30 years old female referred by obstetrician for anomaly scan at 19 weeks of gestation.  

Findings and discussion:

On B mode ultrasound image and cine: (Axial / coronal / sagittal sections)

Both the Fetal kidneys appear echogenic; however, are normal in size for the given gestational age.

Corticomedullary differentiation is maintained at present scan.

No evidence of cystic changes seen at present.

Urinary bladder is normal.

Amniotic fluid volume is normal for the gestational age.

Screening renal ultrasound of the couple done and mother showed multiple cysts in bilateral kidneys representing ADPKD. (Autosomal Dominant polycystic kidney disease)

So, the diagnosis of ADPKD in fetus is given.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) on Antenatal Ultrasound

ADPKD is typically an adult-onset disorder, but in rare cases, it can present in utero or during infancy. Antenatal ultrasound findings depend on the severity of the disease.

Ultrasound Findings in Fetal ADPKD:

1. Bilateral Enlarged Echogenic Kidneys:

1. • The kidneys appear larger than normal for gestational age.
   • They may have increased echogenicity due to microscopic cysts that are too small to be visualized.

2. Loss of Corticomedullary Differentiation:

1. • Unlike normal kidneys, where the cortex and medulla are distinguishable, ADPKD kidneys may appear more homogeneous.

3. Occasional Visible Cysts:

1. • Although rare in utero, some larger cysts (>2 mm) may be seen in more severe cases.

4. Normal or Mildly Reduced Amniotic Fluid Levels:

1. • Unlike Autosomal Recessive Polycystic Kidney Disease (ARPKD), which often causes oligohydramnios due to poor renal function, ADPKD typically has normal amniotic fluid volume because at least one functional copy of the PKD gene is usually present.

Differentiation from ARPKD:

Key Points:

• ADPKD is rare in neonates but can be suspected if there are bilaterally enlarged, echogenic kidneys with normal or mildly reduced amniotic fluid.
• If cysts are visible, the diagnosis becomes more likely.
• Family history is crucial since ADPKD is inherited in an autosomal dominant pattern.