Contribution of three-dimensional volume contrast imaging to the sonographic assessment of the fetal uterus

Prenatal visualization of the fetal uterus in routine 2D ultrasound examination

OBJECTIVE

To establish a new technique to easily identify the fetal cervix-uterus complex in normal female fetuses from 20 to 40 weeks of gestation.

MATERIAL AND METHODS

The study was performed in routine examination in normal fetuses by two observers. Twenty-five consecutive cases per gestational week were assessed between 20 and 40 weeks. The same plane of the bladder used in the assessment of the umbilical arteries was used. In this transverse view of the fetal pelvis different structures can be identified from front to back: the bladder, the bowel and the vertebral body. If the uterus is present, it can be seen between the bladder and the rectum, as a round structure pushing the posterior bladder wall. The echogenicity changes as the uterus develops and increases its size. Voluson E10 ultrasound device (GEHealthcare Ultrasound®, Zipf, Austria) equipped with an RM6Cprobe was utilized.

RESULTS

Successful identification of the cervix-uterus complex was possible overall in 83.4% of cases, reaching more than 93% from 31 weeks onwards. There was a rapid growth of the cervix-uterus complex after 26 weeks, and in the third trimester appears as a solid round structure behind the fetal bladder. Reproducibility analysis showed agreement between 2 observers in 92% of cases.

CONCLUSION

Identification of the uterus and cervix complex is possible from 20 weeks, although it is easier at the end of gestation. This reproducible technique allows the anatomical study of normal female fetuses and the visualization of kidney malformations and disorders of sexual development.

[Management of a fetus suspected of differences of sex development (DSD)]

The management of a fetus suspected of having a difference in genital sexual development (DSD) is a complex situation. In cases of complete discordance or an unusual appearance of the external genitalia (EG), management always begins with a diagnostic morphological ultrasound. This ultrasound aims to provide detailed imaging of the EG and internal genitalia (IG), focusing on identifying the presence of Müllerian derivatives and detecting any associated malformations. During a multidisciplinary meeting, we should assess the appropriateness of determining the genetic sex through cell-free DNA analysis and to refer the patient to an expert center if necessary. These clinical situations include all atypical presentations of the genital organs with the inability to determine the phenotype, as well as any hypospadias associated with other genital organ involvement. Patients presenting with isolated posterior (or proximal) hypospadias also benefit from an assessment at an expert center. Isolated anterior and middle hypospadias (with negative genetic findings) are excluded from this protocol. Performing an invasive sampling is almost always indicated. The expert center provides the couple with information on the different variations of genital development and the perspectives of managing the child, explaining the recently proposed paradigm shift, according to the new French decree of November 15, 2022, in application of Article L-2131-6 of the Public Health Code, which now entails, in some of these situations, delayed surgical management. The diagnostic and prognostic uncertainty of the DSD is communicated to the couples. Multidisciplinary care is therefore essential to establish an accurate diagnosis, define the anatomical and functional prognosis, and propose the most appropriate surgical strategy, taking into account the associated morbidities, defining whether or not to adopt a surgical strategy, and providing the most suitable surgical approach, as well as supporting the couple and the child in dealing with this situation.

Interstitial pregnancy: A retrospective case series of surgically managed patients over a ten-year period

AIMS

To describe the ultrasound diagnostic features and surgical management procedures for patients with an interstitial ectopic pregnancy in our tertiary institution and associated peripheral hospital over a ten-year period.

METHODS

A retrospective audit of all surgically managed cases of interstitial pregnancies over a ten-year period at a tertiary hospital and one associated peripheral hospital in New South Wales.

RESULTS

Sixteen cases of surgically managed interstitial pregnancy were identified. In 43.8% of these cases, patients had previously undergone an ipsilateral salpingectomy. No cases required hysterectomy, post-operative methotrexate or return to theatre. Ten patients underwent diagnostic ultrasound prior to operative management, seven of which were correctly identified to be an interstitial ectopic pregnancy at the time. The proportion of cornuostomies being performed for interstitial pregnancy compared to wedge resection has increased over the period of this review from 33 to 60% between the two five-year periods.

