Association of amniotic fluid index with estimated fetal weight.

OBJECTIVE: The relationship between amniotic fluid volume and gestational age has been described previously. The association of body weight and urine output has been observed in human neonates. Our goal was to assess the correlation of the amniotic fluid index (AFI) with estimated fetal weight (EFW) in the third trimester. METHODS: We conducted a retrospective observational study on 426 pregnant women with singleton gestations who were referred to our unit for sonographic evaluation in the third trimester. The AFI, EFW, and EFW percentile corrected for gestational age were evaluated. The sonographic examinations were stratified into 3 gestational age categories: 28 through 33.9 weeks, 34 through 37.9 weeks, and 38 weeks and later. Maternal and fetal outcome variables were collected from medical records. Linear regression, Mann-Whitney U, and Kruskal-Wallis tests were used for statistical analysis. RESULTS: There was no significant relationship between the AFI and EFW in the entire group of patients (R = 0.08; P = .096). There was a significant relationship between the AFI and EFW after 38 weeks' gestation (R = 0.30; P = .003). In addition, in female fetuses the EFW percentile correlated with higher AFI values at all gestational ages (R = 0.31; P < .001); this, however, was not observed in male fetuses. CONCLUSIONS: There is no relationship between the AFI and EFW during the third trimester, although a positive relationship between the AFI and EFW was noted late in gestation. In pregnancies with female fetuses, the AFI was positively associated with EFW percentile before 38 weeks' gestation.     

Ultrasound estimation of amniotic fluid volume using the largest vertical pocket containing umbilical cord: measure to or through the cord?

OBJECTIVES: The purpose of this investigation was to determine the preferable method, either measuring to the umbilical cord or through the umbilical cord to the base of the pocket, of ultrasonically estimating amniotic fluid volume. SUBJECT AND METHODS: This was a prospective study carried out in singleton pregnancies undergoing a third-trimester amniocentesis. The amniotic fluid index (AFI) and single deepest pocket (SDP) were measured prior to amniocentesis. If measured spaces contained umbilical cord, measurements were made to and through the cord. Actual amniotic fluid volume was determined by the dye-dilution technique. RESULTS: One-hundred pregnancies were evaluated. Low dye-determined volume was identified in a significantly greater number of pregnancies using the AFI to the cord (7/28, 25%) compared to through the cord (2/28, 7%) (P = 0.025). The SDP technique to the cord was superior in low volumes (2/28, 7%) vs. (0/28, 0%) through the cord (although statistical significance could not be determined because there were no low through-the-cord measurements). CONCLUSIONS: For the detection of low amniotic fluid volumes, the AFI to the cord is better than through the cord. Measurement to the cord and through the cord had similar accuracy for both the AFI and SDP techniques in normal and high dye-determined amniotic fluid volumes.     

Correlation between fetal gastric size and amniotic fluid volume

PURPOSE: Since abnormal conditions of the fetal digestive tract may alter both amniotic fluid volume and fetal gastric volume, we sought to determine whether amniotic fluid volume is correlated with fetal gastric volume in normal pregnancy. METHODS: A total of 280 fetal gastric size measurements were made prospectively from routine sonographic examinations of women with normal singleton pregnancies between 16 and 42 weeks of gestation. The fetal stomach was defined as the largest area including the pyloric site on transverse or oblique real-time sonographic scans. Gastric volume was calculated according to the formula for a prolate ellipsoid. The amniotic fluid index (AFI) was used for the evaluation of amniotic fluid volume. RESULTS: Both fetal gastric volume and AFI were significantly correlated with gestational age (R2= 0.422 and R2= 0.128, respectively). Only a weak correlation was found between gastric volume and AFI (R2= 0.036, p <0.001). On multivariate linear regression analysis adjusting for gestational age and fetal biometric measurements, gastric volume was not an independent and significant predictor of AFI. CONCLUSIONS: Although sonographically determined fetal gastric volume measurements appear to be useful in the assessment of fetal digestive tract anomalies, fetal gastric volume has no clinically significant effect on the amniotic fluid volume in normal pregnancy.     

