| disease | Bacterial Liver Abscess |
Pyogenic infections in any part of the body can potentially lead to bacterial liver abscesses. In recent years, the prognosis of this severe abdominal condition has improved due to the application of new antibiotics, advancements in ultrasound imaging, and the widespread use of ultrasound-guided liver puncture techniques.
bubble_chart Etiology
Source, route, and pathogens of infection: Pyogenic infections in various parts of the body, especially intra-abdominal infections, can enter the liver through the following pathways: ① Biliary tract: Reports indicate that approximately 22–52% of bacterial liver abscesses originate from biliary tract inflammation, including gallstones, cholecystitis, biliary ascariasis, and other causes of bile duct stenosis and obstruction. ② Portal vein: All intra-abdominal and gastrointestinal infections can enter the liver via the portal vein. In the past, the most common source of bacterial liver abscesses was suppurative appendicitis, accounting for 30–50%, but this has now been surpassed by biliary tract infections. Other sources include ulcer disease, diverticulitis, ulcerative colitis, large intestine cancer with infection, and hemorrhoid infections. ③ Hepatic artery: Systemic or localized pyogenic diseases, such as sepsis, suppurative osteomyelitis, boils, subacute bacterial endocarditis, and respiratory infections, can enter the liver through the hepatic artery. This route accounts for about 10% of bacterial liver abscesses. ④ Direct spread from adjacent pyogenic inflammatory tissues or organs: These include the gallbladder, right kidney, ulcer perforation, pancreas, and subphrenic abscess. ⑤ Other causes include trauma, foreign bodies, and cases of unknown origin. Pus cultures indicate that Gram-negative bacteria are more common than Gram-positive bacteria, with frequent isolates being Escherichia coli, streptococci, and staphylococci. Others such as Proteus, Pseudomonas aeruginosa, Aerobacter, Salmonella, and fungi have also been reported. Mixed infections are more common than single bacterial infections. Bacterial liver abscesses can be multiple or solitary, with multiple abscesses being more common, and the right lobe is affected far more often than the left. Weakened immune resistance is also an important internal factor in the pathogenesis of this disease.
bubble_chart Clinical ManifestationsDue to the liver's abundant blood supply, once purulent infection occurs, it can rapidly lead to significant systemic symptoms and worsen markedly within a short period. Clinically, it is common to observe certain precursor purulent infections first, such as biliary tract inflammation or suppurative appendicitis, followed by shivering, high fever, liver pain, rapid liver enlargement, elevated white blood cell count, accompanied by lack of strength, poor appetite, nausea, and vomiting. In severe cases, systemic septic symptoms may appear. Liver pain is a symptom with relatively high localization value, mostly caused by rapid liver enlargement and expansion of the liver membrane, resulting in dull pain that is persistent; however, some may experience distending pain, burning pain, throbbing pain, or even colicky pain. If the abscess irritates the right diaphragm, it may cause right shoulder or back pain. Fever is often of the remittent type, moderately high, and usually accompanied by shivering and sweating, though about 15% of cases may present without fever. Symptoms of multiple abscesses are typically more severe than those of a single abscess. Severe cases may develop jaundice. Liver abscesses can also rupture into adjacent cavities, leading to thoracic or pulmonary infections, subphrenic abscesses, peritoneal membrane inflammation, pelvic abscesses, etc. If complications are already present at the time of consultation, they often complicate the diagnosis. Reactive effusion in the right thoracic cavity due to abscesses in the upper right liver is not uncommon.
Signs of bacterial liver abscess include: a severely ill appearance, possible grade I jaundice, liver enlargement with tenderness or percussion pain. If the abscess is located in the upper part, it may show an elevated upper liver border or signs of right pleural effusion. The skin over the liver abscess area may exhibit pitting edema or even local swelling. Laboratory tests may reveal a significant increase in white blood cells, with neutrophils accounting for about 90%, and in severe cases, a left shift may occur.
Ultrasonography is of significant value in the diagnosis, localization, and dynamic observation of liver abscesses, and can also determine the number of abscesses. Once an abscess forms and liquefaction occurs, ultrasound often reveals a poorly defined fluid-filled space-occupying lesion. However, for abscesses that have not yet liquefied or those smaller than 2 cm, ultrasound may not provide a definitive diagnosis in a single examination, necessitating repeated follow-up scans.
