In-utero evaluation of the fetal umbilical-portal venous system among fetuses with persistent right umbilical vein: Two-and three-dimensional ultrasonographic study.

OBJECTIVE: The aim of this study was to describe the anatomy of the portal system in fetuses with persistent right umbilical vein (PRUV). METHODS: Prospective observational study of fetuses diagnosed with PRUV. All patients underwent a comprehensive portal system anatomy scan supplemented by two-dimensional (2D) and three-dimensional (3D) color doppler modalities. RESULTS: 29 fetuses with PRUV were studied. We perceived an identical anatomical pattern in 28 fetuses. The right umbilical vein drains to the portal sinus (future right portal vein, RPV), which has a configuration of a left portal vein (LPV) in the normal left portal system, with three emerging branches: inferior (RPVi), medial (RPVm) and superior (RPVs). The RPV then courses to the left, towards the stomach to the point of the bifurcation of the main portal vein (MPV) to become the left portal vein. The LPV has an RPV configuration in a normal portal system with anterior (LPVa) and posterior (RPVp) branches. This anatomical layout mimics a mirror image of the normal anatomy of left portal system. CONCLUSION: PRUV has unique umbilical portal venous anatomy, which is a mirror image of the normal left portal system. It can be demonstrated prenatally and serve as an additional tool for prenatal diagnosis of PRUV.

Fetal Renal to Abdominal Ratio: A Constant Measurement Throughout Gestation.

BACKGROUND: Sonographic assessment of the fetal kidneys is an integral part of the prenatal anatomical survey. OBJECTIVES: To evaluate the fetal renal to abdominal (RTA) ratio throughout pregnancy and to investigate whether this ratio can be a potential diagnostic landmark for congenital anomalies of the kidney and urinary tract (CAKUT). METHODS: Measurements of the anterior-posterior diameters of the fetal kidney and fetal abdomen (APAD) were obtained prospectively. The RTA was calculated as the ratio between them in in two groups: normal population vs. CAKUT cases. RTA in CAKUT cases was compared to RTA in a normal population. RESULTS: The study group was comprised of 210 women. The mean gestational age for the fetuses was 31 ± 5.6 weeks (range 14-40 weeks). Fetal RTA ratio was found to be 0.28 ± 0.03 throughout pregnancy from early second trimester to term, with high reproducibility of measurements. During the study period the RTA was evaluated in nine cases referred for suspected CAKUT. All cases demonstrated a different ratio according to the renal anomaly. High ratio was observed in one case of overgrowth syndrome (Beckwith Wiedenmann syndrome; 0.47), three cases of infantile polycystic kidney (0.45-0.47), and three cases of a solitary kidney (0.31-0.35), while cases of dysplastic kidneys revealed a low ratio (0.14-0.18). CONCLUSIONS: Prenatal RTA ratio is constant throughout gestation. An abnormal ratio should lead to meticulous renal investigation to rule out kidney disease.

Three-dimensional ultrasonography of the fetal vermis at 18 to 26 weeks' gestation: time of appearance of the primary fissure.

OBJECTIVE: The purpose of this study was to establish the normality of the fetal vermis, ie, the time of appearance of the primary fissure, as well as its measurements between 18 and 26 weeks' gestation, using 3-dimensional (3D) ultrasonography. METHODS: A prospective cross-sectional study of normal singleton pregnancies was conducted. Examinations were performed with high-resolution transabdominal ultrasonography using the axial plane in 173 fetuses between 18 and 26 weeks' gestation. Postprocessing measurements of the fetal vermis were done with 4-dimensional software using static volume contrast imaging and tomographic ultrasound imaging in the C-plane. Detection of the primary fissure was evaluated in all cases, and the time of appearance was documented. RESULTS: Adequate vermis measurements were obtained in 173 fetuses. Vermian length as a function of gestational age was expressed by regression equations, and the correlation coefficients were found to be highly statistically significant (P < .001). The normal mean +/- 2 SD for each gestational week was defined. The primary fissure was observed at 24 weeks' gestation in all cases, at 22 weeks in 94% of cases, and as early as 18 weeks in 40%. CONCLUSIONS: This 3D study documents the appearance of the primary fissure and presents the normal range of vermian measurements, confirming normal development of the fetal vermis starting as early as 18 weeks' gestation. It also shows an easy method for visualizing the vermis with 3D ultrasonography at every gestational week regardless of fetal presentation.