Medical Q&As

Pyelonephritis - what is it?

What is pyelonephritis?

Pyelonephritis is an infection characterised by inflammation of the kidney. The condition may be acute or chronic. Acute pyelonephritis usually occurs as a result of ascending infection that travels up the ureter from the bladder. The ureter is the tube that connects the kidney to the bladder. Pyelonephritis can affect one or both kidneys. The condition can occur at any age. During childhood it is often associated with vesicoureteric reflux, which means that urine from the bladder back tracks up the ureter. In older men it is often associated with enlargement of the prostate gland. It is not uncommon in pregnant women due to pressure from the womb on the lower end of the ureter. Acute pyelonephritis can also occur as a result of the presence of calculi or stones in the urinary tract. The symptoms include pain and tenderness in the loin accompanied by fever and dysuria or stinging when passing urine. The affected person may also experience severe vomiting. The symptom pattern may be quite different in pregnant women and children where it may simply present as a fever without any other localising symptoms. The illness usually subsides in a couple of days with antibiotic treatment. Chronic pyelonephritis may occur as result of an inadequately treated acute infection but is more likely to occur as a result of persistent low grade infection of the urinary tract such as might occur with an undiagnosed calculus or stone. The classic urinary symptoms of stinging and frequency may be absent and the person may have no symptoms that are referable to the urinary tract. An affected person may present with vague ill health, fatigue and lassitude. The course of the illness is long and it may be punctuated by several acute episodes along the way. If undiagnosed it can progress to chronic renal failure.