RUP

Department of Radiology, S.S.G. Hospital, Medical College, Vadodara, India

Received 12 April 2014; accepted 2

Available online 5 August 2014

Ultrasonography

rapid scanning time, lack of radiation exposure, cost effective and easy feasibility. 2014 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier

Contents

1.1.1. Ectopia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1256. . . . . . . . 1256

. . . . . . . . 1257. . . . . . .. . . . . . .. . . . . . .

1.2.5. Congenital megacalyces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1260

1.2.6. Congenital megaureter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12601.3. Anomalies related to the renal growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1260

1.3.1. Renal hypoplasia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1260

1.4. Congenital cystic renal disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1261

* Corresponding author. Address: 5-Durga Nagar Society, Karodiya, Baroda, Gujarat, India. Tel.: +91 9662500537, +91 9825543039.

E-mail addresses: drnapatel59@gmail.com (N.A. Patel), pokhraj_suthar@yahoo.co.in (P.P. Suthar).

Peer review under responsibility of Egyptian Society of Radiology and Nuclear Medicine.

The Egyptian Journal of Radiology and Nuclear Medicine (2014) 45, 12551264

Egyptian Society of Radiology and Nuclear Medicine

The Egyptian Journal of Radiology andNuclearMedicine1.2.3. Duplex collecting system and ureterocele . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12581.2.4. Uretero-pelvic junction obstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12591.1.2. Crossed renal ectopia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.1.3. Horseshoe kidney . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2. Anomalies related to the ureteric bud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2.1. Renal agenesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2.2. Supernumerary kidney . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .http://dx.doi.org/10.1016/j.ejrnm.2014.06.014

0378-603X 2014 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier B.V. All rights reserv1258. 1258. 12581. Technique. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1256

1.1. Anomalies related to ascent of kidney. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1256B.V. All rights reserved.KEYWORDS

GUT;

Renal disease;

Congenital;

a7 June 2014

Abstract Congenital renal diseases consist of a variety of entities. The age of presentation and

clinical examination narrow down the differential diagnosis; however, imaging is essential for accu-

rate diagnosis and pretreatment planning. Ultrasound is often used for initial evaluation. Computed

tomography (CT) and MRI provide additional information. Ultrasonography continues to occupy

central role in the evaluation and detection of congenital renal diseases due to its advantage ofNarrotam A. Patel, Pokhraj P. Suthar *EVIEW

ltrasound appearance of congenital renal disease:ictorial review

www.elsevier.com/locate/ejrnmwww.sciencedirect.comed.

2. Infantile polycystic renal disease autosomal recessive polycystic kidney disease (ARPKD) Potter type I. . . . . . . . 1261

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1261(ADPKD) Potter type III . . . . . . . . . . . . . . . . . . . . . . 1261. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1263

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1263

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1263

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1263

1.1.1. Ectopia

kidney should immediately be performed if the kidney is not

identied within renal fossa (Figs. 1 and 2). If the kidneyascends too high, it may pass through the foramen of Boch-dalek and become a true thoracic kidney, ultrasound is helpful

to determine if the diaphragm is intact or not.

1.1.2. Crossed renal ectopia

Crossed fused ectopia of the kidney is a rare malformation

occurring in 0.050.1% of the population [3]. There is a recog-nized male predilection with a 2:1 male to female ratio. Morethan 90% of crossed renal ectopia results in fusion. Left-

to-right ectopia is thought to be three times more common.

1256 N.A. Patel, P.P. Sutharautopsies [2]. These kidneys are often small and abnormally

rotated. The ureters are often short; poor drainage and collect-ing system dilatation predispose to secondary infection andstone formation. The blood supply is often complex; multiple

arteries may be derived from regional arteries like the internaliliac artery or the common iliac artery. A search for a pelvic

Fig. 1 Ectopia: Transverse sonogram of a new born baby shows

the absent right kidney in right renal fossa between the liver and

right psoas muscle.Failure of kidney to ascend during embryologic developmentresults in a pelvic kidney. Prevalence rate is 1 in 724 paediatric3. Multicystic dysplastic kidneys Potter type II . . . . . . . .4. Early onset autosomal dominant polycystic kidney disease5. Obstructive cystic renal dysplasia Potter type IV . . . . .

6. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Conict of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . .References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Technique

A 35 MHz sector or linear transducer is used to scan the uri-nary tract. Although no specic preparation is required forscanning the kidneys, fasting optimizes the visualization.

Evaluation of the renal vessels is augmented by adequate patienthydration. Harmonic imaging is often useful for difcult-to-scan patients (e.g., obese patient); additional recent software

advances, including compound imaging and speckle reduction,may increase lesion conspicuity and decrease artifacts.

The kidneys are scanned in the transverse and coronal

plane. Optimal patient positioning varies; supine and lateraldecubitus positions often sufce, although oblique and occa-sionally prone positioning may be necessary. Usually, a combi-nation of sub costal and intercostal approaches is required to

evaluate the kidneys fully; the upper pole of the left kidneymay be particularly difcult to image without a combinationof approaches. Varying the degree of respiration can help in

complete evaluation of kidneys.

1.1. Anomalies related to ascent of kidney

Kidneys develop in human embryos in three sets: those arepronephrones, mesonephrones and metanephrones. Proneph-rones appears early in the fourth embryological week and rudi-

mentary and nonfunctioning [1]. The mesonephrones form latein the fourth week and function as interim kidneys until thedeveloping metanephrone begins to function in the ninth week.The metanephrone also known as permanent kidney develops

from two sources: those are the ureteric bud and metanephro-genic blastema. The ureteric bud forms the ureter, renal pelvis,calices and collecting ducts, interacting with and penetrating

the metanephrogenic blastema. This interaction is necessaryto initiate ureteric bud branching and differentiation of neph-rone within the blastema. Initially, foetal kidneys are found in

the pelvis. With foetal growth, the kidney comes to lie in theupper retroperitoneum in the ninth gestational week. Withascent, the kidneys rotate medially 90 so that the renal pelvisis directed anteromedially. With the kidneys ascended, theyderive their blood supply from nearby vessels; adult bloodsupply is from the abdominal aorta.In crossed renal ectopia, both kidneys are found on the sameside. In 8590% of cases, the ectopic kidney will be fused tothe other kidney. The upper pole of the ectopic kidney is

usually fused with the lower pole of the other kidney. Fusionof metanephrogenic blastema does not allow proper rotationor ascent; thus both kidneys are more caudally located,

although the uretero-vesical junctions are located normally.On ultrasound, both kidneys are on the same side and aretypically fused with a characteristic anterior or posterior

notch between the two fused kidneys (Fig. 3) with adifference in orientation of the 2 collecting systems in the fusedkidneys [4,5]. In addition, ultrasonography can give vital infor-

mation on the arterial supply and venous drainage, which canbe grossly abnormal. Calyceal dilatation and distortion,hydronephrosis and urolithiasis can also be diagnosed withultrasonography [6,7]. In patient with renal colic, knowing that

the uretero-vesical junctions are in the normal position isparticularly important.

Fig. 3 Crossed renal ectopia: Sagittal sonogram of 10 day old

neonate in the left lumbar region demonstrates the lower pole of

the left kidney is fused with the upper pole of the right kidney in

left renal fossa with notch in anterior aspect.

Ultrasound appearance of congenital renal disease: Pictorial review 1257Mc Donald and McClellan (1957) classied crossed ectopic

kidney into 4 types

1. Crossed renal ectopia with fusion 90%.

2. Crossed renal ectopia without fusion uncommon.3. Solitary Crossed renal ectopia very rare.4. Bilateral Crossed renal ectopia extremely rare.

Sub types of Crossed renal ectopia [8] (Fig. 4).

(A) Type 1 inferior crossed fused ectopia,

(B) Type 2 sigmoid or S-shaped kidney,(C) Type 3 unilateral lump kidney,(D) Type 4 unilateral disc kidney,

(E) Type 5 L-shaped kidney and(F) Type 6 superior crossed fused ectopia.

