Postoperative abscess following wedge hepatic resection

Clinical History

A woman with history of radical hysterectomy for endometrial adenocarcinoma, two neoplastic recurrences at the vaginal stump respectively treated with brachytherapy and colpectomy, underwent surgical excision of metachronous liver metastasis.
Postoperatively, she suffered from fever. Biochemistry showed blood loss (haemoglobin 8.4 g/dl), leukocytosis and increased C-reactive protein (243 mg/l).

Imaging Findings

Compared to previous studies preoperative multidetector CT (Fig. 1) showed appearance of an isolated 7 mm metastasis in the fifth liver segment.
On fifth postoperative day, emergency CT (Fig. 2) showed a large subcapsular abscess collection originating from the liver resection site, containing sparse gas bubbles and a 3 cm confluent discoidal structure (Fig. 2f, g) with predominant gas-like attenuation consistent with the bioabsorbable haemostatic agent positioned intraoperatively; right-sided pleural effusion and pneumonic-atelectatic consolidation; patent hepatic veins and portal venous system.
Percutaneous drainage (Fig. 3) yielded Staphylococcus aureus-positive pus. The patient’s clinical conditions and laboratory assays slowly improved. Repeated CT six days after drainage (Fig. 4) and 25 days after surgery (Fig. 5) showed cleared lung base, disappearance of pneumoperitoneum, initial decrease of the postoperative abscess and of the haemostatic agent.
After replacement with a multi-hole drainage (Fig. 6) the abscess regressed (Fig. 7) and ultimately disappeared at 6-month follow-up (Fig. 8) without signs of local or distant neoplastic recurrence.

Discussion

Liver surgery (LS) allows treatment of hepatocellular carcinoma, metastases from colorectal, neuroendocrine and selected other primary malignancies, intrahepatic stones, and indeterminate or benign lesions requiring removal. Mostly performed using laparotomy, LS encompasses anatomical (left, right or extended lobectomy, single or multiple segmentectomy) and non-anatomical (wedge, atypical) resections, plus open or laparoscopic cyst fenestration. Due to the complex vascular and functional anatomy, LS is challenging and associated with high (20-50%) morbidity, and a non-negligible in-hospital mortality (<4-5%) which significantly differs between patients with liver metastases (2.6%) and chronic liver disease (7.4%) [1, 2].
Post-hepatectomy infectious complications (PHICs) result from accumulation of blood, bile and sloughed devitalized tissue in the dead space created at the resection site, plus contamination through the drain. Causative bacteria include Gram-negative, Streptococcus and Staphylococcus species, commonly mixed. PHICs occur within 5-8 weeks in 8-12.8% of operated patients, and are favoured by advanced age, comorbidities, major resection, pre-existing liver impairment, portal hypertension, long operation time and high intraoperative blood loss. Sepsis, abdominal pain and peritonitis, worsening function tests or acute phase reactants should not be underestimated since PHICs cause or aggravate liver dysfunction, require intensive antibiotics, prompt imaging diagnosis and drainage, and result in significant mortality (18%) [1-5].
Multidetector CT is invaluable to promptly detect and follow-up treatable complications. Expected imaging findings include hypertrophy from regeneration of remnant liver (limited in cirrhosis, takes approximately 8-12 weeks); shift of abdominal organs; transient pneumoperitoneum; surgical drains; metallic clips and nonenhancing serous, bloody or biliary collections at the surgical site; fatty areas corresponding to omentoplasty [6-8].
Besides PHIC, the commonest complications include right-sided pleural effusion, atelectasis or pneumonia; temporary or worsening liver failure; haematoma at site of resection (20-25% of patients); homogeneous fluid-attenuation biloma (5%), acute pancreatitis; thrombosis of hepatic vein, segmental branches (6%) or main portal vein (3%); wound infection; deep venous thrombosis or pulmonary embolism [1, 3-8].
As this case exemplifies, abscesses appear as hypoattenuating (20-40 Hounsfield Units) collections with peripheral enhancement, gas bubbles or gas-fluid level that occupy the subphrenic space or the resection site. Alternatively, air-like attenuation may result from puncture, or correspond to pieces of biologically absorbable haemostatic agents such as Gelfoam®) or Surgicel®) with interspersed gas foci, which are often placed intraoperatively to control bleeding and can potentially be confused with an abscess. The differentiation should rely on knowledge of surgical details, arrangement of gas bubbles in linear fashion, and regression on serial scanning [6-8].

Differential Diagnosis List

Final Diagnosis

Abscess following wedge hepatic resection, treated with percutaneous drainage.

URL:	https://www.eurorad.org/case/12794
DOI:	10.1594/EURORAD/CASE.12794
ISSN:	1563-4086