MR imaging of the fetal musculoskeletal system.

Magnetic resonance imaging (MRI) appears to be increasingly used, in addition to standard ultrasonography for the diagnosis of abnormalities in utero. Previous studies have recently drawn attention to the technical refinement of MRI to visualize the fetal bones and muscles. Beyond commonly used T2-weighted MRI, echoplanar, thick-slab T2-weighted and dynamic sequences, and three-dimensional MRI techniques, are about to provide new imaging insights into the normal and the pathological musculoskeletal system of the fetus. This review emphasizes the potential significance of MRI in the visualization of the fetal musculoskeletal system.

Tumor disease and associated congenital abnormalities on prenatal MRI.

OBJECTIVE: Fetal tumors can have a devastating effect on the fetus, and may occur in association with congenital malformations. In view of the increasing role of fetal magnetic resonance imaging (MRI) as an adjunct to prenatal ultrasonography (US), we sought to demonstrate the visualization of fetal tumors, with regard to congenital abnormalities, on MRI. MATERIALS AND METHODS: This retrospective study included 18 fetuses with tumors depicted on fetal MRI after suspicious US findings. An MRI standard protocol was used to diagnose tumors judged as benign or malignant. All organ systems were assessed for tumor-related complications and other congenital malformations. Available US results and histopathology were compared with MRI. RESULTS: There were 13/18 (72.2%) benign and 5/18 (27.8%) malignant tumors diagnosed: a cerebral primitive neuroectodermal tumor in 1/18, head-neck teratomas in 4/18; ventricular rhabdomyomas in 4/18; a cardiac teratoma in 1/18; a hepatoblastoma in 1/18; neuroblastomas in 2/18; a cystic hemorrhagic adrenal hyperplasia in 1/18; a pelvic leiomyoma in 1/18; sacrococcygeal teratomas in 3/18. Tumor-related complications were present in 13/18 (72.2%) cases; other congenital abnormalities in 3/18 (16.7%). MRI diagnosis and histology were concordant in 8/11 (72.7%) cases. In 6/12 (50%) cases, US and MRI diagnoses were concordant, and, in 6/12 (50%) cases, additional MRI findings changed the US diagnosis. CONCLUSION: Our MRI results demonstrate the visualization of fetal tumors, with frequently encountered tumor-related complications, and other exceptional congenital abnormalities, which may provide important information for perinatal management. Compared to prenatal US, MRI may add important findings in certain cases.

First-trimester visualization of the fourth ventricle in fetuses with and without spina bifida.

OBJECTIVES: The purpose of this study was to examine the efficacy of nonvisualization of the fourth ventricle for first-trimester detection of spina bifida. METHODS: A total of 250 digitally stored sonographic examinations at gestational ages of 11 weeks to 13 weeks 6 days (245 normal and 5 randomly interspersed spina bifida cases) were retrospectively analyzed by 4 blinded reviewers for the presence or absence of the fourth ventricle followed by an anteroposterior ventricular dimension measurement. The ventricle size was related to the crown-rump length and gestational age by linear regression analysis and Pearson correlation. RESULTS: The fourth ventricle was identified in 971 of 1000 image readings (97.1%). False-negative and false-positive readings occurred in 11 of 20 (55.0%) and 20 of 980 (2.0%) cases, respectively (sensitivity, 0.45; specificity, 0.98.). False-negative and false-positive readings were evenly distributed throughout the gestational age range. When the ventricular size was measurable, its mean dimensions increased linearly with gestational age and were below the fifth percentile in 10 of 245 (4.0%) normal and 0 of 4 spina bifida cases, respectively. Intraclass correlation coefficient estimates were calculated based on the 2-way analysis of variance model and found to be 0.30 for a single rater and 0.64 for the mean of 4 raters. CONCLUSIONS: Nonvisualization of the first-trimester fourth ventricle is a less robust screening parameter for spina bifida than previously published.

Abnormalities of the penis in utero--hypospadias on fetal MRI.

