Operative hysteroscopy intravascular absorption (OHIA) syndrome presenting with severe hypoxemia and abnormal carboxyhemoglobin elevation.

A 40 years old woman undergoing elective hysteroscopic myomectomy under general anesthesia developed progressive hypoxemia and severe metabolic acidosis. The primary etiology was Operative Hysteroscopy Intravascular Absorption (OHIA) syndrome, resulting from massive normal saline irrigation (approximately 18 L used) leading to dilutional hyperchloremic metabolic acidosis and pulmonary edema. Intraoperatively, a sudden drop in end-tidal carbon dioxide (EtCO2) and an incidental elevation in carboxyhemoglobin (COHb) of 15.7% were noted. This COHb elevation was suspected to be due to spectrophotometric interference by dissolved hydrogen gas generated during bipolar electrosurgery, which might have indirectly suggested a concurrent, transient venous gas embolism. However, OHIA remained the principal driver of hypoxemia and clinical deterioration. Management included fluid restriction, diuretics, steroids, and supportive ventilation. The patient recovered uneventfully. This case highlights the dominant role of OHIA in prolonged high-pressure hysteroscopy, with artifactual COHb elevation serving as a potential (though non-definitive) ancillary clue to intravascular gas entry.