Acute ureterolithiasis – is there a correlation between the degree of obstruction and renal parenchymal volume increase?
Authors: Klara Sahlén, Mikolaj Kocemba, Anders Ahnfelt, Anders Magnusson
Background: Secondary signs of obstruction on a non-enhanced CT during an acute urinary tract obstruction are significant contributors to the evaluation of degree of obstruction. Renal swelling is one of the secondary signs. That the obstructed kidney increase in parenchymal volume was quantitatively investigated in a recent study (Sahlén et al1).
Purpose: The aim of this study is to correlate the degree of obstruction to the degree of renal parenchymal volume increase. From the study material, other questions regarding CT-diagnostics in acute ureterolithiasis may be investigated.
Material and methods: 100 patients will be included prospectively. The study population are included at the acute radiology department in Uppsala University Hospital. Inclusion criteria is a unilateral ureteral stone detected at the non-enhanced CT. A dynamic CT-scan is performed to evaluate degree of obstruction as time to contrast medium excretion. The renal parenchymal volume during obstruction is compared to after obstruction at follow-up with a CT-verified stone passage.
Preliminary results (29 patients): 86% of the patients had any degree of obstruction, 14% had no obstruction. The median percentual parenchymal volume increase of the obstructed kidneys was 8% in patients with no obstruction, 13% in patients with mild obstruction, 22% in patients with moderate obstruction and 42% in the group with severe obstruction (p=0,0002).
Conclusion: There is a significant correlation between the degree of renal parenchymal volume increase and obstruction. A larger sample size will increase power of this finding.
1 Sahlén K, Lönnemark O, Lönnemark M, Wernroth L, Magnusson A. Does the kidney actually swell during an acute urinary tract obstruction? Acta Radiol. 2023 Oct;64(10):2820-2827. doi: 10.1177/02841851231190618. Epub 2023 Aug 22. PMID: 37606531.