Acute pyelonephritis

What it is

Acute pyelonephritis is an acute infection of the urinary tract. In urology it is listed with urinary tract infection, chronic cystitis and interstitial cystitis, and prostatitis, epididymitis and orchitis. What sets it apart in daily work is how ill it makes the patient: the patient is sick and febrile, with acute symptoms, not with the mild recurrent symptoms of a quiet condition.

Causes and risk

Stones are one road into it. Kidney stones can lead to severe complications such as hydronephrosis and pyelonephritis, so an obstructed stone in a febrile patient is what to watch for.

Other factors may predispose a patient to cystitis, pyelonephritis, urethritis and asymptomatic bacteriuria:

• Sexual activity
• Pregnancy
• Barrier contraceptives (diaphragm)
• Prior urinary tract instrumentation
• Urinary catheterization, in-dwelling and intermittent
• Anatomic anomalies, congenital and acquired
• Bladder dysfunction

How it presents

The patient is sick, febrile and in acute pain, and that places acute pyelonephritis in two differential lists. When upper abdominal pain is acute, persistent and not responding to analgesics, it is weighed with acute cholecystitis, acute pancreatitis and liver abscess. When the pain is in the lower abdomen, it is weighed with appendicitis, ectopic pregnancy, testicular torsion, ovarian torsion, IBD and renal colic. The obstructed stone that can lead to it gives unilateral flank tenderness, colicky pain radiating to the groin and hematuria.

Dysuria is the other route in, and there the character of the patient is key in diagnosis. In a young female it is cystitis, pyelonephritis or vaginitis; in a perimenopausal female, estrogen deficiency changes; in a male, STI or urinary stones; in a child, urinary tract infection or vesicoureteral reflex.

When infection sits above an obstruction the picture is more marked: persistent worsening flank pain, fever with chills and rigors, and nausea and vomiting, with neutrophilic leukocytosis and mildly increased creatinine. The sign to elicit at the bedside is costovertebral angle tenderness on the side of the pain.