Contribution of the foetal uro-MRI in the prenatal diagnosis of uronephropathies

Antenatal and postnatal management of posterior urethral valves: where do we stand?

Introduction

Posterior urethral valve (PUV) is the leading etiology of lower urinary tract obstruction (LUTO) in boys and is an important cause of end-stage renal disease (ESRD) in children. The aim of this article is to review the current status on antenatal intervention for PUV as well as postnatal medical and surgical management.

Main body

MEDLINE, EMBASE, Pubmed and Google Scholar search was conducted throughout December 2020 using the keywords: posterior urethral valves, congenital urinary obstruction, antenatal, valve bladder syndrome, medical, anticholinergics, alpha blocker, antibiotics, biofeedback, diversion, augmentation cystoplasty and renal transplantation. Only papers written in English were included. The relevant literature was summarized. Despite advances in antenatal intervention for fetal LUTO, it remains associated with considerable fetal and maternal morbidity. Patient selection criteria for antenatal intervention are greatly debated. Fetal intervention has resulted in improved perinatal survival in properly selected cases, with a questionable benefit to postnatal renal function. There is decent evidence supporting the use of anticholinergics in infants and young children following valve ablation, with less robust evidence advocating alpha blockers, overnight catheter drainage and biofeedback. The role of urinary diversion remains contentious. Optimizing bladder dynamics is crucial for successful renal transplantation outcomes.

Conclusion

While antenatal intervention has failed to improve renal function outcomes of PUV, patient-centered medical and sometimes surgical interventions can help delay the progression of chronic kidney disease. Lifelong monitoring and management of the associated bladder dysfunction is indispensable even after successful renal transplantation.

Fetal body MRI for fetal and perinatal management

Fetal magnetic resonance imaging (MRI) has become a valuable adjunct to ultrasound (US) in diagnosing fetal abnormalities. This review is intended to highlight the contribution of MRI in parental counselling and perinatal treatment. A state-of-the-art fetal MRI protocol with experts of maternal-fetal medicine present in the MRI suite allows emphasis on patient-centred care and maximises therapeutic options.

Update on the Prenatal Diagnosis and Outcomes of Fetal Bilateral Renal Agenesis

Importance

Bilateral renal agenesis is a rare congenital anomaly associated with poor prognosis.

Objective

The aims of this article are to review and summarize evidence on prenatal diagnosis and outcomes of bilateral renal agenesis.

Evidence Acquisition

A search was undertaken using PubMed and ClinicalTrials.gov databases from January 1, 1998, to September 1, 2018. Search terms include "prenatal diagnosis" OR "outcomes" AND "bilateral renal agenesis." Search was limited to English language.

Results

Fetal ultrasonography is the primary imaging modality for prenatal diagnosis of fetal urogenital tract abnormalities. However, ultrasonography is limited by several factors; it is operator dependent and associated with small field of view, has limited soft-tissue acoustic contrast, and is also influenced by patient habitus and fetal position. Color Doppler ultrasonography can be used as an adjunct to exclude bilateral renal agenesis by visualizing renal arteries. In the literature, prenatal magnetic resonance imaging has been reported to be equal to or superior to prenatal ultrasonography. Bilateral renal agenesis with oligohydramnios/anhydramnios is associated with a poor prognosis; perinatal death occurs secondary to pulmonary hypoplasia in the majority of cases.

Conclusions

Ultrasonography in combination with color Doppler ultrasonography permits the fetal urinary tract to be assessed in the first and early second trimester of gestation. The magnetic resonance imaging can be used as a complementary adjunctive modality in equivocal or inconclusive ultrasonographic findings.

