Liver abscesses associated with ventriculoperitoneal shunt infection: A rare complication

A six-month-old male baby with history of ventriculoperitoneal (VP) shunt for hydrocephalus presented with 2 weeks history of fever and irritability. Total leukocyte count was elevated, and urinalysis showed acute urinary tract infection.

Grey scale ultrasound revealed few well-defined hypoechoic lesions with internal echoes in both lobes of the liver. VP shunt was seen in situ. There was minimal free fluid with internal septations in the peritoneal cavity. Few oedematous bowel loops were noted.
Contrast-enhanced CT (computed tomography) showed few peripherally enhancing intraparenchymal and subcapsular hypodense lesions along the course of the VP shunt, the largest approximately measuring 3.0 x 2.6 x 2.5 cm indenting segment V of the liver. Peripherally enhancing hypodense collections with multiple septations in the pelvis with minimal free fluid was also seen. A plain CT brain revealed communicating hydrocephalus with shunt in situ.

Ventriculoperitoneal shunt is commonly used to treat hydrocephalus whereby the peritoneal cavity is used for cerebrospinal fluid (CSF) absorption. It can be associated with abdominal complications such as shunt migration, blockage, retraction, infection, incisional hernia and peritoneal pseudocyst formation. Collections may form within the anterior abdominal wall after shunt placement. Other rarer complications include subphrenic abscess, intestinal perforation, volvulus and migration of the shunt into the pleural cavity and heart. Nearly half of the patients thus might need a revision shunt placement sometime. [1]
There have been cased reported in the literature where other organs may be perforated such as gall bladder, liver, stomach, uterus and urethra. [2] Obstruction of the distal catheter requires immediate attention as it can lead to increasing obstructive hydrocephalus, which can be avoided by early detection. Imaging techniques which aid in diagnosis include radiographs, ultrasound, CT and Magnetic Resonance Imaging (MRI).
Contrast-enhanced study can show peripheral enhancement around the abscess and bowel wall enhancement. Shunt infection most commonly occurs after six months of placement. [2] Patients usually present with prolonged fever, chills, vomiting and diarrhoea.  In the above case fluid aspirated from hepatic collection was cultured and showed Staphylococcus aureus. The child improved on antibiotic treatment. It may take 3 weeks to 5 years for the formation of an abdominal pseudocyst, although the duration may be longer. These can get secondarily infected. They can be differentiated from ascites by the pattern of displacement of the bowel loops due to the mass effect of the pseudocyst on ultrasound and abdominal radiographs. The standard treatment is immediate removal of the shunt combined with percutaneous or open drainage. [3] Aggressive antibiotic therapy is also needed in such cases. [4]

Intestinal perforation is another important rare complication which can subsequently lead to fatal meningitis. Shunt contrast studies have been described to assess the function of the shunt and to confirm shunt tip location. [5] Timely detection of complications by imaging can expedite proper neurosurgical care. [5]

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