of the spectrum of blood flow in the umbilical artery, middle cerebral artery and renal artery. We have determined following indices: a) systolic-diastolic ratio S/D, resistance index RI, pulsatility index PI, b) umbilical-cerebral ratio P/M. (PI ua/PI mca), renal--cerebral ratio N/M (PI ra/PI mca).

RESULTS

Statistically significant difference was found between the study and control groups for all the flow indices assessed (S/D, RI, PI) for the middle cerebral artery, for the indices P/M and N/M. (p < 0.001) and pulsatility index in the renal artery (p < 0.01). Similar, although slightly smaller difference (p < 0.05) was seen for the values of flow parameters in the umbilical artery.

CONCLUSIONS

1) Evaluation of blood flow in the middle cerebral artery, and in particular pulsatility index PI, reflects the risk to foetus. Umbilical-cerebral index and renal-cerebral index demonstrate the mechanisms of circulation centralization in case of fetal distress. For the umbilical-cerebral index, the cut-off value is 1.0 and for the renal-cerebral index it is 2.5, 2) Evaluation of the blood flow in foetal vessels is a significant element of prenatal diagnostics. Due to its low sensitivity, it should be compared with the results of other biophysical tests, to achieve complex evaluation of the condition of the foetus.

[Neonatal ultrasonographic cerebral findings: association with risk factor for cerebral palsy]

BACKGROUND

Is it possible to identify patients with cerebral palsy (CP) with postnatal ultrasound scan? Which risk factors are associated with an increased risk of CP?.

PATIENTS AND METHODS

The data of 37 children with CP, who were sonographically investigated during the first 24 hours of life were analyzed retrospectively. The data of 21 preterm infants with gestational age </= 32 wk were compared with the data of 59 without CP.

RESULTS

A tetraparesis was found in 15/21 of preterm babies </= 32 wk, a hemiparesis in 4/8 of premature infants >/= 33 wk and in 5/8 of the mature babies. The mature babies had prenatal brain atrophy or hypoxic-ischaemic cerebral lesions. Cytomegaly and encephalitis were detected in two babies. Immature babies >/= 33 wk showed prenatal porencephaly or encephalomalacia after asphyxia. Premature babies </= 32 wk had cystic periventricular leucomalacia (n=12) or cerebral haemorrhage (n=3); 3 babies had meningitis. Only two prematures </= 32 wk with mild CP had inconspicuous ultrasound scans. Factors associated with cerebral palsy were: cystic periventricular leucomalacia (OR 24,89; 95 % CI: 5,85 - 105,87), cerebral atrophy (OR 4,84; 95 % CI: 1,61 - 14,51), fetal hypoxia (CTG) - (OR 4,78; 95 % CI: 1,31 - 17,45), abruptio placentae (OR 4,32; 95 % CI: 1,16 - 16,13), anemia after birth (OR 18,13; 95 % CI: 1,97 - 166,43), abnormal neurological behavior at term (OR 14,00; 95 % CI: 3,29 - 59,55).

CONCLUSION

Cerebral ultrasound scan after birth is a useful method detect for cerebral lesions in patients with CP-risks.

Umbilical artery Doppler flow velocimetry in intrauterine growth restriction and its relation to perinatal outcome

OBJECTIVE

The purpose of this retrospective analysis was to compare pregnancy outcomes in growth-restricted fetuses retaining normal umbilical artery Doppler flow and the outcomes of pregnancies with end-diastolic velocity either diminished or severely reduced/absent.

METHODS

One hundred pregnant women with growth-restricted fetuses were followed with Doppler velocimetry of the umbilical artery between weeks 28 and 41 of pregnancy. Outcomes were compared for the normal Doppler group (16%), the less-severely abnormal group (77%), and the group with severely reduced or absent end-diastolic velocity waveforms (7%).

RESULTS

The diagnosis-to-delivery interval was significantly shorter, and the average birth weight and gestational age at delivery were significantly lower, for fetuses with abnormal Doppler velocimetry (showing diminished or severely reduced/absent end-diastolic velocity) than for those in the normal Doppler group. Fetuses with abnormal Doppler velocimetry also had a significantly higher incidence of oligohydramnios, low-birth weight (<10th percentile), and admission to the Neonatal Intensive Care Unit. There were no perinatal deaths among the normal Doppler patients.

