Liver Abscess

Three weeks after undergoing gastric bypass surgery for obesity, a 64-year-old woman presented with fatigue, chills, and abdominal pain of 2 days' duration. She denied shortness of breath, nausea, vomiting, changes in bowel habits, melena, and hematochezia. The patient had no significant past medical history.

The pale and diaphoretic patient had right upper quadrant tenderness without rebound or hepatomegaly. Temperature was 37.4°C (99.4°F); heart rate, 110 beats per minute; respiration rate, 22 breaths per minute; and blood pressure, 80/50 mm Hg with orthostatic hypotension. White blood cell (WBC) count was 28,000/µL; the alkaline phosphatase level was 128 U/L (normal, 38 to 112 U/L). Other liver function test results and amylase and lipase levels were within normal limits. No obstruction or perforation was visible on an abdominal radiograph.

A CT scan of the upper abdomen revealed a complex cystic lesion with small pockets of gas within the left lobe of the liver; this finding was consistent with an intrahepatic abscess (A). The abscess was drained percutaneously with CT guidance. A 12F pigtail catheter was placed in the largest pocket of the lesion. Intravenous piperacillin/tazobactam and metronidazole were started. A culture of purulent fluid from the abscess grew Clostridium perfringens.

By the fourth hospital day, the patient was afebrile, and her WBC count had normalized. A second CT scan showed a significant reduction in the size of the abscess (B). The pigtail catheter was removed, amoxicillin/clavulanate and metronidazole were prescribed, and the patient was discharged after 14 days in the hospital.

Sammy Ho, MD, and Robert J. Bonasera, MD, of Mineola, NY, write that pyogenic liver abscess is a relatively uncommon disease¹; however, it is being diagnosed with increasing frequency, most likely because of improved imaging techniques. Typically, affected patients are between 50 and 60 years old; there is no gender or ethnic predilection. About half of patients present with more than 1 abscess. Seventy-five percent of abscesses involve the right lobe; 20%, the left lobe; and 5%, the caudate.²

Bacterial pathogens implicated in liver abscess reach the organ via the portal vein, hepatic artery, biliary tract, penetrating trauma, or direct extension from a contiguous focus of infection. Suppurative ascending cholangitis is the most frequent identifiable cause of pyogenic liver abscess.³ Other causes include transhepatic chemoembolization and endoscopic sphincterotomy for biliary duct stones.⁴ The origin of most abscesses is unknown.⁵

Escherichia coli and Klebsiella pneumoniae are the most common pathogens isolated from hepatic abscesses. Anaerobic organisms are found in 45% of pyogenic liver abscesses and are more common in polymicrobial abscesses.²

Typical presenting symptoms are fever, malaise, anorexia, and weight loss; nausea, vomiting, diarrhea, and abdominal pain also may be present. The classic triad of fever, jaundice, and right upper quadrant pain is seen in only 10% of patients.² Hepatomegaly, right upper quadrant tenderness, and jaundice are the most common physical findings.² Suspect rupture of the abscess when septic shock and diffuse abdominal pain are present. Most patients with pyogenic hepatic abscess have leukocytosis and anemia. The alkaline phosphatase level is often elevated; other liver enzyme levels are more likely to be normal. Overall, laboratory results may suggest liver disease but are neither sensitive nor specific for the diagnosis of pyogenic liver abscess. Imaging studies usually are required to make a definitive diagnosis. CT is the screening procedure of choice for demonstrating pyogenic liver abscess; the detection rate is as high as 97%.¹ This modality is also superior to ultrasonography for guidance of complex drainage procedures.

The introduction of modern imaging techniques has changed initial management from open surgical drainage and antibiotics to antibiotic therapy in conjunction with percutaneous drainage or aspiration; surgical intervention usually is reserved for patients in whom percutaneous drainage fails.

Percutaneous drainage is successful in approximately 90% of patients.^1-3,5 Relative contraindications to the technique include large amounts of ascites, severe coagulopathy, and the presence of multiloculated abscesses. Drainage catheters usually are left in place for 5 to 10 days until drainage subsides.

Initiate antibiotics as soon as the diagnosis is suspected. Initial agents must provide coverage against aerobic gram-negative bacilli, microaerophilic streptococci, and anaerobes, including Bacteroides fragilis. Primary therapy consists of ampicillin, gentamicin, and metronidazole, or a third-generation cephalosporin and metronidazole.¹

The optimal duration of therapy depends on the size of the abscess, extent of prior drainage, response to therapy, and the patient's immune status. Give parenteral antibiotics for at least 7 to 14 days, followed by a 4- to 6-week course of oral therapy. Follow-up ultrasonography or CT can help determine the required length of treatment; obtain scans after 2 months and at the conclusion of treatment.

Occasionally, the abscess does not completely resolve; antibiotics can be stopped in these cases when 2 CT scans separated by several weeks show no change. Careful follow-up of these patients is warranted; perform another CT scan several months after the last one.

Nearly 100% of patients with untreated hepatic abscess die; however, with treatment, between 75% and 90% of patients with pyogenic liver abscess survive.³ Underlying malignancies (especially cholangiocarcinoma), severe hepatic dysfunction, and multiple abscesses are associated with increased mortality.²

REFERENCES:1. Johannsen EC, Sifri CD, Madoff LC. Pyogenic liver abscesses. Infect Dis Clin North Am. 2000;14:547-563.
2. Albrecht H. Bacterial and miscellaneous infections of the liver. In: Zakim D, Boyer TD, eds. Hepatology: A Textbook of Liver Disease. 4th ed. Philadelphia: WB Saunders Company; 2003:chap 36.
3. Kar P, Kapoor S, Jain A. Pyogenic liver abscess: aetiology, clinical manifestations and management. Trop Gastroenterol. 1998;19:136-140.
4. Tanaka M, Takahata S, Konomi H, et al. Long-term consequence of endoscopic sphincterotomy for bile duct stones. Gastrointest Endosc. 1998;48:465-469.
5. Seeto RK, Rockey DC. Pyogenic liver abscess: changes in etiology, management, and outcome. Medicine (Baltimore). 1996;75:99-113.