Assessment Of Amniotic Fluid Volume Research Articles

Sonographic considerations with multiple gestation

Determination of chorionicity is of paramount importance in risk assessment and management. Best performed in the first trimester, dichorionic placentation can be reliably assumed when the membrane is easily seen, there is a "twin peak" sign, there are clearly separate placentas, and there is discordant fetal gender. In a monochorionic twin pregnancy, there is a single placental mass, the dividing membrane is difficult to visualize until the end of the first trimester, and the membrane inserts onto the placental surface without a peaked appearance. Amniotic fluid volume assessment is important in the management of twin pregnancy. Polyhydramnios-oligohydramnios may be a manifestation of twin-twin transfusion syndrome, although oligohydramnios with normal amniotic fluid volume in the other twin's sac may more likely be a sign of velamentous cord insertion, infection, or chromosomal or structural abnormality. Fetal growth discordance is common in twin pregnancy and is associated with increased perinatal mortality and morbidity. The most sensitive indicator of discordant twin growth is thought to be estimated fetal weight, and an intertwin difference of > or = 20% is considered significant. In the clinical care of a patient with twins, it is reasonably standard to confirm chorionicity with ultrasonography in the first or early second trimester. At about 20 weeks, a level II ultrasound for anatomic survey is indicated. In dichorionic pregnancies, ultrasound examinations are then performed at 26 to 28 weeks and every 3 to 4 weeks thereafter to follow growth and amniotic fluid volume. In monochorionic twins, we generally do an additional ultrasound at about 23 to 24 weeks, because of the risk of twin-twin transfusion syndrome. In the late third trimester, careful attention should also be given to fetal position, to help with delivery planning.

Characteristics of monochorionic-diamniotic growth-retarded twins during the third trimester.

The goal of this study was to assess the characteristics of monochorionic-diamniotic (MD) growth-retarded twin infants with twin-twin transfusion syndrome (TTTS) compared with those without TTTS during the third trimester. Retrospective analyses of the growth patterns and amniotic fluid volumes were performed on 5 MD twin pregnancies in which one or both twins showed growth retardation with TTTS, and the results weve compared with those without TTTS. Eighty-three percent of growth-retarded twin infants without TTTS in MD twin gestation showed an asymmetric growth pattern, while all TTTS cases showed a symmetric pattern (p < 0.05). Polyhydramnios of the co-twin was found in 80% of TTTS cases, while no polyhydramnios was found in patients without TTTS (p < 0.05). Assessment of growth patterns and amniotic fluid volume may be useful to exclude the possibility of TTTS in MD growth-retarded twin pregnancies during the third trimester.

Transvaginal Sonography of the Forewaters in the Assessment of Amniotic Fluid Volume in Patients with Oligohydramnios

Transvaginal Sonography of the Forewaters in the Assessment of Amniotic Fluid Volume in Patients with Oligohydramnios

CLINICAL UTILITY OF AMNIOTIC FLUID VOLUME ASSESSMENT

Abnormal amniotic fluid volume is associated with increased maternal risk and perinatal morbidity and mortality. Until the advent of ultrasonography, the invasive nature of amniotic fluid volume assessment limited its clinical utility. Refinements in quantifying the noninvasive sonographic assessment of oligohydramnios and hydramnios have improved the ability of clinicians to identify at-risk pregnancies. This article reviews the available methods of amniotic fluid volume assessment and outlines a comprehensive approach to sonographic screening and monitoring.

Four‐quadrant assessment of gestational age‐specific values of amniotic fluid volume in uncomplicated pregnancies

The purpose of this study was to establish a normative scale of amniotic fluid index (AFI) throughout gestation in uncomplicated singleton pregnancies, and to identify the lower and upper limits for each gestational week. Four-quadrant assessment of amniotic fluid volume (AFV) was performed prospectively in 750 uncomplicated pregnancies between 16 and 43 weeks. The logarithmic transformations were used to get the data in Gaussian distribution. The means, and the 90%, 95% and 98% confidence intervals at each week of gestation were calculated from polynomial regression equation. Statistical differences in AFIs among gestational age groups were tested. The amniotic fluid index observations from regression equation curve were stratified in week-specific normative curve. The variations between mean AFI of the total population and the means of the preterm, term and postdate pregnancies were statistically significant (p<0.0001). The 90%, 95% and 98% confidence limits about the mean (12.5 cm) were 5.4 to 20.6, 4.2 to 22.3, 1.8 to 25.8 cm, respectively in term gestation. The 5th and 95th percentile serves as lower and upper limits of normal, respectively. Gestational age-specific values of AFI were established, determining the significant trends of changes in the AFV with gestation. The normogram may have a clinical benefit to accurate, reliable and semiquantitative diagnosis of oligohydramnios and polyhydramnios.

