Diagnostic Testing

A diagnostic test is useful only when its result can be obtained safely, interpreted in context, and connected to a decision. The nurse therefore assesses more than whether a test has been ordered. The clinical question, pretest probability, timing, specimen or image quality, patient preparation, baseline status, and follow-up plan all determine whether the result clarifies risk or creates false reassurance. The most consequential hazards are often predictable. Iodinated contrast may cause an acute hypersensitivity reaction and can contribute to kidney injury in a small, high-risk group. Sedation can impair ventilation before oxygen saturation falls. Anticoagulants can turn a biopsy or endoscopic intervention into a bleeding emergency. MRI equipment can transform an unrecognized ferromagnetic object into a projectile. Safe preparation prevents these complications rather than merely documenting them afterward.