The subjective assessment of echogenic fetal bowel

Hyperechogenic fetal bowel: Current evidence-based prenatal diagnosis and management

Echogenic fetal bowel (EB) is a prenatal ultrasound finding (0.2%-1.4% of all pregnancies) defined as bowel of similar or greater echogenicity than surrounding bone. In fact, the ultrasound assessment is strongly subjective with inter-observer variability. The pathophysiology depends on the underlying condition, apparently related with meconium stasis and hypercellularity. It is often an isolated finding, with possible association with other structural anomalies. About the origin, it was observed in fetuses with cystic fibrosis, congenital infections, thalassemia, intraamniotic bleeding, fetal growth restriction. Fetuses with EB are at increased risk of adverse perinatal outcome, such as intrauterine growth restriction, placental dysfunction and perinatal death, highlighting the need for a thorough antenatal management and post-natal follow-up. It seems to be associated with a plenty of conditions, such as a poor fetal outcome, fetal growth restriction and placental dysfunction. Therefore management requires a multidisciplinary approach with different specialties' involvement and the prognosis is influenced by the underlying pathophysiology. In this complex scenario, the present review aims to define the clinical pathway which should be offered to pregnant women in case of finding of fetal EB ultrasound marker, to rule out any suspected pathological cause.

A prospective blinded comparison of second trimester fetal measurements by expert and novice readers using low-cost novice-acquired 3D volumetric ultrasound

RATIONALE AND OBJECTIVES

Two-dimensional (2D) ultrasound (US) is operator dependent, requiring operator skill and experience to selectively identify and record planes of interest for subsequent interpretation. This limits the utility of US in settings in which expert sonographers are unavailable. Three-dimensional (3D) US acquisition of an anatomic target, which enables reconstruction of any plane through the acquired volume, might reduce operator dependence by providing any desired image plane for interpretation, without identification of target planes of interest at the time of acquisition. We applied a low-cost 3DUS technology because of the wider potential application compared with dedicated 3DUS systems. We chose second trimester fetal biometric parameters for study because of their importance in maternal-fetal health globally. We hypothesized that expert and novice interpretations of novice-acquired 3D volumes would not differ from each other nor from expert measurements of expert-acquired 2D images, the clinical reference standard.

MATERIALS AND METHODS

This was a prospective, blinded, observational study. Expert sonographers blinded to 3DUS volumes acquired 2DUS images of second trimester fetuses from 32 subjects, and expert readers performed interpretation, during usual care. A novice sonographer blinded to other clinical data acquired oriented 3DUS image volumes of the same subjects on the same date. Expert readers blinded to other data assessed placental location (PL), fetal presentation (FP), and amniotic fluid volume (AFV) in novice-acquired 3D volumes. Novice and expert raters blinded to other data independently measured biparietal diameter (BPD), humerus length (HL), and femur length (FL) for each fetus from novice-acquired 3D volumes. Corresponding gestational age (GA) estimates were calculated. Inter-rater reliability of measurements and GAs (expert 3D versus expert 2D, novice 3D versus expert 2D, and expert 3D versus novice 3D) were assessed by intraclass correlation coefficient (ICC). Mean inter-rater measurement differences were analyzed using one-way ANOVA.

RESULTS

3D volume acquisition and reconstruction required mean 30.4 s (±5.7) and 70.0 s (±24.0), respectively. PL, FP, and AFV were evaluated from volumes for all subjects; mean time for evaluation was 16 s (±0.0). PL, FP, and AFV could be evaluated for all subjects. At least one biometric measurement was possible for 31 subjects (97%). Agreement between rater pairs for a composite of all measures was excellent (ICCs ≥ 0.95), and for individual measures was good to excellent (ICCs ≥ 0.75). Inter-rater differences were not significant (p > .05).

CONCLUSIONS

Expert and novice interpretations of novice-acquired 3DUS volumes of second trimester fetuses provided reliable biometric measures compared with expert interpretation of expert-acquired 2DUS images. 3DUS volume acquisition with a low-cost system may reduce operator dependence of ultrasound.

Predictors for surgical intervention and surgical outcomes in neonates with cystic fibrosis

BACKGROUND/PURPOSE

To identify prenatal and perinatal predictors of surgery and describe surgical findings/outcomes of neonates with Meconium Ileus (MI) secondary to Cystic Fibrosis (CF).

METHODS

Potential risk factors (prenatal bowel echogenicity, CF genotype, birthweight, prematurity and sex) for MI and surgery were examined in a retrospective cohort of neonates with CF presenting to a tertiary center between 1997 and 2015. Following univariable analysis, predictors of MI and surgery were determined using multivariable logistic regression. For surgical patients, detailed operative findings and outcomes were examined.

