ACUTE RENAL FAILURE: EXPECT THE UNEXPECTED

Although appendicitis associated acute renal failure (ARF) has been reported in the literature, the development of asymptomatic ARF which led to the diagnosis of appendicitis has not been reported. We report a patient in whom the development of asymptomatic ARF had led to the discovery of acute appendicitis. Case report: A 39 year old man presented with vague abdominal pain for a two day period. The patient has no medical history of note. Physical examination was normal. Initial blood urea nitrogen (BUN) 9.175 mmol/L (range 2.2–6.973 mmol/L), and creatinine 0.153 mmol/L (range 0.054–0.117 mmol/L). BUN and creatinine levels, two days after admission, were 26.42 mmol/L and 0.837 mmol/L, respectively. Urinalysis was normal. Urinary chemical analysis was consistent with intrinsic ARF. Postvoiding ureteral catheterization excluded bladder outlet obstruction. Physical examination was still unremarkable except for a temperature of 101.1°F (38.4°C). Urine output had decreased to 10–20 cc/h. Renal sonography showed normal kidneys. Abdominal and pelvic computed tomography scan revealed normal kidneys and an inflammatory process in the right quadrant surrounding the cecum. Intravenous broad-spectrum antibiotics were given. Exploration revealed a gangrenous pelvic appendix with an abscess. Appendectomy and drainage of the abscess were performed. Blood cultures were negative. BUN and creatinine levels, eleven days post-surgery were 15.04 mmol/L and 0.171 mmol/L, respectively. The patient has not required dialysis. Discussion: Appendicitis associated ARF due to bilateral or right ureteral obstruction with hydronephrosis, appendiceal abscess secondary to perforated appendix, or after appendectomy has been reported [1-2]. To our knowledge, the development of asymptomatic ARF in an adult, without the evidence of ureteral obstruction or hydronephrosis, secondary to asymptomatic appendicitis and/or perforated appendix, has not been reported.

Variable position of appendix determines the nature of the urological manifestations of appendicitis [[2]]. Upper urinary tract complications may result from right hydrouretronephrosis with ureteral obstruction at the level of the pelvic brim [[2]]. The obstruction of the right ureter by extrinsic compression from a periappendiceal mass does not explain the involvement of the contralateral ureter. This can result from decreased ureteral peristalsis, similar to paralytic intestinal ileus in peritonitis [[2]]. Another possible mechanism for the development of ARF is that the prostatic urethra may become obstructed by the inflammatory mass, sympathetic mechanism leading to a sphincter spasm, or as a result of prostatic congestion [[2]]. Sepsis-associated ARF was contributed to high levels of platelet-activating factor [[3]], and to the presence of microabscesses in the renal interstitium and within the tubular lumina resulting in sepsis-associated ARF in four patients [[4]].

Puskar et al. reported an abnormal urinalysis in 48% of 84 patients with appendicitis. Sonography showed pyelocaliceal dilation of the right kidney in 38% of patients with appendicitis prior to appendectomy [[5]]. Scintigraphy confirmed pyelocaliceal dilation of the right kidney in 38% of patients with abnormal urinalysis [[5]]. Furosemide renography excluded an obstruction in all of the patients [[5]].

Appendicitis may be difficult to diagnose. Although appendicitis rarely mimics acute disorders of the genitourinary tract, the association of appendicitis with abnormal urinalysis, ureteral obstruction, acute prostatitis, acute pyelonephritis, and pyelocaliceal dilation detected by sonography or scintigraphy has been reported [[1]], [[5]]. Our case is unique because the discovery of ARF has led to the diagnosis of appendicitis. In contrary to other reported cases [[5]], the perforated appendix in our patient was asymptomatic, and was not associated with ureteral obstruction or hydronephrosis. Interestingly the urinalysis in our patient was normal despite the presence of ARF, while 48% of the patients reported by Puskar et al. have abnormal urinalysis [[5]].

CONCLUSION

An asymptomatic ARF manifesting only by increased BUN and creatinine levels may be the key to diagnose acute appendicitis. Appendicitis should be included in the differential diagnosis of ARF. Imaging studies should be performed to peruse such a diagnosis [[1]].