Staging of intrauterine growth-restricted fetuses.

OBJECTIVE: The purpose of this study was to evaluate the value of cardiovascular, ultrasonographic, and clinical parameters for developing a staging classification of intrauterine growth-restricted (IUGR) fetuses delivered at 32 weeks or earlier. METHODS: Intrauterine growth restriction was defined as the presence of an estimated fetal weight below the 10th percentile. Intrauterine growth-restricted fetuses were staged according to the following parameters, with the presence of any 1 parameter in a stage placing the fetus in that stage: stage I, an abnormal umbilical artery or middle cerebral artery pulsatility index; stage II, an abnormal middle cerebral artery peak systolic velocity, umbilical artery absent/reversed diastolic flow, umbilical vein pulsation and an abnormal ductus venosus pulsatility index; and stage III, reversed flow at the ductus venosus or reversed flow at the umbilical vein, an abnormal tricuspid E wave (early ventricular filling)/A wave (late ventricular filling) ratio, and tricuspid regurgitation. Each stage was divided into A (amniotic fluid index [AFI] <5 cm) and B (AFI >5 cm). The presence of maternal abnormalities was also reported. RESULTS: Seventy-four IUGR fetuses delivered at 32 weeks or earlier were included. Gestational age at delivery was greater in stage I fetuses compared with the other stages. Birth weight decreased with advancing stages. Stage III fetuses had the lowest AFI. There was a direct correlation between the severity of staging and both perinatal mortality and mortality occurring between 20 weeks' gestation and before the neonates were discharged from the hospital (P < .05). CONCLUSIONS: The staging system proposed here may allow comparison of outcome data for IUGR fetuses and may be valuable in determining more timely delivery for these high-risk fetuses.     

The effects of maternal position on the amniotic fluid index.

OBJECTIVE: We investigated the influence of maternal positioning on the measurement of the amniotic fluid index (AFI) in third-trimester pregnancies. We wanted to determine whether a change in the position of the women, from supine-flat to supine-elevated, would influence the measurement of the AFI. METHODS: Each patient had AFI measurements obtained in both positions by the same investigator. RESULTS: We determined the values of the amniotic fluid index to be consistent in both positions for pregnancies with normal AFI measurements. CONCLUSIONS: Measurements of the amniotic fluid did not appear to be influenced by maternal position in the third trimester when the AFI was in the normal range.     

胎膜早破后残余羊水量对母婴的影响

目的探讨胎膜早破后残余羊水量对母婴的影响。方法对397例胎膜早破孕妇的临床资料进行回顾性分析,根据残余羊水指数（AFI）的多少分成3组,即羊水正常组（80mm〈AFI≤180mm）,羊水偏少组（50mm（AFI≤80mm）,羊水过少组（AFI≤50ram）,对不同残余羊水指数孕妇的分娩方式及胎儿窘迫、宫内感染率、新生儿发病率进行比较。结果羊水过少组较羊水偏少组及羊水正常组剖宫产率、胎儿窘迫发生率、胎儿宫内感染率、新生儿发病率高,差异有统计学意义。结论胎膜早破后残余羊水量过少会促使宫内感染率增加,影响胎儿、新生儿的生命安全,残余羊水指数可作为临床监测胎儿宫内安危的指标,予合理干预,选择正确的分娩方式,提高产科质量。     

Multivariable analysis of tests for the diagnosis of intrauterine growth restriction.