The use of fetal MRI for renal and urogenital tract anomalies

Fetal anomalies are detected in approximately 2% of all fetuses and, among these, genitourinary tract abnormalities account for 30% to 50% of all structural anomalies present at birth. Although ultrasound remains the first line diagnostic modality, fetal MRI provides important additional structural and functional information, especially with the development of faster sequences and the use of functional sequences. The added value of MRI-based imaging is three-fold: (a) improvement of diagnostic accuracy by adequate morphological examination, (b) detection of additional anomalies, and (c) in addition, MRI has the potential to provide information regarding renal function. In this review, we describe the role of fetal MRI in the anatomical evaluation of renal and urogenital tract anomalies, and we also touch upon the contribution of functional MRI to the diagnostic workup of these conditions.

Prenatal diagnosis of renal duplication by magnetic resonance imaging

Purpose: To determine the value of fetal magnetic resonance imaging (MRI) to detect renal duplication.Methods: In this retrospective study, prenatal MRI and ultrasound (US) diagnoses were compared with postnatal imaging and/or surgical data. Twenty-six pregnant women (average age, 32 years; range, 29-36 years) underwent MRI at a mean gestational age of 25 weeks (range, 21-33 weeks). MRI was performed with a 1.5-T unit within 1 week after prenatal ultrasound examination. The steady-state free-precession (SSFP), single-shot turbo spin echo (SSTSE), and T₁-weighted fast imaging sequences were used.Results: Twenty-four cases of fetal renal duplications diagnosed using prenatal MRI were judged to be correct when compared with postnatal imaging and surgical follow-up. In 18 of 26 cases, the diagnoses established using prenatal US were correct when compared with postnatal diagnosis. In 2 of 26 cases, the diagnosis with both prenatal US and MRI were not entirely correct when compared with postnatal diagnosis. In the two cases, magnetic resonance (MR) identified left two pelvicalyceal systems but could not found ipsilateral ectopic ureteral orifice, US only found left hydronephrosis but could not found duplex collection system. In other six cases, MR corrected the US diagnosis by providing a more accurate renal morphology or additional diagnostic information.Conclusions: MRI is an effective method for the diagnosis of fetal duplex kidney deformity and associated ureteral and other abnormalities.

Magnetic resonance imaging for evaluation of foetal multicystic dysplastic kidney

We sought to evaluate the diagnostic value of foetal magnetic resonance imaging (MRI) for multicystic dysplastic kidney (MCDK) disease. We retrospectively identified 55 foetuses with MCDK diagnosed (51 unilateral; 4 bilateral) by foetal MRI. We analysed the anatomical findings by prenatal MRI and compared them with the prenatal ultrasound (US) and postnatal findings. Additional diagnostic information added by MRI was recorded. The gestational age of the 55 foetuses ranged from 22 to 35 weeks (mean, 26.5 ± 3.6 weeks). The age of the pregnant women ranged from 23 to 40 years (mean, 31 ± 4.2 years). All 55 cases were performed at 1.5 T magnetic resonance unit. MRI sequences, including steady-state free precession (SSFP), single-shot fast spin echo (SSFSE), T₁-weighted imaging (T₁WI), and diffusion weighted imaging (DWI) sequences. Follow-up was obtained for 53 cases (2 cases of autopsy, 51 cases of postnatal imaging or surgery confirmed). Among the 51 unilateral cases, 16 cases were associated with other urinary tract anomalies, 3 cases with extra-renal anomalies, and the remaining 32 cases without associated anomalies. 2 of 16 cases with contralateral renal agenesis were with oligohydramnios and pulmonary hypoplasia. 2 of 4 bilateral MCDK presented with oligohydramnios and pulmonary hypoplasia. 52 of 53 cases were correctly diagnosed by MRI compared with the final diagnoses; 40 of 53 (75.5%) cases were correctly diagnosed by prenatal ultrasound. Both prenatal ultrasound and MRI failed to correctly diagnose one case bilateral MCDK, and MRI correctly changed the ultrasound diagnosis in 12 cases. Foetal MRI can add additional diagnostic information to prenatal US in the assessment of MCDK, even change the prenatal counselling and decisions.

