**2. Ventriculoperitoneal shunt**

VP shunts are comprised of a proximal inflow catheter, reservoir, valve mechanism, and a distal outflow catheter. The proximal catheter generally lies in the trigone of the lateral ventricle; however it can be inserted in the frontal horn if it follows an internalization of an external ventricular drain. The proximal catheter leads into the reservoir, which contains a small collection of CSF used for samples or to obtain pressure measurements. A retro-auricular unidirectional valve follows the reservoir and is responsible for controlling the flow of CSF into the distal catheter. The distal catheter then travels subcutaneously from the valve into the right upper abdominal quadrant where the excess CSF can freely drain into the peritoneal cavity [4, 8].

Although a commonly relied upon procedure to treat hydrocephalus, VP shunts are not without complications and failures. VP shunts are subject to a variety of complications of mechanical, functional, and infectious nature [6]. Mechanical complications consist of complications inhibiting the shunt from functioning, including shunt migration, obstruction, malpositioning, disconnection, and fracture. Contrarily, functional complications involve improperly functioning shunts such as overdrainage or underdrainage [6]. Finally, shunts are subject to various infections, the majority arising from normal skin flora and occurring within 30 days of surgery [3]. Current studies suggest an overall infection rate of 8.4% and a shunt failure rate, defined as a catheter-related problem necessitating surgical intervention [9], of 51.4% [10]. It has been shown that patients require 2–3 surgical revisions on average due to shunt failures in the 20 years after the original shunt placement [8], with the majority of shunt revisions occurring in the first 6–12 months [4, 8]. Specifically, 25–30% of all shunt revisions result from distal peritoneal catheter failure [5, 11, 12], such as preperitoneal placement, obstruction due to adhesions or pseudocysts, and malabsorption with secondary ascites [12].