OBJECTIVES: To describe how data from antenatal fetal ultrasound biometry, amniotic fluid index and umbilical artery Doppler can be appropriately combined using multivariable models and to investigate how the addition of these ultrasound parameters influences the ability to predict intrauterine growth restriction (IUGR). METHODS: This was a prospective cohort study involving 274 low-risk pregnancies undergoing serial ultrasound examination at predetermined intervals. Standard deviation (Z) scores of the last values for fetal abdominal area (FAA), growth velocity of the FAA, amniotic fluid index (AFI) and umbilical artery Doppler pulsatility index prior to delivery were calculated for 260 fetuses. Customized estimated fetal weight (cEFW) centiles were also calculated using the last EFW before delivery after adjustment for fetal gender, gestational age, birth order and maternal weight, height and ethnic origin. Following delivery the neonatal ponderal index was calculated and centile position obtained. A neonatal ponderal index <25(th) centile served as the main outcome measure for diagnosis of IUGR. Logistic regression analysis was used to delineate the predictive value of the three fetal growth tests FAA, FAA growth velocity and cEFW and the additional values of AFI and pulsatility index of the umbilical artery. RESULTS: The areas under the receiver-operating characteristics (ROC) curves (95% confidence interval) for FAA, FAA growth velocity and cEFW alone were 0.819 (0.748-0.891), 0.784 (0.699-0.869) and 0.74 (0.643-0.837), respectively, in the prediction of a neonatal ponderal index <25(th) centile. The addition of both the AFI and pulsatility index to FAA, FAA growth velocity and cEFW generated small increases in the areas, to 0.831 (0.758-0.904), 0.817 (0.735-0.899) and 0.766 (0.672-0.859), respectively. These improvements in diagnostic prediction were not statistically significant. CONCLUSIONS: The addition of AFI and umbilical artery pulsatility index to the fetal biometry parameters did not significantly increase the ROC areas in the study population. The approach applied in this study is useful in the context of hypothesis generation. Further studies using larger data sets and other predictors should be carried out using the analytical techniques outlined in this paper to determine the contribution of various antenatal tests in the prediction of IUGR.     

High perinatal survival in monoamniotic twins managed by prophylactic sulindac, intensive ultrasound surveillance, and Cesarean delivery at 32 weeks' gestation.

OBJECTIVES: Increased perinatal mortality in monoamniotic twin pregnancies is attributed to cord accidents in utero and at delivery. We evaluated the following parameters in monoamniotic pregnancies: (1) the incidence of cord entanglement; (2) the effect of sulindac on amniotic fluid volume and stability of fetal lie; and (3) the perinatal outcome with our current management paradigm. METHODS: This is a retrospective review of monoamniotic pregnancies of >or=20 weeks' gestation managed with serial ultrasound surveillance, medical amnioreduction and elective Cesarean delivery at 32 weeks' gestation. Mean amniotic fluid index (AFI) and change in AFI in monoamniotic pregnancies managed with oral sulindac was compared with 40 gestation-matched monochorionic-diamniotic controls. RESULTS: Among 44 monoamniotic pregnancies, 20 with two live structurally normal twins at 20 weeks' gestation satisfied the inclusion criteria. All fetuses survived to 28 days postnatally despite early prenatal cord entanglement in all but one case. Whereas AFI remained stable throughout gestation in the controls, the AFI fell in those patients on sulindac from a mean value of 21.0 cm (95% CI, 18.5-23.6 cm) at 20 weeks to a mean of 12.4 cm (95% CI, 10.1-14.6 cm) at 32 weeks (ANOVA P across gestation = 0.001) but mainly remained within normal limits. Fetal lie was stabilized in 11/20 cases in the monoamniotic group compared with 13/40 in the control group (P < 0.0001). CONCLUSIONS: Cord entanglement appears unpreventable, as it typically occurs in early pregnancy. Sulindac therapy reduces AFI, leads to more stable fetal lie, and may prevent intrauterine death by diminishing the risk of constricting cords that are already entangled. Perinatal survival in monoamniotic pregnancies managed by a regime of sulindac from 20 weeks' gestation, close ultrasound surveillance and elective abdominal delivery at 32 weeks' gestation seems empirically higher than that in the literature.     

Prostate-specific antigen in amniotic fluid of normal and abnormal pregnancies

Objective: To examine if prostate-specific antigen (PSA) is present in amniotic fluid or maternal serum during pregnancy and if its presence is associated with fetal abnormalities.

Methods: Samples tested included amniotic fluids from 853 pregnant women for whom amniocentesis was performed; 312 nonpregnant women who donated blood; 259 pregnant women who donated blood at various gestational ages. Amniotic fluid or serum PSA was measured with an ultrasensitive time-resolved immunofluorometric procedure. 372 pregnancies were studied for the presence of genotypic or phenotypic fetal abnormalities.