Assessment of amniotic fluid volume: ultrasound compared with MRI

Assessment of amniotic fluid volume: ultrasound compared with MRI

Do multiple evaluations improve the accuracy of ultrasound amniotic fluid volume assessment?

Do multiple evaluations improve the accuracy of ultrasound amniotic fluid volume assessment?

Defining limits of survival: Lethal pulmonary hypoplasia after midtrimester premature rupture of membranes

OBJECTIVE: Our purpose was to determine prospectively whether sequential ultrasonographic assessment of amniotic fluid volume (<1 cm vertical pocket constitutes severe oligohydramnios), in conjunction with other readily available clinical data, could predict the occurrence of pulmonary hypoplasia and neonatal mortality in pregnancies complicated by second-trimester premature rupture of membranes. STUDY DESIGN: Singleton pregnancies complicated by premature rupture of membranes at <29 weeks' gestation were prospectively monitored by weekly ultrasonographic assessments. Stepwise multiple logistic regression analysis was used to determine the independent predictive value of ultrasonographically determined factors in the development of lethal pulmonary hypoplasia, neonatal mortality, and skeletal deformations. RESULTS: Neonatal mortality and pulmonary hypoplasia were statistically predicted by gestational age at rupture of membranes and interaction of premature rupture of membranes of >14 days' duration with severe oligohydramnios. The occurrence of skeletal deformations was related to the interaction of duration of premature rupture of membranes and severe oligodramnios (p < 0.0001). Fetal breathing, fetal movements, and thoracic circumference/abdominal circumference ratios were not predictive of outcome. CONCLUSION: Both duration of severe oligohydramnios exposure and gestational age at premature rupture of membranes were independent significant predictors of increased neonatal risk. Severe oligohydramnios >14 days after premature rupture of membranes at <25 weeks' gestation has a predicted neonatal mortality of >90%. (Am J Obstet Gynecol 1996;175:675-81.)

Normal values for amniotic fluid index during uncomplicated twin pregnancy

To establish the gestational age trends of amniotic fluid index (AFI) in uncomplicated twin pregnancies. Amniotic fluid index was measured in uncomplicated twin pregnancies seen between 1985 and 1993 and meeting the following criteria: 1) no maternal medical or obstetric complications, 2) normal growth of both twins by serial ultrasound, and 3) normal amniotic fluid volume by ultrasound. Amniotic fluid index was measured by adding the deepest vertical pockets in four quadrants, defined by the umbilicus and linea nigra. The relation between gestational age and AFI was evaluated using linear regression analysis. Two hundred eighty-two sets of twins were considered uncomplicated; 1101 AFI measurements were performed on these pregnancies between 25.5 and 40.5 weeks' gestation. Percentile values for AFI were determined according to gestational age. The regression equation relating the median AFI to gestational age was: AFI = 19.4 - 0.12 x gestational age (P = .03). The R2 value was 0.04. Gestational age trends in normative AFI measurements for twin pregnancies have been established. Their use will facilitate a more reproducible, quantitative diagnosis of oligohydramnios in twins, compared with subjective, qualitative approaches to amniotic fluid volume assessment.

Biophysical profile for fetal assessment in high risk pregnancies.

Biophysical profile usually includes ultrasound monitoring of fetal movements, fetal tone and fetal breathing, ultrasound assessment of amniotic fluid volume and assessment of fetal heart rate by electronic monitoring. The objective of this review was to assess the effects of biophysical profile tests on pregnancy outcome in high risk pregnancies. We searched the Cochrane Pregnancy and Childbirth trials register. Date of last search: October 1998. Randomised trials comparing fetal biophysical profile with other forms of fetal assessment in women with high risk pregnancies. Trial quality was assessed. Four studies were included. Most trials were not of high quality. No difference was found between biophysical profile and other forms of fetal assessment over a range of fetal and neonatal measures. At present, there is not enough evidence from randomised trials to evaluate the use of biophysical profile as a test of fetal well-being in high risk pregnancies.

