congenital abnormalities

most IDed in utero & can be managed prospectively
1. minimise or prevent progressive renal damage
2. minor abnormalities also detected
  1. most common is mild unilat pelvic dilatation
  2. doesn't need intervention but may-> over ix, unnecessary rx & unwarranted parental anxiety
IDed in 1 in 200-400 births
can be imp cos may
1. be assoc w/ abnormal renal development or function
2. predispose to postnatal infection
3. involve urinary obstruction which needs surgical treatment
anomalies detectable on antenatal ultrasound screening
1. renal agenesis (absence of both kidneys)
  1. severe oligohydramnios
    1. cos amniotic fluid is mainly derived from fetal urine
    2. -> Potter syn (fatal)
2. multicystic dysplastic kidney (MCDK)
  1. results from failure of union of ureteric bud w/ nephrogenic mesenchyme
    1. ureteric bud forms ureter, pelvis, calyces & collecting ducts
  2. non-functioning struc w/ large fluid-filled cysts & no connection w/ bladder
  3. 1/2 will have involuted by 2 years old
  4. indication for nephrectomy
    1. if it remains large
    2. hypertension develops
  5. make no urine
    1. -> Potter syn if lesion bilat
      1. intrauterine compression of fetus from oligohydramnios due to lack of fetal urine
        ->
        Potter facies
        low set ears
        beaked nose
        prominent epicanthic folds
        downward slant to eyes
        lung hypoplasia
        -> resp failure
        postural deformities
        like severe limb talipes
        infant may be stillborn or die soon after birth from resp failure
3. autosomal recessive polycystic kidney disease
  1. some/normal renal func maintained
  2. affects both kidneys
    1. diffuse bilateral enlargement
    2. cystic
  3. incidence of 1 in 1000
4. autosomal dominant polycystic kidney disease
  1. some/normal renal func maintained
  2. both kidneys affected
    1. enlarged
    2. separate cysts of varying size btw normal renal parenchyma
  3. incidence= 1 in 1000
  4. sx in childhood
    1. hypertension
    2. haematuria
  5. causes renal failure in late adulthood
  6. assoc extra-renal features
    1. cysts in liver & pancreas
    2. cerebral aneurysms
    3. mitral valve prolapse
5. pelvic or horseshoe kidney
  1. lower poles fused in midline
  2. due to abnormal pelvic migration
    1. abnormal position predisposes to infection or obstruction to urinary drainage
6. duplex system
  1. caused by premature division of ureteric bud
  2. varies from bifid renal pelvis to complete division w/ 2 ureters
    1. ureters often have abnormal drainage
      1. ureter from lower pole often refluxes
      2. ureter from upper pole may
        drain ectopically into
        vagina
        urethra
        prolapse into bladder (uterocele)
        urine flow may be obstructed
7. bladder extrophy
  1. due to failure of fusion of infraumbilical midline strucs
  2. absence or severe def of anterior abdo wall mm freq assoc w/
    1. large bladder (megacystis)
    2. dilated ureters (megaureters)
    3. cryptochidism
    4. absent musculature syn (prune-belly syn)
8. obstruction to urine flow
  1. at level of
    1. pelviureteric/vesicoureteric junction
      1. unilat hydronephrosis
    2. bladder neck
      1. e.g. due to disruption of nerve supply (neuropathic bladder)
      2. bilat hydronephrosis
    3. posterior urethra in a boy due to mucosal fold or a mb (posterior urethra valves)
      1. bilat hydronephrosis
  2. consequences
    1. dysplastic kidney
      1. small
      2. poorly functioning
      3. contains cysts & aberrant embryonic tissue e.g cartilage
    2. Potter syn
      1. if obstruction severe & bilat
    3. dilatatation of urinary tract prox to site of obstruction
      1. hydronephrosis
        unilat
        bilat
        hydroureters
        thickened bladder wall w/ diverticula
  3. renal dysplasia
    1. can occur in assoc w/ severe intrauterine vesicoureteric reflux
      1. in isolation or in certain, rare, inherited syn affecting many systems
antenatal Rx
1. male fetus w/ post urethral valves may develop severe urinary outflow obstruction->
  1. progressive bilat hydronephrosis
  2. poor renal growth
  3. declining liquor vol
  4. potential to lead to pulmonary hypoplasie
  5. intrauterine bladder drainage procedures
    1. to prevent severe renal damage
    2. disappointing resutls
2. early delivery
  1. rarely indicated
postnatal mx
1. protocol for antenatal diag or urinary tract anomaly
  1. start Abx @ birth (to try prevent UTI)
    1. bilat hydronephrosis &/or dilated lower urinary tract in a male
      1. ultrasound within 48h of birth to exclude post urethral valves
        abnormal
        micturating cystourethrogram (MCUG)
        surgery if needed
        e.g. cystoscopic ablation
        normal
        stop Abx, repeat US after 2-3 months
    2. unilat hydronephrosis in a male, any anomaly in female
      1. ultrasound @ 4-6 weeks
        normal
        stop Abx, repeat US after 2-3 months
        abnormal
        further ix
        newborn kidney has low GFR, urine flow is low & obstruction may not be evident in 1st few das of life, so delay scan

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congenital abnormalities

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	Created by v.djabatey about 10 years ago