Dr. med. Dirk Manski

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Acute Pyelonephritis: Symptoms and Diagnosis

Review literature: (Fihn, 2003) (Nickel, 2001) (Roberts, 1999) (DGU S3-Guideline urinary tract infections).

Signs and Symptoms of Pyelonephritis

Complications of Acute Pyelonephritis:

Diagnosis of Acute Pyelonephritis

The diagnosis is mainly based on the triad of fever, flank pain and symptoms of bacterial cystitis. Radiological signs are discreet and ambiguous, they are found only in every fourth patient. The clinical value of imaging lies in the detection of complications and for differential diagnosis (Dalla-Palma and Pozzi-Mucelli, 2000) (Kawashima et al, 2000).

Blood Tests:

Urine Sediment:

Urine Culture:

Before the start of antibiotic treatment, a urine culture is always indicated for identification and resistance testing of the responsible pathogen.

Ultrasonography of the Kidneys:

Ultrasonography of the kidneys is indicated for the exclusion of urinary obstruction. Sonographic signs of pyelonephritis are nonspecific and only useful in comparison with previous imaging: renal enlargement, hypoechoic parenchyma.

In emphysematous pyelonephritis, the trapped air produces echogenic structures with posterior acoustic shadowing, which are distributed in parenchyma and perirenal fat. A renal abscess presents as hypoechoic mass, which may contain air. This must be distinguished from the emphysematous pyelonephritis. If signs of air or abscess formation are detected, computed tomography is indicated.

Computed Tomography:

Contrast enhanced CT is indicated, if renal abscess, nephrolithiasis, emphysematous pyelonephritis or urinary tract obstruction are suspected. CT should also be done, if no adequate treatment effect is observed within 48–72 h of adequate antibiotic treatment.

CT reliably detects above mentioned complications. The signs of uncomplicated pyelonephritis are subtle: kidney enlargement, wedge-shaped regional limitation of enhancement, delayed nephrogram, perirenal inflammatory infiltrates and possibly a decreased renal function. If retention parameters are elevated, noncontrast spiral CT is a good alternative to detect urolithiasis or to objectify upper urinary tract obstruction

fig. CT emphysematous pyelonephritis   

Emphysematous pyelonephritis of the right kidney: non-enhancing CT shows gas within Gerota's fascia. The patient suffered from severe urosepsis. With kind permission of Prof. Dr. K. Bohndorf, Augsburg.

Intravenous Urography:

Intravenous urography is (was) indicated if urinary obstruction or urinary stones are suspected. Nowadays, intravenous urography is replaced with computed tomography.

Radiological signs of acute PN in urography are descreet and ambiguous: unilateral renal enlargement, delayed enhancement of the affected kidney, slightly spread renal calyces (by the swollen parenchyma). Ureteropyelitis may be visible by ectasia or by streaks of mucosa due to edema. Destructive stages of (chronic) pyelonephritis may show renal atrophy and papillary destruction or necrosis. In emphysematous pyelonephritis, urography may show trapped gas within Gerota's fascia. In these cases, the kidney has usually a poor function and urinary obstruction cannot be excluded, CT is recommended. Gas within the collecting system is less dramatic and should not be confused with emphysematous pyelonephritis.

Diagnosis of vesicoureteral reflux:

Recurrent pyelonephritis require, particular in children, the exclusion or diagnosis of vesicoureteral reflux. Renal ultrasound imaging is done first. In boys older than 1 year and in adults, normal findings in renal ultrasound do not warrant further tests. In girls and in children under 12 months, MCU and/or DMSA scintigraphy should be performed. It is controversial, if MCU or DMSA kidney scintigraphy are done first or if both examinations should be done. In adults, the risk for significant VUR after uncomplicated pyelonephritis is low (2%) and MCU or scintigraphy are not recommended.

Differential Diagnosis of Acute Pyelonephritis

Pancreatitis, basal pneumonia, pleuritis, acute appendicitis, acute cholecystitis, diverticulitis, pelvic inflammatory disease, renal and perirenal abscess.

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


DGU S-3 Guideline Urinary tract infections
Epidemiologie, Diagnostik, Therapie und Management unkomplizierter bakterieller ambulant erworbener Harnwegsinfektionen bei erwachsenen Patienten
AWMF, 2010, Register-Nr. 043/044

Dalla-Palma und Pozzi-Mucelli 2000 DALLA-PALMA, L. ; POZZI-MUCELLI, F.:
[The imaging of chronic renal infections].
In: Radiologe
40 (2000), Nr. 6, S. 537–46

Fihn 2003 FIHN, S. D.:
Clinical practice. Acute uncomplicated urinary tract infection in women.
In: N Engl J Med
349 (2003), Nr. 3, S. 259–66

Kawashima u.a. 2000 KAWASHIMA, A. ; SANDLER, C. M. ; GOLDMAN, S. M.:
Imaging in acute renal infection.
In: BJU Int
86 Suppl 1 (2000), S. 70–9

Nickel 2001 NICKEL, J. C.:
The management of acute pyelonephritis in adults.
In: Can J Urol
8 Suppl 1 (2001), S. 29–38

Roberts 1999 ROBERTS, J. A.:
Management of pyelonephritis and upper urinary tract infections.
In: Urol Clin North Am
26 (1999), Nr. 4, S. 753–63

  Deutsche Version: Klinik und Diagnose der Pyelonephritis