Communicating hydrocephalus

This code signifies a condition where there is an abnormal accumulation of cerebrospinal fluid (CSF) within the brain's ventricles due to impaired reabsorption or obstruction of CSF flow outside the ventricular system. The CSF pathways between the ventricles and the subarachnoid space remain open, allowing communication. This leads to increased intracranial pressure and potential neurological deficits.

Use this code when documentation clearly indicates hydrocephalus where the obstruction or reabsorption defect is distal to the ventricular system, such as in the subarachnoid space or arachnoid granulations. This diagnosis is often supported by imaging studies (CT, MRI) showing ventricular enlargement without evidence of intraventricular obstruction.

• Differentiate carefully from obstructive (non-communicating) hydrocephalus, where the obstruction is within the ventricular system.
• Always look for the underlying cause of the communicating hydrocephalus, if known, and code it as a primary diagnosis when appropriate.
• Documentation should specify "communicating" or describe a mechanism consistent with communicating hydrocephalus.