A 27-year-old woman is admitted to the emergency department complaining of pain across her back. She became unwell 2 days previously when she started to develop a fever and an ache in her back. The pain has become progressively more severe. She has vomited twice in the past 6h. She has had no previous significant medical history, apart from an uncomplicated episode of cystitis 3 months ago.
Examination She looks unwell and is flushed. Her temperature is 39.5°C. Her pulse is 120 beats/min and blood pressure 104/68mmHg. Examination of the cardiovascular and respiratory systems is unremarkable. Her abdomen is generally tender, but most markedly in both loins. Bowel sounds are normal.
Normal Haemoglobin 15.3g/dL 11.7–15.7g/dL White cell count 25.2 109/L 3.5–11.0 109/L Platelets 406 109/L 150–440 109/L Sodium 134mmol/L 135–145mmol/L Potassium 4.1mmol/L 3.5–5.0mmol/L Urea 14.2mmol/L 2.5–6.7mmol/L Creatinine 106amol/L 70–120amol/L Albumin 44g/L 35–50g/L C-reactive protein (CRP) 316mg/L 5mg/L
Urinalysis: protein; blood; nitrites Urine microscopy: 50 red cells; 50 white cells Abdominal X-ray: normal
INVESTIGATIONS
Questions
• What is the likely diagnosis?
• How would you investigate and manage this patient?
ANSWER
This woman has the symptoms and signs of acute pyelonephritis. Acute pyelonephritis is much more common in women than men, and occurs due to ascent of bacteria up the urinary tract. Pregnancy, diabetes mellitus, immunosuppression and structurally abnormal urinary tracts increase the likelihood of ascending infection.
Pyelonephritis causes loin pain which can be unilateral or bilateral. The differential diagnoses of loin pain include obstructive uropathy, renal infarction, renal cell carcinoma, renal papillary necrosis, renal calculi, glomerulonephritis, polycystic kidney disease, medullary sponge kidney and loin-pain haematuria syndrome. Differential diagnosis
Fever may be as high as 40°C with associated systemic symptoms of anorexia, nausea and vomiting. Some patients may have preceding symptoms of cystitis (dysuria, urinary frequency, urgency and haematuria), but these lower urinary tract symptoms do not always occur in patients with acute pyelonephritis. Many patients will give a history of cystitis within the previous 6 months. Elderly patients with pyelonephritis may present with nonspecific symptoms and confusion. Pyelonephritis may also mimic other conditions such as acute appendicitis, acute cholecystitis, acute pancreatitis and lower lobe pneumonia. There is usually marked tenderness over the kidneys both posteriorly and anteriorly. Severe untreated infection may lead on to septic shock. The raised white cell count and CRP are consistent with an acute bacterial infection. Microscopic haematuria, proteinuria and leucocytes in the urine occur because of inflammation in the urinary tract. The presence of bacteria in the urine is confirmed by the reduction of nitrates to nitrites. This woman should be admitted. Blood and urine cultures should be taken, and she should be commenced on intravenous fluids and antibiotics, until the organism is identified, and then an oral antibiotic to which the organism is sensitive can be used. Initial therapy could be with gentamicin and ampicillin, or ciprofloxacin. She should have a renal ultrasound scan to exclude any evidence of obstruction. In patients with obstructive uropathy, infection may lead to a pyonephrosis with severe loin pain, fever, septic shock and renal failure. If there is evidence of a hydronephrosis in the context of urinary sepsis, a nephrostomy should be inserted urgently to prevent these complications. Patients with an uncomplicated renal infection should be treated with a 2-week course of antibiotics, and then have a repeat culture 10–14 days after treatment has finished to confirm eradication of infection. In patients with infection complicated by stones, or renal scarring, a 6-week course of treatment should be given.