Evaluation of the perianal muscular complex in the prenatal diagnosis of anorectal atresia in a high-risk population

Prenatal Ultrasound in the Diagnosis of Anorectal Malformations: Correlating Prenatal Signs With Postnatal Outcomes

OBJECTIVE

This study explored prenatal ultrasound markers in patients with anorectal malformations (ARMs).

METHODS

All patients treated for ARM in our institution from January 2014 to December 2021 with an available expert fetal anomaly scan (eFAS) were reviewed. The eFAS images were assessed to evaluate the fetal anus, specifically by identifying hyperechoic anal mucosa surrounded by hypoechoic anal sphincter, referred to as "target sign" (TS). Furthermore, indirect signs of ARM were assessed and correlated with postnatal clinical symptoms.

RESULTS

Of the 115 patients treated for ARM, 32 mothers underwent eFAS. TS was assessed in 22 fetuses, of which 17 (77.3%) had an absent or abnormal TS. Of the patients with a postnatally confirmed complex type of ARM, 90% had an absent or abnormal TS. One or more indirect signs of ARM were found in 16 out of 32 fetuses (50.0%), comprising echogenic bowel (n = 3), echogenic meconium (n = 2), dilated intestines (n = 7), echo-lucent cavity behind the urinary bladder (n = 4), abnormal external genitalia (n = 6), and polyhydramnios (n = 5).

CONCLUSION

This retrospective cohort study provides valuable insights into the potential role of TS assessment and indirect signs in the prenatal diagnosis of ARM. Future studies should further validate our findings and elicit whether TS assessment should be incorporated into prenatal screening protocols.

Infracoccygeal/transperineal window: new method to prenatally diagnose and classify level of anal atresia

OBJECTIVES

To introduce a two-dimensional sonographic method to assess the fetal anus, and to evaluate the feasibility of this method to diagnose anal atresia prenatally and identify the presence or absence of anoperineal fistula (in males) and anovestibular fistula (in females).

METHODS

This was an observational study of suspected cases of anal atresia referred to a single center in Israel between August 2018 and October 2023. In addition to conventional evaluation of the perineum in the axial plane, fetuses referred to our center for suspected malformation were scanned with a new method termed the 'infracoccygeal/transperineal window'. This window consisted of a midsagittal view of the fetal pelvis, including the distal rectum and the anal canal. Normal anatomy was confirmed when the anal canal was continuous with the rectum and terminated at the expected location on the perineum. In female fetuses, the normal anal canal runs parallel to the vaginal canal and diverges posteriorly, terminating at the perineal skin, distant from the vestibule. In male fetuses, the normal anal canal diverges posteriorly in relation to the corpora cavernosa, terminating at the perineal skin, distant from the scrotum. High anal atresia was identified when a blind-ending rectal pouch was demonstrated in the pelvis without a fistula to the perineum or vestibule. Low anal atresia was determined when a rectal pouch was continuous with an anteriorly deflected fistula. In females, the fistula converges with the vaginal canal, terminating at the vestibule; in males, the fistula deflects anteriorly, terminating at the base of the scrotum. Postnatally, the diagnosis and type of anal atresia were confirmed through physical examination with direct visualization of the fistula, radiographic studies, surgical examination and/or postmortem autopsy.

RESULTS

Of the 16 fetuses diagnosed prenatally with anal atresia, eight were suspected to have low anal atresia and eight were suspected to have high anal atresia. The median gestational age at diagnosis was 23 (range, 14-37) weeks. All cases showed additional structural malformation. Eleven patients opted for termination of pregnancy, of which four had low anal atresia and seven had high anal atresia. Postnatal confirmation was not available in four cases due to curettage-induced mutilation or in-utero degradation following selective termination of the affected twin, leaving 12 cases for analysis, of which seven were diagnosed with low anal atresia and five with high anal atresia. In these 12 cases, all prenatal diagnoses were confirmed as correct, rendering 100% sensitivity and 100% specificity in this high-risk fetal population.

CONCLUSIONS

The infracoccygeal/transperineal window is an effective method to detect and classify the level of anal atresia prenatally. This may improve prediction of postnatal fetal continence and optimize prenatal counseling. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

New ultrasound features in diagnosing fetal anal atresia: a multicenter prospective cohort study

