Spinal anesthesia.
D000773:Anesthesia, Obstetrical; D000775:Anesthesia, Spinal / Q000009:adverse effects; D001808:Blood Vessels / Q000294:innervation; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007022:Hypotension / Q000503:physiopathology; D008297:Male; D011247:Pregnancy; D013564:Sympathetic Nervous System / Q000503:physiopathology