Congenital anomalies of kidney and urinary system Dr. Alia Al-Ibrahim Consultant Pediatric Nephrology Clinical assistant professor

CONTENTS: 1- Anatomy of urinary system 2- Function of urinary system 3- Normal development 4- Congenital anomalies of urinary system: Dysgenesis of the kidney -Agenesis - Hypo plastic - Dysplastic - A plastic Abnormalities in shape & position - Ectopic Kidney - Horse shoe Kidney - Crossed fused Ectopia Abnormalities of collecting system - Hydronephrosis - Bladder extrophy - PUV - Patent Urachus Clinical presentation Antenatal screening Postnatal Evaluation

Development of Urinary system: The Urinary system goes through three phases on its way to becoming fully functioning : 1- Pronephros 2- Mesonephros 3- Metanephros Starting from 4th wk & end on 36 wk of intra uterine life

Normal Anatomy of the Urinary system 4 wks gestation : kidney start development 9 wks : first glomeruli , Bladder 36 wks : nephrogenesis ceases ( 1 million glomeruli in each kidney). Postnatal increase in the size of the kidney is due to enlargement of the Glomerular diameter & significant increase in tubular volume & length

Active period of nephrogenesis between 20-36wks, cease around 36 wks

Nephron Nephron: Glomerulus, Bowman's capsule, convoluted tubule, loop of Henle Formation begin at 8th wk. Postnatal increase in the size of the kidney is due to enlargement of the Glomerular diameter & significant increase in tubular volume & length.

Ascent of kidneys: A: 5th -6th wk the mature kidneys lie in the pelvis with their hila pointed anteriorly B: 7th wk the hilum points medially , kidneys in the abdomen. C: 9th wk kidneys in the retroperitoneal position at level of L1 , complete rotation , anteromedially.

Normal Function of the Urinary system: Kidney : 1- Filters blood- remove and eliminate soluble waste ( urine). 2- Regulates blood volume and composition. 3- Maintains water and electrolyte balance. 4- Hormonal production; Erythropoietin, Renin. 5- Metabolizes vitamin D to active form. Ureters: convey urine from kidneys to bladder. Urinary bladder: Temporary urine storage. Urethra: Conveys urine from bladder to outside.

Abnormalities during development: 1- Dysgenesis of the Kidney a- Renal Agenesis(absent Kidney) : Failure of the ureteral bud to communicate with the metanephric blastema 1:500 – 1: 3200 live births

AGENISIS UNILATERAL BILATERAL

1- Unilateral : absent kidney, no symptoms. Avoid contact sport, other kidney hypertrophy , check for abnormality ( 50% ) Incidence increase with single umbilical artery absent ureter & hemitrigone. Hypertrophy, VUR in contra lateral kidney 2- Bilateral: Incompatible with extra uterine life Oligohyddramnios , no kidneys , non visualized bladder in antenatal US Death shortly after birth from pulmonary Hypoplasia ( Potter’s syn) Detected by US 12th wk of gestation higher in boys. 5% recurrent risk in subsequent pregnancy Associated anomalies include: Anorectal, CVS, Skeletal.

b- Renal Hypoplasia : Small size, non dysplastic, less than normal # of calyces & nephron . 1- Unilateral: Incident diagnosis ( another urinary tract problem or HTN). 2- Bilateral: CRF manifestations. 3- Segmental Hypoplasia: ( Ask-Upmark Kidney). C-Aplasia : rudimentary kidney

d-Renal dysplasia: Abnormality in the structure cartilages, cyst ( Abnormal metanephric differentiation) May affect all or part of the kidney. 1- Cystic 2- cartilelages Hereditary : ARPKD ADPKD Congenital: MCDK

Multicystic dysplastic kidney (MCDK): Non- functioning kidney replaced by large non-communicating cysts of varying sizes, no renal cortex, atretic ureter. Unilateral , 2 times more in male. Detected during antenatal US. Investigations & diagnosis: 1- US. 2- DMSA ( no function in the affected side) , hypertrophy of contra-lateral kidney. 3- MCUG : contra-lateral VUR (20%). Complications: 1- Malignancy: Wilm's’ tumor, adenocarcinoma& embryonic carcinoma. 2- HTN: cured by nephrectomy. 3- Infection, bleeding into, or rupture of cysts if large.

Management: Conservative: 1- cysts < 5cm , high chance of involution, or cause no problems. 2- reviewed annually for: - BP - urinary protein. - US for cysts involution, of MCDK. growth of contra-lateral kidney. Up to 2yrs of age then at 5yrs of age if normal. Nephrectomy: 1- no involution by 2 yrs of age. 2- HTN 3- infections

11- Abnormalities in shape & position: a- Ectopic Kidney: Failure of ascent of the kidney during embryogenesis. Incidence 1;900 Associated anomalies: VUR, undesended testis in , hypospadius, Genital abnormalities in girls Blood supply from internal, external iliac artery ,& or aorta Ectopic in contra lateral side 90% fusion

b- Fusion Anomalies 1- horseshoe Kidney: 1:500 -Commonest form of fusion (95%). -The lower poles of both kidneys unit across the midline -The isthmus of horse shoe kidney lie at the level of L4-L5, is more susceptible to trauma -More common in male, Turner syndrome, trisomy 18 Complications: 50% VUR, abnormal vascular supply. Stone & hydronephrosis 2° PUJO. Wilm’s tumor HTN Diagnosis: DMSA, MCUG ,DTPA . can be missed by us.