CONCLUSION

The combination of expert ultrasound and sophisticated laparoscopic techniques at our institution has facilitated earlier diagnosis and greater use of minimally invasive management of interstitial pregnancy.

Imaging in fetal genital anomalies

Genital anomalies are a heterogeneous group of congenital pathologies that have become increasingly relevant since the Chicago Consensus of 2005. Their postnatal diagnosis has developed significantly in the last two decades, while prenatal diagnosis seems to be underdeveloped, with few protocols available, fragmented scientific literature, and low diagnostic rates. This review aims to examine the current status of this subspecialty from the perspective of prenatal imaging. Indications for the evaluation of fetal genitalia can be divided into medical and non-medical reasons. Medical reasons include sex-linked disorders, detection of other anomalies, relevant family history, or multiple pregnancy. Non-medical reasons include parental request for sex disclosure. Disclosure of fetal sex may be associated with ethical, legal, and medical issues. The main imaging technology used is 2D ultrasound, although there are other complementary techniques such as 3D, MRI, or Color Doppler. Regarding working methodology, several authors have drawn attention to the lack of standardized protocols and guidelines. Most guidelines tend to limit their recommendations to study indications and ethical issues. Technical proposals, measurements, or working methods have not yet been standardized. Fetal sex determination is usually divided into early and late gestation. Early gestation is based on the sagittal sign. Late gestation is based on direct visualization. There are several measurements to describe male and female genitalia, such as penile length, bilabial diameter, or scrotal diameter. Prenatal diagnosis of genital pathologies presents some particularities such as the wide spectrum of phenotypes, the high frequency of associated deformities, or the time of diagnosis. Some of the most frequent pathologies are ambiguous genitalia, fetal sex discordance, hypospadias, micropenis, clitoromegaly, ovarian cysts, hydro(metro)colpos, and cloacal anomalies. Higher-quality studies and direction from scientific societies through the implementation of clinical guidelines are needed.

The Development of Normal Fetal External Genitalia Throughout Gestation

In this review, we describe normal development of fetal genitalia throughout gestation as well as the identification of normal male and female genitalia on ultrasound. We use abnormal and ambiguous genitalia as illustrative tools to assist with the identification of normal genitalia and recognition of some of the most common abnormalities in external genitalia development.

Characteristics of fetal physiological and pathological uterine effusion observed on prenatal ultrasonography: a case report

Background

The prenatal detection rate of fetal uterine effusion is very low, and current case reports mainly focus on pathological hydrometrocolpos. We presented two cases of fetal physiological uterine effusion with different ultrasonic characteristics and compared them with one case of hydrometrocolpos with the hope of identifying strategies to reduce misdiagnosis of fetal uterine effusion.

Case presentation

This paper reports the cases of two female fetuses with abnormal pelvic echoes in the third trimester, referred to a tertiary center to be screened for suspected pelvic teratoma and cystic mass, respectively. Ultrasound consultation revealed fetal uterine effusion. The two fetuses were delivered at our hospital after a full term. Re-examining the uterus and adnexa of the neonates revealed that the uterine effusion had subsided naturally. Another female fetus had a large cystic mass in the pelvic cavity in the third trimester, and prenatal examination indicated fetal hydrometrocolpos. The fetus was delivered at our hospital after a full term. The hydrometrocolpos existed even after birth. After consultation with a neonatal surgeon and gynecologist, the newborn was diagnosed with congenital imperforate hymen with hydrometrocolpos. Hymen puncture and open drainage led to a good prognosis.

Conclusions

Prenatal ultrasonography plays an important role in diagnosing and differentiating between physiological and pathological fetal uterine effusion. It can help reduce misdiagnoses that can lead to incorrect clinical decisions.

Clinical spectrum of female genital malformations in prenatal diagnosis

Introduction

Fetal genital malformations represent a rare and heterogeneous group of congenital malformations of the disorders of sexual development (DSD) spectrum.

Methods

A thorough literature review on the main topics in the prenatal approach towards DSD was conducted.

Results

First, a thorough overview on prenatal characteristics of the most common fetal genital malformations of ovaries, uterus and external genitalia, and second, a standardized approach for differential diagnosis in the presence of direct and indirect prenatal signs of DSDs.

