Week 19: Renal + Stones

Although the patient’s examination is consistent with BPH (associated with increased rates in asymptomatic hematuria), he is also at risk for urologic malignancies and needs urgent referral to urology for further evaluation. His urinalysis and lack of symptoms rule out a urinary tract infection as a cause for the hematuria. If urolithiasis is suspected, a noncontrast CT scan should be ordered to confirm the diagnosis.

Acute tubular necrosis accounts for up to 85% of intrinsic renal failure in adults and might occur in the described patient due to the combined renal insults of ischemia secondary to shock and intravenous contrast. Acute interstitial nephritis is a far less common cause of intrinsic renal failure in adults and is usually caused by a drug hypersensitivity reaction. The patient described in this scenario is unlikely to have postrenal azotemia, which is due to obstruction, given the case details. Hemolytic uremic syndrome is classically a disease of children.

Diuresis in an already dehydrated and therefore pre-renal patient may lead to worsening renal function due to renal ischemia. A “trial of diuretics” is not generally advised and is not without risk to the patient. There is no compelling evidence that the combination of diuretics and dopamine helps to prevent progression to end-stage renal disease for oliguric acute renal failure patients. Therefore neither can be considered “routine” therapeutic interventions.

Peritonitis is a fairly common occurrence in patients maintained on CAPD. It is usually initially recognized when peritoneal fluid is noted to be cloudy at the time it is drained for a routine exchange. With prompt medical attention, including microbiologic evaluation of peritoneal fluid, patients can be treated with intraperitoneal antibiotics as outpatients after an initial intraperitoneal dose is given in the ED. The prognosis of uncomplicated peritonitis is generally excellent, and patients are typically asked to follow up in 2 days. Free air seen on abdominal plain film is most often due to air being introduced during a previous fluid exchange. CT scanning is not indicated unless there is severe abdominal pain and tenderness or other findings suggestive of perforation.

Vascular access infections are not uncommon in hemodialysis patients, and patients may present with fever alone, and no local or systemic findings. Although bacteremia is often found, endocarditis is unusual in the absence of prolonged or recurrent fever, or of the usual risk factors for infective endocarditis. The hemodialysis procedure itself rarely causes fever.

A 25-year-old man is brought from the hemodialysis unit because of hypotension that occurred during dialysis. His blood pressure is currently 94/60, pulse is 84, and he is afebrile. Physical examination is otherwise normal. An ECG is unchanged from a previous tracing. Which of the following is most accurate?

Infected obstructing urolithiasis is a urologic emergency. A critical aspect of treatment is prompt decompression of the renal collecting system by percutaneous nephrostomy catheter or retrograde ureteral stent placement. While adjunctive therapy with broad-spectrum intravenous antimicrobials is important, decompression remains the critical intervention. Foley catheter placement and monitoring of urinary output are important adjunctive interventions in patients with a variety of conditions such as sepsis.

Suprapubic catheters are prey to a number of complications including occlusion by debris or mucus. A clogged suprapubic catheter can be flushed with saline as a first attempt to unclog it. Suprapubic catheters should be changed every 4 to 6 weeks. The tract created by a suprapubic catheter may close rapidly if the tube is removed within the first month; thereafter, rapid tract closure is not a concern.

Commonly tested on boards. Calcium oxalate is the most common type of renal stone, accounting for more than 70% of all stones.

Do not miss an infected kidney stone. Calculous pyelonephritis is a urologic emergency and must be excluded in patients presenting with renal colic.