Renal dysplasia: sonographic findings

Revised guidelines on management of antenatal hydronephrosis

Widespread antenatal screening has resulted in increased detection of anomalies of the kidneys and urinary tract. The present guidelines update the recommendations published in 2000. Antenatal hydronephrosis (ANH) is transient and resolves by the third trimester in almost one-half cases. The presence of oligohydramnios and additional renal or extrarenal anomalies suggests significant pathology. All patients with ANH should undergo postnatal ultrasonography; the intensity of subsequent evaluation depends on anteroposterior diameter (APD) of the renal pelvis and/or Society for Fetal Urology (SFU) grading. Patients with postnatal APD exceeding 10 mm and/or SFU grade 3-4 should be screened for upper or lower urinary tract obstruction and vesicoureteric reflux (VUR). Infants with VUR should receive antibiotic prophylaxis through the first year of life, and their parents counseled regarding the risk of urinary tract infections. The management of patients with pelviureteric junction or vesicoureteric junction obstruction depends on clinical features and results of sequential ultrasonography and radionuclide renography. Surgery is considered in patients with increasing renal pelvic APD and/or an obstructed renogram with differential renal function <35-40% or its subsequent decline. Further studies are necessary to clarify the role of prenatal intervention, frequency of follow-up investigations and indications for surgery in these patients.

Predicting fetal growth restriction with renal volume using 3-D ultrasound: efficacy evaluation

Early detection and management of fetal growth restriction (FGR) is very important in prenatal care and daily practice, because FGR fetuses may suffer increased risk of perinatal morbidity and mortality. Renal volume (RV) might be one of the important parameters of fetal growth. Yet, no prenatal assessment of fetal RV in FGR fetuses by 3-D ultrasound (US) has been reported. We undertook a prospective and cross-sectional study using quantitative 3-D US to assess the efficacy of fetal RV in predicting FGR. All fetuses were singletons and were followed-up to delivery to determine whether they had FGR complications. In total, 221 fetuses without FGR and 28 fetuses with FGR were included. Our results showed fetal RV assessed by 3-D US can differentiate fetuses with FGR from fetuses without FGR. The best predicting threshold for FGR is at the tenth percentile of fetal RV. Using the tenth percentile as the cutoff, the efficacy of fetal RV in predicting FGR was sensitivity 96.4%, specificity 95.9%, positive predictive value 75.0%, negative predictive value 99.5% and accuracy 96.0%, respectively. Fetal RV assessed by 3-D US can be applied to detect FGR prenatally. We believe fetal RV assessment using 3-D US is a useful test in detecting fetuses with FGR.

Displasia renal multiquística segmentaria: hallazgos radiológicos y diagnóstico diferencial

Multicystic dysplasia of the kidney is the second most common cause of renal masses in newborns after hydronephrosis and the most frequent cause of cystic masses in childhood. We present the case of a cystic renal mass in an infant that was definitively diagnosed at histological examination to be segmental cystic dysplasia. Cystic renal dysplasia usually involves an entire kidney, and segmental multicystic renal dysplasia is rare. We review the etiology and pathogenesis of this entity, the radiological findings, and the main differential diagnoses with the aim of establishing the correct diagnosis and differentiating this entity from other focal cystic kidney lesions affecting children.

Is screening for vesicoureteral reflux mandatory in infants with antenatal renal pelvis dilatation?

AIM

To determine whether postnatal ultrasound (US) can guide the use of voiding cystourethrography (VCUG) in infants with antenatally detected renal pelvis dilatation (ARPD).

METHODS

14,000 pregnant women consecutively underwent routine US examination during the second trimester. US examinations later in pregnancy were performed as follow-up of previous anomalies or on obstetrical indications. One hundred and six fetuses with ARPD > or =5 mm were identified. Two postnatal US examinations were performed in the newborns: on the 5th to 7th day and during the 3rd week of life. The findings were considered normal when renal pelvis dilatation (RPD) was < or =7 mm on both US examinations, and no calyceal or ureteric dilatation or signs of renal dysplasia or other anomalies were present. VCUG was done 6 to 8 wk after birth.

RESULTS

In 53 of 103 analysable infants, the postnatal ultrasonographic findings were normal. The VCUG was abnormal in three of these 53 infants, all with vesicoureteral reflux (VUR) grade I. Of 50 infants who had abnormal US examinations, six had VUR, four of which were grade IV and V reflux.

CONCLUSION

In infants with ARPD who undergo two postnatal US examinations with RPD < or =7 mm and have no other abnormalities, VCUG is unnecessary.

Fetal hyperechogenic kidney with normal amniotic fluid volume: a diagnostic dilemma

OBJECTIVE

To determine the prognostic value of sonographically detected fetal hyperechogenic kidneys with normal amniotic fluid volume.

