Congenital anomalies of

kidney and urinary tract

A Review For PG Preparation

Table of contents

Introduction Common congenital renal anomalies Renal agenesis Renal hypoplasia Renal dysplasia Horse shoe kidney Nephronophthisis (NPH)Medullary cystic kidney disease (MCKD) Autosomal recessive polycystic kidney disease (ARPKD) Autosomal dominant polycystic kidney disease (ADPKD) Ureterocele

Introduction

• Normal renal development is dependent upon the interaction between the ureteric bud and metanephric mesenchyme, which induces organogenesis resulting in the formation of nephrons and collecting system of each kidney.

• Note: The neonatal kidney achieves concentrating ability equivalent to adult’s kidney by the age of 1 year.

Common congenital renal anomalies

• The following renal malformations arise when this process is disrupted:

i. Renal agenesis — Congenital absence of kidney(s).

ii. Renal hypoplasia — Congenitally small kidneys with a reduced number of nephrons but normal architecture.

iii. Renal dysplasia — The presence of malformed renal tissue elements, including primitive tubules, interstitial fibrosis +/ the presence of cartilage in the renal parenchyma.

iv. Renal hypodysplasia — Congenitally small kidney with dysplastic features. Renal hypoplasia is more commonly associated with dysplasia than without.

Renal agenesis

• Unilateral renal agenesis is much more common than bilateral one.

• Malformations associated with unilateral renal agenesis:

1. Single umbilical artery

2. Absent ureter

3. Absent ipsilateral vas deferens

4. Contralateral vesico-ureteral reflex.

Bilateral renal agenesis/ Potter syndrome

• Potter syndrome= Bilateral renal agenesis + Pulmonary agenesis + Potter facies.

• Potter facies= Widely separated eyes + epicanthic folds + broad compressed flat nose.

• Death occurs shortly after birth pulmonary hypoplasia.

• Maternal USG demonstrates:

Oligohydramnios

Absence of kidney

Non-visualization of bladder.

Renal hypoplasia

• The diagnosis of unilateral renal hypoplasia is usually incidental.

• When it is bilateral, it usually presents with signs and symptoms of chronic renal failure.

Signs and symptoms of chronic kidney disease in children

• Early symptoms: Polydipsia and nocturia

• Symptoms of advanced chronic kidney disease in children:

Hypertension

Anemia

Bone disease (termed renal osteodystrophy)

Cardiovascular disease

Anorexia, nausea, vomiting.

• Signs of advanced chronic kidney disease in children:

Volume overload

Hyperkalemia

Metabolic acidosis.

Renal dysplasia

• Multicystic dysplastic kidney (MCDK) is the most common cystic disease in infants.

• It is also the most common cause of abdominal mass in neonates; although the mass is non-palpable at birth in majority of cases.

• MCDK is a congenital condition, in which the kidney is replaced by cysts and the entire kidney is dysplastic; so it does not function.

• It is usually unilateral (also called unilateral renal dysplasia).

• When it is bilateral, it is incompatible with life.

• Risk of Wilm’s tumor arising from an MCDK is approx. 1/333.

Horse shoe kidney

• It is a developmental anomaly where there is failure of complete ascent of kidneys with the fusion of lower or upper poles. It is due to fusion of subdivisions of mesonephric duct.

• Salient points:Common in malesSeen in 7% of patients with Turner’s syndromeFusion of lower pole is commonCommonest site is in front of 4th lumbar vertebrae.

• Presents as a fixed, nonmobile, firm mass in the midline at the level of 4th lumbar vertebra which is resonant on percussion.

• Treatment: Complications are treated accordingly.

Uncommon congenital diseases of kidney and urinary tract

Nephronophthisis (NPH)

• Nephronophthisis is the most common genetic cause of ESRD in children and young adults.

• Nephronophthisis is a genetic disorder characterized by development of fluid-filled cysts in the corticomedullary region; followed by inflammation and fibrosis that impairs kidney function.

