Third trimester ultrasonic presentation of infantile polycystic kidney disease.

Infantile polycystic kidney disease (Potter's Type 1) is an autosomal recessive disorder that affects the kidneys and liver. Use of ultrasound to make the diagnosis prenatally is well documented and, in fact, it is advocated as a screening device for second-trimester identification of potentially affected fetuses. The sonographic appearance is characterized by enlarged hyperechoic kidneys, enlarging fetal abdominal circumference, and oligohydramnios. It is suggested that a ratio of the kidney circumference to the abdominal circumference (KC/AC) be used as method of quantifying renal size and as a potential indicator of early kidney enlargement associated with infantile polycystic kidney disease (IPKD). We report a case of serial ultrasound examination of a pregnancy at risk for IPKD where the in utero diagnosis was not established until the third trimester.