This research aimed to assess the validity of ultrasound scans with new features in detecting fetal anal atresia and verify the effectiveness of these new features. Additionally, we aimed at investigating the perinatal incidence of anal atresia. This multicenter prospective study recruited 94,617 normal gravidas and 84 gravidas with anal atresia fetuses. The gold standard for diagnosing perinatal anal atresia is routine neonatal anus examinations. The incidence calculation was based on the results of the gold standard. The validity of our new approach was evaluated via a diagnostic test involving all 94,701 subjects. The effectiveness of our new features was assessed through an ablation study in a randomly established new dataset, with the ratio of anal atresia to non-anal atresia cases of 1:4. The annual perinatal incidence of anal atresia between 2019 and 2023 ranges from 0.57‰ to 1.29‰. Our new method performed great regarding the Youden index, diagnostic odds ratio (DOR), area under the curve (AUC) of the receiver operating characteristic curve (ROCC), AUC of the precision-recall curve (PRC), F1-score, and Cramer's V. In the ablation study, our new approach surpassed its competitors concerning Youden index, DOR, AUC of the ROCC, and AUC of the PRC. Ultrasound scans show high validity and clinical value in detecting fetal anal atresia. Our new ultrasound features significantly promote the detection of fetal anal atresia.

A practical method for prenatal diagnosis of anal atresia by second trimester ultrasound screening - A retrospective study

OBJECTIVES

The study aimed to demonstrate the performance of anal atresia ultrasound screening in the second trimester and to describe associated experiences in a primary care fetal medicine clinic.

MATERIALS AND METHODS

We retrospectively analyzed the medical records of fetuses who underwent a second-trimester screening at the Taiji clinic between November 2019 and May 2022. Fisher's exact test was conducted to investigate potential risk factors.

RESULTS

There were 28 459 fetuses screened in our clinic during the study period; eventually, 6 cases were diagnosed with anal atresia after birth. The incidence of anal atresia in our sample was 2.11 in 10 000. Based on our findings, potential risk factors significantly associated with anal atresia included: multiple pregnancies (p-value = 0.0185) and in-vitro fertilization (p-value = 0.038). Half of the anal atresia cases were associated with abnormalities affecting other organ systems, most frequently the genitourinary system (66.7%) and cardiovascular system (66.7%), especially persistent left superior vena cava (2 cases).

CONCLUSION

Anal atresia is a malformation that requires extensive care; the clinical management after the prenatal discovery of its signs should include testing for chromosomal abnormalities and close monitoring of the amniotic fluid volume. Therefore, prenatal ultrasound screening for anal atresia in the second trimester is critical, particularly in the cases of multiple and IVF pregnancies, and multiple abnormalities. The fetuses with ultrasound signs of anal atresia should be followed at a later gestational period and referred to a specialized institution for postnatal management planning and parental counseling.

High-type anal atresia presenting as a pseudo "target sign" on prenatal ultrasound

OBJECTIVE

We present prenatal ultrasound images of two high anal atresia cases. The main screening tool used in our clinic is the "target sign" in the tangential view of the fetal perineum. In the current report, we discuss some challenges in the existing screening practices.

CASE REPORT

CASE 1: A 28-year-old woman (gravida 1, para 0) with a twin pregnancy underwent ultrasound screening at 21 weeks of gestation when an absent "target sign" in twin A was discovered. At the same time, we were able to present evidence that if the wrong plane was visualized, other structures could be mistaken as the "target sign". Eventually, high-type anal atresia was confirmed postnatally in Twin A. CASE 2: A 29-year-old woman (gravida 1, para 0) came to our clinic for routine screening at 23 weeks of gestation. In the standard tangential view at the level of the perineum, a low-high concentric circle structure resembling a "target sign" was visualized during a prenatal scan. However, anal atresia was discovered postnatally. A retrospective review of prenatal images revealed discrepancies from the typical "target sign".

CONCLUSION

High-type anal atresia may present as a pseudo "target sign" on prenatal ultrasound. Visualization of a "target sign" on fetal ultrasound does not always exclude the diagnosis of anal atresia. It is crucial to evaluate the size, shape, level, and position of the "target sign". The appearance of the bilateral hyperechoic perianal tissue is a hint for the screening of anal atresia.

Clinical Presentations and Diagnostic Imaging of VACTERL Association

Background: VACTERL association consists of Vertebral, Anorectal, Cardiac, Tracheo-Esophageal, Renal, and Limb defects. The diagnosis depends on the presence of at least three of these structural abnormalities. Methods: The clinical presentation and diagnostic prenatal imaging of VACTERL association are comprehensively reviewed. Results: The most common feature is a vertebral anomaly, found in 60-80% of cases. Tracheo-esophageal fistula is seen in 50-80% of cases and renal malformations in 30% of patients. Limb defects including thumb aplasia/hypoplasia, polydactyly, and radial agenesis/hypoplasia are present in 40-50% of cases. Anorectal defects, like imperforate anus/anal atresia, are challenging to detect prenatally. Conclusion: The diagnosis of VACTERL association mostly relies on imaging techniques such as ultrasound, computed tomography, and magnetic resonance. Differential diagnosis should exclude similar diseases such as CHARGE and Townes-Brocks syndromes and Fanconi anemia. New insights into genetic etiology have led to recommendations of chromosomal breakage investigation for optimal diagnosis and counseling.