2- Crossed fused Ectopia: one kidney cross the midline to the other side and lie in an abnormal rotate position & fused upper pole fused to the normal kidney lower pole. ureter inserted in normal position. anomalies of uro-gent.system

III-Abnormalities of the collecting system: A- Duplex kidney : 1% , Familial, more in girls , 70% unilateral. Two pelvicalyceal system within the kidney, complete or partial. Kidney larger than normal. Complete: -Kidney has 2 moieties, each with its own ureter> The upper pole ureter opens lowermost & medially into the bladder . May be ectopic draining in vagina, posterior urethra. Ureterocoele ( obstruction). The lower pole ureter cause reflux, , PUJO, dysplastic part. Incomplete: -Uncomplicated divided pelvis, or 2 Ureters join before entering the bladder.

Hydronephrosis: Dilatation of renal pelvis & collecting system. 0.6- 4.5% antenatal US. Several grading system ( Renal pelvic diameter). Antenatal US ( 18-20 WKS). - severity of antenatal US. - Unilateral vs. bilateral - Renal parenchyma thin or Echogenic. - Bladder - Amniotic fluid Causes: 1- Transient 2- Physiological 3- UPJO 4- VUR 5- Megaureter 6- Ureterocoele 7- PUV

Postnatal evaluation: 1- Physical exam: Abdominal mass, palpable bladder. 2- US 3- VCUG : detect VUR, PUV. 4- Diuretic Renogram : detect urinary obstruction with persistent hydronephrosis

Ureteropelvic junction obstruction ( UPJ): Detected antenatal, frequent cause of hydronephrosis More common in Left side, Ectopic, malrotation, horseshoe kidney Bilateral 40% Present: mass, UTI, Pain, Hematuria

Bladder extrophy: Failure of abdominal wall to close during fetal development & results In protrusion of the posterior bladder wall through the lower abdominal wall. Symphsis pubis diastasis. Multiple abnormalities in pelvis, bladder, urethra, & external genitalia. - Common in males Associated abnormalities: 1- VUR 2- Incontinence 3- Repeated UTI

Posterior urethral valve (PUV):Commonest obstructive Uropathy in boys , 1:5000- 8000 Congenital valve in the posterior urethra due to persistent urogenital membrane. Associated with renal dysplasia ( Back pressure, common developmental insult). Risk of perinatal mortality & risk of chronic kidney disease: 1- US suggestive at < 24 wks gestation. 2- Severe bilateral hydronephrosis. 3- Oligohyddramnios. 4- Echogenic kidneys. Postnatal presentations: 1- pulmonary Hypoplasia. 2- Poor urinary stream 3- Voiding dysfunction. 4- Urosepsis. 5- FTT.

Renal & urological manifestation: 1- Chronic kidney diseases. 60% dysplastic kidney 2- VUR 3- Bladder dysfunction. Management: 1- correction of electrolytes. 2- Treatment of sepsis. 3- Resp.distress 4- Temporary relieve of pressure 5- cystoscopy : valve ablation 6- Vesicostomy

Prune belly syndrome ( Eagle-Barrett syndrome, Triad syndrome) Triad of: 1- Deficiency or absence of anterior abdominal wall musculature. 2- Bilateral cryptorchidism 3- Ureter ,bladder,& urethral abnormalities( megacystis, Megaureter 2° dysplasia. Other systemic abnormalities in 75%: 1- GI : malrotation, gastroschisis. 2- Heart: CHD 3- Skeletal: talipes equinovarus, CDH. 4- Pulmonary hypoplasia

Clinical presentation : Wide spectrum 1- Antenatal screening 0.1- 0.7%. 2- UTI 3- Hypertension 4- Proteinuria 5- Renal impairment 6- Hematuria 7- Stones Antenatal Screening US 1- Fetal kidney 2- Collecting system 3- Amniotic fluid Postnatal Exam: Physical exam: Associated anomalies Urgent evaluation : Bilateral involvement, solitary affected kidney, oligohyddramnios. Renal studies: Renal US, VCUG, MAG3

Take home messages: 1- Congenital anomalies of the kidney are significant causes of ESRF in children. 2- These anomalies often do not exist in isolation. 3- May present beyond the neonatal period. 4- Bilateral involvement. Oligohyddramnios, solitary kidney require urgent evaluation. 5- Long –term follow-up of renal & bladder function is important.

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