Pyelonephritis

Question 1

What is pyelonephritis and what causes it?

Answer 1

Acute pyelonephritis is a potentially organ- and/or life-threatening infection that often leads to renal scarring. Acute pyelonephritis results from bacterial invasion of the renal parenchyma. Bacteria usually reach the kidney by ascending from the lower urinary tract. Bacteria may also reach the kidney via the bloodstream. Timely diagnosis and management of acute pyelonephritis has a significant impact on patient outcomes.

Question 2

What are the signs and symptoms of pyelonephritis?

Answer 2

The classic presentation in patients with acute pyelonephritis is as follows:

1. Fever - This is not always present, but when it is, it is not unusual for the temperature to exceed 103°F (39.4°C)
2. Costovertebral angle pain - Pain may be mild, moderate, or severe; flank or costovertebral angle tenderness is most commonly unilateral over the involved kidney, although bilateral discomfort may be present
3. Nausea and/or vomiting - These vary in frequency and intensity, from absent to severe; anorexia is common in patients with acute pyelonephritis

Gross haematuria (haemorrhagic cystitis), unusual in males with pyelonephritis, occurs in 30-40% of females, most often young women, with the disorder.

Question 3

When do symptoms need to be considered complicated until proven otherwise?

Answer 3

Symptoms of acute pyelonephritis usually develop over hours or over the course of a day but may not occur at the same time. If the patient is male, elderly, or a child or has had symptoms for more than 7 days, the infection should be considered complicated until proven otherwise.

Question 4

How might children present with a UTI/pyelonephritis?

Answer 4

The classic manifestations of acute pyelonephritis observed in adults are often absent in children, particularly neonates and infants. In children aged 2 years or younger, the most common signs and symptoms of urinary tract infection (UTI) are as follows:
•	Failure to thrive
•	Feeding difficulty
•	Fever
•	Vomiting

Question 5

How might elderly patients present with pyelonephritis?

Answer 5

Elderly patients may present with typical manifestations of pyelonephritis, or they may experience the following:
•	Fever
•	Mental status change
•	Decompensation in another organ system
•	Generalized deterioration

Question 6

How is pyelonephritis diagnosed?

Answer 6

1. History
2. Examination
3. Urinalysis
   o Dipstick leukocyte esterase test (LET) - Helps to screen for pyuria
   o Nitrite production test (NPT) - To screen for bacteriuria
   o Examination for hematuria (gross and microscopic) and proteinuria
4. Urine culture
5. Computed tomography (CT) scanning - To identify alterations in renal parenchymal perfusion; alterations in contrast excretion, perinephric fluid, and nonrenal disease; gas-forming infections; hemorrhage; inflammatory masses; and obstruction
6. Magnetic resonance imaging (MRI) – To detect renal infection or masses and urinary obstruction, as well as to evaluate renal vasculature
7. Ultrasonography - To screen for urinary obstruction in children admitted for febrile illnesses and to examine patients for renal abscesses, acute focal bacterial nephritis, and stones (in xanthogranulomatous pyelonephritis)
8. Scintigraphy - To detect focal renal abnormalities
9. CT and MR urography - Used in the evaluation of haematuria

Question 7

How is pyelonephritis managed?

Answer 7

Supportive care

Monitoring of urine and blood culture results

Monitoring of comorbid conditions for deterioration

Maintenance of hydration status with IV fluids until hydration can be maintained with oral intake

IV antibiotics until defervescence and significant symptomatic improvement occur; convert to an oral regimen tailored to urine or blood culture results

Surgery or the complications

Question 8

What type of surgeries would be considered in management of acute pyelonephritis and its complications?

Answer 8

In addition to antibiotics, surgery may be necessary to treat the following manifestations of acute pyelonephritis:

Renal cortical abscess (renal carbuncle): Surgical drainage (if patients do not respond to antibiotic therapy); other surgical options are enucleation of the carbuncle and nephrectomy

Renal corticomedullary abscess: Incision and drainage, nephrectomy

Perinephric abscess: Drainage, nephrectomy

Calculi-related urinary tract infection (UTI): Extracorporeal shockwave lithotripsy (ESWL) or endoscopic, percutaneous, or open surgery

Renal papillary necrosis: CT scan ̶ guided drainage or surgical drainage with debridement

Xanthogranulomatous pyelonephritis: Nephrectomy