Accuracy of antenatal fetal ultrasound in the diagnosis of duplex kidneys

Prenatal diagnosis and outcomes in fetuses with duplex kidney

OBJECTIVE

Duplex kidney is a relatively frequent form of urinary system abnormality. This study aimed to elucidate the value of chromosomal microarray analysis (CMA) and whole exome sequencing (WES) for duplex kidney and the perinatal outcomes of duplex kidney fetuses.

METHODS

This retrospective cohort study included 63 patients with duplex kidney diagnosed using antenatal ultrasound between August 2013 and January 2023. We reviewed the clinical characteristics, genetic test results, and pregnancy outcomes of the patients.

RESULTS

Among the 63 cases based on the inclusion criteria, the CMA detected seven (11.1%) clinically significant variants and nine variants of uncertain significance (VUS), and the pathogenic/likely pathogenic (P/LP) copy number variations (CNVs) in the recurrent region that were associated with prenatal duplex kidney included 17q12, 17p13.3, and 22q11.2. No significant disparity was observed in the CMA detection rate between the unilateral and bilateral groups, or between the isolated and non-isolated groups. WES identified three (50%) P/LP single-gene variants in six fetuses with duplex kidney. We detected the following pathogenic genes in the duplex kidney fetuses: KMT2D, SMPD4, and FANCI. Pregnancy termination in cases where clinically significant variants were detected by genetic testing was different in statistical significance from that in cases with negative results (9/10, 90.0% vs 8/48, 16.7%, P < 0.001).

CONCLUSION

This study elucidated the value of CMA and WES for fetal duplex kidney, proving that CMA and WES may be useful tools in prenatal diagnosis and genetic counseling.

Fetal Renal Duplicated Collecting System at 14-16 Weeks of Gestation

(1) Background: To examine the incidence of the prenatal diagnosis of the renal double-collecting system (rDCS) and describe its clinical outcome and associated genetic abnormalities. (2) Methods: This retrospective study included women who attended the obstetric clinic for early fetal anatomic sonography with findings of a renal DCS. Diagnosis was conducted by an expert sonographer using defined criteria. (3) Results: In total, 29,268 women underwent early ultrasound anatomical screening at 14-16 weeks, and 383 cases of rDCS were diagnosed (prevalence: 1:76). Associated abnormalities were diagnosed in eleven pregnancies; four had chromosomal aberrations. No chromosomal abnormalities were reported in isolated cases. Ectopic uretrocele and dysplastic kidney were diagnosed in 6 (1.5%) and 5 (1.3%) fetuses, respectively. One girl was diagnosed with vesicoureteral reflux and recurrent UTIs, and two boys were diagnosed with undescended testis. The recurrence rate of rDCS was 8% in subsequent pregnancies. (4) Conclusions: In light of its benign nature, we speculate that isolated rDCS may be considered a benign anatomic variant, but a repeat examination in the third trimester is recommended to assess hydronephrosis.

Ultrasound Diagnosis of Malformations of the Fetal Kidneys and Urinary System

Malformations of the fetal kidneys and urinary system are common and easily visualized and diagnosed on ultrasound. This article presents the typical sonographic findings of these abnormalities during the various stages of pregnancy. Because malformations of the urogenital tract often have an association with genetic diseases/ciliopathies, these are also discussed. To complete the article, we provide a brief overview of the normal anatomy of the kidneys and urinary system. The normal anatomy and malformations of the genitalia will not be discussed in this article due to their complexity.

Prenatal imaging features and postnatal outcomes of isolated fetal duplex renal collecting system: A systematic review and meta-analysis

OBJECTIVES

To perform a systematic review of studies reporting the outcome of fetuses with a prenatal diagnosis of isolated duplex collecting system (DCS).

METHODS

Inclusion criteria were studies reporting the outcome of fetuses with a prenatal diagnosis of isolated DCS, defined as DCS not associated with other major structural anomalies at the time of diagnosis. The outcomes observed were: imaging features of DCS on prenatal ultrasound, associated anomalies detected exclusively at prenatal follow-up ultrasound and at birth, abnormal karyotype, symptoms at birth (including vesicoureteral reflux [VUR] and urinary tract infections [UTI]), need for and type of surgical approach, complications after surgery, and accuracy of prenatal ultrasound in correctly identifying this anomaly.

RESULTS

Eleven studies (284 fetuses with a prenatal diagnosis of DCS) were included. On ultrasound, DCS was associated with ureterocele in 70.7% and with megaureter in 36.6% of cases. Worsening of pelvic/ureteric dilatation was reported to occur in 41.3% of fetuses. At birth, 4.3% of fetuses affected by DCS showed associated renal anomalies. After birth, VUR and UTI presented in 51.3% and 21.7% of children respectively, while 33.6% required surgery. Prenatal diagnosis of DCS was confirmed in 90.9% of included cases.

CONCLUSION

DCS diagnosed prenatally is associated with a generally good outcome. Prenatal ultrasound has a good diagnostic accuracy, while detailed postnatal assessment is required in order to identify associated renal anomalies.