Conclusions

This review is mainly directed towards the aspects of female genital malformations with  aspects of male DSD explained as well to aid in the prenatal differential diagnosis.

Discordant fetal sex on NIPT and ultrasound

Prenatal diagnosis of sex discordance is a relatively new phenomenon. Prior to cell-free DNA testing, the diagnosis of a disorder of sexual differentiation was serendipitous, either through identification of ambiguous genitalia at the midtrimester morphology ultrasound or discovery of genotype-phenotype discordance in cases where preimplantation genetic diagnosis or invasive prenatal testing had occurred. The widespread integration of cfDNA testing into modern antenatal screening has made sex chromosome assessment possible from 10 weeks of gestation, and discordant fetal sex is now more commonly diagnosed prenatally, with a prevalence of approximately 1 in 1500-2000 pregnancies. Early detection of phenotype-genotype sex discordance is important as it may indicate an underlying genetic, chromosomal or biochemical condition and it also allows for time-critical postnatal treatment. The aim of this article is to review cfDNA and ultrasound diagnosis of fetal sex, identify possible causes of phenotype-genotype discordance and provide a systematic approach for clinicians when counseling and managing couples in this circumstance.

Congenital Uterine Malformation by Experts (CUME): diagnostic criteria for T-shaped uterus

OBJECTIVES

To identify uterine measurements that are reliable and accurate to distinguish between T-shaped and normal/arcuate uterus, and define T-shaped uterus, using Congenital Uterine Malformation by Experts (CUME) methodology, which uses as reference standard the decision made most often by several independent experts.

METHODS

This was a prospectively planned multirater reliability/agreement and diagnostic accuracy study, performed between November 2017 and December 2018, using a sample of 100 three-dimensional (3D) datasets of different uteri with lateral uterine cavity indentations, acquired from consecutive women between 2014 and 2016. Fifteen representative experts (five clinicians, five surgeons and five sonologists), blinded to each others' opinions, examined anonymized images of the coronal plane of each uterus and provided their independent opinion as to whether it was T-shaped or normal/arcuate; this formed the basis of the CUME reference standard, with the decision made most often (i.e. that chosen by eight or more of the 15 experts) for each uterus being considered the correct diagnosis for that uterus. Two other experienced observers, also blinded to the opinions of the other experts, then performed independently 15 sonographic measurements, using the original 3D datasets of each uterus. Agreement between the diagnoses made by the 15 experts was assessed using kappa and percent agreement. The interobserver reliability of measurements was assessed using the concordance correlation coefficient (CCC). The diagnostic test accuracy was assessed using the area under the receiver-operating-characteristics curve (AUC) and the best cut-off value was assessed by calculating Youden's index, according to the CUME reference standard. Sensitivity, specificity, negative and positive likelihood ratios (LR- and LR+) and post-test probability were calculated.

RESULTS

According to the CUME reference standard, there were 20 T-shaped and 80 normal/arcuate uteri. Individual experts recognized between 5 and 35 (median, 19) T-shaped uteri on subjective judgment. The agreement among experts was 82% (kappa = 0.43). Three of the 15 sonographic measurements were identified as having good diagnostic test accuracy, according to the CUME reference standard: lateral indentation angle (AUC = 0.95), lateral internal indentation depth (AUC = 0.92) and T-angle (AUC = 0.87). Of these, T-angle had the best interobserver reproducibility (CCC = 0.87 vs 0.82 vs 0.62 for T-angle vs lateral indentation depth vs lateral indentation angle). The best cut-off values for these measurements were: lateral indentation angle ≤ 130° (sensitivity, 80%; specificity, 96%; LR+, 21.3; LR-, 0.21), lateral indentation depth ≥ 7 mm (sensitivity, 95%; specificity, 77.5%; LR+, 4.2; LR-, 0.06) and T-angle ≤ 40° (sensitivity, 80%; specificity, 87.5%; LR+, 6.4; LR-, 0.23). Most of the experts diagnosed the uterus as being T-shaped in 0% (0/56) of cases when none of these three criteria was met, in 10% (2/20) of cases when only one criterion was met, in 50% (5/10) of cases when two of the three criteria were met, and in 93% (13/14) of cases when all three criteria were met.

