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Perinephric Abscess
Review literature: (Angel et al, 2003) (Shu et al, 2004).
Definition of a Perinephric Abscess
A perinephric abscess is a collection of pus within Gerota's fascia.
Etiology of Perinephric Abscess
Gram-negative Bacteria:
Perinephric abscesses are most common caused by gram-negative bacteria such as E. coli and Proteus. Perinephric abscesses with gram-negative bacteria usually result from rupture of a renal abscess with cortical location. Nephrolithiasis is a risk factor.Staphylococci:
Before the antibiotic era, perinephric abscesses were often caused by the hematogenous spread of staphylococci. Today's risk groups for hematogenous spread of staphylococci: intravenous drug abuse, intensive care, dialysis patients, valvular heart disease and endocarditis.
.Signs and Symptoms of a Perinephric Abscess
In contrast to a renal abscess, signs and symptoms of a perinephric abscess have a slow onset and are unspecific. Patients present usually with symptoms of more than one week, complaining about fever, flank pain or abdominal pain, night sweat and chills. More than 30% are afebrile.
Perinephric Abscess: Diagnostic Work-Up
Urine culture:
Urine culture is not sensitive and can identify the responsible bacteria in only 30%.
Laboratory tests:
Blood culture (positive in 50%). Blood count, coagulation tests (PTT, PT), CRP, liver enzymes, creatinine. In suspected urosepsis, determination of sepsis parameters such as blood gas testing, AT III and fibrinogen.
Ultrasonography:
Sonographic signs for a perinephric abcess in renal ultrasound are a perirenal hypoechoic area, which may have inclusion of air (echogenic reflex with dorsal shadowing).
Computed tomography:
CT is the diagnostic test of choice [fig. perinephric abscess]. The perinephric abscess appears as a hypodense area. Air inclusion is possible. After administration of contrast media, there is an ring-like enhancement of the abscess capsule.
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CT of a right-sided perinephric abscess: (left horizontal plane, right sagittal reconstruction). The patient complained about night sweats and fatigue, he had no flank pain or fever. With kind permission of Prof. Dr. K. Bohndorf, Augsburg. |
Intravenous urography:
Intravenous urography is not very helpful in suspected perinephric abscess. If done, KUB x-ray may show an absent psoas shadow, a perinephric mass, retroperitoneal air surrounding the kidney and nephrolithiasis. The excretion of contrast media is often without pathological findings.
Treatment of a Perinephric Abscess
Treatment consists of parenteral antibiotics and abscess drainage:
- Parenteral antibiotics: e.g. amoxicillin and clavulaic acid 2,2 g 1–1–1 i.v. in combination with gentamicin 3 mg/kg 1–0–0 i.v. Alternatives are third generation cephalosporins.
- Abscess drainage: in most cases, percutaneous drainage is sufficient. Pus is sent for identification of bacteria and antibiotic resistance testing. In advanced disease, surgical drainage is necessary. Nephrectomy is rarely necessary in a nonfunctioning kidney with persisting sepsis despite maximal therapy.
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References
- Angel u.a. 2003 ANGEL, C. ; SHU, T. ; GREEN, J. ; ORIHUELA, E. ; RODRIQUEZ, G. ; HENDRICK, E.:
- Renal and peri-renal abscesses in children: proposed
physio-pathologic mechanisms and treatment algorithm.
In: Pediatr Surg Int
19 (2003), Nr. 1–2, S. 35–9
- Shu u.a. 2004 SHU, T. ; GREEN, J. M. ; ORIHUELA, E.:
- Renal and perirenal abscesses in patients with otherwise anatomically
normal urinary tracts.
In: J Urol
172 (2004), Nr. 1, S. 148–50
Deutsche Version: Perinephritischer Abszess