Adverse outcome following selective termination of presenting twin vs non-presenting twin.

OBJECTIVE: Data are lacking on the impact on pregnancy outcome of the position of the abnormal fetus in a discordant twin pregnancy undergoing selective termination (ST). Tissue maceration post ST of the presenting twin may lead to early rupture of membranes, amnionitis and preterm labor. The aim of this study was to evaluate pregnancy complications and outcome following ST of the presenting vs non-presenting twin. METHODS: This was a multicenter retrospective cohort study of dichorionic diamniotic twin pregnancies that underwent ST due to a discordant fetal anomaly (structural or genetic) between 2007 and 2021. The study population was divided into two groups according to the position of the reduced twin (presenting or non-presenting) and outcomes were studied accordingly. The primary outcome was a composite of early complications following ST, including infection, preterm prelabor rupture of membranes and pregnancy loss. RESULTS: A total of 190 dichorionic twin pregnancies were included, of which 73 underwent ST of the presenting twin and 117 of the non-presenting twin. The groups did not differ in either baseline demographic characteristics or mean gestational age at the time of the procedure. ST of the presenting twin resulted in a significantly higher rate of early complications compared with the non-presenting twin (19.2% vs 7.7%; P = 0.018). Moreover, the rates of preterm delivery (75.3% vs 37.6%; P < 0.001) and neonatal intensive care unit admission (45.3% vs 17.1%; P < 0.001) were higher, and birth weight was lower (P < 0.001), in those pregnancies in which the presenting twin was reduced. CONCLUSIONS: ST of the presenting twin resulted in a higher rate of adverse pregnancy outcome compared with that of the non-presenting twin. These findings should be acknowledged during patient counseling and, if legislation permits, taken into consideration when planning ST. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Medullary Tegmental Cap Dysplasia: Fetal and Postnatal Presentations of a Unique Brainstem Malformation.

BACKGROUND AND PURPOSE: Medullary tegmental cap dysplasia is a rare brainstem malformation, first described and defined by James Barkovich in his book Pediatric Neuroimaging from 2005 as an anomalous mass protruding from the posterior medullary surface. We describe the neuroimaging, clinical, postmortem, and genetic findings defining this unique malformation. MATERIALS AND METHODS: This is a multicenter, international, retrospective study. We assessed the patients' medical records, prenatal ultrasounds, MR images, genetic findings, and postmortem results. We reviewed the medical literature for all studies depicting medullary malformations and evaluated cases in which a dorsal medullary protuberance was described. RESULTS: We collected 13 patients: 3 fetuses and 10 children. The medullary caps had multiple characteristics. Associated brain findings were a rotated position of the medulla, a small and flat pons, cerebellar anomalies, a molar tooth sign, and agenesis of the corpus callosum. Systemic findings included the following: polydactyly, hallux valgus, large ears, and coarse facies. Postmortem analysis in 3 patients revealed that the cap contained either neurons or white matter tracts. We found 8 publications describing a dorsal medullary protuberance in 27 patients. The syndromic diagnosis was Joubert-Boltshauser syndrome in 11 and fibrodysplasia ossificans progressiva in 14 patients. CONCLUSIONS: This is the first study to describe a series of 13 patients with medullary tegmental cap dysplasia. The cap has different shapes: distinct in Joubert-Boltshauser syndrome and fibrodysplasia ossificans progressive. Due to the variations in the clinical, imaging, and postmortem findings, we conclude that there are multiple etiologies and pathophysiology. We suggest that in some patients, the pathophysiology might be abnormal axonal guidance.

Prenatal diagnosis of rhombencephalosynapsis: neuroimaging features and severity of vermian anomaly.