1.1.3. Horseshoe kidney

Horseshoe kidneys are the most common type of renal fusionanomaly. Horseshoe kidneys are found in approximately 1 in

Fig. 2 Ectopia: Transverse sonogram of same patient in right

iliac fossa (RIF) demonstrates 31 18 mm sized reniform struc-ture with cortico-medullary differentiation indicating the ectopic

right kidney in RIF.400500 adults and are more frequently encountered in males(M:F 2:1) [911]. Horseshoe kidneys occur when metanephro-genic blastema fuses prior to ascent; fusion is usually at the

lower pole (95%). The normal ascent of the kidneys isimpaired by the inferior mesenteric artery (IMA) which hooksover the isthmus. Typically, the isthmus is composed of func-tioning renal tissue, although rarely it is made up of brous tis-

sue. The horse shoe kidney sits anterior to the abdominal greatvessels and derives its blood supply from the aorta or otherregional vessels like inferior mesenteric, common iliac, internal

iliac or external iliac arteries. Abnormal rotation of the renalpelvis often results in ureteropelvic junction obstruction; thehorseshoe kidney is thus predisposed to the infection and stone

formation. Additional associated anomalies include vesicoure-teric reux, collecting system duplication, renal dysplasia, ano-rectal malformation, rectovaginal stula, omphalocele, skeletal

abnormality, cardiac abnormality and retrocaval ureter.On ultrasound, horseshoe kidneys are usually lower than

the normal position, and the lower pole projects medially.Transverse imaging of the retroperitoneum will demonstratethe renal isthmus crossing the midline anterior to abdominal

great vessels (Fig. 5). Hydronephrosis and collecting systemcalculi may occur. Unless aware of the typical appearancesof a horseshoe kidney, the abnormally rotated and inferiorly

located kidney results in poor visualization of the inferior poleand underestimation of the length. This is especially the case ifthe patient is scanned prone, and is an additional argument forscanning patients supine with left and right decubitus positions

Fig. 4 Sub types of crossed renal ectopia: (A) Type 1 inferior

crossed fused ectopia, (B) type 2 sigmoid or S-shaped kidney, (C)

type 3 unilateral lump kidney, (D) type 4 unilateral disc kidney,

(E) type 5 L shaped kidney and (F) type 6 superior crossed

fused ectopia.

[10]. Alternatively the renal tissue located anterior to the aortamay be mistaken for retroperitoneal tissue, such as may beseen in lymphoma or metastatic nodal enlargement [10].

1.2. Anomalies related to the ureteric bud

1.2.1. Renal agenesis

Renal agenesis may be unilateral or bilateral. Bilateral renalagenesis is a rare anomaly that is incompatible with life. It is

traditionally known as the classic Potter syndrome. Renalagenesis and dysgenesis (malformation of the kidney) occurin around one in 1500 births [12].

Unilateral renal agenesis is usually an incidental nding; thecontra lateral kidney of this patient may be quite large second-ary to compensatory hypertrophy. Renal agenesis occurs whenthere is absence of the metanephrogenic blastema, absence of

ureteral bud development, or absence of interaction and pene-tration of the ureteric bud with the metanephrogenic blastema.Renal agenesis is associated with genital tract anomalies,

which are often cystic pelvic mass in both men and women.Other associated anomalies include skeletal abnormalities,anorectal malformation, and cryptorchidism.

kidney. The supernumerary kidney often has only a few calices

and a single infundibulum. The formation of a supernumerarykidney is likely caused by the same mechanism that gives riseto a duplex collecting system. Two ureteric buds reach the met-

anephrogenic blastema, which then divides, or alternatively,there are initially two blastema [14]. On ultrasonography anextra kidney will be found.

1.2.3. Duplex collecting system and ureterocele

Duplex collecting system is the most common congenitalanomaly of the urinary tract, with a reported incidence of

0.510% of all live births [12]. Duplication is complete whenthere are two separate collecting systems and two separate ure-ters, each with their own ureteric orice. Duplication is incom-

plete when the ureters join and enter the bladder through asingle ureteral orice. With complete duplication, the uretersfrom the lower pole of the kidney migrate to assume thenormal position, whereas ureter from the upper pole migrates

muscle Lying down Adrenal Sign.

Fig. 7 Renal agenesis: Sagittal sonogram of same patient shows

normal left kidney.

