Method Of Fetal Assessment Research Articles

Two-tier approach to biophysical assessment of the fetus

The biophysical profile score is widely accepted as a superior predictor of acute-on-chronic fetal asphyxia over the nonstress test. Nevertheless, in the United Kingdom facilities for assessment of high-risk pregnancies by nonstress test are more widely available than with the biophysical profile score. After a retrospective review of 2038 biophysical assessments in 500 high-risk pregnancies, it is suggested that biophysical evaluation of the fetus can be rationalized on the basis of the clinical problem and fetal growth. Terminal acute-on-chronic fetal asphyxia can be excluded by a two-tier method of fetal assessment by initial nonstress test backed up by the biophysical profile score when the nonstress test is suboptimal.

An Overview of Vibroacoustic Stimulation

Vibroacoustic stimulation of the fetus as a test of fetal well-being has become fairly common despite limited research on this tool. A review of the literature reveals that fetal accelerations in response to this stimulus are indicative of fetal health. Vibroacoustic stimulation correlates well with other methods of fetal assessment and is effective in converting nonreactive tracings to reactive tracings in healthy fetuses, saving patients time and expense.

Fetal heart rate monitoring by telephone. II. Clinical experience in four centres with a commercially produced system.

A commercially produced domiciliary fetal monitoring (DFM) system was assessed in four centres in the UK (Bristol, Glasgow, London and Nottingham) chosen to allow for comprehensive assessment in various settings in many different women. Overall, 825 recordings were made from 368 women (2.24 per woman). There were 56 unsuccessful attempts at transmission (6.8%), most were due to problems with telephone equipment. The system worked most efficiently when a dedicated direct line was used. The data transmission time varied between 40 and 60 s. The median telephone time (including data transmission and conversation) with a dedicated direct line was 7 min. Mean acceptance times from the four centres were between 70 and 80%. All recordings with acceptance times of 40% or more were interpretable. Ten recordings were abnormal. The women and mid-wives were equally proficient at using the DFM system. The DFM system represents an important addition to current methods of fetal assessment. Specific guidelines are outlined.

The Significance of Cardiotocographic Monitoring in Pregnancy Complicated by Intrauterine Growth Retardation and Prematurity

Intrauterine growth retardation is a condition of chronic fetal compromise. The most accurate method of fetal assessment in this condition is by serial cardiotocography. In pregnancy associated with intrauterine growth retardation, abnormal cardiotocography with spontaneous decelerations may be an indicator of imminent fetal death in utero. Delivery should be effected immediately if the fetus is at a gestation where viability is probable.

Fetal assessment by biophysical profile scoring: 1985 update.

In extrauterine medicine, physicians have come to rely upon sampling of multiple biophysical variables as a means of differentiating states of well-being and compromise. This basic tenet of medicine is expressed by obtaining an Apgar score or some variant in the newborn and as a measure of vital signs in later life. Few, if any, decisions regarding well-being are ever based on a single-variable assessment and, conversely, definition of compromise is rarely based upon a single variable. Through the use of dynamic ultrasound imaging it now becomes possible to visualize the fetus and its biophysical responses in health and disease. Through such visualization it becomes possible to bring to bear some of the basic principles that sustain extrauterine medicine on the intrauterine patient, the fetus. Fetal biophysical profile scoring describes a method that encompasses this concept. The results obtained by application of this method are promising. We would argue that consideration of multiple fetal biophysical variables will, in most instances, yield superior results to single-variable monitoring alone. Hence we have abandoned antepartum fetal heart rate testing as the sole method of fetal risk assessment and used the tool only in conjunction with others of the many variables that may be monitored by dynamic ultrasound methods. This concept of multiple-variable analysis as the superior method for fetal assessment seems clear and well-justified. It is our opinion, however, that the concept of fetal bioprofile scoring may be more important than the method itself in its original description.(ABSTRACT TRUNCATED AT 250 WORDS)

Single fetal death in twin gestation.