OBJECTIVES: To describe the prenatal neuroimaging spectrum of rhombencephalosynapsis (RES) and criteria for its classification according to the severity of vermian anomaly. METHODS: In this multicenter retrospective study of fetuses with RES between 2002 and 2020, the medical records and brain ultrasound and magnetic resonance images were evaluated comprehensively to determine the severity of the vermian anomaly and the presence of associated brain findings. RES was classified, according to the pattern of vermian agenesis and the extent of the fusion of the hemispheres, as complete RES (complete absence of the vermis) or partial RES (further classified according to the part of the vermis that was missing and, consequently, the region of hemispheric fusion, as anterior, posterior, severe or mixed RES). Findings were compared between cases with complete and those with partial RES. RESULTS: Included in the study were 62 fetuses with a gestational age ranging between 12 and 37 weeks. Most had complete absence of the vermis (complete RES, 77.4% of cases), a 'round-shaped' cerebellum on axial views (72.6%) and a transverse cerebellar diameter (TCD) < 3rd centile (87.1%). Among the 22.6% of cases with partial RES, 6.5% were classified as severe partial, 6.5% as partial anterior, 8.1% as partial mixed and 1.6% as partial posterior. Half of these cases presented with normal or nearly normal cerebellar morphology and 28.5% had a TCD within the normal limits. Infratentorially, the fourth ventricle was abnormal in 88.7% of cases overall, and anomalies of the midbrain and pons were frequent (93.5% and 77.4%, respectively). Ventriculomegaly was observed in 80.6% of all cases, being more severe in cases with complete RES than in those with partial RES, with high rates of parenchymal and septal disruption. CONCLUSIONS: This study provides prenatal neuroimaging criteria for the diagnosis and classification of RES, and identification of related features, using ultrasound and magnetic resonance imaging. According to our findings, a diagnosis of RES should be considered in fetuses with a small TCD (severe cerebellar hypoplasia) and/or a round-shaped cerebellum on axial views, during the second or third trimester, especially when associated with ventriculomegaly. Partial RES is more common than previously thought, but presents an extreme diagnostic challenge, especially in cases with normal or nearly-normal cerebellar morphobiometric features. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Fourth ventricle index: sonographic marker for severe fetal vermian dysgenesis/agenesis.

OBJECTIVE: Prenatal diagnosis of midbrain-hindbrain (MB-HB) malformations relies primarily on abnormal size and shape of the cerebellum and retrocerebellar space, particularly 'open fourth ventricle' (4V), the most common indicator of MB-HB malformations. The aim of this study was to present the fourth ventricle index (4VI), and to evaluate its role as a marker for severe vermian dysgenesis/agenesis in cases without open 4V. METHODS: This was a prospective cross-sectional study of patients with singleton low-risk pregnancy at 14 + 1 to 36 + 6 gestational weeks presenting between May 2016 and November 2017 for routine ultrasound examination. Axial images of the fetal 4V were obtained and the 4VI was calculated as the ratio between the laterolateral and the anteroposterior diameters. Reference ranges were constructed and retrospectively collected values from 44 fetuses with confirmed anomalies involving severe vermian dysgenesis/agenesis (Joubert syndrome and related disorders, rhombencephalosynapsis, cobblestone malformations and cerebellar hypoplasia) but without open 4V were compared with the normal values. RESULTS: In total, 384 healthy fetuses were enrolled into the study, from which reference ranges were produced, and 44 cases were collected retrospectively. The 4VI in the normal fetuses was always > 1. In affected fetuses, it was always below mean -2 SD and < 1. CONCLUSIONS: The 4VI is a sonographic marker for severe fetal vermian dysgenesis/agenesis in the absence of an open 4V. It may be incorporated easily into the routine brain scan; 4VI < 1 indicates a need for dedicated fetal neuroimaging for diagnosis and prenatal counseling. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Application of a novel prenatal vertical cranial biometric measurement can improve accuracy of microcephaly diagnosis in utero.