Prevalence and mortality among children with anorectal malformation: A multi-country analysis

PURPOSE

We examined the total prevalence, trends in prevalence, and age-specific mortality among individuals with anorectal malformation (ARM) METHODS: We conducted a retrospective cohort study using data from 24 population- and hospital-based birth defects surveillance programs affiliated with the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR) from 18 countries and for births from 1974 to 2014. We estimated pooled and program-specific total prevalence per 10,000 total births. Poisson regression was used to assess time trends in prevalence from 2001 to 2012 when most programs contributed data. We calculated selected age-specific proportions of deaths, stratified by case status RESULTS: The pooled total prevalence of ARM was 3.26 per 10,000 total births (95% Confidence Interval = 3.19, 3.32) for birth years 1974-2014. About 60% of cases were multiple or syndromic. Prevalence of multiple, syndromic, and stillborn cases decreased from 2001 to 2012. The first week mortality proportion was 12.5%, 3.2%, 28.3%, and 18.2% among all, isolated, multiple, and syndromic cases, respectively CONCLUSIONS: ARM is relatively rare, with multiple and syndromic cases showing decreasing prevalence during the study period. Mortality is a concern during the first week of life, and especially among multiple and syndromic cases. Our descriptive epidemiological findings increase our understanding of geographic variation in the prevalence of ARM and can be used to plan needed clinical services. Exploring factors influencing prevalence and mortality among individuals with ARM could inform future studies.

Are non-invasive or minimally invasive autopsy techniques for detecting cause of death in prenates, neonates and infants accurate? A systematic review of diagnostic test accuracy

OBJECTIVES

To assess the diagnostic accuracy of non-invasive or minimally invasive autopsy techniques in deaths under 1 year of age.

DESIGN

This is a systematic review of diagnostic test accuracy. The protocol is registered on PROSPERO.

PARTICIPANTS

Deaths from conception to one adjusted year of age.

SEARCH METHODS

MEDLINE (Ovid), EMBASE (Ovid), CINAHL (EBSCO), the Cochrane Library, Scopus and grey literature sources were searched from inception to November 2021.

DIAGNOSTIC TESTS

Non-invasive or minimally invasive diagnostic tests as an alternative to traditional autopsy.

DATA COLLECTION AND ANALYSIS

Studies were included if participants were under one adjusted year of age, with index tests conducted prior to the reference standard.Data were extracted from eligible studies using piloted forms. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. A narrative synthesis was conducted following the Synthesis without Meta-Analysis guidelines. Vote counting was used to assess the direction of effect.

MAIN OUTCOME MEASURES

Direction of effect was expressed as percentage of patients per study.

FINDINGS

We included 54 direct evidence studies (68 articles/trials), encompassing 3268 cases and eight index tests. The direction of effect was positive for postmortem ultrasound and antenatal echography, although with varying levels of success. Conversely, the direction of effect was against virtual autopsy. For the remaining tests, the direction of effect was inconclusive.A further 134 indirect evidence studies (135 articles/trials) were included, encompassing 6242 perinatal cases. The addition of these results had minimal impact on the direct findings yet did reveal other techniques, which may be favourable alternatives to autopsy.Seven trial registrations were included but yielded no results.

CONCLUSIONS

Current evidence is insufficient to make firm conclusions about the generalised use of non-invasive or minimally invasive autopsy techniques in relation to all perinatal population groups.PROSPERO registration numberCRD42021223254.

Challenges in prenatal diagnosis of foetal anorectal malformation and hydrocolpos - Case report

Introduction

and importance: Foetal hydrocolpos and anorectal malformation are difficult to diagnose prenatally due to abundance of differential diagnoses. This case report presents the challenges of diagnosing such disorders.

Case presentation

A G3P2A0 woman came at 32 weeks of pregnancy with a referral for foetal ovarian cyst. Ultrasound revealed a singleton breech pregnancy, estimated foetal weight 3528 g. A septate abdominal cyst measuring 11.31 × 7.17 cm and polyhydramnios were present. Elective caesarean section delivered a female baby weighing 2820 g and measuring 43 cm. Neonatal examination revealed a right lateral suprapubic mass and a rectovestibular fistula. A sinoscopy revealed a suspected hydrocolpos. An abdominal hydrocolpos drainage was performed; a patent urachus and normal bilateral adnexa were present.

Clinical discussion

Hydrocolpos is a rare congenital disorder due to distal obstruction of various etiologies. It may be mistaken with other pathologies, including fetal ovarian cysts. A genitourinary congenital abnormality may occur in conjunction with other abnormalities, including gastrointestinal tract anomalies. The presence of imperforate anus and/or fistula should alert the clinician of a possible association with VACTERL syndrome.

