Can fetal renal artery Doppler studies predict postnatal renal function in morphologically abnormal kidneys? A preliminary report.
PURPOSE: The diagnosis of multicystic kidney in utero can be made with reasonable reliability with real-time sonography. However, a cystic hydronephrotic kidney may be difficult to distinguish from a multicystic kidney, necessitating postnatal renography. We report our preliminary observations of Doppler waveform variation in normal and cystic fetal kidneys. MATERIALS AND METHODS: Five consecutive fetuses with a unilateral cystic kidney, and one with a unilateral hydronephrotic duplex kidney and cystic upper moiety were evaluated in utero with color Doppler renal sonography. RESULTS: Doppler signal on serial ultrasound was consistently absent in the ipsilateral cystic kidney, while normal renal artery Doppler waveforms with a systolic and diastolic component were obtained from the contralateral and unaffected moieties. Postnatal renography confirmed nonfunction in all cystic moieties. The hydronephrotic noncystic moiety of the duplex kidney showed a normal Doppler waveform and good function. CONCLUSIONS: Absence of renal artery Doppler waveforms in fetal cystic kidneys correlates with renal nonfunction. If this observation can be further confirmed by additional cases, fetal Doppler sonography would become an additional tool to diagnose confidently a multicystic kidney in utero, which may allow us to dispense with postnatal renography.