OBJECTIVE: To demonstrate the visualization of penile abnormalities on fetal magnetic resonance imaging (MRI). METHODS: This retrospective study included five fetuses (25+0 to 31+6 gestational weeks) with penile abnormalities, positively depicted on fetal MRI, using prenatal ultrasonography (US) as a standard of reference. On MRI, the penis, as well as the scrotum and testicles, were evaluated. All fetal organs were reviewed to define penile abnormalities as isolated or in association with other anomalies. Furthermore, US and MRI findings were compared. RESULTS: Posterior hypospadias were demonstrated in all five fetuses, and abnormal testicular descent in two. Associated anomalies were present in all five fetuses on MRI, including abdominal/urogenital pathologies in four; brain pathologies in three; and craniofacial, cardiac, musculoskeletal, pathologies each in one fetus, and intrauterine growth retardation in one fetus. Compared to US, additional MRI findings were shown in four of five fetuses. CONCLUSIONS: Our MRI results demonstrate the visualization of fetal penile abnormalities and associated pathologies, which may provide information for perinatal management. MRI may show additional findings compared to prenatal US in certain cases.

Fetal akinesia and associated abnormalities on prenatal MRI.

OBJECTIVE: In view of the increasing role of magnetic resonance imaging (MRI) as an adjunct to prenatal ultrasonography (US), this study sought to demonstrate the visualization of fetal akinesia and associated abnormalities on MRI. METHODS: This retrospective study included six fetuses with akinesia and associated abnormalities, depicted on fetal MRI after suspicious prenatal US. The whole fetus was assessed for musculoskeletal abnormalities and associated pathological conditions elsewhere. Fetal outcome data were compared with prenatal imaging. US and MRI findings were also compared. RESULTS: Akinesia resulting in arthrogryposis was seen in 6/6 fetuses, with abnormal musculature in 5/6 fetuses. Associated brain abnormalities were found in 2/6 fetuses; facial abnormalities in 3/6; lung hypoplasia in 3/6; and polyhydramnios in 2/6. There were 5/6 pregnancies that were terminated and one individual died neonatally. MRI and brain autopsy were concordant in 4/6 cases. MRI and body autopsy were concordant in 1/6 cases and in 5/6 cases, autopsy revealed additional abnormalities. In addition to US, MRI correctly identified central nervous system findings in four cases and lung hypoplasia in three cases. CONCLUSION: Our MRI results demonstrate fetal akinesia and associated abnormalities, which may have an impact on perinatal management, as an adjunct to prenatal US.

Clinical trial of multiplanar real-time 4- versus 2-dimensional sonographic guidance for transcervical chorionic villus sampling.

OBJECTIVES: Real-time 4-dimensional (4D) sonography can visualize the location of a chorionic villus sampling (CVS) catheter simultaneously in 3 dimensions. We determined the utility of 4D versus 2-dimensional (2D) sonographic guidance for transcervical CVS. METHODS: Chorionic villus sampling was performed on 40 patients at 10 to 13 weeks' gestation (20 in each study group). Primary outcomes were as follows: (1) time in seconds needed to complete the procedure; (2) procedure failure, defined as the inability to obtain an adequate sample by a single catheter insertion or a necessity to switch to the alternative imaging modality; and (3) acquisition of a sample of chorionic villi sufficient for cytogenetic analysis. Wilcoxon rank sum and Fisher exact tests were used for categorical and continuous variables, respectively. Figure 1. A, Two-dimensional guidance of the transcervical chorionic villus sampling procedure. Arrows indicate the chorionic villus sampling catheter. B, Multiplanar 3-dimensional guidance of the procedure. RESULTS: The procedure time was significantly longer in the 4D group than the 2D group (161.4 versus 80.4 seconds, respectively; P = .001). The success rate at first introduction of the catheter was higher for 2D guidance (90%) than 4D guidance (70%) but was not statistically significant with the study group sizes. Adequate sample sizes were obtained in all patients. The main limiting factor in 4D guidance was a low frame rate. CONCLUSIONS: Our findings show the feasibility of 4D guidance for transcervical CVS, although at the expense of a prolonged procedure time when compared to 2D sonographic guidance. The value of 4D guidance for less experienced operators remains to be determined.

