urinary tract defects Prof. Z. Babay

Urinary tract defects Accounts for 34% of all malformations detected by ultrasound 32% of these are isolated findings 48% associated with chromosomal abnormality or other syndromes Pelvi calyceal dilatation occur in 87% of all cases Only 13% of cases are isolated parenchymal disease without pelvi-calyceal dilatation Only 25% of the cases of renal dysplasia are detected by ultrasound

Urinary tact defects Kidneys are visible by 12 weeks of gestation At 26-28 renal pyramids are visible The ratio of renal to AC is always 30% Normal ureters are not visible by ultrasound

Urinary tract abnormalities Classification: A) Parenchymal: Multi-Cystic disease Dysplasia (Potters) Renal agenesis B) Obstructive

Urinary tract abnormalities Incidence: Bilateral in 1: 5000 births Unilateral in 1:2000 births Could be isolated or part of a syndrome or chromosomal abnormality If part of a syndrome----the risk of recurrence is 3% If one parent is has unilateral renal agenesis---risk is 15%

Renal agenesis (cont.) Usually associated with oligo- or anhydramnios and empty bladder If unilateral------normal AFI-----good prognosis If bilateral---lethal-----pulmonary hypoplasia Failure to visualize renal arteries by color Doppler can help in the diagnosis

Infantile polycystic kidney (Potter type I) Found in 1:30,000 births Autosomal recessive Carried on the short arm of chromosome 6 Diagnosis by PGD or ultrasound

Potter I (cont.) By ultrasound: Markedly enlarged kidneys, numerous cortical cysts, dilated collecting ducts Oligohydramnios Loss of cortico-medullary junction Usually seen at 24 weeks Usually lethal Can accompany hepatic cysts or fibrosis

Multicystic Dysplastic kidneys(PottersII) Occur in 1: 1000 births Usually sporadic Result from obstruction at early fetal life Could be Associated with chromosomal abnormalities, genetic syndromes or cardiac defects in 50% of cases In 15% of cases there is contra lateral renal agenesis

Potters II (cont.) By ultrasound: Irregular cysts of variable size with intervening hyper-echoic stroma It can be unilateral, bilateral or segmental If bilateral----oligohydramnios--- absent bladder---lethal If unilateral--- good prognosis

Adult polycystic kidney disease (APKD) Autosomal dominant 1:1000 of APKD carry mutant gene Usually asymptomatic until 3rd decade of life Ultrasound: enlarged hyper-echoic kidneys with or without multiple cysts There is accentuation of cortico-medullary junction

Renal Dysplasia (potters III) Markedly enlarged kidneys with cysts of variable size Both kidneys are equally enlarged 1/3 have cysts in the liver, pancreas, spleen or lungs 1/5 have cerebral aneurysm It is the expression of adult poly-cystic kidney (autosomal dominant) and other mendelian disorders e.g. tuberous sclerosis

APKD (cont.) AFI is normal or slightly reduced Prenatal diagnosis is by PGD If one parent is affected----normal kidneys by ultrasound does not exclude the disease

Obstructive uropathies If occur early in fetal life---renal hypo-plasia or dysplasia If occur late in fetal life(2nd trimester) or intermittent--- Hydronephrosis Dilatation of fetal urinary tract does not always mean obstruction and obstruction may not show urinary tract dilatation Hydronephrosis associated with chromosomal abnormality in 20% of cases

Hydronephrosis Found in 1% of fetuses Mild--A-P diameter of renal pelvis >4mm at 15-19 weeks A-P diameter of renal pelvis >5mm at 20-29 weeks A-P diameter of renal pelvis > 7mm at 30-40 weeks Moderate-- > A-P diameter of renal pelvis >10 mm + pelvi-calyceal dilatation

Hydronephrosis (cont.) In 20%---underlying obstruction at pelvi-ureteric junction, or vesico-ureteric reflux, or posterior uretheral valve Post-natal surgery is needed in 50% of cases

Assessment of fetal renal function Ultrasound + analysis of fetal urine by urodochocentesis or pyelocentesis Poor prognostic signs: 1)Bilateral multicystic or severely hydronephrotic kidneys with echogenic kidneys suggesting renal dysplasia 2)Oligo-or anhydramnios 3)High urinary Na,Ca,β2 micro-globulin

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