Pyelonephritis

Pyonephrosis is a surgical emergency - An acutely infected, obstructed kidney progresses to urosepsis, shock, and death unless the obstruction is relieved. The case is a double-J stent or a percutaneous nephrostomy, and percutaneous drainage is preferred in the sickest patients because it avoids manipulating the infected stone and cannot fail to bypass the obstruction. Definitive stone surgery is deliberately delayed, so keep this anesthetic short.

Resuscitate before you induce - Resuscitation often precedes definitive treatment. Aggressive fluid and broad-spectrum antibiotics come first, and septic shock frequently will not respond to fluid alone. Have a vasopressor drawn up and a low threshold to start it on a poor response to fluids. Send a lactate and blood cultures if they have not already gone.

Know the renal function - Check creatinine and BUN. Contrast is nephrotoxic and cannot be used safely once the creatinine is elevated, so the imaging in hand may be a non-contrast CT or ultrasound. Keep other nephrotoxic agents off the plan.

Pregnancy raises the stakes - Pyelonephritis is the most common cause of septic shock in pregnancy. Up to 10% of pregnant patients treated for it develop pulmonary complications from endotoxin-mediated alveolar damage, appearing as pulmonary edema or ARDS, so track oxygen saturation and urine output closely and be deliberate with fluid. Tocolytics add to that pulmonary edema risk. Up to 25% develop an anemia from endotoxin release that resolves with treatment, and endotoxin-driven uterine contractions mean watching for preterm labor.

Emphysematous pyelonephritis - A necrotizing, gas-forming infection, usually E. coli or Klebsiella in a poorly controlled diabetic, with mortality around 38%. Outcomes are better with drainage plus antibiotics than antibiotics alone. Azotemia, thrombocytopenia, shock, hyponatremia, confusion, and hypoalbuminemia are the poor prognostic markers, so look at the platelet count, sodium, and albumin before you go.

Xanthogranulomatous pyelonephritis - The chronic variant, driven by long-standing stones and infection, mimics renal cell carcinoma on imaging and can involve adjacent structures and organs. Nephrectomy is the operation; plan for a long inflammatory dissection and have blood available.

Older patients present differently - The classic triad is fever, flank pain, and nausea or vomiting, with unilateral costovertebral angle tenderness and a fever often over 103 F. The elderly instead arrive with altered mental status and deterioration in other organ systems. Age over 65, male sex, impaired renal function, and disseminated intravascular coagulation each predict higher mortality, so a coagulation panel and platelet count are worth having in front of you.

When the antibiotics are not working - Failure to respond within 48 to 72 hours means something structural: abscess, urinary retention, an obstructing calculus, gas-forming infection, or pyonephrosis. That patient is heading to the OR or interventional radiology, not to a longer antibiotic course.

Acute pyelonephritis is bacterial infection of the kidney, almost always an ascending urinary tract infection that has climbed from the bladder into the collecting system. Gram-negative organisms dominate, E. coli most of all, using P-fimbriae to adhere to uroepithelial cells, followed by Proteus, Klebsiella, and Enterobacter. Anything that causes stasis — an obstructing stone, outflow obstruction, instrumentation, an indwelling catheter — or vesicoureteral reflux sets it up.

The inflammatory response scars renal parenchyma, and when bacterial toxins and cytokines reach the circulation the picture becomes sepsis and shock. Incidence runs 15 to 17 cases per 10,000 women and 3 to 4 per 10,000 men annually in the US. Complications include renal and perinephric abscess, papillary necrosis, renal vein thrombosis, acute renal failure, and emphysematous pyelonephritis.