Conclusion

Hydrocolpos is a rare congenital genitourinary disorder with various differential diagnoses. Simultaneous presence of other abnormalities is likely, with possible association to other syndromes.

Fetal Sacral Ratio: A Novel Method for Prenatal Sonographic Assessment of Sacral Abnormalities

OBJECTIVES

The sacral ratio (SR) was described as a postnatal X-ray-based method to detect sacral abnormalities and predict functional prognosis for fecal continence in children with anorectal malformations (ARMs). The present study aimed to describe a novel method of assessing sonographic fetal sacral ratio (f-SR) in a normal population of fetuses.

METHODS

Sixty three-dimensional (3D) ultrasound reconstruction images of the sacrum obtained from routine low-risk scans performed between 21 and 26 weeks of gestation served for measurement. The f-SR was calculated in a coronal view as the ratio between lines drawn at the upper and lower levels of the iliac bone and the 5th sacral vertebra. Bland-Altman plots assessed the inter- and intrareader variabilities of measurements.

RESULTS

The f-SR in the normal population of fetuses was 0.913 (±0.094). During the study period, three cases with ARM were examined and had a mean f-SR of 0.55. There was good repeatability of measurements and between readers' agreement.

CONCLUSIONS

The present study introduces a novel prenatal sonographic f-SR that can be reliably calculated on prenatal 3D ultrasound with good reliability and reproducibility. Future research will identify the clinical significance of f-SR abnormalities in ARM and their long-term impact on continence.

Significance of the 'line sign' in the diagnosis of congenital imperforate anus on prenatal ultrasound

Background

The prenatal diagnosis of foetal imperforate anus is difficult. Most previous studies have been case reports. To provide useful information for diagnosing foetal imperforate anus, a retrospective review of diagnostic approaches was conducted. Ultrasonography was performed in 19 cases of foetal imperforate anus from 2016 to 2019 at our prenatal diagnostic centre. The prenatal sonographic features and outcomes of each case were collected and evaluated.

Result

The anal sphincter of a normal foetus shows the ‘target sign’ on cross-sectional observation. Of the 19 cases of imperforate anus, 16 cases were diagnosed by the ultrasound image feature called the ‘line sign’. 1 case with tail degeneration was low type imperforate anus with the irregular ‘target sign’ not a real ‘target sign’. There was two false-negative case, in which the ‘target sign’ was found, but irregular.

Conclusion

In this study, we find that the anus of a foetus with imperforate anus presents a ‘line sign’ on sonographic observation. The absence of the ‘target sign’ and then the presence of the ‘line sign’ can assist in the diagnosis of imperforate anus. The ‘line sign’ can be used as a secondary assessment to determine the type of the malformation following non visualization of the ‘target sign’. The higher the position of the imperforate anus is, the more obvious the ‘line sign’. It is worth noting that the finding of the short ‘line sign’ and irregularr ‘target sign’ can not ignore the low type imperforate anus.

Anal atresia as the diagnostic clue in VACTERL association: A first-trimester case report

Anal atresia is the most common malformation occurring in VACTERL association, but it is difficult to diagnose antenatally. We herein present a case of fetal anal atresia in VACTERL association diagnosed by ultrasonography and supported by autopsy. This case emphasizes the clues to ultrasonographic diagnosis of anal atresia at 11-13⁺⁶ weeks of gestation, promoting increased awareness of VACTERL association during first-trimester screening.

Sonographic detection and localization of fistulas in fetuses with imperforate anus: Case reports

Imperforate anus (IA) requires urgent treatment after birth, which is dependent on the type of IA, and is also frequently associated with other congenital abnormalities. Most patients with IA have an accompanying fistula, whose location is strongly associated with the type of IA. The fistula location can be a key factor in defining appropriate treatment, especially in neonates presenting with severe associated abnormalities. Herein, we report three cases of IA in which fistulas were detected and localized prenatally. Examination of the fetal pelvis through the sagittal or coronal view, using high-frequency transducers, revealed the location of the fistulas. In particular, the sagittal view obtained using the fetal infracoccygeal or perineal approach allowed us to determine the precise anatomy of the fistulas. Neonatal assessment confirmed the fistula locations. We recommend using the sagittal view obtained using the fetal infracoccygeal or perineal approach with high-frequency transducers to assess fistulas in fetuses with IA.

