Application of 3‐Dimensional Ultrasonography to Imaging the Fetal Anal Canal

Objective. Ultrasonography has been applied previously to the assessment of the fetal anal canal. We aimed to examine the potential of 3‐dimensional ultrasonography (3DUS) in the evaluation of the fetal anal canal and to obtain normal fetal anal canal measurements. Methods. Patients were recruited from an unselected population of gravidas with known gestational age (by dates or first‐trimester ultrasonography) and without known fetal anomalies presenting for fetal evaluation in the ultrasound units of 2 tertiary care centers between 16 and 39 gestational weeks. In addition to the ordered scan, 3DUS imaging of the fetal anal canal was performed. Transverse and sagittal views and volumes were obtained. Measurements of the fetal anal canal anteroposterior diameter, lateral diameter, and length were performed in transverse and sagittal planes, respectively, and scatterplots of these dimensions were created. Measurements were performed and repeated on raw data sets by 2 independent observers, and the results were analyzed to estimate interobserver and intraobserver reliability. Results. A total of 186 patients were examined for this study at 16 to 39 weeks' gestation (mean, 27.4 weeks). The anteroposterior diameter of the fetal anal canal in this study group ranged from 4 to 21 mm (mean, 11.2 mm; SD, ±3.5 mm), whereas the lateral diameter ranged from 7 to 18 mm (mean, 9.1 mm; SD, ±3.0 mm). The length of the fetal anal canal in this study group ranged from 3 to 24 mm (mean, 14.3 mm; SD, ±3.8 mm). Conclusions. Ultrasonographic assessment of the fetal anal canal with 3DUS is feasible. Scatterplots were created for internal anal sphincter width and length measurements from 16 to 39 weeks' gestation. Larger studies are necessary to establish nomograms of these measurements and their application to the evaluation of pathologic cases. We speculate that 3DUS assessment of the fetal anal canal may improve detection rates of disorders involving this system.     

The development of the fetal vermis: an in-utero sonographic evaluation.

OBJECTIVE: To establish a nomogram for fetal vermis measurements during gestation. METHODS: A prospective cross-sectional study of normal singleton pregnancies. Measurements of the fetal vermis width (in the axial plane) and height (in the sagittal plane) were performed by high-resolution transabdominal ultrasonography between 18 and 38 weeks of gestation in 256 fetuses. RESULTS: Adequate vermis measurements were obtained in 256 fetuses. Vermian width and height as a function of gestational age and biparietal diameter were expressed by regression equations and the correlation coefficients were found to be highly statistically significant (P < 0.0001). The normal mean (+/- SD) for each gestational week was defined. CONCLUSIONS: The present data offer the normal range of the vermian measurements throughout gestation. These values may allow intrauterine assessment of the development of the cerebellar vermis, as well as the posterior fossa.     

Placental Volumes Measured by 3‐Dimensional Ultrasonography in Normal Pregnancies From 12 to 40 Weeks' Gestation

Objective. The purpose of this study was to construct nomograms of placental volumes according to gestational age and estimated fetal weight. Methods. From March to November 2007, placental volumes were prospectively measured by ultrasonography in 295 normal pregnancies from 12 to 40 weeks' gestation and correlated with gestational age and estimated fetal weight. Inclusion criteria were healthy women, singleton pregnancies with normal fetal morphologic characteristics on ultrasonography, and confirmed gestational age by first‐trimester ultrasonography. Results. The mean placental volume ranged from 83 cm³ at 12 weeks to 427.7 cm³ at 40 weeks. Linear regression yielded the following formula for the expected placental volumes (ePV) according to gestational age (GA): ePV (cm³) = ?64.68 + 12.31 × GA (r = 0.572; P < .001). Placental volumes also varied according to estimated fetal weight (EFW), and the following mathematical equation was also obtained by linear regression: ePV = 94.19 + 0.09 × EFW (r = 0.505; P < 0.001). Conclusions. Nomograms of placental volumes according to gestational age and estimated fetal weight were constructed, generating reference values.     

