Download Embryogenesis of the Kidneys and Ureters

Embryogenesis of the Kidneys
and Ureters
Normal Development
• Three excretory organs (pronephroi,
mesonephroi, and metanephroi) develop from
the intermediate mesoderm
• However, since pronephroi are never
functional in human embryos and degenerate
on days 24 or 25, we will present only the
concepts of mesonephroi and metanephroi
A. A pair of cervical nephrotomes forms in each of
five to seven cervical segments, but these quickly
degenerate during the 4th week.
B The mesonephric ducts first appear on day 24
C. Mesonephric nephrotomes and tubules form in
craniocaudal sequence throughout the thoracic
and lumbar regions.
D. The mesonephroi contain functional nephric
units consisting of glomeruli, Bowman's capsules,
mesonephric tubules, and mesonephric ducts.
Ventral views of the abdominopelvic region of
embryos and fetuses (sixth to ninth weeks), showing
medial rotation and 'ascent' of the kidneys from the
pelvis to the abdomen.
Congenital Anomalies
A. Unilateral renal agenesis.
B. Right side, pelvic kidney; left side, divided kidney with a bifid ureter
The left kidney crossed to the right side
and fused with the right kidney
C. Right side, malrotation of the kidney; left side, bifid ureter and double kidney.
D. Crossed renal ectopia.
E. 'Pancake' or discoid kidney resulting from fusion of the kidneys while they were in
the pelvis.
F. Supernumerary left kidney resulting from the development of two ureteric buds.
Common congenital anomalies of the kidney
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Agenesis of the kidney
Hypoplasia & dysplasia
Supernumerary kidney
Horse – shoe kidney
Cystic disorders
Medullary sponge kidney
Horseshoe Kidney
Diagnosed by IVU
• Horseshoe kidney is the most common type of fusion,
occurring in 1 in 400, with 90% fused at the lower poles.
• Associated with urogenital anomalies and an increased
incidence of renal pelvic tumors.
• One third of patients remain asymptomatic, whereas others
may present with symptoms of hydronephrosis [ureteropelvic
junction (UPJ) obstruction], infection, or stones
Renal Hypoplasia
• Hypoplasia refers to reduced renal mass (i.e.,
fewer than normal cells or nephrons) without
histologic evidence of dysplasia
Renal Dysplasia
• Dysplasia is a form of abnormal renal morphogenesis
characterized histologically by primitive ducts and
cartilage.
• Most hypodysplastic kidneys have ectopic ureteral
orifices.
• The more ectopic the orifice, the greater the degree
of dysplasia
Cystic disorders of the kidney
• Quite common
– Polycystic kidney disease: bilateral
condition
– Medullary sponge kidney
– Solitary renal cyst
Polycystic kidney disease
• Cystic genetic disorder of the kidney
• Associated with cysts in the liver, pancreas, brain & heart
• Types:
– Autosomal dominant
– Autosomal recessive
Autosomal dominant polycystic kidney disease
• Late onset
• Due to mutations in either the PKD-1 or PKD-2 gene.
Autosomal recessive polycystic kidney disease
• Early onset
• Less common than ADPKD
Clinical features
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Abdominal lump
Pain
Haematuria
Hypertension
Infection
Uraemia
Investigations
• USG
• Excretory urograms
Complications
• Pyelonephritis
• Infection of cysts
• Renal failure
Treatment
• Conservative: low protein diet, increased intake of fluid
• Surgery:
– Rovsing’s operation
Congenital Multicystic Kidney Disease
• Congenital multicystic kidney disease is a
common benign dysplastic malformation of
the fetal kidney secondary to obstruction from
ureteropelvic occlusion, ureteral atresia, or
agenesis
• Elective surgical excision is indicated if the
mass interferes with respiration or
alimentation
Medullary Sponge Kidney
• Medullary sponge kidney is a congenital
deformity of the renal medulla consisting of
multiple, puddle-like dilatations of the collecting
ducts in the papillae on IVU(fan-shaped
pyramidal blush )
• The disease is bilateral in 75% of patients.
• Predisposition to calcium phosphate
nephrolithiasis in the adult, presenting with renal
colic and hematuria secondary to stone passage.
• Treatment consists of preventing infection and
stone formation.
Congenital anomalies of the ureter
• Absence of one ureter
• Duplication of ureter
• Ureterocele
Ectopic Ureter
• An ectopic ureter is one that opens in some location other than the
bladder.
• Most common sites for insertion of the ectopic orifice in female patients
are the urethra, vestibule, and vagina, and present as urinary
incontinence.
• Most common sites for insertion of the ectopic orifice in male patients are
the posterior urethra and seminal vesicles, often remaining unrecognized
until late in life.
• partial nephroureterectomy of the nonfunctioning upper-pole component
or pyelopyelostomy with only a distal ureterectomy if the upper pole
functions.
Ureterocele
• A ureterocele is a congenital cystic ballooning of the terminal
submucosal ureter.
• It is classified as or
• Simple----represents about 30% of all ureteroceles and occurs
primarily in adult , present with infection
• Ectopic--- 70% of all ureteroceles,in female, with a left
predominance; 10% are bilateral
• Prenatal ultrasound ,IVU
• Excision and reimplantation of the distal ureter,
• A complete nephroureterectomy may be necessary if the
entire kidney is nonfunctional
Megaureter
• Megaureter is a term that most urologists use
to refer to primary ureteral dilatation in the
absence of extraureteral disease
• Most children with megaureter will present
with urinary tract infection, hematuria, or a
flank mass; 25% of cases are bilateral.
• USG, IVU
Classification
• Obstructed megaureter --secondary to urethral
obstruction as with valves, prolapsing
ureterocele, calculi, granulomatous disease, or
other extrinsic causes;
• Refluxing megaureter is from either primary
intrinsic ureteral reflux or reflux secondary to
bladder-outlet obstruction or neurogenic
bladder;
• Nonrefluxing, nonobstructed megaureter is a
congenital idiopathic ureteral dilatation often
associated with megacalycosis
Treatment
• Most patients with primary megaureter have
the nonrefluxing, nonobstructing type that
needs no surgical intervention
• Primary obstructive megaureter requires
surgical correction, commonly by tapering the
lowermost 5 cm of ureter with reimplantation