AN UNEXPECTED CAUSE OF ACUTE KIDNEY INJURY

A 55-year-old woman with history of hypertension presented with 1-day duration of inability to urinate despite adequate fluid intake. Patient has no known history of renal dysfunction. Review of system positive only for dysuria and diarrhea. Past surgical history revealed right Nephrectomy in 2015 to donate her kidney to her husband, who had end stage renal disease at the time. Additional history included abdominal aortic aneurysm status post endovascular repair 8 months prior. Renal ultrasound showed mild to moderate left hydronephrosis, therefore foley catheter was placed. However, patient still had no urine output with foley. Bladder scan showed only minimal residual urine. At this point, a stat CT of the abdomen and pelvis without contrast was obtained and showed a 7 x 6.8cm abdominal aortic aneurysm causing mass effect on the left ureter. The AAA has increased in size from prior studies likely representing endoleak. Vascular surgery was consulted emergently. Meanwhile, patient was transferred to the ICU and started on nicardipine infusion for tight blood pressure control of SBP less than 120 and DBP less than 90. Patient underwent endoleak repair as well as left ureteral stenting to relieve obstruction. She also had post-surgical hemodialysis while her renal function was recovering. Patient was discharged home with full recovery of her renal function after 10 days of hospitalization. 

Discussion:

Acute kidney injury is one of the most common presenting symptoms that require hospitalization. The causes of acute kidney injury are conventionally divided into three categories: pre-renal, renal, and post-renal based on patient presentation. Acute anuric kidney injury usually points to a post-renal obstructive cause, which is why renal imaging is part of the initial work up for kidney injuries. In this case, the cause of obstruction caught us by surprise.

Conclusions:

This case is unusual in the sense that patient’s expanding abdominal aortic aneurysm caused acute kidney injury in the setting of a single functioning kidney. We have to keep in mind that patients’ presenting symptoms are often times manifestations of the more serious underlying cause, and we have to be judicious in developing a comprehensive list of differentials to avoid misdiagnosis.