Use of Multiplanar 3‐Dimensional Ultrasonography for Prenatal Sex Identification

Objective. Determination of fetal sex is an important part of detailed second‐trimester ultrasonography. This task can be hindered by the fetal position, a low amniotic fluid volume, and advanced gestational age. Identification of fetal sex is further important in multiple gestations and prior histories of indeterminate‐sex pregnancies. The goal of the study was to compare the effectiveness of 2‐dimensional ultrasonography (2DUS) versus 3‐dimensional ultrasonography (3DUS) at sex identification and to determine how genitalia measurements taken with 3DUS technology compare with measurements taken with 2DUS. Methods. A total of 111 patients at or beyond 16 weeks' gestation were recruited. Assignments of fetal sex using 2DUS and 3DUS were compared by the test of proportions. The actual neonatal sex was obtained after delivery. Given such small number of misdiagnoses by either 2DUS or 3DUS, the accuracies of the two modalities were not found to be statistically distinguishable from one another (P = .5585). The penile length, scrotal width, and bilabial diameter according to gestational age were measured and compared with previously published 2DUS data by t tests. Results. Sexes were assigned and interpreted in 65 cases. Ranges of genitalia measurements were plotted against gestational age and were found to be comparable with published data. There was a dramatic difference between the bilabial diameter and scrotal width with advancing gestational age that made sex determination much easier in the third trimester. Conclusions. Although 3DUS did not have better prediction of fetal sex when compared with 2DUS, it may be a useful tool in conjunction with traditional imaging techniques in assigning fetal sex.     

Development of the Fetal Spinal Cord

Objective. The purpose of this study was to perform high‐resolution sonographic examinations to determine the normal anatomic relationship of the conus medullaris (CM) of the spinal cord with the vertebral column during different stages of gestation. Methods. In this prospective study, fetal sonographic evaluations were performed between 13 and 40 weeks' gestation. Transvaginal probes (7.5–8 MHz) or abdominal probes (5–8 MHz) were used, depending on gestational age and position of the fetus. The CM was located in coronal longitudinal sections. The positions of the kidneys and lumbosacral junction and the origin of the ribs determined the location of the vertebrae. The locations of the CM were divided into 5 groups according to their positions relative to the vertebrae. Results. A total of 110 fetuses between 13 and 40 weeks' gestation were studied. Between 13 and 18 weeks' gestation, the CM was situated at the level of the L4 vertebra, or more caudally, in 100% of the fetuses. At term, all fetuses showed the CM above L2. A distinct ascent of the CM was detected between 13 and 40 weeks' gestation. The results were statistically significant (P <.0001). Conclusions. A distinguishable ascent of the CM in relation to the vertebral column during fetal life was detected.     

经腹超声检测胎儿小脑蚓部及其临床意义

目的 建立不同孕周正常胎儿小脑蚓部的正常值,并探讨其在评估小脑蚓部发育不全中的临床价值.方法 采用经腹超声测量111例20～40孕周正常胎儿小脑蚓部正中矢状面的前后径(AP)和顶尾径(CC).按照上述测值对15例枕大池扩张的胎儿进行评估.结果 ①小脑蚓部AP、CC随孕周(GA)增加而增大(P＜O.05),整个妊娠过程呈线性相关(AP=-5.406+O.761 GA,r=0.97;CC=-5.795+0.783GA,r=0.973);②正中矢状断面小脑蚓部的测值和原裂、次裂、第四脑室顶部的声像图解剖特征有助于确认小脑蚓部发育畸形.结论 经腹超声是确认中晚期妊娠胎儿小脑蚓部发育异常的有效诊断方法.     

A Thai Reference for Normal Fetal Nasal Bone Length at 15 to 23 Weeks' Gestation

Objective. The purpose of this study was to establish a Thai reference for normal fetal nasal bone length at 15 to 23 weeks' gestation. Methods. The fetal nasal bone was measured by sonography in 295 pregnant women at 15 to 23 weeks' gestation from May to August 2005. One of the first 4 authors performed 3 measurements for each woman when the fetus was in the midsagittal plane and the nasal bone was close to a 45° or 135° angle to the ultrasound beam. All neonates were examined after delivery to confirm an absence of congenital abnormalities. Results. The median nasal bone length increased by gestational age from 3.6 mm at 15 weeks to 7.3 mm at 23 weeks in a linear relationship. The fifth percentile nasal bone lengths were 2.5, 3.04, 3.28, 3.64, 4.21, 4.82, 5.69, and 6.13 mm at 15, 16, 17, 18, 19, 20, 21, and 22 weeks, respectively. The median time for measurement was 5 minutes. Conclusions. The nasal bone length in Thai fetuses at 15 to 23 weeks was found to be on average shorter than that in white and African American fetuses.     

