•The lumbar or iliac ectopic kidney is fixed above the iliac crest but below the level of L2 and L3.

•A thoracic kidney is exceedingly rare and is due to excessive cranial migration prior to diaphragmatic closure or delayed closure with continued ascent.

•Ectopic kidneys are rarely normal. They are often small, lobulated kidneys with abnormal rotation with extrarenal calyces and an irregular vascular supply.

•Associated abnormalities:

–The most common problem associated with an ectopic kidney is vesico-ureteric reflux (VUR) which occurs in up to 85 % of children.

–Pelvi-ureteric junction (PUJ) obstruction is present in 33–52 %.

–This is frequently due to a high insertion of the ureter on the renal pelvis, malrotation of the kidney or an anomalous blood supply which obstructs the collecting system.

–Renal calculi

–The contralateral kidney is abnormal in as many as 50 % of patients.

–Contralateral renal agenesis occurs in 10 %.

–Additional malformations of the cardiovascular, respiratory, genital or skeletal systems are common.

–Associated skeletal anomalies are most commonly scoliosis and hemivertebrae.

–Genital malformations in females include duplication of the vagina, bicornuate uterus and hypoplasia or agenesis of the uterus or vagina.

–The most common genital anomalies in males are hypospadias and cryptorchidism.

Congenital Renal Anomalies

•Renal agenesis

•Renal hypoplasia

•Oligomeganephronia

•Supernumerary kidneys

•Renal dysplasia and multicystic kidney

•Polycystic kidney disease

–Autosomal dominant polycystic kidney disease (ADPKD)

–Autosomal recessive polycystic kidney disease (ARPKD)

•Simple (solitary) renal cyst

•Renal fusion and renal ectopia

–Horseshoe kidney

–Crossed fused renal ectopia

–Ectopic kidney

•Pre tumorous conditions (Nephroblastomatosis)

•Tumors presenting in antenatal and early childhood period

–Mesoblastic nephroma

–Nephroblastoma

–Multilocular cystic nephroma

–Wilms tumor

1.4Abnormalities of the Ureter

•Ureteral atresia (Figs. 1.21, 1.22, and 1.23):

–The ureter may be absent or fail to extend to the bladder and end blindly.

–It is associated with ipsilateral absent or multicystic kidney.

–Bilateral atresia is incompatible with life.

–Unilateral atresia is usually asymptomatic but may cause hypertension.

•Duplication of the ureter:

–This is one of the most common congenital malformations of the urinary tract.

–Duplicated ureter or Duplex Collecting System is a congenital condition in which the ureteric bud, the embryological origin of the ureter, splits (or arises twice), resulting in two ureters draining a single kidney.

–It is the most common renal abnormality, occurring in approximately 1 % of the population.

–The additional ureter may result in a ureterocele, or be an ectopic ureter.

–It is estimated that duplication of the ureter is found in 0.9 % of a series of autopsies.

–It is more common in females and is often bilateral.

–Ureteral duplication is divided into two types:

•Partial ureteral duplication (Figs. 1.24 and 1.25):

–The two ureters drain into the bladder via a single common ureter.

–Partial, or incomplete, ureteral duplication is rarely clinically significant.

•Complete ureteral duplication (Figs. 1.26 and 1.27):

–The two ureters drain separately.

–Complete ureteral duplication may result in one ureter opening normally into the bladder, and the other being ectopic, ending in the vagina, the urethra or the vulval vestibule.

–These cases occur when the ureteric bud arises twice rather than splitting.

–It is often asymptomatic but commonly presents with persistent or recurrent urinary tract infections.

–Urinary tract infection is most commonly due to vesicoureteral reflux.

–Urinary incontinence in females occurs in cases of ectopic ureter entering the vagina, urethra or vestibule.

•Ureterocele (Figs. 1.28 and 1.29):

–This is a sacculation of the bladder end of the ureter that can occur either in the bladder or ectopically.

–It is much more common in girls than in boys.

–In 10 % of cases it is bilateral.

–It may be asymptomatic or cause obstruction, incontinence or infection.

•Ectopic ureteral orifice:

–This usually occurs with ureterocele and duplication of the ureter.

–Single ectopic ureters are also seen.

–Boys may present with recurrent epididymitis, as the ureter drains directly into the vas deferens or seminal vesicle.

–Girls normally present with incontinence with continual dribbling despite normal voiding.

•Obstruction of the ureteropelvic junction (Figs. 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, and 1.39):

–This is a common congenital abnormality of the ureter where there is a partial obstruction at the junction between the renal pelvis and upper ureter.

–The cause of obstruction can be intrinsic or extrinsic.

Fig. 1.28 Pelvic ultrasound showing right ureterocele

Fig. 1.29 Intraoperative photograph showing an obstructed ureterocele. Note the massively dilated ureter and also the small atrophic kidney

ATROPHIC

KIDNEY