This document provides an overview of congenital renal abnormalities, including their embryology, classification, and clinical presentation. It describes anomalies of kidney number, structure, and location. It also discusses anomalies of the urinary tract, including duplication of the ureters, posterior urethral valves, and bladder abnormalities. Specific conditions covered in detail include bilateral and unilateral renal agenesis, horseshoe kidney, polycystic kidney disease, prune belly syndrome, and posterior urethral valves. The overview of embryology provides background on the development of the pronephros, mesonephros, and metanephros.

1. CONGENITAL RENAL
ABNORMALITIES
BY: DR ENOBONG RUNCIE
LECTURER/CONSULTANT PAEDIATRIC NEPHROLOGIST
UNIVERSITY OF UYO TEACHING HOSPITAL

2. OUTLINE
• Introduction
• Overview of embryology
• Anomalies of the kidney
-number
-structure
-location
• Anomalies of the urinary tract
-Duplication of ureters
-Ectopic ureters
-Posterior urethral valve
-Bladder anomalies
• Miscellaneous
• -Prune belly syndrome

3. OVERVIEW OR EMBRYOLOGY
• The urinary and reproductive systems develop from the
intermediate mesoderm.
• Urinary system: 3 slightly overlapping systems are formed in a
cranial and caudal sequence during the intrauterine life.
• These are the pronephros, mesonephros, metanephros

4. • PRONEPHROS: develops at the 3rd week of intrauterine life. It is
found in the caudal region. It degenerates leaving behind the
pronephric duct.
• MESONEPHROS: this develops at 4 weeks of gestation. It is found in
the upper thoracic to upper lumbar L3 segments. It degenerates
leaving behind the mesonephric duct

5. METANEPHROS
• The definitive kidney
• Appears in the 5th week of intrauterine life about day 34
• Ureteral bud arises from the mesonephric duct near its junction with the
cloaca
• The ureteral bud grows cephalad collecting mesoderm from the caudal
portion of the nephrogenic cord of the intermediate mesoderm

6. • Ureteral bud gives rise to the renal pelvis, calyces, papillary ducts
and collecting tubules
• The metanephric tissue around dilated tips of ureteral bud, forms
the S-shape hollow vesicles
• S-shaped hollow vesicles gives rise to the Bowman’s capsule. It
elongates to form the PCT, DCT, loop of Henle.
• Small vessels grow into the lower end of the S-shaped nephron
giving rise to the glomerulus

8. POSITION OF THE KIDNEY
• Initially in the pelvic region
• Later ascents to the level of the 1st lumbar or 12th thoracic
vertebrae
• Ascent of the kidney is caused by diminution of the body curvature
and by growth of the body in the lumbar and sacral regions

9. FUNCTION OF THE KIDNEY
• Definitive kidney becomes functional near the 12th week
• Urine is passed into the amniotic cavity and mixes with the
amniotic fluid
• The fluid is swallowed by the fetus and recycles through the
kidneys
• During the fetal life, the kidneys are not responsible for excretion
of waste products
• The placenta serves this function

10. BLADDER, URETHRA, URETERS
• Between the 4th to 7th week, the cloaca divides into the urogenital
sinus anteriorly and anal canal posteriorly.
• This is separated by the urorectal septum
• The tip of the septum forms the perineal body
• The urogenital sinus has 3 parts; bladder (urinary bladder), pelvic
part (prostatic and membranous part of the urethra) phallic part
(genital tubercule)
• The caudal portions of the mesonephric ducts are absorbed into
the wall of the urinary bladder. The ureters enters the bladder
seperately

11. ANOMALIES OF THE KIDNEY
• Anomalies of number
-Bilateral renal agenesis
-Unilateral renal agenesis
- Supernumerary kidneys
• Anomalies of structure
-Renal hypoplasia
-Renal dysplasia
-Renal aplasia
-oligomeganephronia
-Polycystic kidney disease
• Anomalies of location
-Horse shoe kidney
-Ectopic kidney