Utility of Fetal Echocardiography After Normal Cardiac Imaging Findings on Detailed Fetal Anatomic Ultrasonography

Objective. The purpose of this study was to assess the utility of fetal echocardiography (FE) after normal fetal cardiac imaging findings during detailed fetal anatomic ultrasonography (FAU). Methods. We conducted a retrospective cohort review of obstetric ultrasonographic studies from November 2001 through July 2005. We identified women with a singleton gestation with increased risk for congenital heart disease who received FAU performed by a maternal‐fetal medicine specialist at 16 to 20 weeks' gestation with subsequent FE. These records were compared with newborn outcomes. Results. Of 789 pregnancies that had FAU and FE, 481 had satisfactory cardiac imaging. Of those, only 1 fetus had abnormal FE findings. After delivery, 4 of the 480 neonates with normal FAU and FE findings had a diagnosis of a heart defect. Conclusions. Fetal echocardiography does not substantially increase the detection rate of major cardiac anomalies after normal findings on detailed FAU performed by a maternal‐fetal medicine specialist.     

Methodology for Using 3‐Dimensional Sonography to Measure Fetal Adrenal Gland Volumes in Pregnant Women With and Without Early Life Stress

Fetal adrenal gland volumes on 3‐dimensional sonography have been studied as potential predictors of preterm birth. However, no consistent methodology has been published. This article describes the methodology used in a study that is evaluating the effects of maternal early life stress on fetal adrenal growth to allow other researchers to compare methodologies across studies. Fetal volumetric data were obtained in 36 women at 20 to 22 and 28 to 30 weeks' gestation. Two independent examiners measured multiple images of a single fetal adrenal gland from each sonogram. Intra‐ and inter‐rater consistency was examined. In addition, fetal adrenal volumes between male and female fetuses were reported. The intra‐ and inter‐rater reliability was satisfactory when the mean of 3 measurements from each rater was used. At 20 weeks' gestation, male fetuses had larger average adjusted adrenal volumes than female fetuses (mean, 0.897 versus 0.638; P = .004). At 28 weeks' gestation, the fetal weight was more influential in determining values for adjusted fetal adrenal volume (0.672 for male fetuses versus 0.526 for female fetuses; P = .034). This article presents a methodology for assessing fetal adrenal volume using 3‐dimensional sonography that can be used by other researchers to provide more consistency across studies.     

Interobserver Reproducibility of Transabdominal 3‐Dimensional Sonography of the Fetal Brain

Objective. The purpose of this study was to assess the interobserver reproducibility of transabdominal 3‐dimensional (3D) fetal neurosonography. Methods. This was a prospective observational study. We studied 23 consecutive singleton pregnancies between 18 and 23 weeks' gestation. All cases had normal fetal neurosonographic examination findings, which were confirmed after birth. A 3D sonographic volume of the fetal head was acquired transabdominally by a single operator using an axial approach. Fetal brain anatomy was later analyzed offline by 2 different operators. Axial, sagittal, and coronal views of the fetal brain were obtained to perform a detailed evaluation of the fetal brain. Each operator defined the scanning planes obtained as adequate or inadequate. Results were evaluated with 2 × 2 tables and the Cohen κ coefficient to assess interobserver agreement. Results. Good‐quality multiplanar images were obtained in 23 of 23 cases. The rate of adequate visualization was 100% for all of the axial planes, with κ values of 1.00. For sagittal and coronal planes, the rate of visualization ranged between 78% and 91%, with κ values ranging between 0.61 and 0.83. Conclusions. Transabdominal 3D sonography of the fetal brain at 18 to 23 weeks' gestation has an acceptable degree of interobserver reproducibility.     

三维超声测量胎儿脑干-小脑蚓部夹角和脑干-小脑幕夹角

目的 测量正常胎儿脑干-小脑蚓部夹角(BV角)和脑干-小脑幕夹角(BT角),以定量评估脑干上方小脑蚓部旋转角度和小脑幕插入角度及其与孕周的相关性.方法 应用三维超声容积对比成像技术获取221胎20~37周正常胎儿的小脑蚓部正中矢状切面图像,测量BV角与BT角;并进行重复性检验,分析其与孕周相关性.结果 BV角与BT角测量的可重复性较好,且二者与孕周均无相关(r=-0.39、0.38,P均>0.05);221胎正常胎儿的BV角的正常值范围为1.60°~19.50°,BT角的正常值范围为15.70°~47.80°.结论 BV角和BT角可作为定量衡量脑干上方小脑蚓部旋转角度和小脑幕插入角度的简单、可重复性强的参数;计算二者的正常值范围可进一步为鉴别诊断胎儿颅后窝池畸形提供帮助.     

