Rectus sheath hematoma (RSH) is a rare but potentially serious complication that can occur after abdominal paracentesis. Although RSH is often self-limited, it can lead to life-threatening conditions when diagnosis and/or treatment are delayed. In the neuro-intensive care unit, the diagnosis is often difficult to make or delayed because most patients have poor mental status and are unable to communicate their RSH-related symptoms. We report a case of a giant RSH detected by abnormal hemodynamic conditions on intensive care unit monitoring after abdominal paracentesis.