12. BILATERAL RENAL AGENESIS
• Also known as Potter’s syndrome
• 1:5000 births
• M>F
• Non familial
• Incompatible with extrauterine life
• Death occurs shortly after birth from pulmonary hypoplasia
• Potter’s facies: epicanthic folds, low set ears/malformed ears, broad flattered nose, receding chin.
• Limb anomalies are not uncommon
• Diagnosis is suspected if USS antenatally shows
-Oligohydramnious
-Nonvisualisation of the bladder
-Absent kidneys
-Small for date

14. UNILATERAL RENAL AGENESIS
• 1 per 450-1000 birth
• M>F
• Incidence increased in newborns with single umbilical artery
• Ureter and ipsilateral bladder hemitrigone maybe absent
• Contralateral kidney undergoes hypertrophy
• Maybe asymptomatic

15. SUPERNUMERARY KIDNEYS
• Very rare condition
• These kidneys are usually small and dysplastic
• Can be removed

16. ANOMALIES OF THE KIDNEY
• Anomalies of number
-Bilateral renal agenesis
-Unilateral renal agenesis
- Supernumerary kidneys
• Anomalies of structure
-Renal hypoplasia
-Renal dysplasia
-Renal aplasia
-oligomeganephronia
-Polycystic kidney disease
• Anomalies of location
-Horse shoe kidney
-Ectopic kidney

17. RENAL HYPOPLASIA
• Small nondysplastic kidneys
• Has fewer than normal nephrons and calyces
• Can be unilateral – diagnosis is made accidentally
• Bilateral renal hypoplasia manifests with signs and symptoms of
CRF leading to ESRD in the first decade of life.
• There maybe a history of polydipsia and polyuria in these patients

18. RENAL DYSPLASIA
• This is actually a histologic diagnosis
• Refers to focal, diffused or segmentally arranged primitive structure
• Non renal structures such as cartilage maybe present
• Size of the kidney maybe larger or smaller than normal
• Some have associated anomalies such as vesico-ureteric reflux
• Kidney may have cyst leading to multicystic dysplastic kidney (MCDK)
• Maybe asymptomatic if unilateral
• Bilateral disease leads to CRF that may require dialysis and kidney
transplantation.

19. RENAL APLASIA
• Small mass of tissue unrecognized as kidney
• Ipsilateral ureter is usually atretic

20. OLIGOMEGANEPHRONIA
• Small kidneys with reduced number of nephrons
• Nephrons are abnormally large
• Symptoms include: polyuria, vomiting, dehydration, salt wasting
concentration defects, proteinuria.
• The condition later leads to CRF

21. POLYCYSTIC KIDNEY DISEASE
• Infantile polycystic kidney disease
• Adult polycystic kidney disease

22. INFANTILE POLYCYSTIC KIDNEY DISEASE
• Inheritance is autosomal recessive
• The affected gene is on chromosome 6 with mutations involving
PKHD1 gene
• F>M; 2:1
• Patients are born with large kidneys and oliguria
• They may be stillbirth or die at birth due to pulmonary hypoplasia
and respiratory failure
• Hypertension in these patients is severe and renal failure usually
occurs

23. INFANTILE POLYCYSTIC KIDNEY DISEASE
• Prenatal USS: enlarged kidneys with increased echogenicity and
loss of normal corticomedullary differentiation
• Histology: small cysts with dilated segments of collecting duct and
distal tubules
• Prognosis is poor even for patients with renal transplantation

24. ADULT POLYCYSTIC KIDNEY DISEASE
• Inheritance is autosomal dominant
• Presents in the 2nd decade of life
• Can present in infancy
• Affected gene is on chromosome 4- PKDI; chromosome 16- PKD2
• CF: abdominal pain, haematuria, hypertension, bilateral abdominal
masses, recurrent febrile episodes.
• Diagnosis by USS and IVU shows enlarged kidneys with widely separated
calyces
• Management: BP control, correction of electrolyte derangement, RRT in
patients with CRF, screen family members with USS.