CONCLUSIONS

Growth-restricted fetuses with normal umbilical artery velocimetry are at significantly lower risk than those with abnormal velocity waveforms, and immediate delivery of the fetus with diminished end-diastolic flow may be unnecessary. Knowing this relationship may be useful in the clinical management of such pregnancies. Doppler surveillance of growth-restricted fetuses supplemented with cardiotocography, preferably combined with biophysical profile testing, results in a prolonged gestational age and acceptable fetal outcome.

[Dopplersonography of the ductus venosus: assessment, evaluation and actual clinical importance]

The ductus venosus (DV) connects the intra-abdominal umbilical vein with the infundibulum of the IVC and develops during pregnancy to a trumpet-shaped structure with a narrow isthmus that accelerates the blood jet crossing the IVC directly to the left atrium via the foramen ovale avoiding mixing with deoxygenated blood from the right chamber. In animal studies, blood flow and doppler sonographically analyzed blood flow velocity waveforms mainly is controlled by heart rate and central venous pressure. The velocity waveform of the DV contains two peak components: the first indicates systolic velocity of the ventricle, the second peak diastolic velocity. A nadir is seen during atrial contraction. In animal studies, DV blood velocity in hypoxemia is influenced by central venous pressure and heart rate. The determination of the DV/UV ratio reflects the redistribution of blood flow, increases in hypoxemia and is therefore more reliable than blood velocity measurement for the detection and evaluation of fetal distress. In cases with severely growth-restricted fetuses, recipient twin in TTTS (twin-to-twin transfusion syndrome), tachyarrhythmia-induced cardiomyopathia and congenital heart disease, the measurement and interpretation of DV Doppler waveform pulsatility seems to be a useful tool that provides important information on the fetal condition and outcome. In cases of zero or reverse flow during atrial contraction in most cases the delivery of the fetus is indicated. An improvement of morbidity and mortality using Doppler sonography of the DV has not yet been proven. In cases of fetuses with or without chromosomal aberrations with major defects of the heart it can be used in addition to the standard screening methods of the first trimester of pregnancy for detection of heart failure.

Reduced postnatal cerebral glucose metabolism measured by PET after asphyxia in near term fetal lambs

The effects of fetal asphyxia on cerebral function and development, involve the transition from fetal to neonatal life. Changes in cerebral glucose metabolism may be an early postnatal indicator of fetal asphyxia. The objective is to develop an experimental lamb model involving the transition from fetal to neonatal life and to examine the effect of fetal asphyxia with cerebral hypoxic ischemia on early postnatal cerebral glucose metabolism. Fetal asphyxia was induced by total umbilical cord occlusion in eight near-term fetal lambs (134-138 days) with the ewe under isoflurane-opiate anesthesia. The mean occlusion time until cardiac arrest was 14.5 (4.2) min (SD). Lambs were immediately delivered and standardized resuscitation was instituted after 2 min asystole. At 4 hr postnatal age, [18-F]Fluoro-2-deoxy-glucose (18-FDG) was injected intravenously in eight asphyxiated lambs and in eight controls. Cerebral glucose metabolism was examined by positron emission tomography (PET). As a result the mean arterial blood pressure, acid-base values, blood glucose and serum lactate at 4 hr postnatal age did not differ significantly between lambs subjected to umbilical cord occlusion and controls. EEG was abnormal in all lambs subjected to cord occlusion and normal in the controls at 4 hr postnatal age. Global cerebral metabolic rate (CMRgl) as determined by PET was significantly lower in lambs subjected to cord occlusion mean/median (SD) 22.2/19.6 (8.4) micromol/min/100 g) than in controls mean/median (SD) 37.8/35.9 (6.1); P < 0.01). Global CMRgl is significantly reduced in newborn lambs 4 hr after fetal asphyxia induced by umbilical cord occlusion. A reduction in CMRgl is an early indicator of global hypoxic cerebral ischemia.

