A 26-year-old man is brought to the emergency department with a stab wound to the right side of the back just medial to the posterior axillary line. His blood pressure is 120/80 mm Hg, pulse rate is 98 bpm, and respiration rate is 22 breaths per minute. Physical examination reveals no abdominal tenderness, guarding, or neurologic changes. Local exploration of the stab wound is performed using local anesthesia. The track to the wound ends in the paraspinal muscles. What would be the next step in management?

A patient with definitive negative findings on wound exploration can be discharged from the hospital for outpatient follow-up care. It is sometimes difficult to determine the depth of a stab wound to the back because of the thickness of the paraspinal muscles. Some authors have found that nearly 20% of patients with such injuries have negative findings on exploration. Such patients can be discharged. Deeper stab wounds to the back may injure peritoneal structures without penetration of the peritoneal cavity. Thus, peritoneal lavage is less useful than a CT scan with intravenous, oral, and (particularly) rectal contrast to rule out retroperitoneal colon injuries.