Can Anorectal Atresia Be Diagnosed in the First Trimester of Pregnancy? A Systematic Literature Review

Anorectal atresia (ARA) is a common congenital anomaly, but prenatal diagnosis is difficult, late, and unspecific. Utilizing a case of a 46 year old primipara with an egg donation In Vitro Fertilization (IVF) pregnancy, diagnosed at the first trimester scan with an anechoic isolated structure, which indicates anal atresia, we performed a systematic literature review in order to evaluate early prenatal ARA diagnosis. A total of 16 cases were reported as first trimester ARA suspicion, and only three had no associated anomalies. The most frequent ultrasound (US) sign was the presence of a cystic, anechoic pelvic structure of mainly tubular shape, or a plain abdominal cyst. In the majority of cases, structures were thin-walled and delimitated from the bladder. The presence of hyperechoic spots signifying enterolithiasis and peristaltic movements were helpful in order to establish the bowel origin of the lesion. Considering the high eventuality that the lesion is transitory, meaning later in pregnancy the fetus looks normal, early detection of such a sign should prompt further structural detailed evaluation, karyotyping, and appropriate pregnancy and postnatal counselling.

The diagnosis of an imperforate anus in female fetuses

Imperforate anus is an anomaly caused by a defect in the development of the hindgut during early pregnancy. It is a relatively common congenital malformation and is more common in males. Although there are cases of a solitary imperforate anus, the condition is more commonly found as a part of a wider spectrum of other congenital anomalies. Although urgent reconstructive anorectal surgery is not necessary, immediate evaluation is important and urgent decompressive surgery may be required. Moreover, as there are often other anomalies that can affect management, prenatal diagnosis can help in optimizing perinatal care and prepare parents through prenatal counseling. In the past, imperforate anus was diagnosed by prenatal ultrasonography based on indirect signs such as bowel dilatation or intraluminal calcified meconium. Currently, it is diagnosed by directly checking the perineum with prenatal ultrasonography. Despite advances in ultrasound technology, accurate prenatal diagnosis is impossible in most cases and imperforate anus is detected after birth. Here, we present two cases of imperforate anus in female fetuses that were not diagnosed prenatally.

Foetal Sonographic Anogenital Distance Is Longer in Polycystic Ovary Syndrome Mothers

Anogenital distance (AGD) is a biomarker for the prenatal hormonal environment. Androgen excess is a key element in polycystic ovary syndrome (PCOS). The aim of this study was to assess the sonographic foetal AGD in a population of PCOS mothers in comparison to the general population. Foetal AGD was measured prospectively by 2D ultrasound in PCOS mothers and compared to prenatal AGD nomograms. The results were interpreted regarding maternal and foetal characteristics. The mean sonographic foetal AGD centile measurement in PCOS mothers was significantly longer in comparison to the general population (86.04% ± 18.22; p < 0.001). Estimated foetal weight and birthweight were appropriate for gestational age and did not correlate with AGD. Sonographic foetal AGD was significantly longer in PCOS diabetic mothers and in those who conceived following assisted reproduction treatments when compared to the general population (p < 0.001). Our results support the role of AGD as a biomarker of the prenatal hormonal environment and provide evidence for the hyperandrogenic effect in PCOS pregnancies on foetal androgenic status and genitalia development.

Imaging of anorectal malformations in utero

PURPOSE

To document the imaging findings suggestive of anorectal malformation (ARMs) on prenatal US and MRI.

METHODS

Retrospective evaluation of the screening US and prenatal MRI exams of the rectum and ano-perineal region in normal fetuses and in patients with ARMs.

RESULTS

Examples showing the normal rectal and anoperineal anatomy on prenatal US and MRI exams and the imaging findings observed in different types of confirmed ARMS.

CONCLUSIONS

Prenatal diagnosis of ARMs requires both a systematic evaluation of the fetal pelvis and perineum and an appropriate knowledge of its suggestive imaging findings.

Prenatal imaging of anorectal malformations - 10-year experience at a tertiary center in Switzerland

BACKGROUND

Anorectal malformation is a spectrum of congenital defects of the distal bowel, mostly diagnosed at birth.

OBJECTIVE

To describe the prenatal imaging findings of anorectal malformations, explore the causes of the low rates of prenatal diagnosis, compare the accuracy of prenatal ultrasound (US) and magnetic resonnance imaging [MRI] and evaluate the relevance of information obtained at MRI.

MATERIALS AND METHODS

Children treated for anorectal malformation at our hospital and with available prenatal studies were retrospectively identified and included in the study. We reviewed prenatal imaging exams, listed findings suggestive of the diagnosis, and compared results with the final classification.

RESULTS

Fourteen fetuses and neonates - eight with intermediate-high type anorectal malformation and six with cloacae - fulfilled the inclusion criteria. All had associated congenital anomalies. Prenatal exams included 13 US and 8 MRI exams, with 7 children having both exams. Suggestive findings for anorectal malformation were detected in 50% of the cases prenatally and in 85% upon review. They were prospectively detected in 31% and 50% of the cases at US and MRI and retrospectively in 62% and 100% at US and MRI, respectively. MRI was superior to US because it improved the diagnosis, especially in cloacae, and provided relevant additional information that changed management in two cases.

