Pyelonephritis

Introduction

• Description: Pyelonephritis is an infection of the kidney or upper urinary tract.

• Prevalence: More than 200,000 cases per year in the United States. Acute pyelonephritis during pregnancy: 0.5%–2%.

• Predominant Age: Any.

• Genetics: No genetic predisposition known.

Etiology and Pathogenesis

• Causes: Pyelonephritis generally develops when pathogens associated with a bladder infection (most commonly Escherichia coli ) ascend to the kidneys via the ureters. Seeding of the kidneys may also occur from bacteremia or, in uncommon cases, from lymphatic spread.

• Risk Factors: Bladder infection (acute, chronic, recurrent), pregnancy, urologic abnormalities (nephrolithiasis, strictures, stents, urinary diversions), immunocompromising conditions (neutropenia, advanced human immunodeficiency virus [HIV] infection), poorly controlled diabetes mellitus. Pyelonephritis in pregnancy: Age <20 years, nulliparity, smoking, late presentation to care, sickle cell trait.

Signs and Symptoms

• Flank pain, costovertebral angle tenderness

• Fever (>99.9°F [37.7°C]), chills

• Nausea and vomiting (inconsistent)

• Symptoms of cystitis

• Hematuria

Diagnostic Approach