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 diagnosis:

• Bilaterally enlarged and homogeneously hyperechogenic kidneys. Usually found >24 weeks’ gestation.
• Renal pelvises cannot be visualised.
• Gradual onset of oligohydramnios from the second trimester.

Associated abnormalities:

• 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.

Investigations:

• 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).

Follow up:

• Ultrasound scans every 4 weeks to monitor growth and assess amniotic fluid volume.

Delivery:

• Place: hospital with neonatal intensive care.
• Time: 38 weeks.
• Method: induction of labor aiming for vaginal delivery.

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%.