25. ANOMALIES OF THE KIDNEY
• Anomalies of number
-Bilateral renal agenesis
-Unilateral renal agenesis
- Supernumerary kidneys
• Anomalies of structure
-Renal hypoplasia
-Renal dysplasia
-Renal aplasia
-oligomeganephronia
-Polycystic kidney disease
• Anomalies of location
-Horse shoe kidney
-Ectopic kidney

26. HORSE SHOE KIDNEY
• 1/400-500 birth
• Are seen in 7% of patients with turner syndrome
• Wilm’s tumors are 4x more common in these patients
• Renal function is usually normal
• Usually left alone unless there is complications like infection or stone
formation

28. ECTOPIC KIDNEYS
• The normal process of ascent and rotation of the kidney maybe
incomplete resulting in renal ectopia
• Maybe located in the pelvic, iliac, thoracic, contralateral position
• Incidence is 1/900
• Ectopia maybe bilateral .

29. ANOMALIES OF THE URETERS,URETHRAS AND
BLADDER
• Duplication of the ureters
• Posterior urethral valve
• Bladder abnormalities

30. DUPLICATION OF THE URETERS
• Results from premature branching of the ureteral bud
• Maybe complete or partial
• Maybe unilateral or bilateral
• F>M; 2:1
• There may be stenosis at the uterovesical junction
• CF: dribbling, recurrent infection, reflux, hydroureter, hydronephrosis
• Diagnosis: IVU
• Management: if there is no symptom, then leave it alone. With
symptoms like reflux and recurrent infections, a surgical repair is
necessary

32. POSTERIOR URETHRAL VALVE
• Incidence is 1:8000 boys
• It is the most common cause of obstructive uropathy in children
• About 30% progress to ESRD or CRF later in life
• The urethral valves are tissue leaflets fanning distally from the
prostatic urethra to the external urinary sphincter. A slit-like
opening usually seperats the leaflets
• The prostatic urethra dilates and the bladder muscle undergoes
hypertrophy
• 1/3 have associated vesicoureteral reflux

33. PUV cont
• Prenatal diagnosis (maternal USS)
-Bilateral hydronephrosis
-Distended bladder
-Oligohydramnious
• At birth
-Presence of palpable bladder
-Poor urinary stream
• Later in life
-FTT due to uremia and sepsis
-Recurrent UTI
-Failure to achieve diurnal urinary continence

34. TYPES OF PUV

35. PUV cont
• Diagnosis is established with voiding cystourethrogram (VCUG) which
shows ballooning of the posterior urethra and poor distal filling
• Management
-Neonate: pass a feeding tube for bladder drainage (don’t pass a foleys
catheter)
-Surgery: Transurethral ablation of valve leaflets
-RRT in cases of ESRD
-Supportive treatment such as correction of electrolyte imbalance,
treatment of UTI

38. Prognosis of PUV
• Favorable
-Normal prenatal USS between 18 & 24 weeks gestation
-Serum creatinine <0.8-1.0mg/dl after bladder decompression
-Visualization of corticomedullary junction on renal sonography
• Unfavorable
-Oligohydramnious inutero
-Hydronephrosis before 24 weeks gestation
-Serum creatinine >1.0mg/dl after bladder decompression
-Identification of cortical cyst in both kidneys
-Persistence of diurnal incontinence beyond 5years of age.

39. BLADDER ABNORMALITIES
• These include agenesis, duplication, patent urachus and extrophy
• These conditions are very rare
• In bladder extrophy, the bladder is exposed due to absence of
abdominal wall muscles
• Infections are common in these patients

41. PRUNE-BELLY SYNDROM
• This is also known as Triad syndrome or Eagle-Barret syndrome
• 1:4000 births
• 95% are males
• They have deficient abdominal muscle, undescended testes, urinary tract abnormalities
• Oligohydramnios in fetal life
• Hypoplasia in fetal life
• Many infants are stillborn
• Many patients have vesicoureteral reflux
• Kidneys have various degrees of dysplasia
• Testes are usually intra abdominal
• >50% have abnormalities of musculoskeletal system
• Malrotation of bowel is often present
• Some children with prune-belly syndrome have PUV

42. • Management
-Treat UTI promptly
-Orchidopexy of undesended kidney
-Reconstruction of abdominal wall for cosmetic purposes
-Vesicostomy to relieve obstruction of urethra
• Prognosis
-Depends on the degree of pulmonary hypoplasia and renal dysplasia
-30% develop ESRD later in life
-Renal transplantation offer good result