CONCLUSION

The most important signs suggesting anorectal malformation are an absent target sign and anomalous distal bowel wall and rectal fluid. Complementary prenatal MRI improves the diagnosis of anorectal malformation.

Prenatal diagnosis and postnatal outcome of anterior urethral anomalies

OBJECTIVES

Anterior urethral anomalies (AUA) which present as anterior urethral valve, stenosis or atresia, are a rare cause for congenital urinary tract obstruction. We present our AUA prenatal diagnosis case series.

METHODS

Fetuses presenting with prenatal findings suggestive for AUA according to postnatal reported clinical and imaging signs (urinary tract dilatation, dilated bladder, enlarged edematous fetal penis, dilatation of the fetal urethra and diverticula) were followed prospectively.

RESULTS

Six fetuses were diagnosed with AUA. Diagnosis was confirmed upon examination of the neonate or the abortus. All cases presented with variable degrees of urinary tract dilatation. Four fetuses who presented with additional congenital anomalies of the kidneys and urinary tract (CAKUT) developed intra-uterine or early postnatal renal failure, while two isolated AUA cases have a normal renal outcome.

CONCLUSIONS

AUA is a rare diagnosis. However, high index of suspicion and careful sonographic assessment of the male fetal urethra in cases referred for urinary tract dilatation may enable appropriate parent counseling, optimal prenatal surveillance and timed postnatal urological intervention. As in other lower urinary tract obstructions, future renal function seems to correlate with associated CAKUT, therefore close follow up throughout pregnancy and meticulous sonographic assessment is recommended.

Fetal megacystis: a lot more than LUTO

OBJECTIVE

Fetal megacystis presents a challenge in terms of counseling and management because of its varied etiology and evolution. The aim of this study was to present a comprehensive overview of the underlying etiologies and structural anomalies associated with fetal megacystis.

METHODS

This was a retrospective multicenter study of cases referred to the fetal medicine unit of one of the eight academic hospitals in The Netherlands with a diagnosis of fetal megacystis. For each case, data on and measurements of fetal urinary tract and associated structural anomalies were collected. All available postmortem examinations and postnatal investigations were reviewed in order to establish the final diagnosis. In the first trimester, fetal megacystis was defined as longitudinal bladder diameter (LBD) ≥ 7 mm, and in the second and third trimesters as an enlarged bladder failing to empty during an extended ultrasound examination lasting at least 40 min.

RESULTS

Of the 541 pregnancies with fetal megacystis, it was isolated (or solely accompanied by other signs of lower urinary tract obstruction (LUTO)) in 360 (67%) cases and associated with other abnormal ultrasound findings in 181 (33%) cases. The most common associated ultrasound anomaly was an increased nuchal translucency thickness (22%), followed by single umbilical artery (10%) and cardiac defect (10%). A final diagnosis was established in 418 cases, including 222 (53%) cases with isolated LUTO and 60 (14%) infants with normal micturition or minor isolated urological anomalies. In the remaining 136 (33%) cases, concomitant developmental or chromosomal abnormality or genetic syndrome was diagnosed. Overall, 40 chromosomal abnormalities were diagnosed, including trisomy 18 (n = 24), trisomy 21 (n = 5), Turner syndrome (n = 5), trisomy 13 (n = 3) and 22q11 deletion (n = 3). Thirty-two cases presented with anorectal malformations involving the anus, rectum and urogenital tract. In cases with confirmed urethral and anal atresia, megacystis occurred early in pregnancy and the bladder appeared severely distended (the LBD (in mm) was equal to or greater than twice the gestational age (in weeks)). Fetal macrosomia was detected in six cases and an overgrowth syndrome was detected in four cases, comprising two infants with Beckwith-Wiedemann syndrome and two with Sotos syndrome. Megacystis-microcolon-intestinal hypoperistalsis syndrome was diagnosed in five (1%) cases and prenatally suspected only in one case.

CONCLUSIONS

Although the main cause of fetal megacystis is LUTO, an enlarged fetal bladder can also be present as a concomitant finding of miscellaneous genetic syndromes, developmental disturbances and chromosomal abnormalities. We provide an overview of the structural anomalies and congenital disorders associated with fetal megacystis and propose a practical guide for the differential diagnosis of genetic syndromes and chromosomal and developmental abnormalities in pregnancies presenting with fetal megacystis, focusing on the morphological examination of the fetus. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal Evaluation for Detection of Anorectal Atresia: Value of Ultrasound

OBJECTIVES

To investigate the applicability and value of ultrasound (US) in the diagnosis of anorectal atresia.