A comparison of three ultrasound estimates of intrapartum oligohydramnios for prediction of fetal hypoxia-reperfusion injury

A prospective observational study assessed the predictive value of three techniques for amniotic fluid volume assessment on umbilical cord arterial lipid peroxide levels and acid-base balance. Women with singleton, term, cephalic presentation, and an initially normal fetal heart rate tracing were recruited. All pregnancies had the largest vertical pocket (LVP), two diameter pocket (2phi), and amniotic fluid index (AFI) assessments before and after amniotomy and cord arterial acid-base and lipid peroxide determinations at delivery. In 171 cases with confirmed cord arterial samples, malondialdehyde (MDA), organic hydroperoxide (OHP), pH and base excess (BE) were examined in relationship to intrapartum LVP, 2phi and AFI before and after amniotomy. Improvements in correlation between the estimates of amniotic fluid volume and outcome measures were observed 30 min after amniotomy, particularly with lipid peroxide measurements. Examination of scatter-plots using Lowess regression suggested that the correlation was only valid in cases of oligohydramnios but that the cutoff values recommended in the literature for defining oligohydramnios were not appropriate in our population sample. We suggest that oligohydramnios should be defined as an AFI < 8 cm or LVP < 4 cm. We concur with the recommendation of < 15 cm2 for the 2phi measurement.

Doppler ultrasonographic evidence of intrapartum brain-sparing effect in fetuses with low oxygen saturation according to pulse oximetry

OBJECTIVE

This study was undertaken to verify by means of Doppler ultrasonography and simultaneous fetal pulse oximetry the redistribution of fetal blood flow in favor of the brain during intrapartum hypoxemia.

STUDY DESIGN

During labor 11 term fetuses with abnormal heart rate patterns and arterial oxygen saturation <30% and 14 control term fetuses with normal oxygen saturation were simultaneously monitored by pulse oximetry and Doppler ultrasonography. The results were compared with the Student t test.

RESULTS

The blood flow velocity in the middle cerebral artery was significantly higher in the presence of reduced oxygen saturation, implying lower pulsatility and resistance indices (P <.001). The reduction of blood flow in the umbilical artery was not significant (P =.61).

CONCLUSION

Simultaneous intrapartum pulse oximetry and Doppler ultrasonography proved that reduced arterial oxygen saturation (<30%) is associated with profound changes in fetal hemodynamics and could be tolerated for only a limited period, which should be the subject of further studies.

[Theoretical and experimental models of sonographic diagnosis of umbilical cord knot and their application in practice]

Modern sonographic technique allows the detection of cord complication as neck cord entanglement. Far more difficult is the detection of a real cord knot. This article describes a theoretical model for detection of a cord knot and proves it in an in-vitro model.

Hypoxic-ischemic fetal insult resulting from maternal aortic root replacement, with normal fetal heart rate at term

A patient with Marfan's syndrome was seen at 29 weeks' gestation with acute aortic dissection. She underwent aortic root replacement under deep hypothermia and circulatory arrest. The fetal heart rate was ominous during surgery but recovered later. Serial ultrasonographic examinations showed progressive fetal brain atrophy. The patient was delivered at 38 weeks' gestation of a girl weighing 2305 g, in whom severe spastic tetraplegia, absent psychomotor development, and therapy-resistant epilepsy developed. This is the first case to document progressive fetal brain atrophy after cardiac surgery in pregnancy.

Cerebral Doppler blood flow velocimetry and central hemodynamics in the ovine fetus during hypoxemia-acidemia

The purpose of this study was to assess the effects of hypocapnic hypoxia, acidemia and the combination of hypoxia/acidemia on blood flow velocity variables in the fetal cerebral circulation. Chronically instrumented fetal sheep were used and the ewes were induced to breathe a hypoxic gas mixture for about 90 min. This caused an initial period of hypoxemia followed by a period of mixed hypoxemia/acidemia. When the ewe was reoxygenated, the fetus experienced a period of normoxic acidemia. The fetal cerebral circulation was assessed by recording Doppler blood flow velocity waveform variables in a cerebral vessel and the umbilical artery, using standard ultrasound equipment. External carotid artery blood flow was maintained during hypoxic and hypoxic/acidotic periods despite a fall in cardiac output. In the cerebral vessel, mean maximum velocity (time-averaged maximum velocity), minimum diastolic velocity and maximum systolic velocity manifested increases during hypoxic and hypoxic-acidotic periods, but pulsatility index did not change due to the effect of reduced heart rate on pulsatility index. Umbilical artery pulsatility index increased in the hypoxic and hypoxic-acidotic periods, despite unchanged mean maximum velocity, minimum diastolic velocity and maximum systolic velocity. With acute hemodynamic changes, the measurement of pulsatility index can yield misleading results. For clinical and experimental research on the fetal cerebral circulation, more attention should be paid to the individual Doppler variables, especially to the mean maximum velocity, than to the pulsatility index alone. Changes in mean maximum velocity recorded from the cerebral artery seem to reflect changes in the cerebral arterial flow.