• Symptoms and signs:

Polyuria,

Polydipsia,

Extreme fatigue,

Anemia,

Rickets,

Growth +/ mental retardation.

• Nephronophthisis eventually leads to end-stage renal disease (ESRD).

• Nephronophthisis can be classified by the approximate age at which ESRD begins:

Around age 1 (infantile),

Around age 13 (juvenile), and

Around age 19 (adolescent).

Medullary cystic kidney disease (MCKD)

• Medullary cystic kidney disease (MCKD) and nephronophthisis (NPH) refer to 2 inherited diseases with similar renal morphology [bilateral small corticomedullary cysts in kidneys of normal/ reduced size and tubulointerstitial sclerosis leading to ESRD].

• These disorders have traditionally been considered as parts of a complex (the NPH complex) because they share many of the clinical and histopathological features.

• The major differences are in the modes of inheritance, the age of onset of ESRD and the extrarenal manifestations.

NPH MCKD

Mode of inheritance Autosomal recessive Autosomal dominant

Age of onset of ESRD Around age 1 (infantile)Around age 13 (juvenile)Around age 19 (adolescent)

3rd decade

Extrarenal manifestations In 10% of cases: Blindness Liver problems Growth and mental retardation Neurologic involvement

No extrarenal involvement

Polycystic kidney diseases

Autosomal recessive polycystic kidney disease (ARPKD)

Pathogenesis:

Presentation:

• Neonates (most common): Enlarged kidneys, sometimes Potter facies; H/O oligohydramnios/ dystocia during labour

• Early infancy: Predominantly renal problems: Enlarged kidneys, hypertension, renal failure

• Older children: Predominantly liver problems: Hepatomegaly, portal hypertension.

Treatment:

Supportive (treatment of chronic renal failure) and finally, renal transplantation.

Autosomal dominant polycystic kidney disease (ADPKD)

Pathogenesis:

Presentation:

• Positive family history in 60% of cases

• Prenatal diagnosis: Enlarged kidneys, H/O oligohydramnios

• Children: Asymptomatic; incidental detection of renal cysts in USG

• 2nd decade of life: Episodic hematuria and hypertension, bilaterally palpable kidneys, hepatic cysts (asymptomatic).

Associations:

Coarctation of aorta

Mitral valve prolapse

Cerebral aneurysms.

Treatment:

Control hypertension

Non-opioid analgesics to control pain

Surgical/ percutaneous drainage of cysts to control pain/ infection

Nephrectomy in case of intractable symptoms/ symptoms due to mass effect of enlarged kidneys

Dialysis: Hemodialysis/ peritoneal dialysis

Renal transplantation in ESRD patients

Special note: Newer drug: Tolvaptan, a vasopressin receptor 2 (V2) antagonist.

Ureterocele

• A ureterocele is a cystic out-pouching of the distal ureter into the urinary bladder.

• Ureterocele occurs due to a combination of an abnormality in the submucosal part of ureterand stenosis of ureteric orifice.

Types:

According to renal collecting system:

1. Single-system ureteroceles: Those associated with a single kidney, collecting system and ureter.

2. Duplex-system ureteroceles: Those associated with kidneys that have completely duplicated ureters.

According to position of ureteric orifice:

1. Orthotopic (intravesical) ureterocele is a term used for a ureterocele contained within the bladder.

2. Ectopic (extravesical) ureterocele refers to ureteroceles with tissue that originates at the bladder neck or beyond, into the urethra.

Presentation:

• Currently, most pediatric ureteroceles are found during routine prenatal screening.

• Complications include: infection/ obstruction/ stone formation/ urinary incontinence/ acute bladder neck obstruction.

Diagnosis:

• Presence of filling defect in micturating cysto-urethrogram (MCU) is the most characteristic diagnostic finding of ureterocele.

• Intravenous urography (IVU): Cobra head appearance [of historical importance only].

Treatment:

• Cystoscopic ureteric meatotomy with the removal of cyst wall

• Often ureteric reimplantation is needed.

Thank you…