Cordocentesis in the evaluation of the growth-retarded fetus.

The direct access to the fetal circulation provided by cordocentesis enables a better understanding of physiologic changes and more efficient diagnosis and treatment of many pathologic conditions. Because the procedure of direct fetal blood sampling is relatively safe, it has great potential in both antepartum surveillance and treatment of the severely growth-retarded fetus. Ultrasonography and Doppler instruments are the basis for urgently needed therapeutic trials which most probably will provide the obstetrician with new tools to treat the IUGR fetus early enough to prevent fetal compromise. Intrauterine infusion of nutrient supplements and methods to improve fetal acid-base balance may eventually be incorporated into the management protocols of the jeopardized growth-retarded fetus.     

Cerebral Doppler ultrasound of the human fetus

Maximal flow velocity waveforms were recorded in the internal carotid artery (ICA), middle cerebral artery (MCA), posterior cerebral artery (PCA) and anterior cerebral artery (ACA) in 55 normal pregnancies and 14 complicated by intrauterine growth retardation between 25 and 41 weeks gestation. In normal pregnancy, acceptable flow velocity waveforms were obtained in the ICA in 89%, in the MCA in 91%, in the PCA in 58% and in the ACA in 64%. A decrease in pulsatility was observed in all four intracranial arteries during the latter weeks of gestation. In growth-retarded pregnancies, pulsatility in all vessels was significantly reduced compared with normal pregnancy, suggesting participation of all major intracranial arteries in a brain-sparing effect in the presence of chronic fetal hypoxia.     

Cerebral Doppler ultrasound of the human fetus

Summary. Maximal flow velocity waveforms were recorded in the internal carotid artery (ICA), middle cerebral artery (MCA), posterior cerebral artery (PCA) and anterior cerebral artery (ACA) in 55 normal pregnancies and 14 complicated by intrauterine growth retardation between 25 and 41 weeks gestation. In normal pregnancy, acceptable flow velocity waveforms were obtained in the IC A in 89%, in the MCA in 91%, in the PCA in 58% and in the ACA in 64%. A decrease in pulsatility was observed in all four intracranial arteries during the latter weeks of gestation. In growth-retarded pregnancies, pulsatility in all vessels was significantly reduced compared with normal pregnancy, suggesting participation of all major intracranial arteries in a brain-sparing effect in the presence of chronic fetal hypoxia.     

Abdominal ultrasound examination of the first-trimester fetus

The first-trimester fetus can now be comprehensively studied with ultrasound. Various biometric measurements correlate well with gestational age, such as crown-rump length (r2 = 0.938) and cranial apex to ear diameter (r2 = 0.983). On the other hand, yolk sac diameter (r2 = 0.129) and abdominal perimeter (r2 = 0.58) correlate poorly with gestational age. By 10 weeks' gestation, kidneys can be visualized in 60% of cases; 98% will be seen at 11 weeks; and 100% of cases will be visible by 12 weeks. The bladder appears later, and by 12 weeks' gestation this organ can be identified in 50% of cases. It is likely that renal agenesis can be diagnosed (or excluded) reliably in the first trimester. With improving technology, prenatal diagnosis of some fetal anomalies is now possible in the first trimester.     

Estimated weight of the term fetus. Accuracy of ultrasound vs. clinical examination

A prospective analysis was done of the accuracy of fetal weight estimation comparing clinical and ultrasound estimation with actual birth weight in 100 women at term. The mean error of clinical estimation was 277 g, or 79.4 g/kg, for a 7.9% error. The error of ultrasound in the same population was 286 g, or 81.7 g/kg, for an 8.2% error. Analysis of these data revealed no statistical difference between clinical estimation and ultrasound estimation of birth weight in the term fetus, even at the extremes of birth weight.     

Clinical evaluation of the fetus and neonate

Summary The relation between intra-partum cardiotocography (CTG), cord blood acid-base status, Apgar score and neonatal morbidity was studied in 1228 consecutively live-born babies and in a subgroup of 200 babies (148 babies with a 1 min Apgar score≤8 and 52 randomly selected babies with a 1 min Apgar score≥9). The scores for the individual components of the 1 min Apgar score were strongly associated with each other, whereas the scores for the individual components of the 5 min Apgar score were less strongly associated. At 1 min the scores for muscle tone, reflex irritability and respiration but not the scores for heart rate and skin colour were associated with arterial and venous cord blood pH (low scores being associated with low pH). Out of the individual components of the Apgar score, heart rate and reflex irritability at 1 min were the best discriminators between “healthy or relatively healthy” and “severely ill” babies. Intrapartum CTG, total Apgar score and cord blood acid-base status were only weakly related. Venous cord blood pH was the best predictor of the 1 min Apgar score. Intra-partum CTG (silent pattern), 5 min Apgar score and venous cord blood pH were the best predictors of severe neonatal morbidity.     