RESULTS

MI was diagnosed in 26/120 (21.7%) neonates with CF and 19/26 (73.0%) required surgery. Prematurity was significantly associated with increased risk of MI and operative intervention (p-value 0.022 and p-value 0.016 respectively); lower birthweight was associated with operative intervention (p-value 0.039); genotype and echogenic bowel were associated with neither. Surgical data were available for 17/19 patients; median age at surgery was 2 days (IQR1-3), 4/17 had an atresia and 6/17 received an ostomy. Median NICU and hospital stays were 34.5 and 70 days while median time on TPN and time to ostomy reversal were 28.5 and 97 days, respectively.

CONCLUSIONS

In patients with CF, prematurity and lower birthweight were identified as risk factors for meconium ileus and need for surgery. Specific genotypes and echogenic bowel were not predictors of either.

LEVEL OF EVIDENCE

Level III.

Isolated fetal echogenic bowel in a retrospective cohort: The role of infection screening

OBJECTIVE

Fetal echogenic bowel (FEB) is an ultrasonographic marker of fetal infection. We aimed to determine the utility of infection screening when FEB is isolated.

STUDY DESIGN

Retrospective observational study of isolated FEB cases between 2006-2014. Infection screening included toxoplasmosis, rubella, syphilis, cytomegalovirus (CMV), herpes simplex virus and parvovirus B19. Fetal karyotyping, screening for cystic fibrosis (CF) and follow-up scans were also offered, according to international standards. Incidence of infection and 95% confidence interval (CI) were calculated.

RESULTS

148 patients with 154 fetuses were included. 4.7% of mothers developed acute infection: four patients developed CMV infection (2.7%, 95% CI 1.1-6.9%), in two fetuses infection was confirmed with amniocentesis and pregnancies were terminated; Parvovirus B19 infection was detected in 2 patients (1.4%, 95% CI 0.4-5.0) and confirmed in one fetus, which developed anemia; there was one toxoplasmosis maternal infection (0.7%, 95% CI 0.1-3.8%) treated with spyramicin, whose fetus was not infected. Percentage of chromosomal/genetic abnormalities was 3.2%, CF 1.3%, intra-amniotic bleeding 1.3%, FGR 34% and other ultrasonographic abnormalities at follow-up scans 18%.

CONCLUSIONS

The association between isolated FEB and fetal infection is uncommon (1.9% in our population). CMV maternal infection screening is supported by our findings, whereas screening for other infections needs to be further investigated.

Follow-up of sonographically detected soft markers for fetal aneuploidy

Sonographic soft markers of fetal Down syndrome were first reported in the 1980s. With improvements in aneuploidy screening, detection rates of 90% and higher are possible, and such screening is offered to women of all ages. The utility of sonographic detection and reporting of soft markers, particularly to women at low risk of fetal aneuploidy, is controversial. Some soft markers have no additional significance beyond an association with aneuploidy, while some potentially indicate other pathology, and therefore require sonographic follow-up or other evaluation. The definitions of soft markers vary among reported series, and any practice using such markers to adjust the risk of aneuploidy should carefully determine the most appropriate definitions as well as likelihood ratios and how to apply these in practice.

Effect of B-mode optimization techniques on fetal bowel echogenicity using computerized image analysis

OBJECTIVES

The purpose of this study was to provide and compare measurable parameters for normal fetal bowel echogenicity under predefined B-mode scanning presets.

METHODS

Forty healthy fetuses underwent 14- to 17-week ultrasound scans, and 40 underwent 21- to 25-week scans. Sagittal, coronal, and axial fetal abdominal images were tested using predefined B-mode presets. The presets differed from fundamental imaging by isolated activation of harmonic imaging, compound resolution imaging, speckle reduction imaging, focus and frequency composite imaging, and coded excitation imaging features. A transabdominal probe was used in all fetuses, and transvaginal images were added for the 14- to 17-week scans. The images were studied with custom-developed software, which provided a grayscale analysis of the pixels in the region of interest within the image. The mean brightness of the pixels from the fetal bowel area was calculated.

RESULTS

The 14- to 17-week transabdominal scans showed significantly higher mean brightness on harmonic imaging compared to fundamental imaging (P < .01). Activation of coded excitation and compound resolution imaging in these scans resulted in a significant decrease in the mean brightness compared to fundamental imaging. Mean bowel brightness values on the 21- to 25-week transabdominal scans did not differ significantly with the use of the different imaging presets compared to fundamental imaging.

CONCLUSIONS

Transabdominal harmonic imaging in the early second trimester may significantly increase the mean brightness of the fetal bowel tissue. Contrarily, compound resolution imaging and coded excitation imaging produce the opposite effect on bowel echogenicity.

Perinatal outcomes following the ultrasound diagnosis of echogenic bowel: an Australian perspective

INTRODUCTION

The aim of this study was to describe the association between fetal echogenic bowel (FEB) diagnosed during the second trimester and adverse perinatal outcomes in an Australian antenatal population.