OBJECTIVE: To construct a reference range for a new vertical measurement of the fetal head and to assess whether its combination with fetal head circumference (HC) can prevent the misdiagnosis of microcephaly in fetuses with an acrocephalic-like head deformation. METHODS: A new vertical cranial biometric measurement was defined: the foramen magnum-to-cranium distance (FCD), measured between the foramen magnum and the upper inner cranial border along the posterior wall of the brainstem. The measurement was performed in a precise mid-sagittal plane using a three-dimensional multiplanar display of a sagittally acquired sonographic volume of the fetal head. The normal reference range was developed by measuring 396 healthy fetuses of low-risk singleton pregnancies between 15 and 40 gestational weeks. This reference was applied to 25 fetuses with microcephaly diagnosed prenatally (Fmic) based on HC ≥ 3 SD below the mean for gestational age. We determined an optimal FCD cut-off for combination with HC to detect all cases found with microcephaly at birth (micB), while excluding the fetuses with normal head circumference at birth (NHCB), who were described postnatally as having an acrocephalic-like cranial deformation. RESULTS: In the healthy singleton fetuses, FCD increased with gestational age, with a quadratic equation providing an optimal fit to the data (adjusted R(2) = 0.934). The measurement could be assessed in 95.2% of cases. Of the 25 cases diagnosed with Fmic prenatally, on the basis of HC alone, 14 were micB and 11 were NHCB. We observed FCD below the mean - 2SD for gestational age in all 14 micB cases, but in only four of the 11 NHCB cases (P < 0.003). An acrocephalic-like cranial deformation was described at birth in five of the seven NHCB cases with normal FCD. The mean ± SD FCD Z-score of the micB cases was significantly lower (P < 0.001) than that of the false-positive ones: -3.85 ± 0.96 SD and -1.59 ± 1.45 SD, respectively. Based on HC measurement alone, the positive predictive value (PPV) was 56%. Combination of the HC and FCD criteria raised the PPV to 78%, decreasing the number of false positives from 11 to four, without missing any of the 14 micB cases. CONCLUSIONS: Fetal vertical cranial biometric assessment in the mid-sagittal plane is feasible and correlates well with gestational age. In our series, a vertical cranial deformation was a frequent cause of a false Fmic diagnosis made on the basis of HC alone. Combination of the new vertical cranial biometric measurement with HC measurement can exclude these cases and thus improve diagnostic accuracy for Fmic. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of microcephaly at birth using three reference ranges for fetal head circumference: can we improve prenatal diagnosis?

OBJECTIVE: To evaluate the prediction of microcephaly at birth (micB) using established and two new reference ranges for fetal head circumference (HC) and to assess whether integrating additional parameters can improve prediction. METHODS: Microcephaly in utero was defined as a fetal HC 3SD below the mean for gestational age according to Jeanty et al.'s reference range. The records of cases with fetal microcephaly (Fmic) were evaluated for medical history, imaging findings, biometry and postnatal examination/autopsy findings. Microcephaly was confirmed at birth (micB) by an occipitofrontal circumference (OFC) or a brain weight at autopsy 2SD below the mean for gestational age. The new INTERGROWTH-21(st) Project and a recent Israeli reference for fetal growth were applied for evaluation of the Fmic positive predictive value (PPV) for diagnosis of micB cases. Optimal HC cut-offs were determined for each of the new references with the aim of detecting all micB cases whilst minimizing the number of false positives found to have a normal HC at birth. We also assessed the difference between the Z-scores of the prenatal HC and the corresponding OFC at birth, the frequency of small-for-gestational age (SGA), decreased HC/abdominal circumference (AC) and HC/femur length (FL) ratios, the prevalence of associated malformations and family history. RESULTS: Forty-two fetuses were diagnosed as having Fmic according to the Jeanty reference, but micB was confirmed in only 24 (PPV, 57.1%). The optimal INTERGROWTH and Israeli reference HC cut-offs for micB diagnosis were mean - 3SD and mean - 2.3SD, resulting in a statistically non-significant improvement in PPV to 61.5% and 66.7%, respectively. The presence of a family history of microcephaly, SGA, associated malformations and application of stricter HC cut-offs resulted in a higher PPV of micB, although not statistically significant and with a concurrent increase in the number of false-negative results. The deviation of the HC from the mean, by all references, was significantly larger compared with the actual deviation of the OFC at birth, with mean differences between the corresponding Z-scores of -1.15, -1.95 and -0.74 for the Jeanty, INTERGROWTH and Israeli references, respectively. CONCLUSIONS: The evaluated reference ranges all result in considerable over-diagnosis of fetal microcephaly. The use of the two new HC reference ranges did not significantly improve micB prediction compared with that of Jeanty et al., whilst use of additional characteristics and stricter HC cut-offs could improve the PPV with an increase in false negatives. The postnatal OFC deviates significantly less from the mean compared with the prenatal HC, and we propose that adjustment for this would enable better prediction of the actual OFC deviation at birth. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Early detection by diffusion-weighted sequence magnetic resonance imaging of severe brain lesions after fetoscopic laser coagulation for twin-twin transfusion syndrome.

