Urinary Tract Flashcards
What are the abnormalities associated with the Urinary Tract in pregnancies?
11 Horseshoe kidney Hydronephrosis Kidney tumors Multicystic kidneys Pelvic kidney Autosomal dominant polycystic kidneys Autosomal recessive polycystic kidneys Renal agenesis Uretero-pelvic junction obstruction Urethral obstruction Uretero-vesical junction obstruction
Horseshoe kidney
Prevalence: 1 in 400 births.
More common in male fetuses.
Ultrasound: Fusion of the lower poles of both kidneys in front of the descending aorta.
Horseshoe kidney is best demonstrated on the coronal and transverse scans when renal tissue will be seen crossing the midline.
Normal bladder and amniotic fluid volume.
Assoc abnorm: Chromosomal abnormalities: horseshoe kidney is found in 30% of cases of Turner syndrome and in 20% of trisomy 18.
Associated syndromes are found in 15% of cases. The most common is Caudal regression syndrome (sporadic; sacral agenesis or hypoplasia, hypoplastic veretebral bodies, anal atresia).
Other defects include hydronephrosis, and genital anomalies.
Extra-renal defects, mainly CNS, cardiac or skeletal, are found in 30% of cases.
Follow up: Ultrasound scans every 4 weeks to detect possible late-onset hydronephrosis.
Prognosis: In isolated forms, the prognosis is good. Postnatal follow-up is advised because of significant risk of infections, hydronephrosis and nephrolithiasis (70%).
Recurrence: Isolated or part of Turner syndrome: no increased risk.
Part of trisomy 18: 1%.
Hydronephrosis
Prevalence: 1 in 500 births.
Ultrasound: Dilatation of the collecting system of the kidney observed in the standard transverse view of the abdomen. Ureters and bladder are normal.
On the basis of the anteroposterior diameter of the pelvis the condition is divided into:
Mild (only renal pelvis): 4-7 mm in the 2nd trimester; 7-9 mm in the 3rd.
Moderate (pelvis and calyces): 8-10 mm in the 2nd trimester; 10-15 mm in the 3rd.
Severe (cortical thinning): >10 mm in the 2nd trimester; >15 mm in the 3rd.
Assoc abnorm: Chromosomal defects: low risk in isolated forms.
Abnormalities of the contralateral kidney: multicystic kidney, ectopia, renal agenesis.
Associated syndromes are found in 5% of cases.
Follow up: Ultrasound scans every 4 weeks to monitor the evolution of hydronephrosis and assess amniotic fluid volume.
Prognosis: In the majority of cases, the condition remains stable or resolves in the neonatal period. In about 20% of cases, there may be an underlying ureteropelvic junction obstruction or vesicoureteric reflux that requires postnatal follow-up and possible surgery. Moderate hydronephrosis is usually progressive and in more than 50% of cases surgery is necessary during the first 2 years of life.
Recurrence: Isolated: no increased risk of recurrence.
Kidney Tumors
Prevalence: 1 in 200,000 births. Mesoblastic nephroma (renal hamartoma) is the most frequent renal tumor, while Wilms’ tumor (nephroblastoma) is extremely rare.
Ultrasound: In both tumors there is a solitary mass replacing the normal architecture of the whole or part of the kidney.
Cystic areas may appear due to hemorrhagic necrosis.
In most cases, there is associated polyhydramnios.
Assoc abnorm: The incidence of chromosomal abnormalities is not increased.
Nephroblastoma can be associated with the Beckwith–Wiedemann syndrome with evidence of organomegaly and macroglossia.
Follow up: Ultrasound scans every 2-3 weeks to monitor the size of the tumor and development of heart failure and polyhydramnios.
Prognosis: Mesoblastic nephromas are benign, and nephrectomy is curative in the majority of cases. In a few cases there is local recurrence or distant metastases in the first year of life.
Wilms’ tumor is malignant and about 50% are associated with genetic syndromes (such as Beckwith– Wiedemann syndrome). Treatment of the tumor requires nephrectomy, chemotherapy and sometimes radiotherapy; Survival is >90%.
Recurrence: Mesoblastic nephroma: no increased risk of recurrence.
In nephroblastoma associated with Beckwith–Wiedemann syndrome (autosomal dominant) the risk is increased.
Multicystic Kidneys
Prevalence: 1 in 1,000 births.
Ultrasound: The kidneys are replaced by multiple irregular cysts of variable size with intervening hyperechogenic stroma.
Renal pelvis cannot be visualised.
The disorder can be unilateral (80% of cases), bilateral or segmental; if bilateral, there is associated anhydramnios and the bladder is ‘absent’.
Abnormalities of the contralateral kidney (25%): duplex system, pelvico-uretric obstruction, agenesis, ectopic or affected by vesico-ureteric reflux.