Antepartum surveillance in diabetic pregnancies: Predictors of fetal distress in labor

OBJECTIVE: Our purpose was to evaluate an antepartum testing program based on twice-weekly nonstress testing and amniotic fluid evaluation in pregnancies complicated by diabetes mellitus and to weight the test components in the prediction of fetal distress requiring cesarean delivery. STUDY DESIGN: During the 4-year period of 1987 through 1990, 2134 women with pregnancies complicated by diabetes underwent antepartum testing. Of these 1501 women (class A 1, n = 505; A 2-diet, n = 305; A 2-insulin, n = 580; B, n = 71; C to D, n = 29; R to F, n = 11) were delivered within 4 days of their last test. Categoric analysis of data was performed according to diabetic class, fetal heart rate results, and the presence of decreased, normal, or increased amniotic fluid assessment. A univariate logistical regression was first conducted with cesarean delivery for fetal distress as outcome variable by use of the following variables: fetal weight and sex, diabetic class, gestational age at delivery, presence of additional indications for antepartum testing, largest vertical pocket, amniotic fluid index (summation of the four quadrants of the largest vertical pocket), nonstress test reactivity (two accelerations of ≥ 15 beats/min of 15 seconds' duration), presence of decelerations (≥ 15 beats/min for 15 seconds) during the nonstress test, and the interactions of the nonstress test with deceleration, largest vertical pocket, and amniotic fluid index. Multivariate analysis was then applied to predict the best model. RESULTS: No stillbirths occurred within 4 days of the last antepartum test. However, the corrected stillbirth rate of the entire tested population was 1.4 per 1000. Eighty-five women required cesarean delivery for fetal distress. The factors most predictive of cesarean delivery for fetal distress ( p < 0.05, odds ratio and 95% confidence interval) were a deceleration (3.60, 2.14 to 6.06), nonreactive nonstress test (2.68, 1.60 to 4.49), and the interaction of both a nonreactive nonstress test and decelerations (5.63, 2.67 to 11.9). Amniotic fluid assessment by largest vertical pocket or amniotic fluid index were not statistically significant. The multivariate analysis selected the interaction of nonstress test and deceleration as the best significant predictor for cesarean delivery for fetal distress. CONCLUSION: An antepartum fetal surveillance program using twice-weekly nonstress test and fluid index assessment in pregnancies complicated by diabetes was successful in preventing stillbirth. The absence of fetal heart rate reactivity and the presence of decelerations were predictive of the diagnosis of fetal distress in labor requiring cesarean delivery. Ultrasonographic assessment of amniotic fluid volume was not a significant predictor of fetal distress in labor in the diabetic pregnancy.

Is oligohydramnios is postterm pregnancy associated with redistribution of fetal blood flow?

OBJECTIVE: Our purpose was to determine whether postterm patients with oligohydramnios differ in their fetal and umbilical flow distributions from those with a normal volume of amniotic fluid.STUDY DESIGN: Pulsed-wave Doppler imaging was used prospectively to determine the resistance index in the fetal middle cerebral, renal, and umbilical arteries in 57 postterm (i.e., >41 weeks' gestation) pregnancies. Semiquantitative assessment of amniotic fluid volume was obtained by use of the ultrasonographically determined amniotic fluid index.RESULTS: Oligohydramnios (amniotic fluid index <5 cm) was detected in 15 patients; 42 patients with a normal amniotic fluid index served as a control group. The various resistance index values and the ratios among them were not significantly different when patients with oligohydramnios were compared with controls (0.51 ± 0.1 vs 0.52 ± 0.06, 0.63 ± 0.1 vs 0.64 ± 0.08, and 0.71 ± 0.08 vs 0.73 ± 0.05 for the umbilical, middle cerebral, and renal arteries, respectively). However, the mean birth weight (in grams) was significantly lower (3297 ± 438 vs 3742 ± 448, p < 0.003) in the oligohydramnios group.CONCLUSION: Oligohydramnios was not associated with a major redistribution of blood flow in postterm patients, suggesting that the cause of oligohydramnios in these patients is related to birth weight rather than to renal perfusion.