METHODS

Seven cases of hyperechogenic fetal kidneys were identified by sonography over a 7-year period (1996--2002). Increased renal echogenicity was diagnosed when the renal parenchyma was of greater echogenicity than adjacent liver tissue. Amniotic fluid volume was measured by the semiquantitative sonographic technique known as the amniotic fluid index (AFI).

RESULTS

Three of the live-born infants had autosomal dominant polycystic kidney disease and one had autosomal recessive polycystic kidney. In the remainder, autopsy study revealed multifocal renal dysplasia in two cases and normal kidneys in one.

CONCLUSIONS

Increased renal echogenicity with normal amniotic fluid volume in a fetus without other anomalies is a difficult diagnostic dilemma. Although it is usually indicative of renal parenchymal disease with possible renal failure after birth or in early childhood, in some cases, it represents a normal variant. .

Poor predictability of prenatal ultrasonography for a nonfunctional kidney

We present 2 cases in which the diagnosis of a unilateral nonfunctioning kidney was not anticipated. The first case appeared to be simple, antenatally diagnosed, unilateral hydronephrosis with adequate parenchyma. However, at 3 months postnatally, it was found to be nonfunctional, most likely secondary to early high-grade obstruction. The second case presented prenatally as a left hydronephrotic kidney with parenchymal cysts, and the right kidney showed only mild parenchymal cystic changes. By 6 months, however, the right kidney was nonfunctional. These cases emphasize the need for coordinated prenatal and postnatal care. The sonographic appearance of renal dysplasia is variable (in size, number of cysts, and degree of hydronephrosis), depending on the point at which it is evaluated during the disease course. Subtle signs of dysplasia, such as increased echogenicity, may be the only warning sign of a nonfunctioning kidney, for which one should have a high index of suspicion.

Unilateral renal cystic disease in adults

Unilateral renal cystic disease (URCD) is morphologically indistinguishable from autosomal dominant polycystic kidney disease (ADPKD) except for its unilaterality. Unlike ADPKD, URCD patients show neither a genetic background nor progressive deterioration in renal function; thus, the differential diagnosis of URCD from ADPKD is important. Only a few cases of URCD have been reported. This study reports two cases of URCD in adults together with a literature review. We identified these two cases using abdominal computerized tomography and family screening with renal ultrasonography.

Ultrasound-assisted diagnosis of renal dysplasia in a 3-month-old Quarter Horse colt

A 3-month-old foal was presented for correction of bilateral angular limb deformities. Azotemia was detected as an incidental finding. Small, misshapened, hyperechoic kidneys with decreased corticomedullary demarcation were noted with ultrasonography. Additionally, the internal renal architecture was abnormal in that the intrarenal vessels and distant collecting system were not clearly seen in either kidney. Ultrasound-guided renal biopsy was suggestive of congenital renal dysplasia, which was later confirmed at necropsy. Clinical, sonographic, and pathologic features of equine renal dysplasia are discussed.

Can careful ultrasound examination of the urinary tract exclude vesicoureteric reflux in the neonate?

The aim of the study was to determine whether a urinary tract appearing normal when assessed by meticulous ultrasound (US) examination may coexist with vesicoureteric reflux (VUR) and whether a normal US scan can be used to exclude VUR, thereby avoiding unnecessary voiding cystourethrography (VCUG). The US features of 35 neonates with known VUR were reviewed. Criteria studied included pelvic dilatation above 7 mm on a transverse scan, calyceal or ureteral dilatation, pelvic or ureteral wall thickening, absence of the corticomedullary differentiation (CMD) and signs of renal dysplasia (small kidney, thinned or hyperechoic cortex and cortical cysts); all signs that have been shown to result from or to be associated with VUR. 57 refluxing renal units (RRU) were found among the 35 patients. VUR was bilateral in 22. Among the 57 RRU, at least one US anomaly that would have prompted VCUG was present in 50 (87.7%). Pelvic dilatation above 7 mm was present in 29 RRU (50.9%) only. Calyceal dilatation was present in 24 RRU, the dilatation involving the calyces but not the renal pelvis in seven. Ureteral dilatation was observed in 15 RRU. Pelvic or ureteral wall thickening was present in seven RRU. CMD was absent in 32 RRU (56.1%). US signs of dysplasia were found in 19 RRU. No US anomaly was found in seven RRU (12.3%) in six patients. A careful and meticulous US examination of the neonatal urinary tract allows the detection of over 87% of RRU by showing at least one sonographic abnormality. It is concluded that a normal appearing urinary tract on US does not usually coexist with VUR and that in such cases VCUG is not necessary.

