Perinephric fat stranding is not associated with elevated serum creatinine in patients with acutely obstructing ureteral stones
Gregory Iovanel, BS1, Britney Atwater, MD2, Christine M. Van Horn, MD1, Rachel Engelberg, MD3, Ahmed Sobieh, MBChB, PhD1, Igor Sorokin, MD1.
1UMass Chan Medical School, Worcester, MA, USA, 2Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA, 3Urology Centers of Alabama, Homewood, AL, USA.
Background: Previous literature has reported an association between perinephric fat stranding (PFS) and elevated serum creatinine in patients with acutely obstructing ureterolithiasis. Our aim was to further explore a potential association between severity of PFS and changes in serum creatinine from baseline.
Methods: Patients who presented to the emergency department with acutely obstructing ureterolithiasis between January 2018 and October 2018 were retrospectively reviewed. Data collected and reviewed included demographics such as sex and age, serum creatinine on presentation and baseline values, computed tomography (CT) imaging, and urinalysis and culture findings. A radiologist blinded to serum creatinine data then reviewed all CT images and graded the degree of hydronephrosis and PFS for each patient. Subjects were split into two groups based on degree of PFS and differences between groups in regards to the aforementioned variables were assessed via paired t-test, chi-squared test, and univariate and multivariate analysis.
Results: We identified 141 subjects of whom 114 had imaging consistent with none-mild PFS, Group 1, while 27 had findings consistent with moderate-severe PFS, Group 2. Group 1 had a mean age of 56 years old vs. Group 2 which was significantly older at 65 years (p=0.01). The majority of subjects (77%) in Group 2 had an average duration of disease <24 hours which was a significantly higher percentage than Group 1 in which 50% had symptoms lasting <24 hours (p=0.01). Group 2 had a significantly larger mean stone size (10.1 vs. 7.3 mm, p<0.01). No significant correlation could be found between PFS and degree of hydronephrosis, baseline creatinine, presenting creatinine, or change in creatinine from baseline. Multivariate analysis showed that a 1 year increase in age increased the odds of having moderate-severe PFS relative to none-mild by 3.5% (OR=1.04, p<0.05) while a 1 mm increase in stone size increased the odds of having moderate-severe PFS relative to none-mild by 13.7% (OR=1.14, p=0.01).
Conclusions: Although increased PFS was found to correlate with increased age and stone size, no significant correlation was found between PFS and baseline creatinine, presenting creatinine, or change in creatinine from baseline. Given our findings, PFS likely has poor predictive value in assessing degree of renal function impairment in the case of acutely obstructing calculi.
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