The etiology, frequency, and prevention of gas embolism during CO(2) hysteroscopy.

STUDY OBJECTIVES: To assess the frequency of clinically apparent and undetected cardiopulmonary emboli during diagnostic CO(2) hysteroscopy, to determine the causes of these events, and to define a risk profile.

DESIGN: Retrospective and prospective case study (Canadian Task Force classification II-2).

SETTING: Obstetric-gynecologic clinic of an academic teaching hospital.

PATIENTS: Five thousand one hundred ninety-three women.

INTERVENTION: Diagnostic CO(2) hysteroscopy performed between September 1990 and December 1998.

MEASUREMENTS AND MAIN RESULTS: From September 1990 to December 1996, 1 (0.03%) severe but nonfatal embolism occurred in 3932 diagnostic CO(2) hysteroscopies. Undetected emboli were present in 20 patients (0.51%). Starting in January 1997 the gas supply tube (volume 40 ml) was deaerated before the procedures, and no emboli occurred in the next 1261 examinations up to December 1998. The decrease in frequency was statistically significant (p = 0.009). No pathologic flow sounds were found in any of 50 hysteroscopies monitored by Doppler stethoscope.

CONCLUSION: A manifest gas embolism is rare in diagnostic CO(2) hysteroscopy. The 10% to 50% frequency of undetected gas emboli cited by other authors could not be confirmed. If the supply tube system that holds room air is purged with CO(2) before the procedure, the already low risk drops to zero or almost zero, confirming the theory that emboli that occur during CO(2) hysteroscopy are caused by room air.