Diagnosis is generally not difficult. In patients with suppurative diseases, the sudden onset of marked shivering, high fever, liver pain with tenderness on percussion, hepatomegaly, and elevated white blood cell counts suggesting bacterial infection should raise suspicion of bacterial liver abscess. If ultrasound shows a poorly defined fluid-filled space-occupying lesion, the diagnosis can be established. If pus is obtained via ultrasound-guided percutaneous liver aspiration, the diagnosis is confirmed, and the pus can be cultured to guide treatment.
bubble_chart Treatment Measures
According to domestic data, the mortality rate of bacterial liver abscess treated by various methods is approximately: about 20% for antibiotic therapy alone, and about 15% for antibiotics combined with puncture and aspiration or incision and drainage. However, the mortality rate of multiple abscesses is significantly higher than that of single abscesses. This disease should be treated as a systemic sexually transmitted disease, with the following key points: ① Based on the analysis of the primary infection site, appropriate antibiotics should be selected and adjusted after obtaining bacterial culture results. ② Great importance should be attached to systemic supportive therapy. ③ Appropriate combination with Chinese medicinals treatment. ④ For liquefied and mature abscesses, small and multiple abscesses should be treated with medication alone, while single large abscesses or those with larger abscesses can undergo repeated puncture and aspiration under ultrasound guidance, with antibiotics injected into the abscess cavity. Alternatively, a catheter can be percutaneously inserted for drainage. ⑤ Under the current conditions of better antibiotics and more accurate ultrasound localization, surgical incision and drainage are less commonly used. However, for cases with severe systemic toxic symptoms, large abscesses at risk of rupture, multiple adjacent abscesses where puncture cannot achieve adequate drainage, or cases where medication fails to control rapid progression, incision and drainage may be considered as appropriate. ⑥ Corresponding treatment for the primary suppurative lesion.
The key to puncture and aspiration under ultrasound guidance lies in accurate localization, avoiding entry into the thoracic cavity, and using appropriately sized needles; sometimes a silicone or plastic tube can be percutaneously inserted for continuous drainage.
Incision and drainage are currently mostly performed via the abdominal approach, typically through a right subcostal oblique incision. Under strict protection of the abdominal cavity and organs, the abscess cavity is incised, pus is rapidly aspirated, and a latex tube with side holes is used for drainage. Sometimes a small plastic tube can be attached to the latex tube for postoperative antibiotic injection. For abscesses located posteriorly in the right liver, incision and drainage can also be performed via the extraperitoneal route, usually through an incision in the right twelfth rib bed, with fingers entering the abscess cavity through the retroperitoneal space above the right kidney. This method is now rarely used. Chronic localized liver abscesses that fail to heal after prolonged treatment may also be surgically resected.
Key points for differential diagnosis: ① Amebic liver abscess: Often has a history of amebic dysentery; onset is slower, course is longer, symptoms are milder, and significant toxemia is rare; pus resembles chocolate, usually lacks bacteria but often shows amebic trophozoites; amebic trophozoites may also be detected in stool; anti-amebic treatment is effective. ② Subphrenic abscess: Often has a history of ulcer perforation, appendiceal perforation, or other peritonitis, or follows abdominal surgery; systemic symptoms are generally milder than bacterial liver abscess; careful ultrasound imaging can usually distinguish between intrahepatic and extrahepatic abscesses. ③ Intrahepatic bile duct stones with infection: Difficult to differentiate, but clinical symptoms are usually milder; ultrasound often aids in diagnosing intrahepatic stones. ④ Liver cancer with cancer-related fever: Early bacterial liver abscesses that have not fully liquefied may sometimes need differentiation from liver cancer with cancer-related fever, while liver cancer with necrotic liquefaction may resemble solitary bacterial liver abscess. Typically, cancer-related fever in liver cancer lacks chills, and local hepatic inflammation (e.g., pitting edema, marked tenderness) is absent; although leukocyte counts may rise, neutrophil levels are not significantly elevated; there is often a background of hepatitis or cirrhosis; 70% of patients have elevated alpha-fetoprotein (AFP); ultrasound shows a well-defined, encapsulated solid mass; other localization diagnostic methods can also aid differentiation. Right lower lobe pneumonia may present with symptoms similar to liver abscess, but differentiation is straightforward with chest X-ray and liver ultrasound.
