Chronic Pyelonephritis and UTI Diagnosis

Chronic Pyelonephritis and Urinary Tract Infections (UTIs)

• Chronic pyelonephritis may result in renal scarring and failure

Diagnosis of UTIs

• UTIs may be suspected based on symptoms or findings on urinalysis
• Urine analysis findings:
  • Pyuria (leukocytes on urine microscopy) with a WBC count >3-6 WBCs/high-power field indicative of infection
  • Microscopic hematuria
  • Nitrites and leukocyte esterase are often positive in infected urine
  • Alkaline pH
• A urine culture is necessary for confirmation and appropriate therapy
• Urine culture criteria:
  • >100,000 colonies/ml of a single pathogen (suprapubic or catheter sample)
  • Or >10,000/ml colonies in symptomatic child

Obtaining a Urine Sample

• In toilet-trained children, a midstream urine sample is usually satisfactory
• In children <2-24 mo, a catheterized or suprapubic aspirate urine sample should be obtained
• Alternative method: application of an adhesive, sealed, sterile collection bag after disinfection of the skin of the genitals

Imaging

• No imaging is suggested for first-time, typical UTIs
• Abdominal U/S is recommended for children younger than 6 mo and for children older than 6 mo with recurrent UTIs or known risk factors
• Voiding Cystourethrogram (VCUG) is recommended for children with abnormal U/S and suspected reflux
• DMSA scan is used to detect pyelonephritis and renal scarring

Treatment

• Send a sample for urine culture and start treatment
• Acute cystitis:
  • 3- to 5-day course of therapy with trimethoprim-sulfamethoxazole (TMP-SMX), nitrofurantoin, or amoxicillin
• Acute pyelonephritis (suggested by febrile illness):
  • A course of antibiotics for 7-14 days
  • Oral and parental routes are equally efficacious
  • Hospitalization for intravenous (IV) rehydration and IV antibiotic therapy may be necessary for children who are dehydrated, vomiting, unable to drink fluids, have complicated infection, or have urosepsis

Causes of Frequent Recurrences of UTI

• Voiding dysfunction
• Obstruction and stasis
• Renal calculi
• Neurogenic bladder
• Vesico-ureteral reflux
• Constipation

Management of Recurrent UTIs

• Identification and treatment of predisposing factors is essential
• Long-term antibiotic prophylaxis may be necessary for urologic conditions that can cause recurrent UTIs

Complications

• Chronic pyelonephritis
• Renal failure
• Hypertension

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Acute Renal Failure

• Definition: rapid and usually reversible decline in renal function leading to retention of nitrogenous waste products and disturbance in water and electrolyte balance
• Etiology:
  • Pre-renal causes: dehydration, gastroenteritis, hemorrhage, burns, sepsis, capillary leak, hypoalbuminemia, cardiac failure, anaphylaxis
  • Intrinsic renal causes: glomerulonephritis, interstitial nephritis, acute tubular necrosis, vascular, malignancy, developmental abnormalities
  • Post-renal causes: bilateral PU obstruction or unilateral affection of single kidney, bladder neck obstruction, neurogenic bladder, vesico-ureteric reflux, posterior urethral valves, tumors, and other causes of extrinsic compression, urolithiasis, urethral strictures

Clinical Manifestations and Examination

• The presenting signs and symptoms may be dominated or modified by the precipitating factor
• Symptoms: dehydration, vomiting, lethargy, pallor, oliguria, edema, hypertension
• History and physical examination: focus on volume status, hypertension, edema, and signs of underlying cause

Laboratory Findings

• Increased blood urea, serum creatinine
• Electrolyte disturbances: hyponatremia, hypocalcemia, hyperkalemia, hyperphosphatemia
• Metabolic acidosis
• May be anemia, leucopenia, and thrombocytopenia
• Lab findings of underlying cause: serum C3 level, hematuria, proteinuria, and red blood cell or granular urinary casts

Management of Acute Renal Failure

• According to fluid status:
  • Intravascular volume expansion with IV fluids in hypovolemic patients
  • Furosemide may increase urine output in oliguric patients
  • Fluid restriction in patients with signs of volume overload or edema
• Treatment of surgical causes in post-renal cases
• Management of hyperkalemia, hypocalcemia, and hyponatremia

Indications for Dialysis

• Fluid overload: pulmonary edema, CHF, refractory hypertension
• Electrolyte or acid-base disturbance:
  • Hyperkalemia >7mg/dl
  • Marked hypo-hypernatremia
  • Hyperphosphatemia
  • Acidosis pH