Acute pyelonephritis

Acute pyelonephritis is more common in females, especially in childhood, at puberty, after intercourse(as a complication of ‘Honeymoon cystitis’), during pregnancy and during menopause. It occurs more on the right and is frequently bilateral.

Clinical features

There may be prodromal symptoms of headache, lassitude and nausea, but the onset of pain is usually sudden, often with a rigor and vomiting. There is acute pain in the flank and hypochondrium. In a few cases the pain resembles renal colic. The remitting temperature rises to 39.0’C or more. The symptoms of cystitis commonly set in, with urgency, frequency and scalding dysuria. There is tenderness in the hypochondrium and in the loin. Rarely, in cases of severe bilateral pyelonephritis, especially when there is an associated obstruction, renal dysfunction may be sufficient to cause uraemia. The risk of life-threatening septicaemia is ever present.

Investigations

Bacteriological examination of the urine

A midstream urine specimen should be collected into a sterile container; the urine is centrifuged and the sediment examined micropscopically.In early acute pyelobnephritis, there are usually pus cells and many bacteria. Culture and sensitivity testing of the causative organisms allows a rational choice of antibiotic, but parenteral treatment with a broad-spectrum antibiotic should be started before the results are available.

Severe cases

There are repeated rigors and a temperature of 40’C or more, often without a corresponding rise in pulse rate. There is vomiting, sweating and thirst; the patient feels awful. The blood culture is usually positive, especially if the specimen has been taken during a rigor.

Differential diagnosis

  When the symptoms and signs are typical the diagnosis is straightforward. In other circumstances it may be difficult to be sure that the patient does not have pneumonia, acute appendicitis or acute cholecystitis. A skilled ultrasonographer may be able to detect the typical appearance of pyelonephritis.

Special cases

Pyelonephritis of pregnancy

Usually occurs between the fourth and sixth months of pregnancy in women who have a past history of recurrent urinary infection. In about 10% of cases the disease runs a severe and protracted course and occasionally leads to abortion or premature birth.