[Fetal outcome in reduced flow in the ductus venosus during atrial contraction]

OBJECTIVE

To document the fetal outcome in cases with pathologic Doppler findings in the fetal ductus venosus.

METHODS

The outcome of 12 fetuses with reduced velocities in the ductus venosus during atrial contraction was analyzed retrospectively and compared with that of a group of 57 fetuses with normal flow velocities in the umbilical artery and in the fetal ductus venosus.

RESULTS

The perinatal mortality was higher in the group with pathologic Doppler findings. There was no significant difference of pH (7.20 vs. 7.24) and Apgar scores (7.57 vs. 8.36) of survivors between the two groups. All 12 fetuses showed increased retrograde velocities in the inferior vena cava. Seven fetuses showed umbilical vein pulsations.

CONCLUSIONS

The diagnosis of altered velocities in the ductus venosus may influence prenatal decisions. Therefore Doppler examinations of the fetal ductus venosus should be performed in high-risk pregnancies.

Doppler ultrasound evaluation of ductus venosus blood flow during acute hypoxemia in fetal lambs

It has been demonstrated with invasive techniques in fetal lambs that the ratio of ductus venosus to umbilical vein blood flow rate (DV/UV ratio) increases during hypoxemia and infusion of catecholamines. Recently it was found in human fetuses using pulsed wave Doppler ultrasound equipment that the DV/UV ratio in fetuses with intrauterine growth restriction was significantly increased. The aim of the present study was to show in fetal lambs whether routine Doppler ultrasound devices were capable of determining the DV/UV ratio with sufficient reliability. The experiments were performed on seven near-term instrumented fetal lambs using pulsed wave Doppler ultrasound to measure flow rates (derived, in milliliters per min, from the intensity-weighted mean velocity (Vmean) and the vessel's cross-sectional area) in the ductus venosus and intra-abdominal umbilical vein. Fetal hypoxemia was induced by administering a low-oxygen gas to the ewe (5-7% oxygen, 2% carbon dioxide). Fetal arterial pO2 and heart rate decreased significantly during maternal hypoxia. The proportion of umbilical venous return passing through the ductus venous in controls was 36 +/- 5% (mean +/- SD). This increased to 53 +/- 6% (p < 0.001) because the umbilical venous blood flow fell during late hypoxemia when the heart rate had decreased by 20%. Severe hypoxemia tended to reduce the mean velocity (Vmean) and the minimum velocity (Vmin) (based on the maximum velocity envelope curve) in the ductus venosus, descending aorta and inferior vena cava. The pulsatility index of the umbilical artery significantly increased at the end of hypoxemia. We conclude that determination of the proportion of umbilical vein blood flow entering the ductus venosus by Doppler ultrasound in a clinical setting may contribute to the detection and evaluation of fetal distress.

Fetal cerebral and umbilical artery blood flow changes during pregnancy complicated by malaria

The objectives of our study were to quantify the fetal cerebral artery and umbilical artery blood flow changes daily during a malaria crisis in a pregnant patient and evaluate the sensitivity and the specificity of Doppler indices for the prediction of acute fetal distress at the end of the pregnancy. The study, designed as a prospective and observational one, was carried out in the obstetric department of a government hospital in French Guiana, on 23 women with pregnancies complicated by malaria (age range, 23 +/- 5 years; primiparas, 30%); crisis date: 30.8 +/- 2.5 weeks of gestation; start of treatment: 3.7 +/- 1.3 days after crisis started). The main measures of outcome consisted of daily determinations of fetal Doppler indices during the crisis, evidence of fetal distress (fetal heart rate decelerations) during labor, Apgar scores after birth, gestational age at birth, mode of delivery, and birth weight. During the crisis umbilical artery resistance index increased by 5 to 20% (P < 0.05), cerebral artery resistance index decreased by 5 to 20% (P < 0.05), and CURR decreased by 10 to 35% (P < 0.01), indicating flow redistribution toward the brain. No relationship was found between the CURR value and the following data: parasitemia grade, parity, gestational age of the crisis, date and mode of delivery, and fetal weight. A change in the hypoxia index (% change in CURR during the crisis x number of days of crisis) greater than 150 was associated with abnormal fetal heart rate in 75% of the cases, and a hypoxia index lower than 150 was associated with normal fetal heart rate in 90% of the cases (sensitivity, 89%; specificity, 77%). Lastly, the combination (hypoxia index > 150 and CURR < 1) was associated with abnormal fetal heart rate in 80% of the cases, and one or two of these normal parameters were associated with normal fetal heart rate in 84.6% of the cases (sensitivity, 80%; specificity, 84%). The CURR and the hypoxia index during the malaria crisis can be used to predict acute fetal distress at delivery.