CONCLUSIONS

The diagnosis of T-shaped uterus is not easy; the agreement among experts was only moderate and the judgement of individual experts was commonly insufficient for accurate diagnosis. The three sonographic measurements with cut-offs that we identified (lateral internal indentation depth ≥ 7 mm, lateral indentation angle ≤ 130° and T-angle ≤ 40°) had good diagnostic test accuracy and fair-to-moderate reliability and, when applied in combination, they provided high post-test probability for T-shaped uterus. In the absence of other anomalies, we suggest considering a uterus to be normal when none or only one criterion is met, borderline when two criteria are met, and T-shaped when all three criteria are met. These three CUME criteria for defining T-shaped uterus may aid in determination of its prevalence, clinical implications and best management and in the assessment of post-surgical morphologic outcome. The CUME definition of T-shaped uterus may help in the development of interventional randomized controlled trials and observational studies and in the diagnosis of uterine morphology in everyday practice, and could be adopted by guidelines on uterine anomalies to enrich their classification systems. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Acoustic Radiation Force Based Ultrasound Elasticity Imaging for Biomedical Applications

Pathological changes in biological tissue are related to the changes in mechanical properties of biological tissue. Conventional medical screening tools such as ultrasound, magnetic resonance imaging or computed tomography have failed to produce the elastic properties of biological tissues directly. Ultrasound elasticity imaging (UEI) has been proposed as a promising imaging tool to map the elastic parameters of soft tissues for the clinical diagnosis of various diseases include prostate, liver, breast, and thyroid gland. Existing UEI-based approaches can be classified into three groups: internal physiologic excitation, external excitation, and acoustic radiation force (ARF) excitation methods. Among these methods, ARF has become one of the most popular techniques for the clinical diagnosis and treatment of disease. This paper provides comprehensive information on the recently developed ARF-based UEI techniques and instruments for biomedical applications. The mechanical properties of soft tissue, ARF and displacement estimation methods, working principle and implementation instruments for each ARF-based UEI method are discussed.

Counting ovarian antral follicles by ultrasound: a practical guide

This Consensus Opinion summarizes the main aspects of several techniques for performing ovarian antral follicle count (AFC), proposes a standardized report and provides recommendations for future research. AFC should be performed using a transvaginal ultrasound (US) probe with frequency ≥ 7 MHz. For training, we suggest a minimum of 20-40 supervised examinations. The operator should be able to adjust the machine settings in order to achieve the best contrast between follicular fluid and ovarian stroma. AFC may be evaluated using real-time two-dimensional (2D) US, stored 2D-US cine-loops and stored three-dimensional (3D) US datasets. Real-time 2D-US has the advantage of permitting additional maneuvers to determine whether an anechoic structure is a follicle, but may require a longer scanning time, particularly when there is a large number of follicles, resulting in more discomfort to the patient. 2D-US cine-loops have the advantages of reduced scanning time and the possibility for other observers to perform the count. The 3D-US technique requires US machines with 3D capability and the operators to receive additional training for acquisition/analysis, but has the same advantages as cine-loop and also allows application of different imaging techniques, such as volume contrast imaging, inversion mode and semi-automated techniques such as sonography-based automated volume calculation. In this Consensus Opinion, we make certain recommendations based on the available evidence. However, there is no strong evidence that any one method is better than another; the operator should choose the best method for counting ovarian follicles based on availability of resources and on their own preference and skill. More studies evaluating how to improve the reliability of AFC should be encouraged. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

True Reproducibility of UltraSound Techniques (TRUST): systematic review of reliability studies in obstetrics and gynecology

OBJECTIVES

To examine the quality of methods used and the accuracy of the interpretation of agreement in existing studies that examine the reliability of ultrasound measurements and judgments in obstetrics and gynecology.

METHODS

A systematic search of MEDLINE was performed on 25 March 2014, looking for studies that examined the reliability of ultrasound measurements and judgments in obstetrics and gynecology with evaluation of concordance (CCC) or intraclass (ICC) correlation coefficients or kappa as a main objective.

