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SU28.10 | Liver Abscess, Hydatid Disease, Liver Injury and Liver Tumors — SDL Guide

Learning Objectives

• Describe the applied surgical anatomy of the liver and use it to explain the behaviour of focal liver lesions.
• Differentiate amoebic from pyogenic liver abscess, recognise hydatid disease, and outline the principles of managing each.
• Explain the assessment and management of liver injury and the approach to benign and malignant liver tumours.

INSTRUCTIONS

Right upper quadrant pain with fever, a mass found on a scan, or a liver laceration after blunt trauma — all bring the surgical liver into the clinic and the emergency room. This SDL builds from the patient's presentation, through the anatomy and pathology that explain it, to the investigations and the principles of management. Read it actively: at each step ask yourself why the anatomy makes a lesion behave as it does, and why one abscess is drained, another is never aspirated blindly, and a stable liver injury is often best left alone.

References

• Bailey & Love's Short Practice of Surgery, The Liver (textbook)
• SRB's Manual of Surgery, Liver (textbook)
• Sabiston Textbook of Surgery, The Liver (textbook)

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The Patient with Liver Disease: Presentations You Must Recognise

Surgical liver disease announces itself in a handful of recognisable ways, and the pattern of presentation already narrows the differential before any test is ordered. The first is the febrile, painful liver: a patient with fever, right upper quadrant pain, tender hepatomegaly and often a history of dysentery or travel suggests a liver abscess — amoebic or pyogenic. The second is the incidental or slowly enlarging mass: a smooth cystic swelling found on a scan, sometimes with a vague dragging discomfort, which may be a hydatid cyst or a benign tumour, while a hard, irregular liver with weight loss and a background of cirrhosis points to hepatocellular carcinoma. The third is the injured liver: blunt abdominal trauma from a road accident or fall producing right-sided pain, abdominal distension and signs of blood loss. Pain referred to the right shoulder tip (diaphragmatic irritation) and a reactive right basal lung crackle or effusion are clues common to abscess, large tumour and injury alike. A careful history of fever pattern, dysentery, contact with dogs and sheep, alcohol intake, viral hepatitis and trauma mechanism is therefore the most powerful diagnostic tool you have at the bedside, and it should be taken before you reach for imaging.

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The competency groups these problems together for a reason: they share an organ and an anatomy but demand very different responses. Sorting the presentation into one of these four buckets — abscess, hydatid, injury, tumour — is the first clinical task.

• Liver abscess — fever, RUQ pain, tender hepatomegaly; amoebic (single, right lobe, history of dysentery) vs pyogenic (often multiple, biliary or portal source)
• Hydatid disease — slow-growing cystic mass, often asymptomatic; contact with dogs, sheep-rearing area; risk of rupture and anaphylaxis
• Liver injury — trauma history, haemorrhagic shock, right-sided abdominal pain and distension
• Liver tumours — benign (haemangioma, focal nodular hyperplasia, adenoma) usually incidental; malignant HCC (cirrhosis, hepatitis, weight loss, raised AFP) or secondary metastases

Applied Anatomy and the Pathology of Liver Lesions

The behaviour and the surgery of every liver lesion follow from the liver's functional anatomy, so this is where understanding must start. The surgically useful map is Couinaud's segmental anatomy, which divides the liver into eight functionally independent segments, each supplied by its own portal pedicle (a branch of the portal vein, hepatic artery and bile duct) and drained by the hepatic veins that run between the segments. Because each segment is self-contained, a surgeon can resect one or several without devascularising the rest — this is the anatomical basis of anatomical liver resection. The old division into right and left lobes by the falciform ligament is a surface marking only; the true functional division runs along the plane of the middle hepatic vein (Cantlie's line). The ligamentum teres within the free edge of the falciform ligament is the remnant of the umbilical vein. The liver's dual blood supply also explains pathology: the portal vein delivers gut organisms to cause pyogenic abscess, while the rich arterial supply makes injured or resected liver bleed briskly.

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The pathology of each problem can now be understood against this background. Amoebic abscess results from Entamoeba histolytica trophozoites reaching the liver through the portal vein from colonic infection; they cause liquefactive necrosis producing the classic "anchovy-sauce" (reddish-brown) sterile pus, usually a single cavity in the right lobe. Pyogenic abscess is bacterial (often polymicrobial, including E. coli and anaerobes) and arises from biliary disease, portal pyaemia (e.g. appendicitis), or haematogenous spread; abscesses are frequently multiple. Hydatid disease is caused by the larval stage of the tapeworm Echinococcus granulosus; humans are accidental intermediate hosts who ingest eggs shed by dogs, and the larva forms a slowly expanding cyst with a laminated wall and daughter cysts containing infective scolices. Liver tumours include benign lesions (haemangioma — the commonest, a vascular malformation; focal nodular hyperplasia; and hepatic adenoma, linked to oral contraceptives) and malignant lesions — primary hepatocellular carcinoma arising on a background of cirrhosis, hepatitis B or C, and secondary metastases, which are in fact the commonest malignant liver tumours overall.

Examination and Investigation of the Liver Lesion

Examination begins with the general state — fever, weight loss, jaundice, pallor, signs of chronic liver disease — and proceeds to the abdomen, where you palpate for tender or non-tender hepatomegaly, assess its surface (smooth in abscess and hydatid, hard and irregular in malignancy), and check for ascites, a palpable gallbladder and splenomegaly. In trauma you are looking instead for the signs of intra-abdominal haemorrhage: tachycardia, hypotension, abdominal distension and tenderness. Investigation is then directed by the suspected diagnosis. Ultrasound is the first-line imaging in almost every case — cheap, quick and excellent for distinguishing solid from cystic, locating an abscess for drainage, and showing the daughter cysts and laminated membrane of hydatid disease. Contrast-enhanced CT characterises lesions further, defines segmental anatomy for surgery, stages tumours, and in trauma grades the injury and detects active bleeding. Blood tests include a full blood count (leucocytosis in abscess), liver function tests, and serology: amoebic serology is positive in most invasive amoebic disease, and Casoni's test and hydatid (echinococcal) serology support hydatid disease. The tumour marker alpha-fetoprotein (AFP) is often markedly raised in hepatocellular carcinoma, though a normal level does not exclude it.

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A crucial safety rule belongs here. A cystic liver lesion that might be hydatid must never be aspirated blindly for diagnosis, because spillage of cyst fluid can trigger fatal anaphylaxis and disseminate daughter cysts throughout the peritoneum. Diagnosis of hydatid rests on imaging plus serology, not on a diagnostic tap. By contrast, an amoebic or pyogenic abscess can be safely aspirated under ultrasound guidance when needed — confirming the diagnosis (anchovy-sauce pus, or pus that grows organisms) and relieving the cavity.