A 29-year-old primigravida at 34 weeks' gestation presents with new-onset headache, visual disturbance and right upper quadrant discomfort. Her blood pressure is 168/112 mm Hg, and urinalysis shows 3+ protein. Reflexes are brisk with no clonus. Fetal movements are present. According to SOGC guidance, what is the most appropriate immediate management priority?