Assoc abnorm: Chromosomal defects, mainly trisomy 18, are found in 3% of unilateral lesions and 15% of bilateral ones.
Associated syndromes are found in 10% of cases. The most common are: Brachio-otorenal syndrome (autosomal dominant; brachial cyst presenting as anterolateral neck cyst, multicystic kidneys), VACTERL association (sporadic; vertebral and ventricular septal defects, anal atresia, tracheoesophageal fistula, renal anomalies, radial dysplasia and single umbilical artery), Short-rib polydactyly syndrome (autosomal recessive; short limbs, hypoplastic thorax, polydactyly, heart and brain defects, multicystic kidneys), Meckel-Gruber syndrome (autosomal recessive; polydactyly, multicystic kidneys, occipital cephalocele).
Follow up: Unilateral: Ultrasound scans every 4 weeks to detect possible late-onset hydronephrosis.
Bilateral: if the pregnancy continues then follow-up should be standard.
Prognosis: Bilateral: lethal either in utero or in the neonatal period due to pulmonary hypoplasia.
Unilateral: normal prognosis. Postnatally, most urologists adopt an expectant approach because the kidney gradually shrinks and may disappear. The parents and family should also be scanned to exclude autosomal dominant branchio-otorenal syndrome.
Recurrence: Isolated: 1-2%.
Pelvic Kidney
Prevalence: 1 in 1,000 births.
Ultrasound: Visualisation of the kidney in the pelvis above the bladder.
Empty renal fossa on the affected side with the adrenal gland filling the space.
Color Doppler might be useful to locate the hilum of the ectopic kidney.
Normal bladder and amniotic fluid volume.
Assoc abnorm: The incidence of chromosomal defects and genetic syndromes is not increased.
Follow up: Ultrasound scans every 4 weeks to detect possible late-onset hydronephrosis.
Prognosis: Good prognosis. Vesico-ureteral reflux and uretero-pelvic junction obstruction may occur.
Recurrence: No increased risk of recurrence.
Autosomal Dominant Polycystic Kidneys
Prevalence: 1 in 1,000 people carry the mutant gene.
Clinical onset of this disorder is typically in the third to fifth decade of life.
Ultrasound: The kidneys are enlarged and hyperechogenic, but smaller than in autosomal recessive disease.
Renal pelvises can be visualised.
Bladder and amniotic fluid volume are normal.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndroms is not increased.
Associated with hepatic, pancreatic or ovarian cysts.
Follow up: Ultrasound scans every 4 weeks to assess amniotic fluid volume.
Ultrasound examination of parents’ kidneys.
Prognosis: In counselling affected parents with ADPKD, it should be emphasized that the prenatal demonstration of sonographically normal kidneys does not necessarily exclude the possibility of developing polycystic kidneys in adult life.
Dialysis and transplant are the treatment options when the pathology becomes symptomatic in the third to fifth decades of life.
Recurrence: Risk of recurrence: 50%.
Autosomal Recessive Polycystic Kidneys
Prevalence: 1 in 30,000 births.
The disease has a wide spectrum of renal and hepatic involvement and it is subdivided into perinatal, neonatal, infantile and juvenile types on the basis of the age of onset of the clinical presentation.
Ultrasound: Bilaterally enlarged and homogeneously hyperechogenic kidneys. Usually found >24 weeks’ gestation.
Renal pelvises cannot be visualised.
Gradual onset of oligohydramnios from the second trimester.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndroms is not increased.
Cystic fibrosis of the liver: the liver appearances are normal, despite the presence of cysts, portal fibrosis and proliferation of bile ducts. The more severe the renal disease, the less severe is the hepatic fibrosis.
Follow up: Ultrasound scans every 4 weeks to monitor growth and assess amniotic fluid volume.
Prognosis: The prenatal type is lethal either in utero or in the neonatal period due to pulmonary hypoplasia.
The infantile and juvenile types result in chronic renal failure, hepatic fibrosis and portal hypertension; many cases survive into their teens and require renal transplant.
Recurrence: Risk of recurrence: 25%.
Renal Agenesis
Prevalence: Unilateral: 1 in 2,000 births.
Bilateral: 1 in 5,000 births.
Ultrasound: Unilateral: nonvisualisation of one kidney with normal bladder and amniotic fluid. Color Doppler demonstrates single renal artery. There may be compensatory hypertrophy of the contralateral kidney.
Bilateral: nonvisualisation of the kidneys and bladder in combination with anhydramnios >17 weeks’ gestation. Failure to visualise renal arteries with colour Doppler. Adrenal glands assume discoid shape and move laterally and inferiorly. Small fetal chest, cardiac hypertrophy and talipes are seen.
Assoc abnorm: In the majority of cases, renal agenesis is a sporadic and isolated abnormality.
Chromosomal defects, mainly trisomy 18, are found in 1-2% of cases.