OBJECTIVE: Monochorionic twins treated by fetoscopic laser coagulation (FLC) for twin-twin transfusion syndrome (TTTS) are at increased risk of neurodevelopmental impairment. Our aim was to evaluate the additional value of diffusion-weighted imaging (DWI) over fetal sonography and T2 magnetic resonance imaging (MRI) in the detection of acute ischemic cerebral lesions shortly following FLC. METHODS: This was a prospective cohort study of fetuses with TTTS treated by FLC. All fetuses underwent brain DWI and T2-MRI within 24-96 h after the procedure and a follow-up MRI at 30-32 weeks' gestation. All fetuses also had frequent ultrasound evaluation until delivery. RESULTS: Thirty pregnancies with TTTS were included in the study. Eight resulted in survival of only one twin after the procedure (Group A), while the other 22 pregnancies resulted in the survival of both twins (Group B), as assessed at the time of initial MRI. Two fetuses in Group A and four in Group B had evidence of transient bleeding in the germinal matrix. Three fetuses in Group B and none in Group A had diffuse ischemic changes in the white matter. One fetus died in utero 24 h after MRI. The other two fetuses in Group B demonstrated an acute infarct 24-48 h after the procedure. Subsequent scans at 28-29 and 32 weeks showed brain atrophy compatible with an old infarct. CONCLUSIONS: DWI can demonstrate cerebral damage immediately after FLC. Larger cohorts are needed to determine the role of fetal MRI in the prenatal assessment and follow-up of patients with TTTS.

Late diagnosis of fetal central nervous system anomalies following a normal second trimester anatomy scan.

OBJECTIVE: The aim of this study was to describe the nature of central nervous system (CNS) anomalies diagnosed during the third trimester following a normal anatomy scan at 21-24 weeks of gestation. METHODS: Retrospective cohort study of all pregnant women referred to the fetal medicine unit at Sheba Medical Center between 2005 and 2011 due to fetal CNS anomalies detected at the late second and third trimesters following a normal anatomy scan at 21-24 weeks of gestation. RESULTS: During the study period, 47 patients were diagnosed with fetal CNS anomalies at a median gestational age of 31.1 weeks (range 24-38). The four most common anomalies found included intracranial cysts (19%), mild ventriculomegaly (15%), absence or dysgenesis of the corpus callosum (10%), and intracerebral hemorrhage (10%). Other CNS anomalies detected in this group of patients included hydrocephalus, Dandy walker malformation, large cysterna magna, microcephalus with lissencephaly, craniosynestosis, periventricular pseudocysts, global brain ischemia, cerebellar hypoplasia, and sub-ependymal nodule. CONCLUSIONS: Fetal brain continues to evolve throughout gestation, and therefore, some of the CNS anomalies can be diagnosed only during late second and third trimesters of pregnancy. Consequently, in patients who have a third trimester scan for any reason, assessment of the fetal CNS should be considered.

Diffusion MRI findings in monochorionic twin pregnancies after intrauterine fetal death.

