Fetal abnormalities » Urinary tract
Autosomal recessive polycystic kidneys
- 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.
- Bilaterally enlarged and homogeneously hyperechogenic kidneys. Usually found >24 weeks’ gestation.
- Renal pelvises cannot be visualised.
- Gradual onset of oligohydramnios from the second trimester.
- 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.
- Detailed ultrasound examination.
- Genetic testing: the disease is caused by mutations in the PKHD1 gene on chromosome 6p21. Prenatal diagnosis in families at risk can be carried out by first-trimester chorion villous sampling (reliable prenatal diagnosis in 80% of affected families).
- Ultrasound scans every 4 weeks to monitor growth and assess amniotic fluid volume.
- Place: hospital with neonatal intensive care.
- Time: 38 weeks.
- Method: induction of labor aiming for vaginal delivery.
- 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.
- Risk of recurrence: 25%.