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Kidney Diseases

Fetal Fluid Behind the Kidneys



My daughter in law is 4 1/2 months pregnant and they found fluid behind the kidneys of the fetus yesterday at her ultrasound? Is this something to be concerned about? They are having her make an appt. with a fetal specialist.


I am puzzled by the description of fluid behind the kidneys. A common finding in prenatal ultrasound studies is fluid within the kidney or kidneys. The medical term for this is hydronephrosis. Prenatal hydronephrosis affects approximately 1 in 50 to 1 in 100 fetuses. Usually it is mild and insignificant, but in some cases it is severe and requires surgical correction. "Fluid behind the kidneys" suggests that the kidney has ruptured and that urine is building up around the kidney or kidneys. This condition is rare. but needs immediate treatment shortly after delivery. Usually there are other findings, such as a distended bladder, and the amniotic fluid volume often is low. The amount of amniotic fluid (normal or low) tends to correlate with the severity of the condition; if the fluid is reduced, then often surgery is necessary, whereas if the amniotic fluid volume is normal, then the majority do not need surgery. A complete evaluation of the urinary tract is performed after delivery.

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Response by:

Jack S Elder, MD, FACS, FAAP Jack S Elder, MD, FACS, FAAP
Clinical Professor of Urology
School of Medicine
Case Western Reserve University