Aseptic dilatation of the kidney caused by obstruction to the outflow of urine
Congenital PUJ and calculus are the commonest causes of unilateral HN
Unilateral hydronephrosis more common in women and on the right
Dietel’s crisis (Intermittent hydronephrosis): in unilateral hydronephrosis, a swelling in the loin is associated with acute renal pain. Some hours later the pain is relieved and the swelling disappears with passage of large volume of urine
USG is the least invasive means of detecting and used to diagnose PUJ obstruction in utero
Isotope renography - best test to establish that the dilatation of the renal collecting system is caused by obstruction
Obstruction is diagnosed by a combination of USG and isotope renography
Whitaker test – a percutaneous puncture of kidney is made through the loin and fluid infused at a constant rate with monitoring of intrapelvic pressure. An abnormal rise in pressure confirms obstruction
Pyeloplasty
Anderson-Hynes operation when reasonable functioning parenchyma remains
V-Y pyeloplasty
Nephrectomy when renal parenchyma is largely destroyed
Aberrant renal vessels
Aberrant renal artery or vein in the lower pole of kidney can compress the PUJ causing hydronephrosis
Multiple renal arteries are most common on the left.
Renal arteries are functional end-arteries, so division of an aberrant renal artery leads to infarction of a section of parenchyma.
Aberrant renal veins can be divided with impunity.
Treatment–ligation