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Pyogenic liver abscess


Overview

Pyogenic liver abscess (PLA) may be solitary or multiple collections of pus within the liver, the result of bacterial infection. PLA causes significant morbidity, mortality, and increased consumption of healthcare resources. PLA represents the most common visceral abscess, with an incidence of 5 to 20 in 100,000 hospitalizations in the Western population. In 1938 Ochsner et al. reported the first series of patients with hepatic abscesses in the modern surgical era treated by surgical drainage. This study included 47 patients and reported an overall survival of 67%. The advent of antibiotic therapy marked the basis of the contemporary treatment of liver abscesses, becoming a major part of the therapy, combined with surgical drainage. The first landmark report in minimally invasive treatment of liver abscess was that of McFadzean et al. in 1953. They presented a group of 14 patients who underwent percutaneous drainage for PLAs with no deaths within the group. Although potentially effective for dealing with the acute problem, such approaches are associated with the disadvantage of overlooking the underlying abdominal pathology because of the lack of surgical exploration.

The development of clinical ultrasound (US) in the 1960s and the introduction of computed tomography (CT) in the 1970s represent the two major advances in the diagnosis and treatment of PLAs. Surgical exploration as a diagnostic tool was replaced by abdominal imaging, thus allowing minimally invasive techniques to become the first choice of treatment. Currently, percutaneous needle aspiration (PNA) and percutaneous catheter drainage (PCD) have become standard methods for both single and multiple PLAs (see Chapter 31 ). Surgical debridement, done either in an open or a laparoscopic fashion, has a limited therapeutic role for patients in whom nonoperative treatment fails or in those requiring surgical treatment for the underlying cause of the abscess. In addition, surgical exploration may be indicated as the initial procedure when coexistence of peritonitis is suspected as result of abscess rupture into the peritoneal cavity.

Etiology

During the 19th century, PLAs were well known as a complication of acute appendicitis. Since then, etiology and presentation have dramatically changed. Inflammatory abdominal diseases are no longer the most common underlying conditions for PLAs, being replaced in later decades by a higher incidence of biliary causes, including malignancies, immunocompromised status, and advanced age. In 1996 Huang et al. (1996) presented a review that spanned more than 40 years in the treatment of PLAs. They analyzed and compared patterns of clinical presentation in 80 patients treated between 1952 and 1972 with a second group of 153 patients treated from 1973 to 1993. The authors concluded that the increased incidence of biliary malignancies as a cause of PLAs was due to a more aggressive approach in the treatment of this pathology, which includes more frequent instrumentation of the biliary tree (see Chapters 30 , 31 , 51 , and 52 ). Hilar cholangiocarcinoma was the most frequent single condition found during the second period reviewed, with the use of biliary stents and broad-spectrum antibiotics leading to the emergence of mixed bacterial and fungal infections (see Chapters 51 and 52 ). Biliary malignancy was an important risk factor for hospital mortality.

Elucidating the underlying condition that caused a liver abscess is as important therapeutically as the correct treatment of a PLA. In a simplified schema, infection may get to the liver by five different avenues: (1) portal vein, (2) hepatic artery, (3) biliary tree, (4) adjacent organ infection, and (5) direct trauma to the liver. The term cryptogenic PLA applies when no underlying pathology is identified ( Box 70.1 ).

BOX 70.1
PLA, Pyogenic liver abscess.
Classification of PLA According to the Underlying Mechanism of Dissemination

Hepatobiliary

  • Cholelithiasis

    • Benign strictures

    • Acute cholangitis

    • Periampullary tumors

    • Gallbladder cancer

Portal

  • Diverticulitis

    • Anorectal suppuration

    • Pelvic suppuration

    • Postoperative sepsis

    • Intestinal perforation

    • Pancreatic abscess

    • Appendicitis

    • Chronic inflammatory bowel disease

    • Colonic cancer

    • Gastric cancer

Arterial

  • Endocarditis

  • Vascular sepsis

  • Ear, throat, nose, or dental infection

Traumatic

  • Open or closed abdominal trauma

    • Chemoembolization

    • Percutaneous ethanol injection or radiofrequency ablation

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