**7. Obstructive cystic dysplasia (Potter type IV)**

Definition: obstructive cystic dysplasia results from early and severe obstruction of the collecting system causing the formation of renal cysts [5].

Pathology: most cases result from early urethral obstruction, but vesicourethral junction obstruction and upper urinary tract obstruction are also a possible cause. Obstruction leads to ascension of fluid in the upper tract, with fluid retention in the nephron, with secondary cyst formation, and with a decrease in the number of normal nephrons.

Ultrasound findings: sonographic examination reveals renal macrocysts and signs of urinary tract obstruction (hydronephrosis, hydroureter, bladder distension). In cases of urethral obstruction, thickening of the bladder wall and severe oligoamnios are met.

Differential diagnosis:


Clinical facts:

**6. Autosomal dominant polycystic kidney disease (Potter type III)**

when screening is targeted to families at risk.

280 Congenital Anomalies - From the Embryo to the Neonate

are also present in the liver, spleen, and pancreas.

Amniotic fluid and the bladder are usually normal.

bladder, and family history help us make the difference.

• Once diagnosed, serial monitoring is recommended.

• Normal ultrasound cannot exclude the disease later in life!

**7. Obstructive cystic dysplasia (Potter type IV)**

lecting system causing the formation of renal cysts [5].

formation, and with a decrease in the number of normal nephrons.

obstruction, thickening of the bladder wall and severe oligoamnios are met.

Incidence: 1:1000.

Clinical facts:

disease.

transplant.

Differential diagnosis:

• Hydronephrosis.

• MCDK.

• ARPKD.

Definition: ADPKD is a bilateral renal anomaly where cysts arise from all areas of the nephron or collecting ducts. It commonly appears in adults but can rarely be seen prenatally, especially

Pathology: the genetic mechanism involves two genes PKD1 and PKD2 on chromosome 16. The condition is associated with multiple renal cysts, hypertension, and renal failure. Cysts

Ultrasound findings: the kidneys are hyperechoic, in some cases only in the cortical region.

Differential diagnosis: ARPKD (autosomal recessive polycystic kidney disease). Normal fluid,

• Examination of parent's kidneys is indicated due to the autosomal dominant nature of the

• The disease manifests in the third to fifth decade, most patients needing dialysis and

Definition: obstructive cystic dysplasia results from early and severe obstruction of the col-

Pathology: most cases result from early urethral obstruction, but vesicourethral junction obstruction and upper urinary tract obstruction are also a possible cause. Obstruction leads to ascension of fluid in the upper tract, with fluid retention in the nephron, with secondary cyst

Ultrasound findings: sonographic examination reveals renal macrocysts and signs of urinary tract obstruction (hydronephrosis, hydroureter, bladder distension). In cases of urethral