The impact of amniotic fluid volume assessed intrapartum on perinatal outcome

OBJECTIVE: Our purpose was to determine the value of routine intrapartum amniotic fluid volume assessment on perinatal outcome. STUDY DESIGN: Patients admitted for labor and delivery who were ultimately delivered between January 1988 and June 1989 with a gestational age ≥26 weeks and who had an intrapartum amniotic fluid index composed the study group. The amniotic fluid index was determined by the four-quadrant technique on admission to labor and delivery. Oligohydramnios was defined as an amniotic fluid index ≤5 cm ( n = 170), borderline oligohydramnios as an amniotic fluid index 5.1 to 8.0 cm ( n = 261), and normal amniotic fluid volume as an amniotic fluid index 8.1 to 20 cm ( n = 336). Nine patients with an amniotic fluid index >20 cm were excluded from data analysis. The oligohydramnios and borderline oligohydramnios groups were compared with the normal group with regard to antenatal, intrapartum, and postpartum variables. RESULTS: The groups had similar maternal age, parity, gestational age at delivery, and antenatal complications. Meconium-stained amniotic fluid occurred significantly less often in the oligohydramnios group compared with the normal group (relative risk 0.67, 95% confidence interval 0.49 to 0.92). However, variable decelerations occurred significantly more often in the oligohydramnios group compared with the normal group (relative risk 1.44, 95% confidence interval 1.12 to 1.87), and cesarean delivery for fetal distress also occurred significantly more often (relative risk 6.83, 95% confidence interval 1.55 to 30.4). There was no difference in Apgar scores or neonatal complications between groups. The efficacy of intrapartum-determined oligohydramnios predicting cesarean delivery for fetal distress gave a sensitivity of 78%, a specificity of 74%, a positive predictive value of 33%, and a negative predictive value of 95%. CONCLUSION: The amniotic fluid index for detecting intrapartum oligohydramnios is a valuable screening test for subsequent fetal distress requiring cesarean delivery.

The Biophysical Profile as a Tool for Prediction of Preterm Delivery

Our objective was to determine if any of the following parameters is a predictor of preterm delivery: gestational age, cervical dilatation, or biophysical profile score. Sixty-two women with certain dates, intact membranes, and preterm contractions more frequent than 300 min underwent a 30-min ultrasonographic assessment of fetal breathing movements, fetal tone, fetal movement and amniotic fluid volume, each of which was scored as 0, 1, or 2 before any tocolytics were given. The total score (0–8) was calculated and cervical dilatation was recorded. All women were subsequently placed on tocolytics. Data were analyzed using survival analysis with stepwise regression of the covariates to determine the predictive values of the total score, its individual parameters, gestational age, and cervical dilatation to the outcome variable of hours to delivery. Gestational age, cervical dilatation and time interval to delivery were categorized and entered into a logistic regression model with the total score and its components to determine predictive odds. Total score (p < 0.0001) and cervical dilatation (p < 0.0001) were the most significant variables associated with time interval to delivery, followed by gestational age (p = 0.035). When the individual biophysical parameters were entered into the model, fetal tone (p < 0.0001), cervical dilatation (p < 0.0001) and gestational age (p < 0.014) were the only variables related to time interval to delivery. Predictive odds of delivery in less than 48 h in relation to fetal tone and cervical dilatation were calculated. Total score, fetal tone, and cervical dilatation were strongly associated with time interval to delivery. Our study did not support fetal breathing movements as a predictor of preterm delivery. Copyright © 1994 International Society of Ultrasound in Obstetrics and Gynecology

Assessment of fetal activity and amniotic fluid volume in the prediction of intrauterine infection in preterm prelabor amniorrhexis

OBJECTIVE: Our purpose was to assess fetal activity, fetal heart rate patterns, and amniotic fluid volume in the prediction of intrauterine infection in pregnancies complicated by preterm prelabor amniorrhexis. STUDY DESIGN: A prospective study was performed on 89 patients with preterm prelabor amniorrhexis undergoing fetal blood and amniotic fluid sampling for microbiologic investigations. Within 2 hours before cordocentesis and amniocentesis, computerized fetal heart rate monitoring was carried out and ultrasonographic examination was performed for assessment of biophysical profile and amniotic fluid volume. RESULTS: In the pregnancies with microbiologic evidence of intrauterine infection compared with those with no infection, there was a tendency for a lower biophysical profile score and amniotic fluid index and an increased fetal heart rate. However, in the majority of pregnancies with positive amniotic fluid or fetal blood cultures the results of the various tests were normal. CONCLUSION: In pregnancies complicated by preterm prelabor amniorrhexis assessment of fetal activity and amniotic fluid volume do not provide useful prediction of intrauterine infection.