Nomograms of the Axial Transverse Diameter of the Fetal Foramen Magnum Between 14 and 40 Weeks' Gestation

Objective. The purpose of this study was to create reference range nomograms of the axial transverse diameter of the fetal foramen magnum (TDFM) between 14 and 40 weeks' gestation. Methods. This cross‐sectional study included pregnant patients between 14 and 41 weeks' gestation. Inclusion criteria consisted of well‐established dates (confirmed by early sonography) and nonanomalous singleton fetuses with intact amniotic membranes. Sonographic measurements included biparietal diameter, head circumference, abdominal circumference, femur length, humerus length, transcerebellar diameter, and sonographically estimated fetal weight. Values of the TDFM were each calculated as the mean of 3 separate measurements. The 5th, 50th, and 95th percentiles were estimated at each week of gestational age (GA) by least squares regression for the mean and SD of the TDFM as functions of GA. R² and associated P values for the relationships between the TDFM and other biometric measurements were calculated. Results. The study included 602 consecutive patients meeting the inclusion criteria. The mean maternal age ± SD was 27.5 ± 6.4 years; median gravidity, 3 (range, 1–12); and median parity, 1 (range, 0–7). The mean TDFM was 13.5 ± 3.7 mm. The reference curve formulas for the mean and SD of the TDFM (mm) were TDFM = ?12.58 + GA/0.5616 – GA ² /24.9 + GA ³ /2430.7, and SD_TDFM = 1.05 – GA/19.4 + GA ² /588.8. The TDFM correlated significantly and strongly with biparietal diameter, head circumference, abdominal circumference, humerus length, femur length, transcerebellar diameter, and estimated fetal weight (all R² ≥ 0.90; all P < .0001). Conclusions. We present reference range nomograms of the TDFM between 14 and 40 weeks' gestation.     

Patterns of Fetal Growth in a Rural Indian Cohort and Comparison With a Western European Population

Objective. The purpose of this study was to describe fetal size on sonography in a rural Indian population and compare it with those in European and urban Indian populations. Methods . Participants were from the Pune Maternal Nutrition Study of India. Fetal growth curves were constructed from serial ultrasound scans at approximately 18, 30, and 36 weeks' gestation in 653 singleton pregnancies. Measurements included femur length (FL), abdominal circumference (AC), biparietal diameter (BPD), and occipitofrontal diameter, from which head circumference (HC) was estimated. Measurements were compared with data from a large population‐based study in France and a study of urban mothers in Vellore, south India. Results. Fetal AC and BPD were smaller than the French reference at 18 weeks' gestation (?1.38 and ?1.30 SD, respectively), whereas FL and HC were more comparable (?0.77 and ?0.59 SD). The deficit remained similar at 36 weeks for AC (?0.97 SD), FL (?0.43 SD), and HC (?0.52 SD) and increased for BPD (?2.3 SD). Sonography at 18 weeks underestimated gestational age compared with the last menstrual period date by a median of ?1.4 (interquartile range, ?4.6, 1.8) days. The Pune fetuses were smaller, even at the first scan, than the urban Vellore sample. Conclusions. Fetal size was smaller in a rural Indian population than in European and urban Indian populations, even in mid pregnancy. The deficit varied for different fetal measurements; it was greatest for AC and BPD and least for FL and HC.     

Association of Crown‐Rump Length at 11 to 14 Weeks' Gestation and Risk of a Large‐for‐Gestational‐Age Neonate