BACKGROUND AND PURPOSE: Monochorionic twin pregnancies complicated by the IUFD of 1 twin are associated with substantial morbidity to the survivor twin. The aim of this study was to determine whether fetal sonography, T2 MR imaging, and DWI can diagnose acute cerebral lesions in the survivor of an MC twin pregnancy shortly after fetal death of the co-twin. MATERIALS AND METHODS: During the study period (2007-2010) 34 cases of single IUFD were evaluated. Group A included 6 cases complicated by spontaneous IUFD. Group B had 10 cases of fetal death shortly after treatment of severe TTTS. These were compared with group C, with 18 pregnancies treated by selective termination due to severe complications in MC pregnancies. RESULTS: Altogether 9/34 patients had abnormal prenatal cerebral findings. In group A, in 2/6 of pregnancies with spontaneous death, MR imaging showed findings of severe cerebral infarct, while cerebral damage was not evident by sonography. In another case, the surviving fetus was found to be hydropic on sonography, while MR imaging findings were normal. In group B, in 1/10 cases, cerebral infarct was demonstrated only by DWI. In 2 other cases, sonographic findings were normal, but MR imaging showed germinal matrix bleeding. In group C, in 1/18 cases, only DWI showed bilateral cerebral ischemia. In 2 other cases, MR imaging findings suggested germinal matrix bleeding and focal changes in the basal ganglia. In both cases, fetal sonographic findings were normal. CONCLUSIONS: In our study, early manifestations of cerebral ischemia in monochorionic twin pregnancies were better diagnosed with MR imaging, especially with DWI.

3-Dimensional demonstration of fetal anal canal and sphincter.

PURPOSE: To identify the fetal anal canal and sphincter using 3-dimensional (3 D) ultrasound. MATERIALS AND METHODS: 3 D volumes of the fetal pelvis were acquired prospectively in 52 fetuses between 10 and 39 gestational weeks. A standard method for evaluating the fetal anal canal and sphincter was developed. Measurements of mucosal and muscular circumferences and the length of the anal canal were taken. RESULTS: The anal canal was demonstrated in 46 out of 50 patients (92 %). The sonographic characteristics of the anal canal in the axial plane appear like a "target sign" with an echogenic mucosa in the center, the hypoechoic internal sphincter muscle surrounding it and an outer echogenic circle reflecting the external sphincter. Measurements of mucosal and internal sphincter circumferences and the length of the anal canal demonstrated linear growth during pregnancy (p < 0.01). One case of anal atresia was demonstrated. CONCLUSION: The fetal anal canal can be visualized when a systematic analysis is performed using a 3 D volume dataset.

Comparison of ex-vivo high-resolution episcopic microscopy with in-vivo four-dimensional high-resolution transvaginal sonography of the first-trimester fetal heart.

OBJECTIVE: To compare the capability of three-dimensional (3D) reconstructed images produced by high-resolution episcopic microscopy (HREM) with that of in-vivo four-dimensional high-resolution transvaginal sonography (4D-HRTVS) to discern morphological features of the first-trimester human fetal heart. METHODS: This was a prospective study of fetal hearts between 9 and 14 weeks' gestation. For ex-vivo 3D analysis, 30 human fetal hearts (at 9 + 0 to 14 + 6 weeks) were retrieved from surgical terminations of pregnancy. The specimens were embedded in resin and episcopic ('block-face') imaging was used to obtain a digital volume dataset (HREM) using 3-micron slicing. 4D-HRTVS was performed in 28 separate pregnancies at 10 + 2 to 14 + 0 weeks using a Voluson E8 ultrasound machine with volumetric transvaginal RIC 6-12-MHz transducers. Heart volumes obtained by both methods were compared to assess their ability to demonstrate first-trimester cardiac morphology. Comparisons were made in the transverse and sagittal planes, and using volume rendering. RESULTS: All hearts were structurally normal, although abdominal situs was not examined in the isolated hearts that underwent HREM. 4D-HRTVS demonstrated each of the complete five transverse cardiac views in 32-86% of cases. HREM showed four features unique to the first-trimester human heart: prominent atrial appendages, spiral ventricular arrangement, prominent coronary arteries and thickened arterial walls. 4D-HRTVS could demonstrate the first two, but ultrasound resolution was too poor to quantify wall thickness and demonstrate coronary arteries in the 3-5-mm diameter heart. CONCLUSIONS: 4D-HRTVS showed limited morphological features of the first-trimester fetal heart compared with HREM. HREM provides a gold standard of ex-vivo imaging against which developments in ultrasound resolution could be compared.

