Topic Discussion: Non Dilated Obstructive Uropathy

Anuric renal failure has very few causes. The top three are usually: hydronephrosis, hydronephrosis and hydronephrosis! But sometimes, it’s the sonogram and imaging that sways you away from the diagnosis. The sonogram reads- no hydronephrosis and or dilatation.  But clinically, the only thing that makes sense to you is obstruction? What do you do then?

Non dilated obstruction is not uncommon especially in patients with cancer that effects the retroperitoneal regions. There is so much cancer mass that there is no ROOM for the kidney to expand. But doesn’t mean that hydronephrosis is not present. The syndrome of non-dilated obstructive uropathy (NDOU) and AKI is well reported. However, the literature suggests that this syndrome is rare, accounting for less than 5% of cases of urinary obstruction.

One of the earlier studies had looked at a series of patients at a single center and found that most common cause of these type of situations were cancers ( likely RP related)- so prostate, colon, bladder, lymphomas and other series have found cervical cancer as well.  Antegrade urography had found the obstruction in all of the cases in that one series. 

The first ever case of this was described by Ormand in 1948 with someone with retroperitoneal fibrosis.

A more recent study from Mayo Clinic has a case series of 3 cases. Despite the absence of dilatation on renal imaging, strong suspicion for NDOU led to decompression procedures with prompt recovery of kidney function in all three patients - two required percutaneous nephrostomy tube placements and/or ureteric stents and one responded to simple Foley catheter drainage. Here is another case series summarizing the data.

Treatment is usually diagnostic.  Given the pathology and the cause of the obstruction being present after the ureteral stents are placed, they usually only temporize the treatment. Percutaneous nephrostomy is usually the best procedure in such situations. 

When one encounters such cases, Urology and IR help is critical in getting the right diagnosis and prompt treatment.