1258 N.A. Patel, P.P. SutharOn ultrasonography, the kidney is absent (Fig. 6) withabsent ipsilateral renal artery, a normal adrenal gland is usuallyfound. The term lying down adrenal sign (Fig. 7) has beenascribed to the elongated appearance of the adrenal not nor-

mally moulded by the adjacent kidney [13]. The adrenal glandwill be absent in 817% of the patients with renal agenesis[1]. It may be difcult to differentiate between renal agenesis

and a small, hypoplastic or dysplastic kidney. With all theseconditions the contra lateral kidney is enlarged due to compen-satory hypertrophy. Usually, the colon falls into the empty

renal bed. Care should be taken not to confuse a loop of gutwith a normal kidney. Renal vessels are absent on same side(Figs. 1214).

1.2.2. Supernumerary kidney

It is a rare anomaly. It is usually small in size than the normalone and found above, below, in front of or behind the normal

Fig. 5 Horseshoe kidney: Transverse sonogram shows the

connecting isthmus crossing anterior to the retroperitoneal

(Aorta) great vessels, with the renal parenchyma of each limb of

the horse shoe draping over the spine.Fig. 6 Renal agenesis: Sagittal sonogram of 11 year old female

shows the absent right kidney in right renal fossa between the liver

and right psoas muscle with adrenal gland resting over right psoas

abnormally to a more medial and inferior ureteral orice. Incomplete duplication, the ureter draining the lower pole hasa more perpendicular course through the bladder wall making

it more prone to reux. The ectopic ureter from the upper poleis prone to obstruction, giving rise to an ureterocele.

On ultrasonography, a duplex collecting system is seen as

two central echogenic renal sinuses with intervening, bridgingrenal parenchyma. Unfortunately, this sign is insensitive andis seen only in 17% of duplex kidneys [15]. Hydronephrosis

of the upper pole moiety and visualization of two distinct col-lecting systems and ureters are diagnostic (Fig. 8). The bladdershould be evaluated for ureterocele. An ureterocele will appearas a round, cyst like structure within the bladder. Sometimes it

may be large enough to occupy the bladder (Fig. 9). In femalepatients TVS can detect even small ureterocele [16]. ColourDoppler and spectral analysis can provide additional informa-

tion about ow dynamics due to transient change in size [17](Fig. 10]. The ultrasonographic appearance of a duplex kidneyis specic but not sensitive. Ultrasonographic ndings provide

Fig. 9 Ureterocele: Transverse sonogram of same patient shows

dilatation of the ureter from the upper ureter from upper pole

moiety and a large anechoic cystic structure at left VUJ

representing as ureterocele.

Fig. 10 Ureterocele: Transverse sonogram of same patient on

application colour Doppler shows ureteric jet.

Fig. 11 Right renal agenesis with left sided PUJ obstruction:

Sagittal sonogram of 5 year old female patient shows the absent

right kidney in right renal fossa between the liver and right psoas

muscle.

Ultrasound appearance of congenital renal disease: Pictorial review 1259excellent anatomic information but do not necessarily differen-tiate a bid renal pelvis from a bid ureter or from 2 completeureters [18].

1.2.4. Uretero-pelvic junction obstruction

Incidence in paediatric population is at 1 per 10002000 new-borns [19]. It is a common anomaly with a 2:1 male predomi-

nance. The left kidney is affected twice as frequently as theright kidney. It is bilateral in 1030% of cases [20]. Patientspresent with chronic, dull aching back or loin pain. Symptom-

atic patients and those with complications like stone, infectionor impaired renal function should be treated. There isincreased incidence of contra lateral renal agenesis or multicy-stic dysplastic kidneys (Fig. 11). Most of idiopathic UPJ

obstruction is thought to be functional rather than anatomical.On microscopic examination, excessive collagen between mus-cle bundle, decient/absent muscle, and excessive longitudinal

muscle was found [20]. Sometimes aberrant artery, intrinsicvalve or luminal stenosis lead to obstruction.

On ultrasonography, hydronephrosis is present to the level

of UPJ with marked ballooning of the renal pelvis. A chroniccase shows renal parenchymal atrophy (Figs. 1214). Ureter isnormal. Look at contra lateral kidney for renal agenesis ormulticystic dysplastic kidneys using Doppler sonography, the

Fig. 8 Ureterocele: Sagittal sonogram of 12 year old female

patient shows central parenchymal separating the upper pole and

lower pole moieties. There is mild dilatation of both moieties.

obstructed kidneys can show higher RIs (resistive indices)(Fig. 15) [21].