Teaching forceps: the impact of proactive faculty.

OBJECTIVE: The objective of the study was to evaluate the impact on resident forceps experience by a single proactive teacher. STUDY DESIGN: A study was performed to assess the impact on delivery statistics and outcome following the assignment of a single attending to teach forceps to residents. A 2 year period immediately preceding and 2 years following the study was compared using χ(2) and Student t tests. RESULTS: After appointment of the specific teaching attending, forceps deliveries increased by 59% (8% of all births), whereas vacuum procedures decreased to 3% of births (P < .0001) compared with the prior 2 years. The overall percentage of operative vaginal deliveries remained unchanged (11%). Cesarean section rates were unchanged during the study period at 27% of all births. Perineal laceration, 5 minute Apgar less than 7, and birth injuries were also not statistically different. There were fewer fetal pH events less than 7.1 in the teaching period (P = .003). CONCLUSION: In the population studied, there was an association between increasing resident forceps use and a positive impact on birth outcomes from the designation of a full-time, experienced, and proactive faculty member to obstetrics teaching duty.

Teaching 3-dimensional fetal ultrasound: a randomized study.

OBJECTIVE: Three-dimensional ultrasound has become an integral mode of fetal imaging. However, unclear but foundational concepts such as 'rotational axes' and 'sectional planes' are key to obtaining, manipulating, and understanding 3d volumes. This randomized study utilized 'analogical transfer', as a novel method of teaching three-dimensional ultrasound. We hypothesized that the cognitive processing of medical professionals dealing with medical imaging is less structure-based and more intuitive. METHODS: Ninety-four ultrasound education naïve subjects (50 conventional vs 44 experimental) were randomly assigned to using one of two teaching instruments to determine whether there was a difference in learning three-dimensional concepts. One instrument used the conventional approach (prose description of concepts) while the second teaching instrument used visual descriptors. Time to complete the instrument (self-learning + quiz) was recorded and quiz results were analyzed. RESULTS: One hundred potential subjects were offered participation and 94 accepted. The mean score (scale 0-8) using the analogical transfer approach was 5.32 ± 1.64 (n = 44) and using the traditional approach was 3.42 ± 1.93 (n = 50). Using an unpaired t-test, (α = 0.05), the calculated p value was 0.0001 (95% CI 1.16-2.64). CONCLUSIONS: Those subjects exposed to the analogical transfer method were more likely to better comprehend three-dimensional ultrasound concepts as represented by higher quiz scores.

Discordance of first-trimester crown-rump length is a predictor of adverse outcomes in structurally normal euploid dichorionic twins.

OBJECTIVE: The purpose of this study was to determine the association between discordant crown-rump length (CRL) measurements in structurally normal euploid dichorionic twins and adverse pregnancy outcomes. METHODS: This retrospective cohort study included women with dichorionic twins who underwent chorionic villus sampling and delivered in our facility from January 2000 to September 2007. Only pregnancies with viable twin fetuses and normal karyotypes were included. The association between CRL discordance, defined as a CRL discrepancy of 9% or greater, and adverse pregnancy outcomes was evaluated. RESULTS: Seventy-eight women met inclusion criteria and included 24 discordant twins (group 1) and 54 concordant twins (group 2). Maternal ages were similar: mean ± SD, 38.2 ± 3.1 years in group 1 versus 39.2 ± 3.9 years in group 2 (P = not significant). The median gestational ages at delivery were 35.6 ± 3.1 weeks in group 1 and 37.3 ± 2.0 weeks in group 2 (P < .01). At least 1 major complication occurred in 19 women (79%) in group 1 and 25 (46%) in group 2 (P = .01). Group 1 had significantly more major complications overall (P = .0008). Preterm premature rupture of membranes occurred in 10 women (42%) in group 1 and 6 (11%) in group 2 (P = .005). Delivery before 37 weeks' gestation occurred in 19 of 24 women (79%) in group 1 and 24 of 54 (44%) in group 2 (P = .006). There was a significant difference for younger gestational age at delivery in the discordant group (P < .01). CONCLUSIONS: Our data suggest that there is an increased risk of adverse pregnancy outcomes in chromosomally normal dichorionic twins with first-trimester discordant CRL measurements. These results may be clinically useful for counseling, management, and antenatal surveillance.

