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Key Points

  • Multicystic dysplastic kidney (MCDK) is a severe renal abnormality associated with atretic ureter and absence of normal renal parenchyma, which is replaced by multiple large noncommunicating cysts.

  • MCDK is generally easily diagnosed prenatally, often due to the large size of the kidney and its constituent cysts.

  • It is usually unilateral, while the rare cases of bilateral MCDK present as Potters syndrome.

  • In almost half of the cases of unilateral MCDK, the contralateral kidney will have associated malformations, the severity of which determines the overall prognosis.

  • Management of pregnancy and delivery generally does not need to be changed following the prenatal diagnosis of MCDK.

  • While some cases of unilateral MCDK will regress prenatally or in pediatric life, there is no agreement on need for nephrectomy in those cases with persistent MCDK.

  • MCDK greater than 6 cm, cases in which the MCDK obstructs the diaphragm or gastrointestinal tract, or cases in which hypertension develops will generally require nephrectomy.


Multicystic dysplastic kidney (MCDK) is the second most common cause of a flank mass in the newborn (Kaplan, 1998). MCDK was first described by Schwartz in a 7-month-old child in 1929 as a “bunch of grapes” replacing the kidney with associated ureteral atresia. Spence (1955) subsequently described MCDK and distinguished it from other cystic renal diseases.

MCDK is an extreme form of dysplasia associated with an atretic ureter. There is oftena lack of normal reniform shape, with multiple large cysts and little stroma, giving the “bunch of grapes” appearance. MCDK is typically unilateral, but bilateral MCDKs have been reported in stillborn infants with oligohydramnios and Potter syndrome facies. In unilateral MCDK, the contralateral kidney is normal but at high risk for other abnormalities (Greene et al., 1971; DeKlerk et al., 1977). The contralateral kidney may be affected by ureteropelvic junction obstruction, vesicoureteral reflux, or obstructive megaureter.

MCDK often presents as an asymptomatic abdominal mass in the neonate (Langino and Martin, 1958). However, currently approximately 85% to 100% of MCDKs are detected by prenatal sonographic examination (Manzoni and Caldamone, 1998; Kuwertz-Broeking et al., 2004). MCDK was often discovered during the course of investigation of other associated congenital anomalies. In particular, esophageal atresia and cardiac anomalies may be associated with MCDK. Other associated nongenitourinary anomalies include anencephaly, hydrocephalus, spina bifida, cleft palate, microphthalmia, duodenal stenosis, tracheoesophageal fistula, and imperforate anus. The pathogenesis of this disorder is poorly understood but is thought to involve failure of the ureteric bud to integrate and branch appropriately into the metanephron during the development of the kidneys (Kitagawa et al., 2000).


The incidence of MCDK is estimated at between 1 in 1000 and 1 in 4300 livebirths (Sanders, 1996; Kaplan, 1998). The incidence of bilateral MCDK is estimated at 1 ...

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