Understanding Pyelitis: Causes, Symptoms, Pathophysiology, and Treatment

What is Pyelitis

Pyelitis is an inflammation of the mucous membrane of the pelvis and calices of the kidney. This condition is typically as a result of ascending urinary tract infections (UTIs) and primarily affects children and young women and can lead to serious kidney complications when left untreated.

Bacteria ascending from UTI

Causes of Pyelitis

Bacteria: Most commonly E. coli, Proteus, or Klebsiella.

Urinary Tract Obstructions: Kidney stones, congenital abnormalities, or tumors that block urine flow.

Vesicoureteral Reflux which arises from the backflow of urine caused by obstructions.

Pathophysiology of Pyelitis

The condition typically starts when bacteria, most commonly Escherichia coli, invades the lower urinary tract. These organisms often ascend through the urethra and bladder, entering the ureters and eventually reach the renal pelvis. Factors like vesicoureteral reflux (VUR), which causes urine to flow back into the kidneys, and urinary tract obstructions (stones or anatomical abnormalities), contribute to bacterial ascension and also create a serene environment for these bacteria to thrive.

Urinary system anatomy

Once the bacteria begins to colonize the urothelial cells lining the pelvis, there is an immune response, which involves the release of pro-inflammatory cytokines (like interleukins and tumor necrosis factor-alpha) to attract white blood cells to the site of infection. Neutrophils, macrophages, and other immune cells migrate to the area, releasing enzymes that lead to inflammation of the renal pelvis. While this response aims to eliminate the pathogen, it can cause collateral damage to surrounding tissues.

In response to the infection, the affected tissues of the renal pelvis become inflamed, which causes edema (swelling). This swelling can impair the normal outflow of urine, increasing intrarenal pressure. If urine flow becomes obstructed, the pressure buildup can extend to the renal tubules and parenchyma. As inflammation continues, pus and exudate may form within the renal pelvis, further exacerbating the obstruction and contributing to pain and systemic symptoms like fever.

Prolonged infection and inflammation lead to cellular damage in the renal pelvis and, if left untreated, in the renal parenchyma as well. The tubules and surrounding tissues may become necrotic, and repeated or severe infections can result in fibrosis (scarring) of the kidney tissue. The infection may progress beyond the local site and enter the bloodstream (septicemia), causing a systemic inflammatory response.

Signs and Symptoms of Pyelitis

• Fever and chills
• Flank pain
• Dysuria
• Hematuria
• Nausea and vomiting
• Malaise and fatigue
• Urinary frequency/urgency

Diagnostic Investigations of Pyelitis

• Urine analysis to look for the presence of white blood cells, red blood cells, and bacteria in urine.
• Urine culture and Sensitivity
• Imaging studies: Ultrasound or CT scan to detect structural abnormalities or kidney involvement.
• Blood tests: Assess for elevated white blood cell count, creatinine, and other signs of infection.

Treatment of Pyelitis

Antibiotic management includes;

• Ciprofloxacin (500 mg orally twice daily) for 7-14 days.
• Trimethoprim-sulfamethoxazole (160/800 mg twice daily) for 10-14 days.
• Amoxicillin for pregnant women or if bacterial sensitivity indicates.
• Analgesics

Hydration: Encourage increased fluid intake to flush out bacteria.

Nursing care of Pyelitis

Monitoring vital signs in order to observe for fever, pain levels, and blood pressure.

Administer prescribed medication.

Teach patients about medication adherence, hygiene practices, and recognizing symptoms of recurrent infection.

Complications of Pyelitis

• Pyelonephritis.
• Sepsis
• Chronic kidney disease (CKD)
• Renal abscess