S INGLE FETAL DEATH is an unusual complication of a twin pregnancy. Occasionally, death may be attributed to placental insufficiency associated with maternal disease. However, the cause of death is usually unclear. Theoretical explanations include cord accidents, twin-to-twin transfusion syndrome, and placental abruption. It appears that the surviving twin is at risk for perinatal morbidity and mortality. The incidence of neurologic sequelae was reported to be 20%) l and a recent review of 14 published reports indicated that 46.2 % of the liveborn twins suffered major morbidity or death. 2 The prenatal death of one twin could result in the transfer of tbromboplastin to the live fetus. Thromboembolism might then produce multiple organ injury from intravascular coagulation within the shared fetal circulation, in the absence of maternal coagulopathy. It is also feasible that in cord accidents, damage to the survivor occurs at the time of the insult, which results in the demise of the co-twin. Whether neurologic injury to the survivor could precede death of the co-twin is an intriguing question. The answer becomes crucial in the discussion of whether early delivery might be of benefit to the remaining twin. Perinatal neuropathology cannot establish the nature and timing of the insult, as there is no single pathologic change in the neonatal brain that is specific for a particular etiologic factor. Preterm delivery and intrapartum complications resulting in neonatal morbidity make it difficult to assess whether a given outcome was related to an antepartum event. Currently used methods of fetal assessment, such as the non-stress-test (NST), contraction-stress test (CST), and biophysical profile score (BPS), will give no indication of brain damage unless there is brainstem involvement. The antenatal diagnosis of intraventricular hemorrhage (IVH) can be made by high-resolution ultrasound scans of the fetal head. IVH is the most common neurologic lesion resulting from perinatal asphyxia or trauma and preterm delivery. However, IVH does not seem to be a prominent pathologic feature in this clinical situation. This may reflect failure of diagnosis, as neonatal head scans of high-risk neonates are not performed routinely in many centers. The literature suggests that neurologic injury after single fetal death in twin gestation occurs largely to the cortical white matter from thromboembolism and/or ischemia. Hence, it is unlikely that ultrasound or computerized tomography (CT) scans will be useful for antenatal diagnosis of neurologic damage in the survivor. The newer technique of magnetic resonance imaging (MRI) could potentially detect this kind of neurologic lesion in the early stages and is an area for future investigation. The risk of maternal complications such as preeclampsia and disseminated intravascular coagulation (DIC) must be considered in any approach to management. Additional factors, including the psychologic impact on the mother, a theoretical risk of delayed sepsis, and the possibility of intrapartum problems (obstructed labor or fetal distress), create a complex and perplexing problem for the clinician. Maternal transfer to a tertiary care perinatal center is recommended to provide the intensive fetal surveillance, neonatal care, and pediatric follow-up which becomes necessary. Finally, in the area of prevention, new techniques to measure fetal and uterine blood flow using pulsed Doppler ultrasound may allow earlier detection of twin to twin transfusion syndrome than standard biometric evaluation.

Weight-specific stillbirths and associated causes of death: An analysis of 765 stillbirths

An analysis of 765 consecutive stillbirths associated with 98,927 pregnancies during a 6-year interval showed significant differences for cause of death at specific weight categories. In addition, 57% of stillbirths occurred at infant weights of ≥1500 gm. Hypoxia accounted for 43% of all stillbirths. The implications with respect to preventability and for changes in routine prenatal care through the incorporation of the several methods of fetal assessment currently available are discussed.

The role of real-time scanning in antenatal fetal surveillance

The additional value of real-time ultrasound scanning (RTBS) in antepartum assessment of fetal well-being was studied in 158 high-risk patients after a nonstress test (NST). Fetal breathing movements (FBM), fetal movements (FM), tonus (TON), and normal amniotic fluid volume (AFV) when present on RTBS were reliable signs of fetal well-being. These ultrasound markers of fetal well-being appeared to be as reliable indicators of good outcome as the reactive NST. Multiple indicators did not improve the accuracy of the prediction of normal outcome. All test results were normal in only about 50% of patients. In general, abnormal test results were poor indicators of poor outcome. Only when all parameters were abnormal were babies invariably affected. Five of six babies with major anomalies showed increased AFV, and seven of 13 growth-retarded or postmature babies demonstrated decreased AFV. The parameters obtained on RTBS appeared to be far more reliable than the contraction stress test (CST) in discriminating the truly abnormal fetus. Three babies with positive CST in this study had normal outcomes. These results, if confirmed in larger studies, suggest that RTBS after a nonreactive NST is an effective and potentially economical method of fetal assessment.

REAL‐TIME ULTRASOUND OBSERVATION OF FETAL ACTIVITY IN LABOUR

Fetal activity was observed by realtime ultrasound for one hour in 25 patients in labour. Fetal respiratory movement, although reduced compared to the antenatal period, was observed in 13 patients. In three patients, hiccough-like movements were noted. Fetal body and/or extremity movements were observed in all patients (mean 41/hour) and frequently occurred in episodes. These bursts of movements were significantly correlated with contractions and fetal heart rate (FHR) accelerations. There was a significant association between absent or reduced number of fetal respiratory movements and/or hiccoughs (10 or less/hour) and an abnormal FHR. Absence of any type of fetal activity was also significantly associated with an abnormal FHR. The correlation between fetal activity and conventional methods of fetal assessment is discussed.