RESULTS

Seven hundred and thirty-three records were examined on the basis of their title and abstract, of which 141 full-text articles were examined completely for eligibility. We excluded 29 studies because they did not report CCC/ICC/kappa, leaving 112 studies that were included in our analysis. Two studies reported both ICC and kappa and were counted twice, therefore, the number used as the denominator in the analyses was 114. Only 16/114 (14.0%) studies were considered to be well designed (independent acquisition and blinded analysis) and to have interpreted the results properly. Most errors occurring in the studies are likely to overestimate the reliability of the method examined.

CONCLUSIONS

The vast majority of published studies examined had important flaws in design, interpretation and/or reporting. Such limitations are important to identify as they might create false confidence in the existing measurements and judgments, jeopardizing clinical practice and future research. Specific guidelines aimed at improving the quality of reproducibility studies that examine ultrasound methods should be encouraged.

Three-dimensional ultrasound with volume contrast imaging for preoperative assessment of myometrial invasion and cervical involvement in women with endometrial cancer

OBJECTIVES

To evaluate the accuracy of transvaginal three-dimensional ultrasound with volume contrast imaging (VCI) for preoperative assessment of depth of myometrial invasion and cervical involvement in women with endometrial cancer.

METHODS

Transvaginal volume acquisition of the uterus was performed in 60 consecutive patients with histological diagnosis of endometrial cancer who were scheduled for primary surgical treatment. Depth of myometrial invasion and presence or absence of cervical involvement were assessed using VCI in multiplanar display mode. Results were compared to final postoperative histopathological findings. Patients with histological high-risk cell types, including Grade 3 endometrioid adenocarcinoma, clear cell carcinoma, papillary serous carcinoma and carcinosarcoma, were excluded.

RESULTS

Forty patients were included in the analysis. The accuracy of VCI in assessing single-stage myometrial invasion (superficial or deep) was 92.5%. In the prediction of deep myometrial invasion, sensitivity, specificity, PPV and NPV of VCI were 100%, 89.7%, 78.6% and 100%, respectively. The accuracy of VCI in assessing cervical involvement was 90.0%. Sensitivity, specificity, PPV and NPV of VCI in predicting the presence of cervical involvement were 100%, 86.2%, 73.3% and 100%, respectively.

CONCLUSION

Transvaginal VCI is an uncomplicated method that is able to predict with reasonable accuracy the depth of myometrial invasion and cervical involvement in women with endometrial cancer.

Transfrontal three-dimensional visualization of midline cerebral structures

OBJECTIVE

To compare sonographic visualization of midline cerebral structures obtained by two-dimensional (2D) imaging and three-dimensional (3D) multiplanar and volume contrast imaging in the coronal plane (VCI-C), with transfrontal 3D acquisition.

METHODS

Sixty consecutive healthy fetuses in vertex presentation at a mean gestational age of 24 (range, 20-33) weeks underwent 2D and 3D ultrasound examination. Sagittal cerebral planes were reconstructed using 3D acquisition from axial planes by multiplanar analysis and by VCI-C. The reconstructed midline images of both these techniques were compared with the midline structures visualized directly in the A-plane by transfrontal 3D acquisition using a sweep angle of 30 degrees . Measurement of the corpus callosum and cerebellar vermis and visualization of the fourth ventricle and the main vermian fissures were compared. The sharpness of the images was also assessed qualitatively. Mid-sagittal tomographic ultrasound imaging (TUI) was also performed. 3D planes were compared with 2D transfontanelle median planes obtained by transabdominal or, when required, transvaginal sonography.

RESULTS

The midline plane could be obtained in 88% of multiplanar, 82% of VCI-C and 87% of transfrontal analyses. Measurements of the corpus callosum and cerebellar vermis obtained by 3D median planes were highly correlated. The clearest and sharpest definition of midline structures was obtained with transfrontal acquisition. Primary and secondary fissures of the cerebellar vermis could be detected in 13-26% of multiplanar, 18-35% of VCI-C and 52-79% of transfrontal analyses. 2D visualization was superior or equal to the 3D transfrontal approach in all the parameters compared.