Results: PSA was present in most amniotic fluids; the median PSA concentration increased from gestational week 11 to 22 and stabilized thereafter until delivery. The most prominent PSA concentration change occurred during gestational weeks 13–14. Pregnant women had significantly higher serum PSA concentrations than nonpregnant women; the pattern of serum fSA concentration change during pregnancy was similar to that of amniotic fluid; however, serum PSA concentrations were lower by a factor of 20–40. No association existed between amniotic fluid F'SA and maternal age, gender of fetus, or length of abstinence of mother from sexual intercourse. After gestational week 15, fetuses with trisomy 21 or 18, anencephaly, or renal disorders were associated with low amniotic fluid PSA levels.

Conclusion: Our data suggest that PSA may play a role in fetal development, especially at gestational ages between 13–20 weeks. The diagnostic usefulness of PSA in identifying fetal abnormalities remains to be determined.     

羊水量正常时胎儿肾发育不良的超声诊断及临床意义

目的 探讨产前超声检查对于羊水量正常时胎儿肾发育不良的诊断价值和临床意义.方法 于孕中晚期对羊水量正常胎儿中发现的单侧或双侧肾超声表现异常(包括大小、回声、形态异常,出现囊肿等)病例进行系统二维超声检查、孕期及生后随访观察、病理学检查等,并进行总结分析.仅有肾盂增宽的胎儿不包括在本组研究中.结果 发现羊水量正常但单侧或双侧肾发育不良的胎儿11例.其中单侧多囊性肾发育不良5例,4例不合并其他异常,1例合并同侧手缺如;单侧肾缺如2例,其中1例不合并其他畸形,另1例合并多发畸形包括脑积水、骶尾部脊柱裂、同侧桡骨缺失及单脐动脉,符合VACTERL综合征;盆腔.肾1例,马蹄肾1例,生后超声证实;常染色体显性遗传多囊肾1例,胎儿一侧肾可见多发囊肿,合并心脏横纹肌瘤,孕妇为双侧多囊肾;双侧肾发育不良1例,产前超声表现为双侧肾回声增强.结论 单侧多囊性肾发育不良是羊水量正常时产前超声最常检出的胎儿肾发育不良性疾病.根据产前超声表现并结合家族史,能在大多数胎儿肾发育不良病例中进行病因学诊断并帮助判断预后.     

Maternal Intravenous Administration of Azithromycin Results in Significant Fetal Uptake in a Sheep Model of Second Trimester Pregnancy

Treatment of intrauterine infection is likely key to preventing a significant proportion of preterm deliveries before 32 weeks of gestation. Azithromycin (AZ) may be an effective antimicrobial in pregnancy; however, few gestation age-approriate data are available to inform the design of AZ-based treatment regimens in early pregnancy. We aimed to determine whether a single intra-amniotic AZ dose or repeated maternal intravenous (i.v.) AZ doses would safely yield therapeutic levels of AZ in an 80-day-gestation (term is 150 days) ovine fetus. Fifty sheep carrying single pregnancies at 80 days gestation were randomized to receive either: (i) a single intra-amniotic AZ administration or (ii) maternal intravenous AZ administration every 12 h. Amniotic fluid, maternal plasma, and fetal AZ concentrations were determined over a 5-day treatment regimen. Markers of liver injury and amniotic fluid inflammation were measured to assess fetal injury in response to drug exposure. A single intra-amniotic administration yielded significant AZ accumulation in the amniotic fluid and fetal lung. In contrast, repeated maternal intravenous administrations achieved high levels of AZ accumulation in the fetal lung and liver and a statistically significant increase in the fetal plasma drug concentration at 120 h. There was no evidence of fetal injury in response to drug exposure. These data suggest that (i) repeated maternal i.v. AZ dosing yields substantial fetal tissue uptake, although fetal plasma drug levels remain low; (ii) transfer of AZ from the amniotic fluid is less than transplacental transfer; and (iii) exposure to high concentrations of AZ did not elicit overt changes in fetal white blood cell counts, amniotic fluid monocyte chemoattractant protein 1 concentrations, or hepatotoxicity, all consistent with an absence of fetal injury.     