Current State of Fetal Intervention for Lower Urinary Tract Obstruction

PURPOSE OF THE REVIEW

In this article, we explore the origins of intervention of fetal lower urinary tract obstruction, and we specifically discuss the background and recent outcomes of vesicoamniotic shunt placement and fetal cystoscopy. The article seeks to provide a comprehensive overview of the field while bringing the reader quickly up to speed on the pertinent literature and the critical data that are available to guide decision-making regarding intervention.

RECENT FINDINGS

Appropriate patient selection for fetal intervention remains challenging despite advances in prenatal imaging. Both a randomized controlled trial and multiple systematic reviews show evidence of a perinatal survival benefit following fetal intervention but rates of renal morbidity remain very high. Despite 30 years of research, fetal lower urinary tract obstruction remains a difficulty entity to treat. Intervention may lead to survival, but physicians and caregivers must remain alert for the distinct possibility of long-term renal morbidity in survivors.

Lower urinary tract obstruction: fetal intervention based on prenatal staging

The authors present an overview of lower urinary tract obstruction (LUTO) in the fetus with a particular focus on the insult to the developing renal system. Diagnostic criteria along with the challenges in estimating long-term prognosis are reviewed. A proposed prenatal LUTO disease severity classification to guide management decisions with fetal intervention to maintain or salvage in utero and neonatal pulmonary and renal function is also discussed. Stage I LUTO (mild form) is characterized by normal amniotic fluid index after 18 weeks, normal kidney echogenicity, no renal cortical cysts, no evidence of renal dysplasia, and favorable urinary biochemistries when sampled between 18 and 30 weeks; prenatal surveillance is recommended. Stage II LUTO is characterized by oligohydramnios/anhydramnios, hyperechogenic kidneys but absent renal cortical cysts or apparent signs of renal dysplasia and favorable fetal urinary biochemistry; fetal vesicoamniotic shunting (VAS) or fetal cystoscopy is indicated to prevent pulmonary hypoplasia and renal failure. Stage III LUTO is oligohydramnios/anhydramnios, hyperechogenic kidneys with cortical cysts and renal dysplasia and unfavorable fetal urinary biochemistry after serial evaluation; fetal vesicoamniotic shunt may prevent severe pulmonary hypoplasia but not renal failure. Stage IV is characterized by intrauterine fetal renal failure, defined by anhydramnios and ultrasound (US) findings suggestive of severe renal dysplasia, and is associated with death in 24 h of life or end-stage renal disease (ESRD) within the first week of life; fetal vesicoamniotic shunt and fetal cystoscopy are not indicated.

[Ultrasound of the fetal urinary system during the first trimester of pregnancy]

The detection of abnormalities of the fetal urinary system in the first trimester of pregnancy is constantly improving, namely owing to the improved resolution of the image, the use of the endovaginal approach and thanks to sonographers' constant training. The pathological aspects, usually detected in the second trimester of pregnancy, can be suspected early in the first trimester and range from kidneys' cavity dilation to bilateral renal agenesis, polycystic kidney disease, multi-cystic dysplasia and bladder megavessia or bladder exstrophy. A poly-malformative syndrome is to be found out. The detection of an abnormality of the urinary tract requires a close ultrasound check. Very often, the pathological aspects tend to disappear spontaneously. In particular, the non-visualization of the bladder requires repeated examinations during the same session or even a little later in the pregnancy. We will carry out a review of the literature by pointing out the usual and unusual aspects of the fetal urinary system visible in the first trimester and we will as well propose an algorithm describing how to deal with abnormalities of the urinary tract that can be found out at first trimester ultrasound.

[Segmental approach to congenital heart diseases: Principles and applications to prenatal imaging]

This pictorial essay will initially present the origin, definitions, objectives and main principles of the segmental approach to congenital heart diseases. Then, through ultrasound scans iconography we will consider its practical applications to prenatal screening. Eventually, through both ultrasound and MRI cases, we will discuss its potential use in fetal diagnostic evaluation.