[The evaluation of umbilical arterial Doppler spectrum fractal characterization in obstetrics]

OBJECTIVE

To evaluate the clinical value of fetal umbilical arterial Doppler spectrum fractal.

METHODS

104 cases with 22-41 gestational weeks were included, and divided into two groups: normal pregnant group, 59 cases; abnormal pregnant group, 45 cases. Umbilical arterial Doppler spectrum were obtained by color Doppler ultrasound, then Doppler signal were transformed into computer through sound-frequency, and fractal were calculated.

RESULTS

The fractal was 1.83 +/- 0.03 in normal pregnant group. The frequency of abnormal fractal was significantly higher in abnormal pregnant group than that in normal pregnant group (P < 0.001). Compared with the ratio of peak systolic to lowest diastolic flow velocity (S/D), the fractal was more sensitive than S/D ratio in abnormal pregnancy (P < 0.05). There were significant correlation between fractal and gestational weeks (r = 0.266).

CONCLUSION

Fractal responses to complexity of umbilical arterial blood flow, and it is a better parameter than S/D ratio in monitoring abnormal umbilical arterial blood flow.

[Fetal circulation and malaria]

OBJECTIVE

To quantity the fetal vascular changes during flare-up, and to evaluate the sensitivity and the specificity of Doppler indices for the prediction of acute fetal distress at the end of the pregnancy.

METHOD

Every day of flare-up the umbilical resistance (Rp), cerebral resistance (Rc), cerebro-placental ratio (CPR = Rc/Rp), and hypoxia index (HI = delta % CPR x crisis duration) were calculated.

RESULTS

Twenty-three pregnancies were investigated at St Laurent du Maroni Hospital (French Guiana). During flare-ups the Doppler placental resistance increased (placental disorder), cerebral resistance decreased (vasodilation), CPR decreased (flow redistribution toward the brain), and HI increased. An abnormal CPR (< 1) was associated with abnormal fetal heart rate (FHR) in 61.5% of the cases, a CPR > 1 was associated with a normal FHR in 80% of the cases. (sensitivity: 80%, specificity 61%). A CPR < 1 was associated with one of the abnormalities (abnormal FHR, cesarean section, abnormal Apgar) in 71% of the cases, a CPR > 1 was associated with normal delivery in 55% of the cases (sensitivity: 71.4%, Specificity 55%). A HI higher than 150 was associated with abnormal FHR in 75% of the cases, a HI < 150 was associated with normal FHR in 90% of the cases (sensitivity: 89%, specificity: 77%). Lastly the combination (HI > 150 + CPR < 1) was associated with abnormal FHR in 80% of the cases, 1 or 2 of these parameters were associated with normal FHR in 84.6% of the cases (sensitivity: 80%, specificity: 84%). The minimum CPR and the HI during malaria flare-up can be used to predict acute fetal distress at delivery.

