Congenital anomalies of Renal system

Objectives To give an over view of common congenital renal anomalies. Implications of these anomalies in childhood and beyond.

Development Three sets of excretory organs: Pronephros (rudimentary & non functional) Mesonephros (Briefly functional) Metanephros (Permanent) initiated by an interaction between ureteric bud(branch of mesonephric duct) & metanephric mesoderm. Collecting system is formed by branching of ureteric bud.

Developmental Abnormalities Developmental process is disturbed Normal development Kidneys arise from mesoderm, develop in pelvis, ascend to final position Bladder derived from lower end of intestinal tract Excretory ducts (ureters, calyces, pelvis) develop from ureteric buds that extend from bladder into the developing kidneys

Nomenculature Malformation of parenchyma Agenesis/Aplasia Hypoplasia Dysplasia Cystic Disease. Aberrant migration of renal parenchyma Renal ectopia, Fusion anomalies.

Agenesis/Aplasia/Hypoplasia Due to failure of mesonephric duct to bud. Bilateral fatal (oligohydramnios) 1 in 3000 births. Unilateral 1 in 1000 new borns. compatible with normal life. Other kidney hypertrophies.

Multicystic/Polycystic dysplastic kidneys Failure of ureteric bud derivatives to join the tubules of metanephric mesoderm. Kidneys consists of groups of cysts with minimal parenchyma. 1in 2400 births.

Ectopic Kidneys Aberrant migration of renal parenchyma One or both kidneys may be in an abnormal position. Pelvic kidney due to failure of kidney to ascend. If both are close to each other---pancake or discoid. Horseshoe kidney 1 in 500 Lower poles fuse. Usually lies in hypogastrium because they are caught by root of inferior mesenteric A. U shaped. May remain asymptomatic.

Fusion anomalies Crossed renal ectopia Kidney may cross to the opposite & fuses or remains unfused with contralateral kidney.

Abnormalities of development of collecting system. Pelvi ureteric junction obstruction (Hydronephrosis) Ureteric Mega ureter, Ectopic ureter, Duplication, Vesico ureteric reflux. Urinary Bladder Exstrophy (ectopia vesicae). Urethra Posterior urethral valves, Hypospadias, Epispadias.

Hydronephrosis

Hydronephrosis

Duplication of ureter Results from division of the ureteric bud or separately from two buds. Complete. Incomplete.

Ectopic ureter Results when ureteric bud is not incorporated into the posterior part of urinary bladder. It may open at a place other than in the bladder at two upper angles of trigone. May be a part of duplex system.

Ectopic ureter Males Neck of the bladder, prostatic urethra, seminal vesicle or vas deferens. May cause epididymo orchitis or urinary incontinence. Females Bladder neck, urethra, Vagina or Vestibule.

Mega Ureter Larger than normal size ureter. Obstructive due to some congenital obstruction like stenosis or atresia. Non obstructive due to vesico ureteral reflux.

Mega Ureter

Vesicoureteral Reflux Urine is normally prevented from flowing back into the ureters during micturation by a valve like mechanism at ureteovesical junction. Failure of mechanisms allows bladder urine to reflux into ureter during voiding. Predisposes to urinary tract infection Predisposes to pyelonephritis

Vesicoureteral Reflux

Urinary Bladder Exstrophy ( Ectopia vesicae) 1 in 40,000 births. Protrusion of posterior bladder wall due to incomplete medial closure of inferior part of anterior abdominal wall & also involves anterior bladder wall. Results from failure of migration of mesenchymal cells between cectoderm of anterior abdominal wall and cloaca.

Posterior Urethral Valves Most common form of obstructive uropathy leading to renal failure in newborn boys. These leaf like structures arise from the distal portion of verumontanum, course in the anterolateral direction & in more severe cases fuse with the opposite valve in the anterior midline resulting in outlet obstruction

Urachal anomalies Urachal Fistula Patent Urachus Cyst Diverticulum

Urethral anomalies Hypospadias means below & spadon means defect or rent. Incidence is 8.3 per 1000 male births. It results from failure of fusion of urethral folds on ventral aspect of penis.

Urethral anomalies Epispadias External ure meatus is on the dorsal aspect of the shaft of the penis

Take home message Congenital renal anomalies may present beyond neonatal period. Bilateral involvement, solitary kidney etc. require urgent evaluation. Long term follow up of renal & bladder functions are needed.

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