Subdiaphragmatic Renal Ectopia: Case Report and Review of the Literature

Background. We report the case of a male infant whose right kidney migrated to an ectopic position after birth. The migration of a kidney in postnatal life without any symptoms has not been reported in literature so far. Case Presentation. In a series of antenatal and the first postnatal ultrasound scans, the right kidney was normally located within the right renal fossa. During the first 3 months of life, the kidney migrated to a subdiaphragmatic position. This was confirmed on MRI scan. The infant was asymptomatic with normal renal function and blood pressure. Conclusion. Postnatal migration of a kidney has been described in cases of diaphragmatic hernia or nephroptosis. In this report, we describe a case of kidney migration where there were no underlying anatomical defects to provide an explanation for the kidney migration. This is the first report in literature of a case of postnatal migration of a kidney.

Magnetic resonance urography in evaluation of duplicated renal collecting systems

Duplex renal collecting systems are common congenital anomalies of the upper urinary tract. In most cases they are incidental findings and not associated with additional pathologies. They demonstrate, however, higher incidences of hydroureteronephrosis, ureteroceles, and ectopic ureters. The most comprehensive morphologic and functional evaluation of duplex systems can be achieved using magnetic resonance urography. Functional magnetic resonance urography allows better separation of the renal poles, thus more accurate calculation of the differential renal functions compared with renal scintigraphy. Magnetic resonance urography is the study of choice when upper urinary tract anatomy is complex or when functional evaluation is needed.

Atrophic upper pole of a duplex collecting system masquerading as suprarenal mass: a case study and literature review

The growing use of maternal fetal ultrasound is leading to the discovery of an increasing number of suprarenal masses. Our experience with a cystic suprarenal mass detected on antenatal ultrasound is described. Location and radiographic features could not rule out the possibility of a cystic neuroblastoma; therefore, surgical resection of the mass was performed. Despite the absence of common radiologic characteristics, the pathology of the specimen revealed a non-functioning upper pole of a duplex kidney with complete duplication of the collecting system. Neonatal evaluation and management and the differential diagnosis are discussed.

Antenatally diagnosed renal duplex anomalies: sonographic features and long-term postnatal outcome

OBJECTIVES

The purpose of this study was to assess the diagnostic accuracy and infant outcomes of antenatally detected renal duplex anomalies.

METHODS

An observational longitudinal study of cases of renal duplex anomalies diagnosed on prenatal sonography was conducted. Information on the prenatal sonographic findings, antenatal course, and perinatal outcome was obtained by reviewing the sonography reports and delivery records. Postnatal follow-up, including neonatal and infant evaluations, was obtained from hospital records.

RESULTS

During a 7-year period, a total of 24 cases of renal duplex anomalies were identified prenatally. Three cases were excluded from subsequent analysis because of termination of pregnancy after the diagnosis of a severe brain abnormality, loss to follow-up, and an inability to confirm the prenatal diagnosis on neonatal renal sonography. Among the 21 confirmed cases, the presence of two separate renal pelvises was the most common prenatal sonographic feature (n = 15 [71%]), followed by dilatation of a single moiety with a dilated ipsilateral ureter or ureterocele (n = 6 [29%]). In 43% of cases, the renal duplex anomalies had no adverse associations, but in 48%, they were complicated by a urinary tract infection, and 48% of the infants required a surgical procedure during early childhood.

CONCLUSIONS

Renal duplex anomalies can be accurately diagnosed by prenatal sonography even when there is minimal dilatation of the renal pelvis. Antenatal diagnosis allows planning of postnatal care, which may prevent urinary tract infections and renal function impairment. The natural history of antenatally diagnosed duplex anomalies seems to be overall benign, with urinary tract infections and the need for surgery being the most common complications in affected infants.

The sensitivity of antenatal ultrasound for predicting renal tract surgery in early childhood

OBJECTIVE

To establish the sensitivity of antenatal ultrasound for identifying the need for renal tract surgery in infancy and early childhood.

METHODS

A retrospective analysis of the surgical records in children under 5 years of age undergoing renal tract surgery in a regional pediatric urological surgery referral unit was carried out. All records between May 1997 and July 2002 were examined to assess the relationship between prenatal ultrasound findings and postnatal surgical pathology.

RESULTS

A total of 106 operations had been performed. The detection rate of multicystic renal dysplasia was 100% (17/17). The equivalent detection rates for pelviureteral junction obstruction, duplex renal system and vesicoureteral reflux were 82.8, 67 and 26.1%, respectively. None of the babies with renal tumors had abnormal antenatal ultrasound findings. The diagnosis of postnatal renal surgical pathology was made on the basis of prenatal scan findings in 59.6% of cases, while recurrent urinary tract infection led to the diagnosis in 26.0%.

CONCLUSIONS

Approximately 40% of children requiring surgery for renal tract pathology will have a normal antenatal ultrasound examination. The prevalence of abnormal antenatal ultrasound findings varies depending on the type of renal tract pathology. Despite these findings, the commonest indicator for surgery remains abnormal prenatal scan findings, followed by recurrent urinary tract infections.