Methamphetamine use during pregnancy: maternal and neonatal implications.

OBJECTIVE: To report the demographic characteristics and clinical morbidity of methamphetamine-exposed pregnancies compared with control patients in a tertiary care, urban, academic medical center. METHODS: A single-site chart review from 2000 to 2006 was conducted. International Classification of Diseases, 9th Revision code 648.3x was used to identify potential study participants. Specific inclusion criteria required either a positive urine drug screen for methamphetamine use or by patient statement of methamphetamine use during pregnancy. Data from 276 identified patients were then compared with the 34,055 in the general obstetric population during the same period for various demographic factors and perinatal outcomes. RESULTS: Two hundred seventy-six patients responsible for 273 live births were identified between 2000 and 2006. Factors that were significantly associated with methamphetamine use were age younger than 20 years (9% methamphetamine compared with 16% control patients), non-Hispanic white ethnicity (55% compared with 71%), married (12% compared with 46%), preterm delivery (52% compared with 17%), low Apgar scores (6% compared with 1-2%), cesarean delivery (29% compared with 23%), and neonatal mortality (4% compared with 1%). Additionally, the maternal demographic characteristics suggested that these women were more likely to be unemployed, use other abusive substances, and have higher rates of domestic violence and adoption when compared with the control population. CONCLUSION: Methamphetamine use in pregnancy is complicated by more morbid maternal and neonatal outcomes when compared with the general obstetric population. Because the patients in this study were in a variety of ways demographically distinct, attempts to identify these patients early and intervene in an effort to improve pregnancy-related outcomes appears possible and warranted. LEVEL OF EVIDENCE: II.

The esophageal 'pouch sign': a benign transient finding.

OBJECTIVE: Sonographic finding of an esophageal pouch is considered pathognomonic for fetal esophageal atresia (EA). We investigated the clinical significance of this finding. METHODS: Longitudinal sonographic follow-up in pregnancy and neonatal diagnostic work-up was performed in six fetuses with an esophageal neck pouch referred for polyhydramnios and a small or absent stomach. Fetal swallowing and cyclic distension of the pouch were observed for at least 30 min, and follow-up examinations were conducted at 2 to 3 weeks intervals. RESULTS: First visualization of the pouch occurred between 18 and 29 weeks of gestation. All pouches were located above the fetal clavicle. No additional anomalies were detected on detailed anatomic survey. Five fetuses had normal karyotypes. At 21 to 33 weeks of gestation, polyhydramnios had resolved, and the stomach was found to be normal in size and shape in all cases. The neonatal work-up ruled out EA in all cases. CONCLUSION: The fetal esophageal pouch sign occurs in structurally normal fetuses and should not be considered pathognomonic for EA or serve as the grounds for pregnancy termination.

Lack of correlation between elevated maternal serum hCG during second-trimester biochemical screening and fetal congenital anomaly.

