Acute Oligohydramnios of Renal Origin: A Different Entity?

Purpose Oligohydramnios (OI) has long been considered a good marker of Urinary Tract Abnormalities (UTA) and, as such, it usually has an early and progressive onset with poor prognosis However no reports exist about an abrupt decrease of Amniotic Fluid (AF) in pregnancies with UTA. Material and methods 28 cases of Bilateral Obstructive Uropathy (BOO) were seen at our Institution. All cases had the diagnosis made between 17 and 20 weeks g.a. with bilateral hydro, distended bladder and dilated posterior urethra. Amniotic Fluid Index (AFI) and its variations throughout pregnancy were recorded at each follow up encounter. Fetuses with OI since diagnosis were excluded from the study as were those with persistently normal AFI. Results A sudden decrease in AFI ( Conclusions OI of renal origin may also have a delayed, acute onset which may be speculatively related to a pop off mechanism at the vesico-ureteric junction producing gross reflux. Unlike cases with progressive decline, acute onset OI is not necessarily associated with deterioration of RF later in life and its prognostic value must be evaluated with caution.