1.2.5. Congenital megacalyces

Non obstructive enlargement of the calices and being typicallyunilateral increase the chances of secondary infection andstone formation. It is associated with primary megaureter

[22]. On ultrasonography, numerous enlarged clubbed shapedcalices are seen. Papillary impression is absent and corticalthickness is maintained.

1.2.6. Congenital megaureter

Congenital megaureter also known as megaloureter results infunctional ureteric obstruction. Men are affected more often,

and the left ureter is typically involved [20]. But bilateralinvolvement is seen in 850% of patients. In megaloureter dis-tal segment of the ureter is aperistaltic which leads to insignif-

icant distal ureterectasis to progressive hydronephrosis orhydroureter. On ultrasonography, classical nding is fusiformdilatation of distal third of ureter (>7 mm) sometimes

markedly [23]. Sometimes pyelectasis may be present in longstanding cases. Calculi were also noted proximal to adynamicsegment.

1.3. Anomalies related to the renal growth

1.3.1. Renal hypoplasia

Renal hypoplasia refers to a congenitally small kidney wherethere is essentially normal residual parenchyma but smallercalyces, lobules and papillae. This is in contrast to renal atro-

phy where renal development which was initially normal hasbecome smaller as secondary sequel from various other pathol-ogies. In an adult patient the distinction from the latter how-

ever can be difcult. Renal hypoplasia can be divided intotwo broad groups: complete (global) renal hypoplasia andsegmental renal hypoplasia (Ask Upmark kidney) [13]. If

unilateral renal hypoplasia is usually asymptomatic bilateralrenal hypoplasia is present with renal insufciency. Onultrasonography, the kidney appears small in size butotherwise normal [13].

Fig. 12 Right renal agenesis with left sided PUJ obstruction:

Sagittal sonogram of 5 year old female patient shows marked

ballooning of the left renal pelvis with abrupt cut off at PUJ.

Fig. 15 Right renal agenesis with left sided PUJ obstruction:

Transverse sonogram of the left kidney in ureteropelvic junction

on application of colour Doppler demonstrates raised RI value.

1260 N.A. Patel, P.P. SutharFig. 13 Right renal agenesis with left sided PUJ obstruction:

Transverse sonogram of 5 year old female patient demonstrates

the absent right renal artery.Fig. 14 Right renal agenesis with left sided PUJ obstruction:

Transverse sonogram of same patient demonstrates absent right

renal vein.

1.4. Congenital cystic renal disease

(1) Infantile polycystic renal disease Autosomal recessive

polycystic kidney disease (ARPKD) Potter type I.(2) Multi cystic dysplastic kidneys Potter type II.(3) Early onset Autosomal dominant polycystic kidney

disease (ADPKD) Potter type III.(4) Obstructive cystic renal dysplasia Potter type IV.

2. Infantile polycystic renal disease autosomal recessive

polycystic kidney disease (ARPKD) Potter type I

Autosomal recessive polycystic kidney disease is one of thecommonest inheritable infantile cystic renal diseases, but isfar less common than autosomal dominant polycystic disease

(ADPKD) which affects adults. The incidence is estimated at1:20,00050,000 [24]. There is no recognized gender or racialpredilection. Results from a mutation in the PKHD1 gene(polycystic kidney and hepatic disease) location on chromo-

some 6p. This results in bilateral symmetric microcystic disease

occur in up to 60% of cases, but may take up to 10 years tooccur [30].

On ultrasonography, lobulated renal contour with multipleinternal cysts of varying sizes and shapes is visible (Fig. 18).The renal parenchyma is usually brous and echogenic with

absent or small hilar vessels. Real time imaging is extremelyuseful to exclude any communication with the ureter andbetween each other.

4. Early onset autosomal dominant polycystic kidney disease

(ADPKD) Potter type III

Autosomal dominant polycystic kidney disease is one of themost common serious hereditary diseases, found in 1:500 to1:1000 individuals, and by far the most common hereditarycause of end stage renal failure (ESRF) and accounts for