Umbilical vein anomaly in fetuses with Down syndrome.

OBJECTIVE: To describe the prevalence of abnormal umbilical vein (UV) anatomy in fetuses with Down syndrome. METHODS: This was a retrospective survey covering a 24-month period of fetuses with a genetic diagnosis of Down syndrome following a routine early second-trimester (12-16-week) detailed fetal anomaly scan at a single academic tertiary referral center. In our unit this exam includes fetal umbilicoportal venous system evaluation. RESULTS: During the study period, 37 fetuses were diagnosed with Down syndrome and had a detailed early anatomy scan. In four (11%) the detailed early anomaly scan revealed that the UV was connected to the hepatic portion of the inferior vena cava (IVC) at a position lower than its usual site. Their average gestational age at diagnosis was 13 + 6 (range, 11 + 6 to 15 + 2) weeks. Three of the four fetuses had a nuchal translucency thickness of 3-4 mm. In one fetus there was an additional finding of significant tricuspid regurgitation and the one with normal nuchal translucency thickness had an atrioventricular septal defect (atrioventricular canal) and umbilical cord hernia. During the same period three of 2500 (0.12%) fetuses with normal karyotype demonstrated similar anomalous insertion of the UV into the IVC, creating a portocaval shunt which had normal ductus venosus-like Doppler flow in all three cases. The odds ratio for abnormal umbilicoportal venous system in fetuses with Down syndrome compared with the normal population was 107.4 (95% CI, 19.2-637.1). CONCLUSIONS: Fetuses with Down syndrome demonstrate an increased prevalence of abnormal connection of the UV to the IVC.

Prenatal diagnosis of congenital agenesis of the fetal portal venous system.

OBJECTIVE: To describe the prenatal diagnosis and review our experience of fetal congenital agenesis of the portal venous system (CAPVS) and to review the current literature on this poorly documented vascular malformation. METHODS: This was a retrospective survey covering the 12-year period between 1996 and 2008. The database of a single, large, ultrasonographic tertiary academic referral center in Israel was analyzed and cases with a prenatal diagnosis of CAPVS were identified. All fetuses underwent detailed biometric and structural ultrasound examinations and a precise anatomical description of the fetal umbilical, portal and hepatic venous system was noted, as well as the presence of aberrant vessels, shunt location and the presence or absence of the DV. Results of fetal echocardiography, karyotyping and toxoplasma, rubella, cytomegalovirus and herpes evaluations were determined. Medical records were evaluated. Diagnosis was confirmed by pathology, postmortem venography or neonatal ultrasound or venography. Liveborns were examined by a certified neonatologist and long-term follow-up from pediatric gastroenterology units was determined. RESULTS: Nine cases with CAPVS were studied. In all cases an aberrant umbilical-portal vein was the primary indication for detailed portal system evaluation. Five fetuses demonstrated total CAPVS (Type I) and four showed partial agenesis of the portal vein (Type II). Among the five Type I fetuses, there was a shunt from the umbilical vein to the inferior vena cava in three (60%), to the right atrium in one and to the coronary sinus in one. In this group, in only one case could we delineate a common confluence between the splenic vein and the superior mesenteric vein shunting to the inferior vena cava. In four cases termination of pregnancy was performed due to additional findings: one case with hydrothorax, ascites and mitral atresia, one with cleft lip/palate and one with trisomy 21. One case had no additional anomalies, but the parents elected to terminate the pregnancy. All four of the Type II fetuses had a portosystemic shunt: in two cases to the right atrium, in one to the iliac vein and in one to the right hepatic vein. In three, the shunt resolved spontaneously. In only one case was abnormal liver function present over a follow-up period of 2-10 years. CONCLUSION: CAPVS can be detected prenatally. An abnormal course of the umbilical vein necessitates prompt sonographic evaluation of the umbilical-portal venous system and meticulous investigation for additional anomalies. Complete CAPVS may be associated with remote clinical consequences of which the parents should be informed. Partial CAPVS has a favorable prognosis.