Fetal trunk and head volume in chromosomally abnormal fetuses at 11+0 to 13+6 weeks of gestation.

OBJECTIVE: To examine the pattern of growth in chromosomally abnormal fetuses at 11+0 to 13+6 weeks of gestation and compare the trunk and head volume to crown-rump length (CRL) in defining the growth deficit in such fetuses. METHODS: The fetal trunk and head volume was measured using three-dimensional (3D) ultrasound in 140 chromosomally abnormal fetuses at 11+0 to 13+6 (median 12) weeks of gestation, and the values were compared to 500 chromosomally normal fetuses. In each chromosomally abnormal fetus, the observed fetal trunk and head volume was subtracted from the expected mean (delta value) of the chromosomally normal fetuses of the same gestational age, and this difference was expressed as a percentage of the appropriate normal mean. The Mann-Whitney U-test was used to determine the significance of differences between the chromosomally normal and abnormal groups. RESULTS: In trisomy 21 (n=72) and Turner syndrome (n=14) fetuses, compared to chromosomally normal fetuses, the CRL for gestation was similar (P=0.335 and P=0.317, respectively), but the fetal trunk and head volume was about 10-15% lower (P<0.001 and P=0.004, respectively). In trisomy 18 (n=29), trisomy 13 (n=14) and triploidy (n=11), the deficit in volume was about 45% (P<0.001), whereas the deficit in CRL was less than 15% (P<0.001). CONCLUSIONS: In the quantification of the degree of early growth impairment in chromosomally abnormal fetuses, measurement of the fetal trunk and head volume using 3D ultrasound may be better than measurement of CRL.     

Effect of maternal hydration on mild fetal pyelectasis.

The aim of our study was to determine whether maternal hydration status prior to prenatal sonography affects fetal renal pelvic diameter. The renal pelvic diameters of fetuses from two different institutions were compared prospectively. At one institution 74 women were asked to drink 32 to 48 ounces of water prior to undergoing sonography (hydration group), whereas at the second institution, no specific hydration regimen was requested of 176 subjects. The inclusion criteria were as follows: greater than 15 weeks' gestation, otherwise normal obstetrical sonogram, normal amniotic fluid volume, and negative family history for renal disease. Renal pelvic diameter, degree of maternal bladder fullness, and gestational age were compared between the two groups using logistic regression analysis and log-linear analysis. A P value < 0.01 was considered significant. Bladder fullness in the two groups differed significantly (P < 0.001). Logistic regression analysis showed a very strong effect of maternal bladder fullness on fetal renal pelvic diameter (P < 0.001). The log-linear analysis model showed a highly significant association between maternal bladder fullness and fetal renal pelvic diameter (P < 0.001). We conclude that maternal hydration influences fetal renal pelvic diameter. The larger fetal renal diameters seen in the hydrated group support physiologic theories that the effects of maternal hydration on amniotic fluid volume are partially mediated via fetal urine production.     

妊娠期妇女感染HPV对产妇和胎儿的影响

目的分析妊娠期妇女感染人乳头瘤病毒(HPV)对产妇和胎儿的影响。方法选取116例感染人乳头瘤病毒的产妇作为实验组,另选取健康孕妇116例为对照组,分别对产妇分娩时羊水、胎盘组织及胎儿脐静脉血、口咽部分泌物与外阴分泌物中的HPV进行检测,分析产妇HPV的感染分型。随访1年,观察HPV感染对产妇和胎儿的影响。结果实验组中单型HPV感染及高危型HPV感染的患者所占比例较大,分别为66.38%和76.72%;患者宫颈肉眼形态异常炎症、细胞学检验呈鳞状上皮病变是感染HPV的危险因素;2组患者在分娩方式、产后出血及胎儿生长受限等方面比较,差异无统计学意义(P0.05);正常阴道分娩与剖宫产分娩的胎儿在羊水、胎盘组织及脐静脉血、口咽部分泌物、外阴分泌物或包皮分泌物中的HPV阳性检出率比较无显著差异(P0.05);胎儿HPV感染率为24.14%。结论单型HPV感染及高危型HPV感染是妊娠期妇女HPV感染的主要分型。     