Antepartum fetal heart rate testing: The nonstress test

Antepartum assessment of fetal well being relies heavily on the observation of FHR. Fetal stress testing was introduced in the early 1970's in an attempt to define the fetus at risk. The stress factor most widely used has been uterine contractions, which isolate the fetus from its oxygen supply, and in the compromised fetus would be anticipated to provoke late decelerations in the FHR. Although the contraction stress test or “oxytocin challenge test” is useful in evaluating fetal condition, it is time consuming, not easily quantitatable or repeatable, and many times difficult to interpret. An attractive alternate approach of antepartum FHR testing (AFHRT) is the “nonstress” test. The positive experience of European investigators has led to interest in this method of fetal assessment in North America. Investigation from the literature contrasting the “stress” versus “nonstress” methods is discussed and observations derived from 2 year experience at LAC/USC Medical Center are presented. A protocol for AFHRT currently being evaluated clinically is presented.

Diabetic pregnancy and perinatal morbidity

Pregnancy outcome was analyzed in 147 diabetic women, 71 per cent of whom were dependent on insulin for more than 10 years. Ambulatory management of diabetes was carried out with weekly clinic visits until hospitalization at 36 to 37 weeks' gestation. Modern methods of fetal assessment were applied, and the timing and route of delivery were individualized. Of these patients, 35 per cent were delivered at or beyond 38 weeks' gestation. The primary cesarean section rate was 55 per cent. Polyhydramnios was a frequent maternal complication and was associated with premature labor and neonatal death in two cases. Polyhydramnios was least common in women with the lowest mean outpatient blood glucose. The perinatal survival rate was 96.6 per cent, and there were no instances of unexpected intrauterine fetal death. The incidence of respiratory distress syndrome (RDS) in the newborn infant was 7.6 per cent. No severe RDS was seen when the lecithin/sphingomyelin (L/S) ratio was greater than 3.0, but three of 24 infants delivered with an L/S ratio of 2.1 to 3.0 developed severe RDS. Other forms of neonatal morbidity noted in this population were 9 per cent major congenital anomalies; 7 per cent transient tachypnea of the newborn, 22 per cent hypocalcemia, 19 per cent hyperbilirubinemia, and 47 per cent hypoglycemia. The latter was more common in macrosomic infants, defined as greater than the ninetieth percentile of birth weight for gestational age (LGA), who represented 36 per cent of the neonates. Mean outpatient postprandial blood glucose was higher in patients delivered of LGA infants and was correlated with birth weight in White Classes B to D.

Review: Trends in Fetal Assessment

Summary: Progress in methods of fetal assessment in late pregnancy has been reviewed by analyzing the papers on this subject in 4 obstetrical journals in 1975. Among 107 papers on fetal assessment, the most common subjects were phospho‐lipid assays for fetal lung maturity, antenatal fetal heart rate measurements, ultrasonic studies, and oestrogen assays. The lecitbin/sphingomyelin ratio test has become established as the best currently available measure of functional fetal maturity. Antenatal fetal heart monitoring, with or without oxytocin infusion, is a valuable means of identifying the fetus at risk in late pregnancy.

Fetal Assessment in Late Pregnancy: A Current Review*

Summary: A review of papers in 4 selected obstetrical journals showed that oestrogen assays held a dominant place amongst methods of fetal assessment during 1971 and 1972. Plasma oestriol assays appear likely to increase in clinical importance.Ultrasonic studies have maintained their place in fetal assessment. Human placental lactogen assays appear to have been accepted as an adjunct to other tests.The phospholipid assay of fetal lung maturity showed the greatest rise in interest and activity amongst methods of fetal assessment in the past 2 years.

Amniotic fluid spectrophotometry, urinary estrogen estimations, and intrauterine transfusion in severe Rh isoimmunization

Amniotic fluid spectrophotometry, urinary estrogen levels, and intrauterine transfusion were utilized in the management of 11 severely Rh-isoimmunized pregnancies. Four infants survived. Three deaths were directly related to the transfusion procedure, and the clinical and biochemical data suggested that the remainder were moribund at the time of initial therapy. A modification of the Liley method of amniotic fluid analysis is presented in which bilirubin is reported as milligrams per cent with a semilogarithmic scale. A rapid estrogen assay, taking 6 hours, was carried out and found to relate well to bilirubin levels. The estrogen excretion curve is the only useful method for fetal assessment following intrauterine transfusion, and stable or rising levels give the clinicians confidence to carry the pregnancy closer to term. Falling levels of urinary estrogens, even if still within normal limits, indicate fetal deterioration, except immediately after transfusion when the fall may be due to fetal trauma.