40 J. REYNARD
FIGURE 3.13. Continued
3. NONTRAUMATIC RENAL EMERGENCIES 41
and abdominal pain, with radiographic evidence of gas within and around the kidney (on plain radiography or CT). It usually occurs in diabetics, and in many cases is precipitated by urinary obstruction by, for example, ureteric stones. The high glucose levels of the poorly controlled diabetic provides an ideal environment for fermentation by enterobacteria, carbon dioxide being produced during this process.
Emphysematous pyelonephritis presents as a severe acute pyelonephritis (high fever and systemic upset) that fails to respond within 2 to 3 days with conventional treatment in the form of intravenous antibiotics. E. coli is a common causative organism, with Klebsiella and Proteus occurring from time to time. Obtaining a KUB x-ray and ultrasound in all patients with acute pyelonephritis may allow earlier diagnosis of this rare form of pyelonephritis. An unusual distribution of gas on x-ray may suggest that the gas lies around the kidney (e.g., crescent or kidney shaped). Renal ultrasonography often demonstrates strong focal echoes, indicating gas within the kidney. Intrarenal gas will be clearly seen on CT scan.
Patients with emphysematous pyelonephritis are usually very unwell. Mortality is high. Selected patients can be managed conservatively, by intravenous antibiotics and fluids, percutaneous drainage, and careful control of diabetes. In those where sepsis is poorly controlled, emergency nephrectomy is required.
ACUTE PYELONEPHRITIS, PYONEPHROSIS, PERINEPHRIC ABSCESS, AND EMPHYSEMATOUS PYELONEPHRITIS— MAKING THE DIAGNOSIS
Maintaining a degree of suspicion in all cases of presumed acute pyelonephritis is the single most important thing in making an early diagnosis of complicated renal infection, such as a pyonephrosis, perinephric abscess, or emphysematous pyelonephritis. If patients are very unwell, or diabetic, or have a history suggestive of stones, for example, ask yourself whether they may have something more than just a simple acute pyelonephritis. They may give a history of sudden onset of severe flank pain a few days earlier, which suggests that they may have passed a stone into their ureter at this stage, and that later infection supervened.