Prenatally diagnosed bilateral hyperechoic kidneys with normal amniotic fluid: postnatal outcome

We evaluated a subset of infants with bilateral markedly hyperechoic "bright" kidneys noted prenatally in association with normal amniotic fluid volume during gestation. Prenatal ultrasound showed increased renal parenchymal echogenicity bilaterally with preservation of the medullary pyramid architecture. These children were followed for up to 3 years to determine potential changes in the sonographic appearance of the echogenic renal parenchyma and to assess renal function. In 3 years 8 cases of bilateral hyperechoic fetal kidneys were identified. During postnatal followup renal echogenicity resolved in 4 cases, diminished in 1 and remained the same in 3. The serum creatinine and electrolytes were normal in all cases followed for more than 3 months. Other renal findings included vesicoureteral reflux in 2 of 7 cases, mild pelvic ectasia in 1 and tiny medullary calcifications in 1. The specific etiology of increased echogenicity is unknown, although 1 infant appeared to have a form of autosomal recessive disease with liver hyperechogenicity as well. We conclude that fetuses with bilateral hyperechoic kidneys associated with normal amniotic fluid volume have a favorable outcome. Ultrasonographic finding of marked parenchymal hyperechogenicity appears to improve with time; in our experience renal function is normal and the infants thrive. Continued followup is necessary to determine the long-term natural history of this phenomenon, as is subsequent prenatal and postnatal evaluation of future siblings to assess genetic risk.

Intrarenal aneurysm associated with "Ask-Upmark kidney": imaging pitfalls and limitations

The imaging of a case of intrarenal aneurysm with associated "Ask-Upmark kidney" is presented. Pitfalls and limitations encountered with imaging in this case are discussed. Magnetic resonance imaging (MRI) proved to be the best imaging modality for visualization and characterization of the mass lesions present.

Renal imaging in children with persistent hypertension

The role that imaging plays in the evaluation of the child with hypertension depends in large part on the results of thorough historical, physical, and laboratory examinations. How aggressively one searches for an underlying renal parenchymal or renovascular disorder must be individualized in each child. An individualized approach to renal imaging in children with hypertension is presented.

In utero sonography of genitourinary anomalies

Congenital anomalies of the genitourinary system represent the commonest fetal anomaly. The sonographic findings in hydronephrosis, multicystic kidney (dysplastic kidney), polycystic kidney, and renal agenesis are reviewed.

The predictive value of ultrasonography in evaluation of infants with posterior urethral valves

Between 1981 and 1989, 28 infants less than 6 months old with posterior urethral valves underwent ultrasound evaluation as part of the initial evaluation at our hospital. The single ultrasound feature that correlated with subsequent renal function was the status of corticomedullary differentiation. The presence of corticomedullary junctions in at least 1 kidney in 17 infants was always associated with a serum creatinine level of 0.8 mg./dl. or less in long-term followup. Of 11 patients with absent corticomedullary differentiation 7 had eventual creatinine levels of greater than 0.8 mg./dl. with 5 of them suffering clinically significant renal insufficiency. An association between vesicoureteral reflux and absent corticomedullary junctions was also found.

Familial renal adysplasia

Renal dysplasia and agenesis as isolated findings are usually considered sporadic, noninherited abnormalities. We report three kindreds with familial renal adysplasia. Two or more children were affected in each of the families and at least one member--whether proband, sibling, or parent--had a clinically silent anomaly. Normal kidneys in the parents did not preclude the occurrence of renal adysplasia in more than one child. The empiric risks for offspring and first-degree relatives were 50% and 25%, respectively, suggesting a strong genetic factor such as a major dominant gene with variable expression. Because the disease appears to be genetic in some cases of renal adysplasia, careful screening of the proband's family, subsequent children, and pregnancies is important for the purpose of accurate genetic counseling.

Renal obstructive dysplasia: ultrasound diagnosis and therapeutic implications

57 cases of renal obstructive dysplasia (defined as the abnormal development of nephronic and ductal structures due to in utero obstruction of the urinary tract) were evaluated in terms of sonographic findings, renal and other associated anomalies, and current status of the child. More than one-third of the cases had bilateral disease and although not uniformly fatal bilateral involvement was associated with significant morbidity and mortality. In 12 of the 33 cases with unilateral dysplasia there was an association with contralateral renal problems including uretero-pelvic junction obstruction, vesicoureteral reflux and aplasia. Almost one-half of the cases had congenital anomalies, these included VACTERL association, congenital heart disease, cranial abnormalities and gastrointestinal malformations. Fifteen stillborns and 12 of the patients with bilateral involvement and four with unilateral involvement have died. Four patients are on dialysis (two with bilateral involvement and two with unilateral renal obstructive dysplasia). Only one-quarter are otherwise normal. More serious problems are reported in this mixed age population of patients with obstructive renal dysplasia than has been identified in previous studies. Management decisions of the fetus and child must be based on this new age-expanded population.