Objective. The purpose of this study was to evaluate the association between crown‐rump length (CRL) and the risk of a large‐for‐gestational‐age (LGA) neonate. Methods. Data were retrospectively collected on consecutive women with a healthy singleton pregnancy followed to delivery at our center from 2003 to 2006 who underwent nuchal translucency, pregnancy‐associated plasma protein‐A, and free β‐human chorionic gonadotropin screening at 11 to 14 weeks' gestation. Pregnancies were dated by the last menstrual period (LMP) confirmed by CRL at 6 to 10 weeks or the known time of fertilization. The fetal CRL at 11 to 14 weeks was obtained from frozen sonographic images. The measured CRL was converted to gestational weeks using the method of Hadlock et al (Radiology 1992; 182:501–505). The expected gestational age (GA) by the LMP was subtracted from the measured GA to yield the ΔCRL. The association between the ΔCRL and birth weight was statistically analyzed. Results. The sample included 521 women. Fifty neonates (9.6%) were LGA (≥90th percentile), 38 (7.3%) small for gestational age, and 433 (83.1%) appropriate for gestational age. The LGA group was characterized by significantly larger‐than‐expected CRL measurements (P = .033). The birth weight percentile and rate of LGA neonates were significantly higher in pregnancies in which the ΔCRL was ½ week or greater (P = .007 and .033, respectively). There was a significant linear correlation between the ΔCRL and birth weight percentile (P = .001). On multivariate logistic regression analysis, the ΔCRL was the only significant predictor of an LGA neonate (odds ratio, 1.6; 95% confidence interval, 1.07–2.4; P = .023). Conclusions. Pregnancies with LGA neonates are characterized by larger‐than‐expected CRL measurements at 11 to 14 weeks' gestation.     

Clinical Findings of Multiple Pregnancy With a Complete Hydatidiform Mole and Coexisting Fetus

Objective. The aim of this series was to evaluate the clinical features, management, and outcomes of multiple pregnancy with a complete hydatidiform mole and coexisting fetus (CHMCF). Methods. Between 1998 and 2008, we investigated 6 women with a diagnosis of a CHMCF. The gestational age at diagnosis, symptoms, serum b‐human chorionic gonadotropin levels, cytogenetic and molecular analysis findings, complications, routes of delivery, and pregnancy outcomes were assessed. Results. All cases were diagnosed before 14 weeks' gestation by sonography. Only 1 ended with the delivery of a live‐born neonate, whereas the other 5 cases required termination of pregnancy (TOP) before 21 weeks' gestation because of severe maternal complications (eg, preeclampsia, thyrotoxicosis, lung metastasis, and heavy bleeding) or intrauterine fetal death. The pathologic diagnosis of a complete hydatidiform mole was confirmed in all cases. Two patients required methotrexate for treatment of persistent trophoblastic disease (PTD). Conclusions. On the basis of our experience, in cases with a normal karyotype and no gross fetal abnormalities on sonography, we carefully recommend continuation of pregnancy as long as maternal complications are absent or controllable. However, updated treatment criteria are still needed, and intensive maternal follow‐up is necessary in the postpartum period because maternal complications during pregnancy and PTD after TOP are not uncommon.     

Embryonic Heart Rate as a Prognostic Factor for Chromosomal Abnormalities

Objective. The purpose of this study was to evaluate the role of a slow embryonic heart rate in embryos before 7 weeks' gestation as a marker in screening for chromosomal abnormalities. Methods. Fifty‐seven embryos before 7 weeks' gestation with slow heart rates were compared with 1156 embryos of the same gestational period with normal heart rates. Embryos that showed an increased risk of chromosomal abnormalities in the screening blood tests underwent invasive analysis for abnormal karyotype detection. Results. The rates of first‐trimester death were 15.8% for pregnancies with slow embryonic heart rates (9 of 57) and 2.5% for those with normal heart rates (29 of 1156). Because of the increased risk of chromosomal abnormalities, amniocentesis was performed on 6 with slow embryonic heart rates and 61 with normal embryonic heart rates. After karyotype analysis, there were 2 fetuses with trisomy 21 in each group, which represented significantly higher percentage of embryos with trisomy 21 in the slow–heart rate group compared with the normal–heart rate group (P < .05). Conclusions. When a slow embryonic heart rate is detected before 7 weeks' gestation, there is a higher likelihood of chromosomal abnormalities.     

A prospective evaluation of fetal femur length as a predictor of gestational age.

Variability (+/- 2 SD) in prediction of fetal gestational age from ultrasonographic measurements of fetal femur length was evaluated prospectively in 287 fetuses between 18 and 42 weeks' gestation. Variability increased throughout pregnancy, ranging from +/- 11.6 days between 18 and 24 weeks to +/- 22.7 days in the last six weeks of pregnancy. These findings are comparable with variability in prediction of gestational age from biparietal diameter measurement between 18 and 42 weeks, which indicates that the femur length may serve as an adequate alternative for prediction of gestational age in cases in which the biparietal diameter cannot, for technical reasons, be obtained.     

