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

Development of a Standardized Algorithm for Management of Newly Diagnosed Anorectal Malformations

Neonates with a new diagnosis of anorectal malformation (ARM) present a unique challenge to the clinical team. ARM is strongly associated with additional midline malformations, such as those observed in the VACTERL sequence, including vertebral, cardiac, and renal malformations. Timely assessment is necessary to identify anomalies requiring intervention and to prevent undue stress and delayed treatment. We utilized a multidisciplinary team to develop an algorithm guiding the midline workup of patients newly diagnosed with ARM. Patients were included if born in or transferred to our neonatal intensive care unit (NICU), or if seen in clinic within one month of life. Complete imaging was defined as an echocardiogram, renal ultrasound, and spinal magnetic resonance imaging or ultrasound within the first month of life. We compared three periods: prior to implementation (2010-2014), adoption period (2015), and delayed implementation (2022); p ≤ 0.05 was considered significant. Rates of complete imaging significantly improved from pre-implementation to delayed implementation (65.2% vs. 50.0% vs. 97.0%, p = 0.0003); the most growth was observed in spinal imaging (71.0% vs. 90.0% vs. 100.0%, p = 0.001). While there were no differences in the rates of identified anomalies, there were fewer missed diagnoses with the algorithm (10.0% vs. 47.6%, p = 0.05). We demonstrate that the implementation of a standardized algorithm can significantly increase appropriate screening for anomalies associated with a new diagnosis of ARM and can decrease delayed diagnosis. Further qualitative studies will help to refine and optimize the algorithm moving forward.

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.

Magnetic resonance imaging of fetal abdominal pathology: a complementary tool to prenatal ultrasound

Fetal magnetic resonance imaging (MRI) is increasingly being used worldwide as a complementary tool to prenatal ultrasound (US) for multiple fetal pathologies. The aim of this article is to describe and illustrate how MRI can help US to evaluate fetal abdominal anomalies, based on cases performed in a tertiary public university hospital. Prenatal US, fetal MRI and postnatal imaging of these cases will be shown side-by-side to describe and illustrate the added value of fetal MRI in the different organs/systems and its impact on clinical management.

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.

Avoiding the antenatal counselling faux pas: bridging the gap between prenatal prognostication and postnatal outcome of closed spina bifida

PURPOSE

Closed spina bifida (CSB) is rare in prenatal literature, and various lesions are grouped under this broad nosological entity CSB, leading to confusing and misleading prognostic conclusions.

METHODS

This is a retrospective observational cohort study of prenatally detected CSB cases using two-dimensional ultrasound, complemented by three-dimensional ultrasonography and foetal MRI in indicated cases, from October 2014 to October 2021 in a tertiary-level single centre.

RESULTS

The most common upper vertebral level of CSB was lumbar in 66.6% (10/15). The sub-classification of lesions based on prenatal ultrasound showed an agreement in 53% of the cases. Sixty percent had associated abnormalities identified postnatally, the most common being anorectal malformation seen in 33.3%. On postnatal follow-up, 46.6% had bowel incontinence and bladder dysfunction, and 33.3% developed lower limb deformities.

CONCLUSIONS

All CSBs do not have a uniformly favourable prognosis. The prognosis of CSB depends on the pathological type, the presence of associated abnormalities and the management.

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.

Imaging of anorectal malformations: where are we now? Abdominal imaging task force of the European Society of Paediatric Radiology

Anorectal and cloacal malformations are a broad mix of congenital abnormalities related to the distal rectum and anus. Confusion exists between all the forms in this large and heterogeneous group. The spectrum includes everything from anal stenosis, ventral anus, anal atresia (with and without fistula) and the full spectrum of cloacal malformations. Imaging in these conditions is done through the whole armamentarium of radiologic modalities, with very different imaging strategies seen across the centres where these conditions are managed. In 2017, the European Society of Paediatric Radiology (ESPR) abdominal imaging task force issued recommendations on the imaging algorithm and standards for imaging anorectal malformations. This was followed by further letters and clarifications together with an active multispecialty session on the different imaging modalities for anorectal malformations at the 2018 ESPR meeting in Berlin. Through this paper, the abdominal task force updates its guidelines and recommended imaging algorithm for anorectal malformations.

Genetic Counseling and Diagnostics in Anorectal Malformation

Anorectal malformation (ARM) is a relatively frequently occurring congenital anomaly of hindgut development with a prevalence of 1 in 3,000 live births. ARM may present as an isolated anomaly, but it can also be associated with other anomalies, sometimes as part of a recognizable syndrome. After birth, much medical attention is given to the treatment and restoring of bowel function in children with ARM. Effort should also be given to studying the etiology of the ARM in these patients. This information is important to both the medical community and the family, because it can help guide treatment and provides information on the long-term prognosis of the patient and recurrence risk in the family.In this article, we will review the current knowledge on the (genetic) etiology of (syndromic) ARM and provide guidelines for (family) history taking and clinical and genetic studies of ARM patients and their families, which is needed to study the causal factors in an ARM patient and for genetic counseling of the families.

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.