OBJECTIVE: Isolated elevations in midtrimester maternal serum human chorionic gonadotrophin concentrations (MShCG) have been reported to be associated with a substantially increased likelihood of fetal congenital malformations. The reported malformations included a wide range of organ systems, originating at different embryologic developmental stages. The purpose of our study was to determine the significance of an isolated elevated MShCG (>2.5 MoM) in midtrimester for the detection of fetal structural anomalies in a large population. METHODS: Among 10,144 women who underwent a biochemical triple screen at 15 to 18 weeks' gestation, 463 patients, who had an elevated MShCG, but normal alpha-fetoprotein (AFP) and unconjugated estriol (uE3) levels, were identified. Patients with an integrated calculated Down syndrome risk above 1:250 were excluded. Only nonsmokers, at ages <35 years, without a history of prior fetal anomalies were included. The control group consisted of 463 patients with normal serum analyte concentrations and Down syndrome risks below 1:250, who were matched for maternal age and date of biochemical screen. All patients underwent a detailed genetic sonogram in which an anatomic survey and multiple 'soft markers' for aneuploidy were looked for. Newborns were examined by a senior pediatrician trained in dysmorphology. RESULTS: MShCG levels were 3.18 +/- 0.72 versus 0.99 +/- 0.43 MoM (p < 0.0001) in study and control groups respectively. Sonography revealed 8 versus 6 cases of major congenital anomalies among the 463 patients of their respective groups, and 39 versus 36 sonographic 'soft markers' for aneuploidy. Fetal karyotyping and neonatal examination for dysmorphology revealed 6 chromosomal anomalies (4 Down syndrome; 2 Turner syndrome) among the 8 major malformations in the study group, but none in the controls (p < 0.0001). Three of the 39 fetuses with 'soft markers' and elevated MShCG were found to have trisomy 21. CONCLUSION: Isolated elevation of MShCG does not confer an increased risk of fetal congenital anomalies other than chromosomal abnormalities. However, elevated MShCG levels in combination with sonographic 'soft markers' for aneuploidy were associated with a high incidence of chromosomal anomalies, despite a normal biochemical triple screen risk estimate.

Failure of physiologic transformation of the spiral arteries in patients with preterm labor and intact membranes.

OBJECTIVE: The purpose of this study was to determine whether abnormal placentation (defined as the failure of physiologic transformation of spiral arteries) is present in patients with preterm labor and intact membranes who delivered a preterm neonate. STUDY DESIGN: A cross-sectional study was conducted to examine the histopathologic findings in the placental bed and placenta of patients with preterm labor and intact membranes (n=27), preeclampsia (n=43), and healthy pregnant women at term (n=103). Immunohistochemistry studies with cytokeratin 7 and periodic acid-Schiff were used to detect trophoblast and fibrinoid, respectively, and diagnose the failure of physiologic transformation of the spiral arteries. RESULTS: The mean percentage of spiral arteries with failure of physiologic transformation in the myometrium was significantly higher in patients with preterm labor and preeclampsia than in normal pregnant women at term (P=.0004 and P<.0001, respectively). Similar findings were observed in the decidual segment of spiral arteries within the placental bed (P=.001 and P<.0001). In contrast, the mean percentage of the spiral arteries with failure of physiologic transformation in the decidua of the basal plate was not significantly different between patients with preterm labor and normal pregnant women (P=.17). CONCLUSION: Failure of physiologic transformation of the spiral arteries in the myometrial and decidual segments of the placental bed is frequent in patients with preterm labor and intact membranes.

Failure of physiologic transformation of the spiral arteries in the placental bed in preterm premature rupture of membranes.

OBJECTIVE: The purpose of this study was to determine whether failure of physiologic transformation of the spiral arteries occurs in patients with preterm premature rupture of membranes (PROM). STUDY DESIGN: A cross-sectional study was designed to examine the histopathologic findings in the placental bed and placenta of patients with preterm PROM, preeclampsia, and normal women at term. Immunohistochemistry with cytokeratin 7 and periodic acid-Schiff (PAS) were used to detect trophoblast and fibrinoid and to diagnose failure of physiologic transformation of the spiral arteries. RESULTS: One hundred thirteen cases met the inclusion criteria, 59 from patients with normal pregnancies, 31 with preterm PROM, and 23 with preeclampsia. The mean number of the spiral arteries with failure of physiologic transformation of the myometrial segment was significantly higher in patients with preterm PROM and preeclampsia than in normal pregnant women at term (P =.006 and P <.0001, respectively). In contrast, the mean number of the spiral arteries with failure of physiologic transformation of the decidual segment of the spiral arteries in the basal plate of the placenta was not significantly different in patients with preterm PROM from that in normal pregnant women (P >.05). Placentas from patients with preterm PROM had a higher frequency of vascular lesions than those from normal pregnant women (P =.02). CONCLUSION: Defective placentation, defined as failure of physiologic transformation of the myometrial segment of the spiral artery, is frequently present in preterm PROM.