Routine versus clinically indicated cerebrospinal fluid sampling for infection in external ventricular drains: a systematic review.

BACKGROUND: External ventricular drains (EVDs) are commonly used in neurosurgery but carry a risk of ventriculostomy-related infection. Routine cerebrospinal fluid (CSF) sampling is commonly performed for surveillance, although its clinical value and potential risks are still uncertain. METHODS: A systematic review was performed following PRISMA 2020 guidelines. PubMed was searched from inception to identify studies assessing CSF sampling strategies and/or clinical and laboratory screening for infection in patients with EVDs. Eligible studies included retrospective and prospective cohorts, case-control, and case series reporting infection-related outcomes. Data were extracted and categorized by causal relevance. Due to heterogeneity in studies, findings were summarized descriptively. RESULTS: Fourteen studies were included, covering various study designs and sampling methods. Only 2 studies directly compared routine versus clinically indicated CSF sampling and found no benefit of routine daily sampling for detecting or reducing infections. Most studies were noncomparative and demonstrated the limited predictive value of routine clinical and laboratory parameters. Indirect evidence suggested that catheter duration, system manipulation, and patient-related factors were more strongly associated with infection risk than sampling frequency. Infection rates across studies ranged from 4.1% to 16.3%, with considerable variation in definitions and methodologies. CONCLUSION: Routine CSF sampling is not supported by high-quality evidence as a strategy to improve detection or prevent EVD-related infections. A selective, clinically guided approach may be more appropriate, with emphasis on reducing catheter manipulation and optimizing overall catheter management. Further prospective studies with standardized protocols are necessary to clarify the role of CSF sampling strategies.