Antenatal Hydronephrosis (Urinary Tract Dilation) Clinical Presentation

Updated: Jul 27, 2021
  • Author: Dennis B Liu, MD; Chief Editor: Marc Cendron, MD  more...
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The finding of antenatal hydronephrosis (dilatation of the upper urinary tract) should prompt a series of inquires regarding onset, fetal sex, oligohydramnios, laterality, severity of hydronephrosis, bladder cycling, other anomalies, prior pregnancy complications, and family history of urologic disease.

Ultrasonography (US) can provide important information, such as sex of the fetus, unilateral or bilateral disease, renal anterior-posterior (AP) pelvic diameter, bladder distention, bladder sagittal length, volume of amniotic fluid, and associated pathologic conditions. For example, Reuss et al found that 16 of 31 fetuses (55%) with bilateral hydronephrosis and oligohydramnios had an associated structural or chromosomal abnormality. [24]

Other aspects of the history that can be helpful in identifying the cause of hydronephrosis include family and maternal history.



Fetuses at highest risk for neonatal demise or pulmonary complications are those with bilateral hydronephrosis, a distended bladder, and oligohydramnios. These patients should be referred to a tertiary care center early in gestation. These neonates may require extensive cardiopulmonary support, as well as interventional support from a pediatric urologist early in the neonatal period.