In-utero evaluation of the fetal umbilical-portal venous system: two- and three-dimensional ultrasonic study.

OBJECTIVES: To describe the normal anatomy of the fetal umbilical-portal venous system (UPVS) and to assess possible anatomical variants of the main portal vein (MPV) insertion into the portal sinus (PS). METHODS: This was a prospective cross-sectional study of low-risk patients between 14 and 36 weeks of gestation. Two- (2D) and three-dimensional (3D) ultrasound techniques combined with color and high-definition flow Doppler were used to evaluate the fetal UPVS. The standard transverse plane of the fetal upper abdomen, used for measuring the abdominal circumference, was taken in all cases as the point of reference. A longitudinal section was taken to identify the normal course of the umbilical vein and ductus venosus (DV). We performed offline analysis of all gray-scale and color Doppler 2D and 3D volume datasets. RESULTS: Two hundred and eight fetuses were included in the study. The umbilical vein was observed to course in a cephalad direction from its entry point into the fetal abdomen, joining the L-shaped PS, a confluence of vessels that is the main segment of the left portal vein (LPV). Three branches emerge from the LPV: two to the left, the inferior and superior branches, and one to the right, the medial branch. The main LPV then courses abruptly to the right. Following the emergence of the DV, the communication of the MPV with the LPV marks the point at which the vessel becomes the right portal vein (RPV), giving rise to its anterior and posterior branches. We were able to define three main variants of connection between the MPV and the PS. In 140 (67.3%) fetuses the MPV was connected to the LPV in an end-to-side T-shaped anastomosis, in 26 (12.5%) fetuses the MPV connected with a side-to-side X-shaped anastomosis and in 30 (14.4%) fetuses the two vessels ran in parallel with a short communicating segment, in an H-shaped anastomosis. In the remaining 12 (5.7%) cases classification into one of these three groups was not possible due to intermediate morphology. CONCLUSIONS: Knowing the normal anatomy of the UPVS and being aware of the possible variants of the connection between the MPV and the PS is a fundamental requirement for accurate prenatal diagnosis of the anomalies of the fetal UPVS.

Three and four dimensional ultrasound: a novel method for evaluating fetal cardiac anomalies.

OBJECTIVE: To evaluate the role of various new models of 3- and 4-dimensional (3D and 4D) ultrasound (US) applications in prenatal assessment of fetal cardiac anomalies. METHODS: Volume data sets of 81 fetuses with fetal cardiac anomalies, as previously diagnosed by 2D US, were acquired by 3D and cine 4D using spatiotemporal image correlation (STIC) software. Various additional rendering tools were applied. Color, power, high definition Doppler and B-flow were added to the volumes acquired. A retrospective offline analysis of the cardiac defects was performed. RESULTS: The mean gestational age at diagnosis was 24 weeks (range 13-38); 128 anomalies were detected and were classified into the following categories: I, Situs anomalies in 8 cases; II, abnormal four-chamber view in 63 cases; III, outflows tract anomalies in 27 cases; IV, arches anomalies in 21 cases; and V, veins anomalies in 9 cases. Rendering tools differed in each groups of anomalies. CONCLUSIONS: Fetal cardiac anomalies can be evaluated adequately by the information gained by 3D and 4D volumes obtained by STIC. Since no single module is sufficiently accurate for the diagnosis of all cardiac anomalies, each of the cardiac anomaly categories requires different and appropriate module of visualization.