Diabetes and urosepsis. What procedure is indicated? • Xray of the Week
Figure 1. Axial CT image of the abdomen with contrast shows right renal abscess with ring enhancement around the fluid collection.
Figure 2. Axial CT images of the abdomen with contrast highlighting right renal abscess with subsequent drainage.
A. Right renal abscess (white arrow) with ring of hyperdensity surrounding the fluid collection.
B. Percutaneous access needle entering the renal abscess (white arrow).
C. Insertion of drainage catheter into the abscess (white arrow).
D. Drainage catheter coiled in the abscess (white arrow).
Renal abscesses are collections of walled-off, infected, and purulent fluid in the renal parenchyma that are commonly associated with underlying pyelonephritis. Other factors that predispose patients to formation of renal abscesses include diabetes mellitus and anatomical abnormalities such as vesicoureteral reflux, neurogenic bladder, polycystic kidney disease, and ureteral calculi (1,2). Clinical manifestations of renal abscesses include fever and chills, flank pain with radiation to the abdomen and costovertebral tenderness (1,2,3). Laboratory findings exhibit leukocytosis with elevation of erythrocyte sedimentation rate and C-reactive protein, however this is non-specific.
Contrast enhanced CT is useful to evaluate urosepsis and may reveal renal abscess formation (Fig. 1) (4). CT is also helpful in visualizing the renal parenchyma, suppurative changes, and nearby viscera (4,5,6). CT findings of renal abscesses are a focal collection of fluid with a thickened, irregular enhancing wall (Fig. 1) (2). Other findings of renal abscess may include gas within the central fluid, fascial and septal changes, and perinephric fat plane dissipation (2,3). Beyond CT imaging, ultrasound has some usage in identifying renal abscesses. Ultrasound findings show a hypoechoic or cystic mass with lack of vascular flow indicating an infectious process rather than neoplasm (1).
Treatment of renal abscesses includes antibiotic therapy and minimally invasive, percutaneous drainage via CT or ultrasound guidance (Fig. 2). The percutaneous approach is favored over surgical drainage due to improved outcomes and reduced morbidity (1). Abscesses less than 5 cm can be treated conservatively with antibiotics and close follow up (1). When larger than 5 cm, renal abscesses should be treated with percutaneous drainage in conjunction with antibiotics (1).
1. Siegel JF, Smith A, Moldwin R. Minimally invasive treatment of renal abscess. The Journal of Urology. 1996; 155(1):52-55. https://doi.org/10.1016/S0022-5347(01)66536-46
2. Yen DH, Hu SC, Tsai J, et al. Renal abscess: early diagnosis and treatment. Am J Emerg Med. 1999;17(2):192-197. https://doi.org/10.1016/S0735-6757(99)90060-8
3. Lee BE, Seol HY, Kim TK, Seong EY, Song SH, Lee DW, Lee SB, Kwak IS. Recent clinical overview of renal and perirenal abscesses in 56 consecutive cases. Korean J Intern Med. 2008;23(3):140. https://doi.org/10.3904/kjim.2008.23.3.140
4. Demertzis, J., Menias, C.O. State of the art: imaging of renal infections. Emerg Radiol. 2007; 14, 13–22. https://doi.org/10.1007/s10140-007-0591-3
5. Kawashima A, Sandler CM, Goldman SM, Raval BK, Fishman EK. CT of renal inflammatory disease. Radiographics. 1997;17(4):851-868. https://doi.org/10.1148/radiographics.17.4.9225387
6. Mitreski G, Sutherland T. Radiological diagnosis of perinephric pathology: pictorial essay 2015. Insights Imaging. 2017;8(1):155-169. https://doi.org/10.1007/s13244-016-0536-z
Corey Stump is a medical student and aspiring radiologist at the Marian University College of Osteopathic Medicine in Indianapolis, Indiana. Prior to medical school, he graduated summa cum laude from Wittenberg University where he received a B.S. degree in Biology. He is excited to pursue a career in Diagnostic Radiology with interests in medical education. His current project involves a webinar titled “Navigating The Virtual Match; Program Directors Vs Medical Students” through the Academy of Online Radiology Education with other medical students and radiologists around the country in an effort to provide insight on the upcoming residency match. He is passionate about teaching and he hopes to provide a meaningful experience to medical students one day.
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Kevin M. Rice, MD is the president of Global Radiology CME
Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator.
Follow Dr. Rice on Twitter @KevinRiceMD
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