产前超声及胎儿磁共振对先天性食管闭锁的诊断价值

目的:提高对先天性食管闭锁(CEA)的认识,探讨产前超声及胎儿MRI对CEA的临床价值.方法:回顾性分析29例经临床证实的CEA胎儿产前超声及胎儿MRI资料.纳入29例正常胎儿作为对照组.分析CEA影像征象,比较组间羊水深度(AFD)、羊水指数(AFI)、双顶径(BPD)、头围(HC)、腹围(AC)、股骨径(FL)、脐...     

胎儿肾脏体积的MRI测量及相关因素分析

目的利用MRI体积测量技术精确测量胎儿肾脏体积,并分析其与孕周、羊水指数（AFI）、胎儿性别等因素的关系。方法对5只兔的10只肾脏采用5mm层厚、0.5mm层间距进行T2WI横、矢、冠状位扫描,分别测量出体积;扫描后解剖取肾脏测量实际体积,计算MRI各方位测量的误差率,找出最佳方位;采用与动物实验相同层厚与间距及最佳方位对114例30～39孕周无泌尿系统异常（经MRI检查和随访确认）胎儿双侧肾脏进行MRI扫描,测量出肾脏体积,进行统计分析。结果 （1）兔的MRI肾脏体积测量最佳扫描方位为横轴位,MRI测量误差率为（2.26±0.55）%;（2）胎儿平均肾脏体积由30孕周的（6.42±1.28）cm^3逐渐增长至39孕周的（14.14±2.26）cm^3,与孕周相关系数r=0.766（P〈0.05）,与AFI相关系数r=0.179（P〉0.05）;相同孕周男性肾脏体积大于女性（P〈0.05）。结论 MRI体积测量技术可以精确测量胎儿肾脏体积;胎儿肾脏体积与孕周呈正相关,与AFI无明显相关性,有性别差异。     

Use of the amniotic fluid index combined with estimated fetal weight within 10 days of delivery for prediction of macrosomia at birth.

OBJECTIVE: The purpose of this study was to assess the value of combining the sonographically estimated fetal weight (EFW) and amniotic fluid index (AFI) measured within 10 days of term delivery for prediction of macrosomia at birth. METHODS: Prospective sonographic fetal biometric measurements and delivery ward data of a single center, uploaded separately over a 4-year period, were retrospectively linked to yield an unselected sample of nondiabetic pregnancies with live-born term neonates. RESULTS: Of the 1925 pregnancies evaluated, 140 (7.2%) were macrosomic (birth weight > or =4000 g). The AFI was significantly higher in the macrosomic group (P < .001). On receiver operating characteristic curve analysis, the area under the curve was larger for predictions based on the EFW alone than on the AFI. An EFW of 4000 g or higher had a positive predictive value of 46.6% for macrosomia at birth. Use of the previously suggested combined EFW and AFI cutoffs of 3689 g and 119 mm, respectively, yielded a positive predictive value of 30.3%. CONCLUSIONS: Combined use of the EFW and AFI rather than the EFW alone does not improve prediction of macrosomia at birth.     

Androgen receptors influence the production of pulmonary surfactant in the testicular feminization mouse fetus.

