Renal Corticomedullary Abscess Treatment & Management

In most patients with acute focal or multifocal pyelonephritis, treatment with appropriate antibiotics should produce a clinical response within one week of initiating therapy. However, well-established large abscesses are often difficult to treat with antibiotics alone, with most studies limiting treatment of renal abscesses with antibiotics alone to lesions smaller than 3 cm.

In most patients with suspected corticomedullary abscess, a prompt attempt at treatment with intravenous antibiotics directed against culture-specific bacteria in addition to intravenous fluid resuscitation may be used. Medical treatment alone should be limited to hemodynamically stable patients with small (< 3 cm) corticomedullary abscesses. Patients with signs of hemodynamic instability due to sepsis or with large renal abscesses (≥3 cm) should undergo percutaneous or surgical drainage for abscess management (see Surgical Care). Moreover, medical therapy alone in the treatment of perinephric abscesses is inappropriate, as the risk of mortality associated with perinephric abscess treated with antibiotics alone is upward of 33%.

Intravenous administration of a penicillin derivative, a cephalosporin, an aminoglycoside, or a fluoroquinolone is the appropriate initial medical treatment. Following sufficient resolution of nausea/vomiting and fever, antibiotics may be administered orally.

For combination therapy, a beta-lactam antibiotic plus an aminoglycoside should be administered intravenously. Administer this line of therapy until culture and sensitivity results are received and then modify the antimicrobial therapy to the most appropriate agent.

The duration of therapy is not well defined. Continue parenteral antibiotics for at least 24-48 hours after patient symptoms clinically improve and the fever resolves. Then, administer a suitable oral antibiotic medication and continue this treatment regimen for an additional 2-4 weeks, as determined by complete clinical and radiographic resolution of the intrarenal process.

Factors that may contribute to medical treatment failure include elderly age, diabetes mellitus, large abscesses, obstructive uropathy, and urosepsis.

Antimicrobial therapy alone is not indicated for patients with xanthogranulomatous pyelonephritis (XGP). Nephrectomy is required.

Surgical debridement, drainage, and nephrectomy were once widely used to treat corticomedullary abscesses. However, since the advent of effective antibiotics along with percutaneous techniques, the open surgical approach is now reserved for more severe, refractory cases.

Indications to intervene aggressively include persistent infection unresponsive to appropriate antibiotics, impending sepsis, and ongoing hemodynamic instability.

Coagulopathy is the main contraindication to percutaneous drainage or surgical intervention. In most cases, the coagulopathy can be corrected so that the appropriate therapy can be delivered.

Abscess drainage

In general, large intrarenal abscesses require drainage if the patient has persistent fever and no clinical improvement after one week of appropriate antimicrobial therapy. Percutaneous drainage plus parenteral antibiotics is indicated as the initial treatment for abscesses 3-5 cm in size. Renal abscesses may be drained percutaneously under CT or ultrasonographic guidance.

In cases that involve perirenal abscess or infected urinoma, also place a percutaneous perirenal drain. Drainage via the percutaneously placed tube should continue at least until the patient is afebrile and stable, and then until drain output is minimal.

Surgical therapy

Surgical debridement, drainage, and nephrectomy were once used widely to treat corticomedullary abscesses. Since the advent of effective antibiotics along with percutaneous techniques, the open surgical approach is now reserved for more severe, refractory cases.

If surgical intervention is indicated, the abscess should be explored and drained. Copious irrigation of the infected renal fossa with an antibiotic irrigant along with placement of perirenal drains should follow. Reserve nephrectomy for patients with diffusely damaged renal parenchyma or patients who are septic and require urgent intervention for survival.

Nephrectomy

Simple nephrectomy is usually adequate.

Partial nephrectomy may be possible in patients with focal disease confined to the kidney (stage I) or perinephric fat (stage II); however, the more common presentation is diffuse disease involving most of the kidney and extending to the perirenal fat (stage II) and beyond (stage III).

Nephrectomy is often required for patients with symptomatic XGP. Following nephrectomy, the prognosis is excellent in patients without other urinary tract pathology. The xanthogranulomatous process does not recur after excision.

Preoperative details

A thorough workup that involves screening for risk factors that predispose to intrarenal abscess is necessary. This workup should include preoperative imaging to define the extent of the parenchymal process (see Imaging Studies). Contrast CT scanning is the standard imaging modality and allows greatest definition of the patient’s anatomy, degree of abscess extension, and associated conditions (eg, obstructive uropathy). Moreover, if surgical intervention is necessary, CT imaging can be used to help determine the optimal surgical approach.

Intraoperative details

Either supine or flank positions may be used. Usually, the flank position is preferred because of ease of establishing a drainage tract and prevention of possible peritoneal exposure to infected material.

Postoperative details

Postoperative parenteral antibiotic therapy should continue following surgery, with subsequent conversion to oral administration when the patient is able to tolerate a diet.

Antibiotic therapy is generally continued for at least 2 weeks.

Discharge patients under the following conditions:

• Tolerating diet
• Ambulating
• Afebrile
• Adequate pain control on oral analgesics

Follow-up

• Instruct the patient to return to the clinic in 1-2 weeks for follow-up examination.
• Check the wound for signs of surgical-site infection.
• Remove staples or sutures.
• Obtain a follow-up contrast CT scan to ensure resolution of renal parenchymal abnormalities.
• Following surgery, inform the patient that normal activities can resume in 4-6 weeks.