CONCLUSION

3D planes obtained from axial acquisitions are simpler and easier to display than are transfrontal ones. However, artifacts and acoustic shadowing are frequent in 3D axial acquisition and spatial resolution is better in the direct visualization transfrontal technique. If the standard examination includes a view of the fetal facial profile, a quick 3D acquisition through the frontal sutures provides direct visualization for assessment of the midline structures. We believe that this volumetric methodology could represent a step towards incorporating a comprehensive fetal neuroscan into routine targeted organ evaluation.

Fetal sex assignment by sonographic evaluation of the pelvic organs in the second and third trimesters of pregnancy

OBJECTIVE

The purpose of this study was to determine the feasibility and reliability of fetal sex assignment by prenatal sonography of the pelvic organs in the second and third trimesters.

METHODS

A prospective study, on an axial pelvic image with the umbilical arteries in cross section at the midpoint of the bladder, measured the distance between the posterior wall of the bladder and the anterior wall of the rectum. The bladder interface was scored as concave, flat, or convex. Endometrium visualization was recorded. A video loop of the pelvis was obtained. Each case was read by a second reader aware of only the gestational age.

RESULTS

The study population included 205 fetuses. The primary reader was 98.8% accurate in identifying true female fetuses and 100% accurate in identifying true male fetuses. The intraclass correlation coefficient for axial measurement was 0.99. Video loop analysis achieved 96% inter-reader concordance. In the second trimester, measurements in 100% of male fetuses were less than 3.3 mm, and those in 94% of female fetuses were greater than 3.3 mm. In the third trimester, measurements in 96% of male fetuses were less than 4.7 mm, and those in 100% of female fetuses were greater than 4.7 mm. Ninety-eight percent of all fetuses with concave interfaces were female. The endometrium was visualized in 74%. The additional time per examination was less than 5 minutes in 87.7%.

CONCLUSIONS

Internal pelvic fetal sex assignment is a reliable additional method for fetal sex determination. A numerical discriminatory level can be used to distinguish between male and female internal genitalia. Larger numbers will be required to further refine these values.

How useful is 3D and 4D ultrasound in perinatal medicine?

AIM

The purpose of this paper is to review and analyze the published literature on the use of three-dimensional (3DUS) and four-dimensional (4DUS) ultrasound in perinatal medicine.

METHODS

We systematically searched Medline through PubMED (January 2000-January 2006), including EMBASE/Excerpta Medica database as well as the Cochrane Database of Systematic Reviews. The search terms used to identify clinical application of 3DUS and 4DUS studies in perinatal medicine were technical development, special features, and recommendation for fetal imaging, research on 3DUS or 4DUS, and the usage of invasive 3DUS or 4DUS procedures. The reference bibliographies of relevant books were also manually searched for supplementary citations. Inclusion criteria were as follows: (1) studies related to the use of 3DUS or 4DUS in perinatal medicine; (2) full text were available in English; (3) publication format of original scientific articles, case reports, editorials or literature reviews and chapters in the books.

RESULTS

Five hundred and seventy-five articles were identified, and among those, 438 were relevant to this review.

CONCLUSIONS

3DUS and 4DUS provided additional information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical utility of 3DUS and 4DUS for the diagnosis of congenital heart disease, central nervous system (CNS) anomalies and detection of fetal neurodevelopmental impairment assessed by abnormal behavior in high-risk fetuses.

[Contribution of three dimensional imaging techniques in the visualization of the fetal uterus]

The prenatal diagnosis of ambiguous genitalia requires a complete examination of the fetal anatomy to rule out any other congenital defects and the analysis of the fetal genotype. In addition any additional information on the anatomy of the internal genitalia, i.e. the presence or absence of fetal uterus, may be relevant to the prenatal evaluation of female pseudo-hermaphroditism. The recent development of 3D and 4D ultrasound technology may be relevant to a more clearly identification of the fetal uterus. Volume contrast imaging (VCI) provides high contrast images by the realization of thick slices of the region of interest (ROI) thereby providing a clearer picture of the fetal uterus. The multiplanar mode may also facilitate the differentiation of the fetal uterus from the other intra-pelvic organs by offering images in three perpendicular planes. Finally, the tomographic ultrasound imaging (TUI) mode offers the ability to display on a single panel numerous 2-dimensional sections, as obtained using computed tomography imaging.