Fetal arterial Doppler-IUGR and hypoxia

Vascular resistances of various fetal areas are assessed by Doppler ultrasound. The PI, RI and S/D indices are measured on the cerebral, renal, aortic and umbilical Doppler spectrum. Ratios of these indices based on the comparison of the cerebral (Rc) and the umbilical (Rp) resistances, or carotid (Rcc) and umbilical resistances, or cerebral (Rc) and aortic (Rao) resistances (Rc/Rp or Rp/Rcc, or Rc/Rao), measure the flow redistribution between the placenta and brain. The umbilical resistance indices, when greater than the upper limit of the normal range (> 2sd) are frequently associated with IUGR. (Sensitivity about 65 to 70%). Absent end diastolic flow is most of the time associated with severe IUGR and hypoxia and poor fetal outcome. A fairly good correlation was found between the existence of significantly decreased (< .2.sd) cerebral resistance and the development of post asphyxial encephalopathy in the neonate (Specificity 75% Sensitivity 87%). The earliest detectors of IUGR and hypoxia are the cerebral-umbilical cerebral-carotid, or cerebral-aortic ratios (Sensitivity 85% specificity 90%). When used as predictor of poor perinatal outcome in growth retarded fetuses, the cerebral umbilical ratio shows a sensitivity of 90% compared with 78% of the middle cerebral artery, and 83% for the umbilical artery indices. Changes of this ratio are well correlated with the fetal pO2 changes. The renal flow response to hypoxia depends on the degree of hypoxia. Opposite responses were found in case of moderate, and severe IUGR or hypoxia. Thus, it is too early to conclude if the renal indices are reliable parameters for the evaluation of fetal hypoxia. The sensitivity in predicting IUGR was for the aortic PI: 41% and for the aortic BFC (Blood flow classes): 57%. In predicting delivery for fetal distress, the corresponding values were 76 and 87%, respectively. Because the resistance indices are heart rate-dependent, it is dangerous to draw any conclusion from one single value of any of these parameters. Only several successive measurement of the Doppler indices or of their ratio, may lead to a reliable evaluation of fetal hemodynamics. In the case of significant IUGR with abnormal Doppler indices it is recommended to repeat the Doppler measurements daily both at the cerebral and umbilical or aortic level in order to follow up the fetal flow redistribution which is highly correlated with the fetal pO2 changes.

[Colour Doppler ultrasonographic indices in predicting fetal hypoxia and acidosis]

OBJECTIVE

To evaluate the effect of uterine-placental-fetal blood flow velocity waveforms (FVWs) on predicting fetal hypoxia and acidosis in high risk pregnancy.

METHODS

46 women of normal term pregnancy (normal group) and 32 women of high risk term pregnancy (high risk group) were examined with colour Doppler ultrasound for their FVWs including maternal uterine artery (UtA), fetal umbilical artery (UmA), middle cerebral artery (MCA), and renal artery (RA). Umbilical artery blood gases were analysed at delivery in high risk group.

RESULTS

The resistance index (RI), pulsatile index (PI) and ratio of peak systolic to least diastolic flow velocity (S/D) of UtA, UmA and RA were higher and the PI, S/D of MCA was lower significantly in the high risk group than that of normal the group (P < 0.05). In the high risk pregnancy, when UmA PO2 was less than 2.5 kPa, the S/D of UtA, PI, S/D of UmA and RI, PI, S/D of RA were increased, and the PI of MCA was decreased (P < 0.05). There were a positive correlation between PI of UmA, RA and PO2 pH of UmA, and a negative correlation between the former and PCO2 of UmA. But there were a negative correlation between PI of MCA and PO2, pH of UmA, and a positive correlation between the former and UmA PCO2.

CONCLUSION

In the high risk pregnancy, fetal cerebral blood flow increased, whereas blood flow of fetal peripheral vessels (especially renal vessel) decreases. There is a good correlation between fetal hypoxia and fetal blood FVWs. The indices of the fetal blood FVMs can identify fetal hypoxia and acidosis.

Doppler velocimetry and nonstress test for predicting outcome of pregnancies with decreased fetal movements

Because fetal motor activity reflects the fetal condition in utero, maternal counting of fetal movements has been suggested as a useful method for monitoring fetal well-being, based on empirical evidence that a decrease in or absence of fetal movements often presages fetal death. The aim of this study was to compare the predictive capacity of umbilical artery (UA) Doppler velocimetry with that of nonstress test (NST) cardiotocography in 599 women with low-risk pregnancies, reporting decreased fetal movements. In 19 cases the fetus was dead on maternal admission. Umbilical artery Doppler velocimetry and NST were performed in the remaining 580. In 541 the NST and UA velocimetry findings were reassuring, and the women were discharged. There was one perinatal death in this group, due to extreme prematurity and placental abruption 1 week later. Thirty-nine women who gave birth on the day of admission or next day were especially given closer attention. Umbilical artery velocimetry was abnormal in only one fetus. In 6 cases, the NST trace on admission indicated fetal distress, and emergency cesarean section was performed, resulting in 3 infant deaths and 3 infants with sequelae. The umbilical cord pH was normal in 3, suggesting an earlier temporary intrauterine hypoxic event. Overall perinatal mortality was thus 23 (3.8%). Decreased fetal movement perception by mothers should therefore be taken seriously, even though an irreversible insult to the fetus might already have occurred.