METHODS

Between January 2008 and January 2016, we prospectively evaluated 63,101 fetuses (gestational age, 20-38 weeks), including low- and high-risk populations using 2-dimensional US scans. An abnormal imaging finding was defined as an anal canal diameter of less than the 95% confidence interval (small anal canal) of the normal range or the absence of an anal canal and rectum. Imaging findings were considered normal on detection of an anal canal with a normal width and the absence of abnormalities. Prenatal imaging findings were confirmed by a postnatal or postmortem examination.

RESULTS

Among the investigated fetuses, 28 showed evidence of anorectal atresia on US scans, and 22 of those with anorectal atresia had additional anomalies. Six cases of isolated anorectal atresia were successfully detected during the preclusive prenatal US scans. Four cases of a low imperforate anus (including 2 covered anuses) yielded false-negative results, indicating a diagnostic rate of 87.5% (28 of 32). The normal appearance of the fetal rectum and anal canal ruled out anorectal atresia in 30 fetuses with a dilated colon. Additionally, there were 3 false-positive cases, in which a narrow anal canal was observed.

CONCLUSIONS

Identifying the abnormal appearance or absence of the fetal anal canal and rectum on preclusive US anomaly scans is useful for prenatal diagnosis or exclusion of anorectal atresia, which may help improve the detection of isolated anorectal atresia. Furthermore, a combined evaluation of the longitudinal and axial appearances of the fetal anal canal and rectum can improve diagnostic accuracy.

Prenatal Diagnosis of Enterolithiasis in 20 Cases

BACKGROUND

Enterolithiasis is a sonographic sign defined by hyperechogenic foci within the - often distended - fetal bowel.

OBJECTIVES

We report on a series of 20 cases with enterolithiasis diagnosed prenatally and illustrate the spectrum of associated malformations.

METHOD

This was a retrospective study involving 20 fetuses with enterolithiasis at two large tertiary referral centers in Germany over a 17-year period (2000-2017).

RESULTS

Median diagnosis was made with ultrasound at 18+2 weeks of gestation (IQR25,75: 14+5, 26+5). Additional malformations included urogenital malformations (cloacal malformation in 7/20 fetuses [35%] and kidney defects in 7/20 fetuses [35%]), cardiac malformations (3/20 fetuses [15%]), and vertebral malformations (5/20 fetuses [25%]). Of 20 fetuses, 14 could be attributed to the anorectal malformation spectrum, 3/20 fetuses presented with caudal regression syndrome, and 1 fetus with bilateral kidney agenesis, congenital diaphragmatic aplasia, and enterovesical fistula, respectively.

CONCLUSION

Enterolithiasis is a rare prenatal sonographic feature. Because of the frequent occurrence of uro-recto-genital malformations, thorough prenatal counseling should be performed.

How to Explore Fetal Sacral Agenesis Without Open Dysraphism: Key Prenatal Imaging and Clinical Implications

The estimated prevalence of fetal caudal dysgenesis is 1 per 100,000 births. The functional prognosis of sacral agenesis is dominated by the large spectrum of associated caudal malformations. Except for cases associated with hydrocephalus secondary to open spinal dysraphism or chromosomal anomalies, association with mental deficiency is rare. We propose a systematic prenatal approach to cases of fetal sacral agenesis based on 9 etiologic items: clinical context, type of sacral dysgenesis, associated spinal cord malformations, mobility of lower limbs, investigation of the presacral region, analysis of the gastrointestinal tract, analysis of the genitourinary tract, associated vertebral defects, and cytogenetic analysis.

Prenatal Diagnosis of Anal Atresia - A Case Report

Anal atresia can be divided into high type and low type depending on the relationship between the distal rectal pouch and the puborectalis muscle. Prenatal diagnosis of anal atresia is very challenging. Indirect findings include dilated distal bowel segments and calcified intraluminal meconium in 2^nd & 3rd trimester. Direct findings include no PAMC (perianal muscular complex) and no target sign (hypoechoic anal sphincter and echogenic anal mucosa). PAMC is intact in low atresia, no PAMC can only be applied to high atresia. A visible echogenic anal mucosa excludes all cases of high atresia and most cases of low atresia, with the exception of the mildest cases with only a thin membrane covering the anal opening.

Sonographic Determination of Type in a Fetal Imperforate Anus

OBJECTIVES

The purpose of this study was to determine the type of an imperforate anus by using sonography in the prenatal period.

METHODS

This retrospective study evaluated the fetal anus in all pregnant women, including low- and high-risk populations, between February 2010 and November 2013. High-type imperforate anuses were diagnosed by prenatal sonography when the anal sphincter muscles and anal canal mucosa were not visible. Low-type imperforate anuses were prenatally suspected when at least 1 of the following was present: (1) a small anus; (2) no visible anal mucosa; or (3) close location of the genitalia by the anus without a visible perineal body, particularly in a female fetus.

