Acute Pyelonephritis: Symptoms and Diagnosis

Acute pyelonephritis (1/3): definition, causes and pathology
Acute pyelonephritis (2/3): symptoms and diagnostic work-up
Acute pyelonephritis (3/3): treatment

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

Signs and Symptoms of Pyelonephritis

Sudden fever and chills, malaise and weakness
Constant flank pain. Children often complain about abdominal pain.
Flank tenderness
Frequency, dysuria, (micro)-hematuria
Possible symptoms: nausea, vomiting, diarrhea, abdominal tenderness, decreased bowel sounds.
Tachycardia, hypotension and further symptoms of urosepsis

Complications of Acute Pyelonephritis:

Renal scarring, especially in children, with the development of chronic pyelonephritis
Kidney abscess
Urosepsis with septic shock
Emphysematous pyelonephritis in diabetes mellitus (high mortality)

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:

Leukocytosis
Elevated ESR, elevated CRP
Blood culture: pathogen can be detected in severe disease (high fever, signs of urosepsis)

Urine Sediment:

Pyuria: cloudy urine, positive dipstick leukocyte esterase test, granulocytes (and white cell casts) in microscopic examination
Proteinuria
Microhematuria is typical, sometimes visible hematuria

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

In CT, above mentioned complications can be reliably detected. 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.

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

Intravenous Urography:

Intravenous urography is (was) indicated in sonographic suspicion of urinary obstruction or urinary stones. Nowadays, intravenous urography is replaced with computed tomography as the imaging technique of. If retention parameters are elevated, noncontrast spiral CT is a good alternative to detect urolithiasis or to objectify upper urinary tract obstruction.

Radiological signs of acute PN in urography are descreet and ambiguous: unilateral renal enlargement, delayed enhancement of the affected kidney, slightly spread renal calices (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.

Voiding Cysturethrogram:

Recurrent pyelonephritis require, particular in children, the exclusion or diagnosis of vesicoureteral reflux (VUR) with an voiding cysturethrogram. In adult women after uncomplicated pyelonephritis, the rate of clinical relevant VUR is low (2%).

Renal Scintigraphy:

Static DMSA renal scintigraphy is used in children to confirm pyelonephritis, to detect renal scarring and to assess the distribution of renal function between both kidneys.

Differential Diagnosis of Acute Pyelonephritis

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

Pyelonephritis

Index

PN treatment

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

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References

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

Last update

Dr. med. Dirk Manski
man...@urologielehrbuch.de