* Service de Gynécologie, Hôpital Félix Guyon, 97400 Saint-Denis, Ile de la Réunion, France.
** Cabinet d'Echographie, Route de Moufia, 97400 Saint-Denis, Ile de la Réunion, France

This is a  30-year-old primigravida referred at our unit at 36 weeks. During the first trimester, the nuchal translucency and the triple test were normal. At the end of the second trimester, a sonographer diagnosed a left ectopic polycystic kidney without urethral dilatation. The right kidney was normal with a normal corticomedular differentiation. The bladder was also normal. The patient refused investigation.

At 36 weeks, the ultrasound findings were:

• Normal bladder
• Normal umbilical cord
• The amniotic fluid was in the reference range
• Normal right kidney with corticomedullary differentiation (45 X 15 mm)
• Abnormal left kidney which was hypoplastic (35 X 12 mm) with an abnormal corticomedullary differentiation

At 37 weeks, these anomalies did not change. The baby was delivered vaginally (male, 3000g). At day five, the kidney abnormalities were confirmed by a renal scan. Nevertheless the creatinine level was normal. One month latter, a scan revealed a normal right kidney (58 mm) and a hypoplastic left kidney without parenchyme and only few cysts. The children did not undergo a surgery.

This left kidney abnormalities was certainly the consequence of multicystic kidney involution.

Axial section of both kidneys

Note some cysts on the left kidney

Absence of vascularization and small cysts on the left kidney