Objective: Determine the recent incidences of and reasons for anesthesia related to unplanned admissions. The secondary outcome was to determine factors and complications following ambulatory surgery at Ramathibodi Hospital.

Material and Method: A retrospective study was conducted by reviewing medical records of all unplanned admissions between 2008 and 2012 in Ramathibodi Hospital.

Results: Over the five-year period, 10,489 patients underwent ambulatory surgery, 67 of whom were admitted for anesthesia-related reasons. The incidence rate of anesthesia related to unplanned admissions was 0.64% (67/10,489). The most common indications for admission were intractable vomiting (40.30%), dizziness (19.40%), and somnolence (8.96%). Most of the complications were nausea, vomiting, pain, and dizziness. The majority of the admitted patients were female and aged 41 to 50 years (29%), and 88% had ASA physical status class I or II. Gynecological patients had the highest unplanned admission rate (35.82%). None of the patients developed cardiac arrest or died.

Conclusion: The recent incidence rate of unplanned admissions at Ramathibodi Hospital was 0.64%. The most common reason and complication was intractable vomiting. Factors that might be related to unplanned admissions were female gender, age between 41 and 50 years, ASA physical status I or II, and gynecological patients.

Keywords: Ambulatory surgery, Day surgery, Unplanned admission, Anesthesia for OPD patient