1015% of all cases of ESRF [13]. The kidneys are normal

Ultrasound appearance of congenital renal disease: Pictorial review 1261occurring in the distal convoluted tubules and collecting ducts.It may be associated with Caroli disease [25] or congenital

hepatic brosis [26,27].On ultrasonography, antenatal ultrasound associated oligo-

hydramnios may be identied. Cysts are initially too small to

resolve but with time may become discernible. Unlike ADPKDthe cysts rarely exceed 12 cm in diameter (Figs. 16 and 17).The kidneys appear enlarged and echogenic but usually retaina reniform shape. Medullary pyramids initially may appear

hypoechoic compared to cortex, which can give a peripheralhalo during this stage. They eventually become increasinglyhyperechoic and corticomedullary differentiation is eventually

lost. High-resolution ultrasound (linear-array transducer,7.5 MHz or greater) allows visualization of numerous cylindri-cal cysts in the medulla and cortex, which represent ectatic

collecting ducts [28]. Ultrasound is also useful in assessingthe liver for congenital hepatic brosis and may demonstratenormal or coarsened echotexture, biliary tract cystic change

(Caroli disease) and portal hypertension.

Fig. 16 ARPKD: Sagittal sonogram shows multiple micro cysts

in the right kidney which are not communicating with each other.3. Multicystic dysplastic kidneys Potter type II

MCDK develops in utero and the diagnosis is often madeeither in antenatal or in the early neonatal period, if an ultra-

sound is performed. It may otherwise go unrecognized andmay be a common cause of renal agenesis, following completeinvolution during childhood. The unilateral incidence is esti-

mated at 1:25004000. There may be a predisposition for theleft kidney, a slightly higher incidence in males for unilateralMDCK and a higher incidence in females for bilateral MCDK.The affected kidney (or renal segment) has no functioning

renal tissue and is replaced by multiple cysts. Two main types:pelvi-infundibular and hydronephrotic-obstructive [29]. Pelvi-infundibular type is most common and multiple small non-

communicating renal cysts representing the dilated calycesand it may sometimes regress spontaneously. In hydrone-phrotic-obstructive type a dominant cyst is present in the renal

pelvis. Associated contralateral renal tract abnormalities arecommon and include vesicoureteric reux (VUR) most com-mon and seen in up to 20% [30], pelviureteric junction (PUJ)

obstruction, ureteral ectopia, vesicoureteric junction (VUJ)obstruction, and ureterocele. Syndromic associations includeMeckelGruber syndrome and Zellweger syndrome. A normallife expectancy can be expected as long as the contralateral kid-

ney is normal. Complete spontaneous involution is said to

Fig. 17 ARPKD: Sagittal sonogram shows multiple micro cysts

in the left kidney which are not communicating with each other.

Fig. 19 ADPKD: Few well dened anechoic cystic lesions noted

in the liver in ADPKD patient.

Fig. 20 ADPKD: Sagittal sonogram in same patient shows

multiple well dened anechoic cysts in the right kidney which are

not communicating with each other with enlarged right kidney.

1262 N.A. Patel, P.P. Sutharat birth, and with time develop multiple cysts. At the age of30 years, approximately 68% of patients will have visible cysts

by ultrasound. That gure increases over time, such that essen-tially all patients eventually demonstrate cystic change. By theage of 60 years approx. 50% of patients have end stage renalfailure (ESRF). The risk of renal cancer is not increased.

Clinical presentation is variable and includes dull ank painof variable severity and time course, abdominal/ank masses,haematuria, hypertension, and renal functional impairment

to renal failure. The majority of cases are inherited in an auto-somal dominant fashion. In a minority of cases, no familyhistory is present, and the disease is due to a spontaneous

mutation. Two genes have been identied, with slightly differ-ent phenotypes PKD1 and PKD2 [31]. PKD1 is located onchromosome 16p and seen in 85% of cases and presentation

is earlier and more likely to progress to end stage renal failure(ESRF). PKD2 is located on chromosome 4q, 15% of casesand is less severe. Associated with cerebral berry aneurysmsfound in 6% of patients with ADPKD without a family history

of aneurysms and in up to 16% of patients with ADPKD witha family history [32], intracranial dolichoectasia in 23%,colonic diverticulosis, small bowel diverticula, bicuspid aortic

valve, mitral valve prolapse in up to 25%, aortic dissection,

Fig. 18 Multi cystic dysplastic kidney: Sagittal sonogram in

neonate shows multiple anechoic cysts of variable size in the right

kidney which are not communicating with each other.cysts in other organs like liver: common (Fig. 19), 75% byage 60 years. The defect results in cystic dilatation of the renal

