 Liver - most subject to abscess formation  Solitary or multiple  Arise from ◦ hematogenous spread of bacteria ◦ local spread from contiguous sites of infection within the peritoneal cavity  Most common source- associated disease of the biliary tract Harrison’s Principles of Internal Medicine, 17 th ed

Primary Infection from other sites (Biliary tree, Peritoneal Cavity, Pelvis) Transmission via Portal vein, arterial supply, biliary tract, direct invasion Secondary Infection of Liver and Abscess Formation

 The right hepatic lobe is affected more often than the left hepatic lobe by a factor of 2:1.  Bilateral involvement is seen in 5% of cases.  The predilection for the right hepatic lobe can be attributed to anatomic considerations.

Liver Abscess Pyogenic Parasitic Amebiasis Hydatid disease Fungal

 Liver is probably exposed to portal venous bacterial loads on a regular basis  Inoculum of bacteria exceeds the liver's ability to clear it  Abscess  Potential routes of hepatic exposure to bacteria: ◦ Biliary tree ◦ Portal vein ◦ Hepatic artery ◦ Direct extension of a nearby focus of infection ◦ Trauma Sabiston Textbook of Surgery, 18 th ed.

Etiology:  Ascending cholangitis ◦ Enteric Gram Negative aerobic Bacilli and Enterococci  Infection from the pelvis and other intraperitoneal sources ◦ Mixed infection with aerobic and anaerobic species is common ◦ Bacteroides fragilis- species most frequently isolated  Hematogenous spread- S. aureus, S. milleri Harrison’s Principles of Internal Medicine, 17 th ed

Extraintestinal infection by E. histolytica Trophozoites invade veins to reach the liver through the portal venous system Travelers of endemic areas - more susceptible Young patients- present w/ acute phase with symptoms of <10 days duration Older patients - subacute course of 6 months with weight loss and hepatomegaly Harrison’s Principles of Internal Medicine, 17 th ed

CLINICAL FEATURESAMEBIC ABSCESSPYOGENIC ABSCESS Age (yr)20-40>50 Male-to-female ratio≥10:11.5:1 Solitary vs. multipleSolitary 80% [*] Solitary 50% LocationUsually right liver Travel in endemic areaYesNo DiabetesUncommon (∼2%)More common (∼27%) Alcohol useCommon JaundiceUncommonCommon Elevated bilirubinUncommonCommon Elevated alkaline phosphatase Common Positive blood cultureNoCommon Positive amebic serology YesNo Table Features of Amebic Versus Pyogenic Liver Abscess Sabiston Textbook of Surgery, 18 th ed.

 caused by the larval/cyst stage of Echinococcus granulosus, in which humans are an intermediate host  In the human duodenum, the parasitic embryo releases an oncosphere containing hooklets that penetrate the mucosa, allowing access to the bloodstream  In the blood, the oncosphere reaches the liver (most commonly) or lungs, where the parasite develops its larval stage known as the hydatid cyst Sabiston Textbook of Surgery, 18 th ed.

 Candida spp.  Follow fungemia in patients receiving chemotherapy from cancer  Often present when PMNs return after a period of neutropenia Harrison’s Principles of Internal Medicine, 17 th ed

Fever - most common presenting sign Pain, guarding, punch and rebound tenderness localized to the right upper quadrant * Hepatomegaly * Jaundice * Non-specific symptoms: Chills Anorexia Vomiting Harrison’s Principles of Internal Medicine, 17 th ed

PatientLiver Abscess Vague RUQ pain – 3 monthsRUQ pain Low-grade feverFever – most common presenting sign Weight lossWeight loss in older patients with a chronic subacute course Past Medical History PTB Acute Viral Hepatitis Biliary tract disease Ruptured appendicitis Pylephlebitis Personal, Family History Smoker Half a bottle of gin everyday since age 30 Mother died of HCC Travel to an endemic area PE findings Pale palpebral conjunctivae Icteric sclerae Spider angiomas, palmar erythema Slightly distended abdomen Liver palpable with a span of 14cm, tender, nodular Jaundice Tenderness over the liver Hepatomegaly

