Intra-operative pulmonary embolism. Detection by pulse oximetry.

A case is presented of a 49-year-old patient who had a pulmonary embolism during ovarian cystectomy. The only evidence of its occurrence was a sudden, marked reduction in arterial oxygen saturation as detected by a pulse oximeter. The diagnosis was confirmed 24 hours later by a chest radiograph and a ventilation perfusion scan. Anticoagulant treatment was instituted.