ENDOMETRIAL ABLATION COMPLICATED BY FATAL HYPONATREMIC ENCEPHALOPATHY

Objectives.- To investigate the occurrence of hyponatremic encephalopa thy and the effects of therapy for symptomatic hyponatremia on outcome in women undergoing endometrial ablation. Design and Setting.- Consul tations from university-affiliated and community hospitals from June 1 991 to June 1992. Patients.- Four generally healthy women who underwen t elective endometrial ablation for dysfunctional bleeding and develop ed hyponatremic encephalopathy. Interventions.- Three patients were pr omptly treated with hypertonic (514 mmol/L) sodium chloride such that the serum sodium level increased from 102 to 123 mmol/L within 24 hour s. The fourth patient was not treated until after suffering grand mal seizures followed by respiratory arrest. Main Outcome Measures.- Of th e four patients who developed hyponatremic encephalopathy, the diagnos is was established before respiratory arrest occurred in three. The op erative procedure was terminated and all three were aggressively treat ed with intravenous hypertonic sodium chloride. which raised the serum sodium level to modestly hyponatremic levels (120 to 130 mmol/L). All three completely recovered without sequelae. The fourth patient suffe red respiratory arrest before therapy could be initiated. The patient remained comatose, and central diabetes mellitus and insipidus develop ed. She never regained consciousness and died after several days. Auto psy revealed cerebral edema and tonsillar herniation. Results.- The me an (+/-SD) preoperative serum sodium level was 138+/-1 mmol/L; at the time of diagnosis of hyponatremia, it was 107+/-13 mmol/L. In two pati ents, hyponatremic encephalopathy was diagnosed intraoperatively becau se of tremulousness and either hypothermia or hypoxemia. In the other two patients, the diagnosis was made postoperatively because of headac he, nausea, emesis, and in one of these patients, respiratory arrest. Conclusions.- Women undergoing elective endometrial ablation can devel op severe symptomatic hyponatremia, which can be fatal. The presence o f symptoms suggesting hypo-osmolality should lead to immediate measure ment of plasma sodium level. If hyponatremia with hypo-osmolality is p resent, early and appropriate therapy for the hyponatremia should be i nstituted before respiratory insufficiency occurs.