Sonographic assessment of amniotic fluid in normal twin pregnancy.

A sonographic standard for assessment of amniotic fluid volume in normal twin pregnancy is provided. In 210 uncomplicated twin pregnancies, amniotic fluid volume was assessed sonographically, by measuring the total amniotic fluid index (AFI), as well as the deepest single vertical pocket in each sac. The mean AFI was greater than values found in singleton gestations; the AFI increased up to 27 weeks' gestation, and decreased thereafter. It correlated well with measurement of the deepest vertical pocket in each sac (r = 0.71; p < 0.0001). In twin pregnancy at 26 to 32 weeks' gestation a fluid pocket of at least 8 cm was found in 9.8% of cases and did not indicate pathologic states. Either AFI or measurement of the deepest fluid pocket in each sac can be used to assess fluid volume in twin pregnancy. A table specific to twin pregnancy should be used when evaluating twin gestations sonographically.

Sonographic evaluation of intrauterine growth retardation.

Intrauterine growth retardation (IUGR) may arise from a variety of causes, including placental insufficiency, maternal diseases, and fetal anomalies. Sonography plays a number of important roles in the diagnosis and management of growth retardation. Diagnosis of IUGR is based on fetal measurements, assessment of amniotic fluid volume, and other sonographic findings. Once IUGR has been diagnosed, sonography can help establish its cause. If a lethal cause is excluded, the fetus is monitored for the remainder of the pregnancy using sonography, including serial fetal measurements, biophysical profiles, and Doppler waveform indexes. Used appropriately, sonography can improve the outcome of fetuses with IUGR.

Assessment ofAmniotic Fluid Volume in At-Risk Pregnancies

Assessment ofAmniotic Fluid Volume in At-Risk Pregnancies

Maternal hyperoxygenation in the treatment of mild intrauterine growth retardation: a pilot study.

The aim of this study was to determine the efficacy of long-term maternal hyperoxygenation in comparison with bed rest in the management of mildly growth-retarded fetuses (5-10th centile).Thirty-eight patients with intrauterine growth retardation were studied. The patients were divided into oxygen-treated (n = 18) and untreated (n = 20) groups. Ultrasound assessment of amniotic fluid volume was performed on alternate days, and the fetal abdominal circumference was evaluated weekly. Doppler analysis of fetal/maternal circulation was performed upon the patient's arrival at hospital, after 12 h, and thereafter on alternate days until parturition. Fetal blood was sampled by cordocentesis for immediate blood gas analysis at the start of the study and on the day of delivery. Although in the treated patients there was significant improvement in Doppler flow pat tern and blood gas indices, no significant differences in type of delivery and perinatal outcome were noted between the groups. Maternal hyperoxygenation in mild intrauterine growth retardation did not improve perinatal outcome.

The biophysical profile as a tool for prediction of preterm delivery.

Our objective was to determine if any of the following parameters is a predictor of preterm delivery: gestational age, cervical dilatation, or biophysical profile score.Sixty-two women with certain dates, intact membranes, and preterm contractions more frequent than 300 min underwent a 30-min ultrasonographic assessment of fetal breathing movements, fetal tone, fetal movement and amniotic fluid volume, each of which was scored as 0, 1, or 2 before any tocolytics were given. The total score (0-8) was calculated and cervical dilatation was recorded. All women were subsequently placed on tocolytics. Data were analyzed using survival analysis with stepwise regression of the covariates to determine the predictive values of the total score, its individual parameters, gestational age, and cervical dilatation to the outcome variable of hours to delivery. Gestational age, cervical dilatation and time interval to delivery were categorized and entered into a logistic regression model with the total score and its components to determine predictive odds.Total score (p < 0.0001) and cervical dilatation (p < 0.0001) were the most significant variables associated with time interval to delivery, followed by gestational age (p = 0.035). When the individual biophysical parameters were entered into the model, fetal tone (p < 0.0001), cervical dilatation (p < 0.0001) and gestational age (p < 0.014) were the only variables related to time interval to delivery. Predictive odds of delivery in less than 48 h in relation to fetal tone and cervical dilatation were calculated. Total score, fetal tone, and cervical dilatation were strongly associated with time interval to delivery. Our study did not support fetal breathing movements as a predictor of preterm delivery.