A sexual dimorphism in fetal pulmonary maturation has been described in which the female fetal lung produces surfactant earlier in gestation than the male fetal lung. This is felt to be related to the increased incidence in male newborns of the Respiratory Distress Syndrome. Dihydrotestosterone will delay surfactant production in the female fetus, and a relationship between fetal sexual differentiation and fetal lung maturation has been proposed. We hypothesized that the dimorphism in fetal surfactant production is dependent on androgen receptor function. We measured phosphatidylcholine (PC), saturated phosphatidylcholine (SPC), and sphingomyelin (S) in the amniotic fluid of fetal mice of the mouse model of testicular feminization (Tfm mouse). In this model, male carriers of the X-linked Tfm gene have no functional androgen receptors. The mean amniotic fluid phosphatidylcholine to sphingomyelin ratio (PC/S ratio) was 28% higher in females than in normal males, and the amniotic fluid PC/S ratio of the Tfm male fetuses was the same as the females. The ratio of amniotic fluid saturated phosphatidylcholine to sphingomyelin (SPC/S ratio) was lowest in males, intermediate in females, and highest in Tfm males. A significant relationship between the fetal groups and the amniotic fluid SPC/S ratio was identified by analysis of variance. There were no differences in the whole lung phospholipid content between the three groups. To substantiate the effect of androgen receptors, dihydrotestosterone was injected into pregnant carriers of the Tfm mutation, 2.5 mg/d from day 10 of gestation through the day of sacrifice. The amniotic fluid PC/S ratio was decreased in the female fetuses (consisting of both homozygous normal and heterozygous carriers of the Tfm gene), but not in the Tfm male fetuses. The overall result was no significant difference between the male and female amniotic fluid PC/S ratio while the Tfm amniotic fluid PC/S ratio remained at the level of the untreated females. We conclude that androgens affect fetal lung development via a mechanism dependent on the presence of androgen receptors.     

Accuracy of ultrasonography in evaluating amniotic fluid volume at less than 24 weeks' gestation.

The purpose of this investigation was to evaluate the accuracy of common sonographic techniques in assessing the amniotic fluid volume in pregnancies of less than 24 weeks' gestation. Patients at less than 24 weeks' gestation undergoing an amniocentesis for the placement of prostaglandin F2 alpha for termination (because of genetic or fetal anomalies, or both) were assessed for amniotic fluid volume. All fetuses were alive at the time of prostaglandin instillation. The amniotic fluid index and two-diameter pocket were used to determine the amniotic fluid volume. Prior to the prostaglandin instillation, the amniotic fluid volume was determined with para-aminohippurate using a diazo dye reaction with spectrophotometric analysis. The amniotic fluid volume was determined in 21 pregnancies between 15 and 24 weeks' gestation, yielding volumes ranging from 189 to 1840 ml. Using published standards for amniotic fluid volume in singleton pregnancies, oligohydramnios was present in three gestations, the volume was found to be normal in 15, and hydramnios complicated three pregnancies. The two-diameter pocket identified the amniotic fluid volumes correctly more often (18 of 21 [85.7%]) than the amniotic fluid index (10 of 21 [47.6%]) (P = 0.02). Normal amniotic fluid volume was identified in nine of 15 (60%) pregnancies by the amniotic fluid index and in 14 of 15 (93.3%) by the two-diameter pocket (P = not significant). Abnormal amniotic fluid volumes, oligohydramnios, and hydramnios were recognized more often by the two-diameter pocket (66.7%) than by the amniotic fluid index (1 of 6 [16.7%], P = not significant).     

Fetal arterial and venous Doppler parameters in the interpretation of oligohydramnios in postterm pregnancies.

OBJECTIVE: The objective of the current study was to evaluate fetal arterial and venous Doppler parameters in postterm pregnancies with oligohydramnios and those with normal amniotic fluid. STUDY DESIGN: A cross-sectional study was performed in 38 pregnancies beyond 41 weeks' gestation. Pulsed Doppler imaging was used to determine the pulsatility index (PI) for the fetal middle cerebral artery (MCA), renal artery, umbilical artery, inferior vena cava (IVC) and ductus venosus. The amniotic fluid index (AFI) was used for semiquantitive assessment of amniotic fluid volume. Oligohydramnios was defined as an AFI < 5 cm. RESULTS: Oligohydramnios was detected in 10 cases, and a normal AFI was present in 28 cases. In the presence of oligohydramnios the PI of the MCA was decreased, while the renal artery PI and the MCA PI/UA PI ratio were found to be elevated. In cases of oligohydramnios the PI in the IVC was increased but was unchanged in the ductus venosus. CONCLUSION: Oligohydramnios in post-term pregnancies is associated with arterial redistribution of fetal blood flow typifying the brain sparing effect and with decreased resistance in the MCA and increased resistance in the fetal IVC.