tubules (of all parts of the nephron) in a minority of nephrons.The cysts are variable in size and result in compression of theremainder of the kidney (Figs. 20 and 21), resulting inincreased renin and erythropoietin secretion, and gradual renal

dysfunction.On ultrasonography, simple renal cysts will appear anec-

hoic with well dened imperceptible walls, posterior acoustic

enhancement (amplication) and lateral shadowing (extinc-tion) [31]. Cysts with haemorrhage or infection will demon-strate echogenic material within the cyst, without internal

blood ow. Calcication may develop. Renal cell carcinomasin contrast, although usually cystic in the setting of ADPKD,will have solid components of thick septae with blood ow.

Perinephric haematomas may be visible and collections of var-iable echogenicity surrounding the kidney. It should be differ-entiated with primary renal disease related cysts, autosomalrecessive polycystic kidney disease (ARPKD) and medullary

Fig. 21 ADPKD: Sagittal sonogram in same patient shows

multiple well dened anechoic cysts in the left kidney which are

not communicating with each other with enlarged left kidney.

cystic disease. In primary renal disease related cysts the renal (5) Goodman JD, Norton KI, Carr L, Hsu-Chong Y. Crossed fused

Ultrasound appearance of congenital renal disease: Pictorial review 1263parenchyma appears abnormal, reduced in volume withincreased echogenicity on ultrasound. In Autosomal recessive

polycystic kidney disease (ARPKD) enlarged kidney, cystsare very numerous and small, changes are present in childhoodand corticomedullary differentiation is lost. In medullary

cystic disease cysts are smaller and located in the medulla.

5. Obstructive cystic renal dysplasia Potter type IV

It is a potential complication that can occur from prolongedobstruction of the bladder outlet or urethra during gestation.Ureteric obstruction during active nephrogenesis results in cys-

tic renal dysplasia; the earlier and longer the obstruction themore severe the histopathological changes of dysplasia [33].Any obstructive renal tract pathology distally involving the

renal tract can be a potential cause which includes posteriorurethral valves, urethral agenesis, Duplex collecting systemwith obstructing ureterocele and congenital vesicouretericjunction obstruction. Associated anomalies may be present in

up to 50% of cases that can include VACTERL association,congenital heart disease, CNS abnormalities, and congenitalgastrointestinal malformations [34].

On ultrasonography, the kidneys are usually normal tosmall in size [28,35] with highly echogenic cortices, loss of cor-tico-medullary differentiation, and scattered cysts (usually

smaller than those seen with multicystic dysplastic kidneys).The reniform shape is often preserved until late in disease.General differential considerations include multicystic dysplas-tic kidneys in which no distal obstruction and Meckel Gruber

syndrome which has occipital encephalocoele and polydactyly.

6. Summary

Congenital renal diseases are commonly encountered onultrasound imaging studies. Clinical presentation along withultrasound imaging features and vascularity as assessed by

Doppler US help in accurate diagnosis. Despite dramaticimprovements in MRI, CT and nuclear study, sonographycontinues to occupy a central role in the evaluation and detec-

tion of congenital renal diseases due to its advantage of rapidscanning time, lack of radiation exposure, cost effective andeasy feasibility.

Conict of interest

None declared.

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1264 N.A. Patel, P.P. Suthar

Ultrasound appearance of congenital renal disease: Pictorial review1 Technique1.1 Anomalies related to ascent of kidney1.1.1 Ectopia1.1.2 Crossed renal ectopia1.1.3 Horseshoe kidney

1.2 Anomalies related to the ureteric bud1.2.1 Renal agenesis1.2.2 Supernumerary kidney1.2.3 Duplex collecting system and ureterocele1.2.4 Uretero-pelvic junction obstruction1.2.5 Congenital megacalyces1.2.6 Congenital megaureter

1.3 Anomalies related to the renal growth1.3.1 Renal hypoplasia

1.4 Congenital cystic renal disease

2 Infantile polycystic renal disease autosomal recessive polycystic kidney disease (ARPKD) Potter type I3 Multicystic dysplastic kidneys Potter type II4 Early onset autosomal dominant polycystic kidney disease (ADPKD) Potter type III5 Obstructive cystic renal dysplasia Potter type IV6 SummaryConflict of interestReferences