 Laboratory work-up  Amebic serologic testing (positive in 95% of cases)  ELISA test for Echinoccocal antigens ( positive for 85% of infected patients)  Imaging studies ◦ Ultrasound ◦ CT scan

Elevated serum concentration of Alkaline Phosphatase Single most reliable laboratory finding Documented in 70% of patients with liver abscesses Other tests of liver function may yield normal results 50% of patients have elevated serum levels of bilirubin 48% have elevated concentrations of aspartate aminotransferase Other laboratory findings Leukocytosis in 77% of patients Anemia (usually normochromic, normocytic) in 50% Hypoalbuminemia in 33% Concomitant bacteremia is found in one-third of patients

 Hypoechoic masses with irregularly shaped borders.  Internal septations or cavity debris may be detected.  Allows for close evaluation of the biliary tree and simultaneous aspiration of the cavity.  The major benefits of this technique are its portability and diagnostic utility in patients who are too critical to undergo prolonged radiologic evaluation or to be moved out of monitored setting.  Operator dependence affects its overall sensitivity.

 Well-demarcated areas hypodense to the surrounding hepatic parenchyma.  Peripheral enhancement is seen when IV contrast is administered.  Gas can be seen in as many as 20% of lesions.  CT scan is superior in its ability to detect lesions less than 1 cm.  This technique also enables the evaluation for an underlying concurrent pathology throughout the abdomen and pelvis. Indium-labeled WBC scans are somewhat more sensitive in this regard.

CT examination: Unenhanced axial scan: Round-shaped, hypodense masses of 5-6 cm of diameter, with isodense wall, are visible in both liver lobes (arrows). A small amount of hypodense fluid is observed within the liver capsule

CT examination: Postcontrast axial scan The irregular hypodens lesions of variable sizes (arrows) are better visualized in the contrast-enhancing liver parenchyma.

 Basilar atelectasis  Right hemidiaphragm elevation  Right pleural effusion are present in approximately 50% of cases  Before advancements in radiologic technique, these served as diagnostic clues.

Drainage, either percutaneous or surgical, is the mainstay of therapy for intraabdominal abscess ◦ Percutaneous needle aspiration ◦ Percutaneous catheter drainage ◦ Surgical drainage (open or laparoscopic) ◦ Medical therapy

 Solitary dominant abscess  Under CT scan or ultrasound guidance, needle aspiration of cavity material can be performed.  Needle aspiration enables rapid recovery of material for microbiologic and pathologic evaluation. ◦ Gram’s stain and culture  Needle aspiration can be performed with the initial diagnostic procedure.

Complex abscess or an abscess containing particularly thick fluid Small cysts  A catheter is placed under ultrasound or CT guidance using the Seldinger technique  The catheter is flushed daily until output is less than 10 cc/d or cavity collapse is documented by serial CT scanning.  Multiple abscesses have been drained successfully by this method.  Failure to respond to catheter drainage is the main reported complication and is also an indication for surgical intervention.

Was the standard of care until the introduction of percutaneous drainage techniques in the mid 1970s For cysts greater than 5 cm Ruptured cysts Multiloculated cysts Failure of percutaneous drianage  Lack of response in 4-7 days

 Diagnostic aspirate of abscess should be obtained before initiation of empirical therapy ◦ Empiric drug therapy – covering gram negative aerobic, facultative and anaerobic organisms ◦ Adjusted to specific antibiotic when results for Gram’s stain and culture become available

 Hydatid disease ◦ Oral antihelmintics, albendazole, is the mainstay of treatment ◦ For those with anatomically appropriate lesions PAIR: percutaneous aspiration, instillation of absolute alcohol, respiration ◦ If refractory to PAIR: open/laparoscopic cyst removal with instillation of scolicidal agent

 Amebiasis ◦ Metronidazole for at least 1 week ◦ Most patients will respond rapidly with complete defervescence within 3 days. ◦ Aspiration of the abscess is rarely necessary and should be avoided, except in patients in whom secondary infection from pyogenic organisms is suspected.