Sonographic diagnosis of a viable abdominal pregnancy with planned delivery after fetal lung maturation

We report a case of a viable abdominal pregnancy with successful outpatient management until fetal lung maturation and planned delivery. Advanced abdominal pregnancy is a very rare extrauterine pregnancy, which results in serious maternal and fetal morbidity. A 28‐year‐old nullipara was referred from the local clinic to our tertiary center at 18 weeks' gestation. We diagnosed an extrauterine fetus on sonographic examination. The patient had weekly antenatal sonographic examinations. We performed a planned laparotomy at 34 weeks' gestation, and a female baby weighing 2,100 g was delivered. The placenta was completely removed and the uterus was preserved. Both the mother and the baby had no postoperative morbidity. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound 41 :563–565, 2013.     

Three‐Dimensional Sonography of Placental Mesenchymal Dysplasia and Its Differential Diagnosis

Objective. Placental mesenchymal dysplasia (PMD) is an uncommon vascular anomaly of the placenta characterized by mesenchymal stem villous hyperplasia. Its main sonographic feature is a thickened placenta with hypoechoic areas, and an accurate sonographic diagnosis is challenging. The aim of this study was to report 2 cases of PMD and discuss the differential diagnosis of its sonographic features. Methods. Cases of placental masses were studied by 2‐dimensional (2D), 3‐dimensional (3D), and color Doppler imaging. Results. In case 1, a thick placenta with multiple hypoechoic areas was noted at 13 weeks' gestation. At 19 weeks, the multicystic area, clearly demarcated from a normal‐looking placenta, measured 6.5 × 8.5 cm and enlarged gradually. The patient gave birth to a 625‐g female neonate after spontaneous labor at almost 26 weeks' gestation. In case 2, a first sonographic examination at 25 weeks' gestation revealed a thickened placenta with hypoechoic areas and a fetus with a single umbilical artery and a ventricular septal defect. At 27 weeks, the abnormal area of the placenta measured 14.5 × 7.5 cm. At 32 weeks' gestation, a caesarean delivery was performed because of a nonreassuring fetal heart tracing, and a 1415‐g female neonate was delivered. Both cases were evaluated by 2D, 3D, and color Doppler imaging, and the pathologic features of both placentas were consistent with PMD. Conclusions. Placental mesenchymal dysplasia should be considered in the differential diagnosis of every placental mass, especially in cases of multicystic placental lesion with lack of high‐velocity signals inside the lesion, and a normal karyotype.     

The fetal cerebellar vermis: anatomy and biometric assessment using volume contrast imaging in the C-plane (VCI-C).

OBJECTIVES: To describe the normal appearance and study the biometry of the fetal cerebellar vermis by three-dimensional (3D) volume contrast imaging in the coronal (C-) plane (VCI-C). METHODS: A total of 203 normally developed fetuses were examined prospectively at 18-33 weeks' gestation. At the level of the view used to measure the transverse cerebellar diameter (TCD), a VCI-C plane was displayed to examine, using a transabdominal probe, the fetal mid-saggital vermis. The volumes acquired were stored for later review and measurement of the anteroposterior (AP) diameter, craniocaudal (CC) diameter and surface area of the cerebellar vermis. Each dataset was evaluated by two independent observers. Measurements as a function of gestational age (GA), biparietal diameter (BPD), head circumference (HC) and TCD were expressed by regression equations. Interobserver variability was evaluated. Nomograms were produced. In order to validate the use of VCI in fetal biometry, datasets from 57 patients were selected arbitrarily for comparison of their VCI-C measurements with those from mid-sagittal sections of a stored 3D multiplanar examination. Intraclass correlation was used to evaluate the agreement between these measurements. RESULTS: The mean maternal age was 32 years. We were able to measure mid-sagittal CC diameter, mid-sagittal AP diameter and cerebellar vermis surface area in all fetuses. Interobserver variability analysis showed no significant differences between the two observers (P > 0.05). Measurements of the cerebellar vermis (AP diameter, CC diameter and surface area) correlated linearly with GA, BPD, HC and TCD (r > or = 0.82, P < 0.0001). CC and AP diameters estimated from the mid-sagittal section of the multiplanar measurements were significantly correlated with VCI-C measurements (r = 0.96, P < 0.00001 and r = 0.95, P < 0.00001, respectively). CONCLUSIONS: VCI-C is a valuable tool, allowing intrauterine assessment of the normal appearance of the fetal cerebellar vermis. The nomograms developed in this study should enable accurate evaluation of the cerebellar vermis.