A nurse is providing care for a client who is scheduled for electroconvulsive therapy. Which of the following conditions should the nurse identify as an increased risk for complications?

A. Renal calculi are unrelated to the safety of ECT and do not pose specific risks during the procedure. B. Subdural hematoma increases intracranial pressure, and the seizure activity induced by ECT can exacerbate cerebral injury or bleeding. This condition poses a significant contraindication or high-risk factor for ECT. C. Hyperthyroidism may increase metabolism but does not directly contraindicate ECT; it simply requires monitoring for tachycardia. D. Diabetes mellitus requires glucose monitoring before and after ECT but is not a contraindication or major complication risk.