METHODS

A retrospective analysis of ultrasound scans was performed between March 1, 2004 and March 1, 2009 at The Royal Women's Hospital, Melbourne, Vic., Australia. Cases reported as having FEB on second trimester ultrasound were included. Medical records of each case were reviewed and information concerning additional investigations and perinatal outcomes were extracted.

RESULTS

A total of 66 cases were identified in our database. Three patients (5%) were excluded from further analysis as they were lost to follow-up, leaving 63 (95%) cases in this series. Thirty-two fetuses (52%) underwent karyotyping via amniocentesis, 5 (16%) of which were found to have chromosomal defects. Maternal serology for cytomegalovirus (CMV) was performed in 49 (78%) cases. Investigations indicated a total of 5 women who had CMV infection during their pregnancy. Thirty-three pregnancies (53%) were tested for cystic fibrosis (CF) and 1 baby was confirmed to have CF postnatally. Among the 50 liveborn infants, 3 cases of fetal growth restriction were apparent. Overall, 42 of the 50 liveborn infants (84%) and 67% of the entire cohort of 63 patients with a midtrimester diagnosis of FEB had a normal short-term neonatal outcome.

CONCLUSION

This study reiterates the increased prevalence of aneuploidy, CMV, CF and fetal growth restriction in pregnancies complicated by the midtrimester sonographic finding of FEB. However, reassuringly, 67% of cases with ultrasound-detected echogenic bowel in the second trimester had a normal short-term neonatal outcome in this multiethnic Australian population.

Intraabdominal fetal echogenic masses: a practical guide to diagnosis and management

Intraabdominal calcifications and other echogenic masses are relatively common findings during fetal sonography. Many are associated with no additional risk for the fetus or neonate. They may arise from the liver, gallbladder, spleen, kidneys, adrenal glands, gastrointestinal tract, or peritoneal cavity. Detection of such lesions should prompt a detailed survey for additional findings and a review of the maternal history. In some cases, fetal karyotyping may be indicated. In most cases, the diagnosis, management, and outcome are determined according to a combination of specific ultrasound appearances and at least one additional maternal or fetal factor. In utero diagnosis can often be achieved with careful evaluation of the lesion echotexture, associated calcifications, additional findings, and evolution over time. In most cases, expectant management is sufficient, but some patients require transfer to a facility where early postnatal intervention is available. A systematic approach to the findings aids in differential diagnosis and management.

Controversial ultrasound findings

This article has reviewed a few of the more controversial findings in the field of obstetric ultrasound. For each one evidence-based strategies for the management of affected pregnancies have been suggested, derived from what the authors believe is the best information available. In some cases, this information is very limited, which can make counseling these patients extremely difficult. Some physicians find using specific likelihood ratios helpful in these complex discussions. An example of the relative likelihood ratios for several markers of trisomy 21 is illustrated in Table 10. Although the management of each of the findings discussed in this article is different, a few generalizations can be made. To begin with, the detection of any abnormal finding on ultrasound should prompt an immediate detailed ultrasound evaluation of the fetus by someone experienced in the diagnosis of fetal anomalies. If there is more than one abnormal finding on ultrasound, if the patient is over the age of 35, or if the multiple marker screen is abnormal, an amniocentesis to rule out aneuploidy should be recommended. Of the six ultrasound findings reviewed here, the authors believe that only echogenic bowel as an isolated finding confers a high enough risk of aneuploidy to recommend an amniocentesis in a low-risk patient. The other findings in isolation in a low-risk patient seem to confer only a modest increased risk of aneuploidy, if any, and this risk is certainly less than the risk of unintended loss from amniocentesis. Wherever possible, modifiers of this risk, such as maternal age, history, and first and second multiple marker screening, should be used to define more clearly the true risk of aneuploidy. As obstetric ultrasound moves forward, particularly into the uncharted waters of clinical use of three- and four-dimensional ultrasound, one can expect a whole new crop of ultrasound findings with uncertain clinical significance. Clinicians are well advised to await well-designed studies to determine the clinical significance of these findings before altering clinical care.

The value of minor ultrasound markers for fetal aneuploidy

As a result of improvements in ultrasound image quality and scanning technique, an increasing number of subtle morphological changes in fetal anatomy have been identified in the second trimester. Most of these ultrasound features were originally described as normal variants of development with no clinical significance. However, subsequent studies in high-risk populations showed that some of these variants were more prevalent in fetuses with chromosomal defects and therefore proposed as prenatal markers for the detection of aneuploidy. The implications for pregnancy management when one of these so-called minor ultrasound markers is detected have been a matter of continuous controversy in the field of prenatal diagnosis and yet the definitive answer on their clinical significance in the low-risk population is still debated.