RESULTS

Among the 9499 fetuses, 41 were prenatally suspected of having an imperforate anus, and 32 were confirmed to have this disorder. During the same study period, there were 11 false-negative cases, for a diagnostic sensitivity rate of 74%. All 9 fetuses who were confirmed to have a normal anus were prenatally suspected of having a low-type imperforate anus. Among the 32 fetuses with a confirmed imperforate anus, 19 were confirmed to have a high or intermediate type and 13 to have a low type. The type in 3 fetuses was incorrectly determined prenatally.

CONCLUSIONS

Although an imperforate anus is not always diagnosed prenatally, its type can be determined by prenatal sonography.

Imaging Evaluation of Fetal Megacystis: How Can Magnetic Resonance Imaging Help?

Evaluation of the kidneys, bladder, and amniotic fluid volume forms part of any standard obstetrical ultrasound. When a fetal genitourinary anomaly is suspected, a more detailed evaluation is necessary. This detailed imaging can be challenging in the setting of decreased or absent amniotic fluid or large maternal body habitus, and in complex malformations. In these situations, magnetic resonance imaging can help to better define the fetal anatomy and provide a more confident and specific prenatal diagnosis.

Evaluation of the development of the fetal anal sphincter with tomography ultrasonography imaging

The aim of the study described here was to examine the potential of tomography ultrasonography imaging (TUI) in evaluation of the fetal anal sphincter. In this prospective cross-sectional study of the fetal anal sphincter with TUI, 326 singleton pregnancies (mean age = 28 y, range: 22-38 y) were scanned at 19-40 wk of gestation. The fetal anal region and ischium were revealed in 320 of 326 patients (98.2%). The normal fetal anal sphincter diameter and ischial space reached maximums of 15 and 39 mm, respectively. The normal fetal anal sphincter diameter and the ischial space were plotted as a function of gestational age (GA) on a linear curve, and the regression equations for normal fetal anal sphincter diameter and ischial space as a function of GA in weeks were obtained. A scatterplot was also created that revealed a significant positive relationship between normal fetal anal sphincter diameter and ischial space. On the basis of these criteria, imperforate anus was diagnosed in one fetus. Ultrasonographic assessment of the fetal anal sphincter and the ischium with TUI is feasible. The reference values reported in this article may be useful in prenatal diagnosis of fetal anal sphincter abnormalities.

Outcome of first-trimester fetal abdominal cysts: cohort study and review of the literature

OBJECTIVES

The aims of this study were to ascertain the outcome of fetuses with an abdominal cyst detected at 11-14 weeks' gestation in our unit and to undertake a review of cases reported in the literature.

METHODS

This was a retrospective study that included all fetuses found to have an abdominal cyst on ultrasound examination at 11-14 weeks, identified over a 14-year period. Pregnancy management and outcome were ascertained from maternal and neonatal records. We also performed a review of the literature using a systematic search strategy, to identify the outcome of similar cases and propose a management algorithm.

RESULTS

Fourteen cases were identified during the study period, of which four had associated abnormalities. Of the 10 isolated cases, the cyst had resolved at follow-up scan in eight (80.0%), one fetus died in utero at 15 weeks' gestation and the other case underwent surgery for a choledochal cyst 9 weeks after birth. An additional 19 cases were reported in the literature. In eight fetuses there were associated structural abnormalities, of which four had a diagnosis of anorectal malformation after birth. In two of these four, the cyst resolved in the second trimester. Of those cases with an isolated cyst (n = 11), the cyst resolved in seven (63.6%). The remainder were variably diagnosed as hepatic cyst, ileal duplication or choledochal cyst.

CONCLUSION

Fetal abdominal cysts at 11-14 weeks' gestation are rare. They constitute an isolated finding in the majority of cases and are usually associated with a good perinatal outcome. In view of the reported association with anorectal and other gastrointestinal malformations, perinatal assessment is recommended, even if the cyst resolves during pregnancy.

[Anorectal malformations]

Anorectal malformations (ARM) are the result of an abnormal development of the terminal part of the digestive tract interesting anus and/or rectum that occur early between the sixth and tenth week of embryonic development. They carry a malformation spectrum of severity depending on the level of disruption of the anorectal canal and of the associated caudal malformations (sacrum and spine). ARM are associated in over half the cases with other malformations that can be integrated in some cases in known syndromes. If surgical treatment to restore anatomy as normal as possible is indispensable, post-operative care is essential for these patients whose defecation mechanisms are altered, to reach if not continence, at least a socially acceptable cleanliness.