Associated syndromes are found in 10% of cases. The most common are: Fraser syndrome (autosomal recessive condition characterized by renal agenesis, laryngeal atresia, cryptophthalmos, syndactyly) and VACTREL association (vertebral and ventricular septal defects, anal atresia, tracheoesophageal fistula, renal anomalies, radial dysplasia and single umbilical artery), MURCS association (sporadic; hypoplastic or bicornuate uterus, renal agenesis or dysplasia, vertebral and rib abnormalities).
Follow up: In isolated cases follow-up should be standard.
Prognosis: Bilateral is lethal, usually in the neonatal period due to pulmonary hypoplasia.
Unilateral has normal prognosis. In some patients there may be vesicoureteric reflux. Girls should have a pelvic ultrasound to look for abnormalities in the Müllerian structures postnatally.
Recurrence: Non-syndromic: 3%.
In 15% of cases, one of the parents has unilateral renal agenesis and in these families the risk of recurrence is increased.
Uretero-pelvic junction obstruction
Prevalence: 1 in 2,000 births
More common in males.
Ultrasound: Pelvicalyceal dilatation without ureteral dilatation. The degree of pelvicalyceal dilatation is variable and, occasionally, perinephric urinomas (encapsulated collection of urine due to a tear in the renal pelvis or calyces or the ureter) and urinary ascites may be present.
Unilateral in 80% of cases.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndromes is not increased.
Abnormalities of the contralateral kidney: multicystic kidney, ectopia, renal agenesis.
Follow up: Ultrasound scans every 4 weeks to monitor the evolution of hydronephrosis and assess amniotic fluid volume.
Prognosis: The majority of infants have moderate or good function and can be managed expectantly. Pyeloplasty is performed if there is deterioration of renal function.
Recurrence: No increased risk of recurrence.
Urethral obstruction
Prevalence: 1 in 1,500 males
Ultrasound: Urethral obstruction can be caused by urethral agenesis, persistence of the cloaca, urethral stricture or posterior urethral valves.
With posterior urethral valves, there is usually incomplete or intermittent obstruction of the urethra, resulting in an enlarged and hypertrophied bladder with varying degrees of hydroureters, hydronephrosis, a spectrum of renal dysplasia (echogenic renal parenchyma with peripherally placed cysts), oligohydramnios and pulmonary hypoplasia.
In some cases, there is associated urinary ascites from rupture of the bladder.
Reduced amount of the amniotic fluid >17 weeks’ gestation.
In the first trimester the condition presents as megacystis (longitudinal bladder diameter of ≥7 mm). If the bladder diameter is 7-15 mm there is spontaneous resolution of the megacystis in about 90% of cases. If the bladder diameter is ≥15 mm the condition is invariably associated with progressive obstructive uropathy leading to hydronephrosis and dysplastic kidneys.
Assoc abnorm: Chromosomal defects, mainly trisomies 21, 18 or 13, are found in about 10% of cases.
Other defects, mainly cardiac and gastrointestinal are found in up to 40% of cases.
Follow up: If pregnancy continues, ultrasound scans every 4 weeks to monitor the evolution of the condition and assess amniotic fluid volume.
Antenatal evaluation of renal function relies on a combination of ultrasonographic findings and analysis of fetal urine obtained by urodochocentesis. Poor prognostic signs are:
The presence of bilateral multicystic or severely hydronephrotic kidneys with echogenic or cystic cortex;
Anhydramnios implying complete urethral obstruction;
High urinary sodium (more than 100 mg/dL), calcium (more than 8 mg/dL) and ß2 microglobulin (more than 40 mg/L).
Prognosis: Severe: high perinatal mortality due to pulmonary hypoplasia secondary to severe oligohydramnios. Even in those that survive, about 30% develop renal failure necessitating dialysis and / or transplantation before the age of 5 years.
Recurrence: Isolated: no increased risk of recurrence.
Part of trisomies: 1%.
Uretero-vesical junction obstruction
Prevalence: 1 in 10,000 births.
Ultrasound: Presence of hydroureter and hydronephrosis with normal bladder.
The dilated ureter is tortuous and appears as a collection of cysts of variable size, localized between the dilated renal pelvis and the bladder.
The etiology is diverse, including ureteric stricture or atresia, vascular obstruction, diverticulum, or ureterocele. Ureteroceles (visible as a thin-walled and fluid-filled small circular area inside the bladder) are usually found in association with a duplex kidney and collecting system. The upper pole characteristically obstructs and the lower one refluxes.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndromes is not increased.
Follow up: Ultrasound scans every 4 weeks to monitor the evolution of hydronephrosis and assess amniotic fluid volume.
Prognosis: Postnatal intervention is indicated if the vesico-uretric reflux is associated with abnormal renal function.
Recurrence: No increased risk of recurrence.