Venous Doppler evaluation of the growth-restricted fetus

Evaluation of venous Doppler parameters has significantly contributed to the understanding of the vascular mechanisms that lead to fetal growth restriction (FGR) and subsequent fetal deterioration in the setting of progressive placental dysfunction. Venous redistribution of umbilical venous blood flow away from the fetal liver precedes fetal growth delay. Venous Doppler examination allows adjustment of monitoring intervals in recognition of accelerating fetal deterioration. The timing of delivery in early-onset FGR remains challenging because gestational age has an overriding effect on the neonatal outcome until the late second trimester and randomized trials of specific delivery triggers are lacking.     

Visualisation and measurement of tracheal diameter in the sheep fetus: an ultrasound study with stereomicroscopic correlation.

OBJECTIVE: There is no information on ultrasonographic visualisation of the upper airways in the sheep fetus, but this species permits to examine the accuracy of ultrasonography in measuring the inner tracheal diameter. This was the aim of our study. METHODS: Transabdominal ultrasonography to visualise the trachea was attempted in 16 unsedated Welsh Mountain ewes with a singleton pregnancy at 70 (SD 2) days gestation (term 148 days). The ultrasonographically measured inner tracheal diameter was compared with the actual inner tracheal diameter obtained by stereomicroscopy post-mortem. RESULTS: High-resolution ultrasonography permitted clear imaging of the fetal trachea in 87% (14/16) of the cases analysed. The ultrasound measurements were smaller than the corresponding stereomicroscopic measurements, the mean +/- SD difference between the measurements being 0.40 +/- 0.12 mm. CONCLUSIONS: Improvements in ultrasound have led to increased interest in the assessment of the trachea in human fetuses. Our study in the ovine fetus at mid gestation shows that optimal views of the fetal trachea allowing accurate measurements can be obtained in almost all the cases.     

Three-dimensional multiplanar ultrasound in a limb-body wall complex fetus: clinical evidence for counseling.

A rare dysmorphologic fetal anomaly at the 17th week of gestation was suspected during a second trimester routine scan for fetal and maternal screening data. First findings were significant for a severe abdominal wall defect, limb and foot compromised positions. Fetal biometry was appropriate in biparietal diameter and head circumference measurements; the long upper bones were normal both for length and development. The patient was referred to a prenatal unit to complete the sonographic diagnosis. Two- and three-dimensional sonographic investigations were performed and techniques were complementary for fetal maldevelopment specification. Limb-body wall complex with lumbosacral spine torsion and lower limbs with severely abnormal features were identified. With 2D color Doppler, a heart defect was confirmed and the umbilical cord was missing from the amniotic cavity. An invasive procedure by amniocentesis was made to ascertain alpha-fetoprotein levels and fetal karyotype. Following parental counseling, pregnancy was terminated and feto-pathological examination confirmed the sonographic diagnosis. The 17-week fetus affected by limb-body wall complex is reported herein; 2D and 3D scans of the fetus identified organ displacement due to a combination of very early events.     

Earlier gestational age at ultrasound evaluation predicts adverse neonatal outcomes in the preterm appropriate-for-gestational-age fetus with idiopathic oligohydramnios

Oligohydramnios is related to adverse perinatal outcomes particularly when associated with fetal growth restriction. The purpose of this study was to delineate predictors of adverse perinatal outcomes in cases of preterm idiopathic oligohydramnios associated with appropriate-for-gestational-age (AGA) fetal biometry. A database of preterm AGA fetuses (< 37 weeks) presenting for evaluation of idiopathic oligohydramnios (defined as an amniotic fluid index [AFI] < 10th percentile) in the third trimester with delivery information and uterine artery Doppler indices (average resistance index [RI] and bilateral notching) available was prospectively collected ( N = 90). AFI and birth weight (BW) percentiles were calculated using standard tables. Chi-square and Student T test were used to evaluate for predictors of adverse perinatal outcomes including BW < or = 10th percentile, stillbirth, neonatal intensive care unit admission, 5-minute Apgar score < 7, preterm delivery < 35 weeks, and preeclampsia. Patients destined to experience poor perinatal outcomes (22%) were demographically similar to those experiencing normal outcomes in terms of maternal age ( P = 0.5), ethnicity ( P = 0.9), body mass index ( P = 0.3), and parity ( P = 0.9). However, at-risk patients were more likely to present with oligohydramnios at an earlier gestational age (GA) than those not at risk (33.0 +/- 3.0 versus 34.4 +/- 2.0 weeks; P = 0.02). There were no differences in perinatal outcomes associated with AFI percentile ( P = 0.9), increased average uterine artery RI ( P = 0.5), bilateral notching ( P = 0.4) or a combination of increased uterine artery RI and bilateral notching ( P = 0.2). Patients with preterm AGA fetuses who present with idiopathic oligohydramnios at an earlier GA are at risk for adverse perinatal outcomes compared with those presenting later in gestation. Sonographic indices, particularly uterine artery Doppler findings, were not found to be useful predictors of adverse outcomes.