Resumen: Unexpected hospitalization in ambulatory surgery is normally due to inadequate selection of patients, procedures more extensive than those originally planned or postoperative complications. In 18 months, 1000 patients from six different surgical specialties were scheduled for day surgery at a university hospital. Local anesthesia was used in 33.4% of cases, spinal in 31.9%, general in 21.9%, intravenous in 5.7%, epidural in 3.4% and other types in 3.7%. The most frequent procedures were: hernioplasty157, herniorrhaphy 131, subcutaneous tumor excision 117, surgical metal extraction 71, laryngeal microsurgery 66 and hydrocoele surgery 62. A total of 11.7% of patients developed some minor complications: urinary retention, wound infection, vomiting, inadequate pain control or wound hematoma. A total of 4.7 of patients needed to be hospitalized and 1.4% readmitted. The most important reasons for these admissions were nausea–vomiting, dizziness, fever, social problems and surgical difficulties. The incidence of complications and unplanned admissions were influenced by anaesthetic techniques and type of pathology but not by age of patients, sex or their ASA physical status. Idioma: Inglés Año: 1998 Publicado en: Ambulatory surgery 6, 3 (1998), 163-167 ISSN: 0966-6532 Tipo y forma: Artículo (Versión definitiva) Área (Departamento): Área Otorrinolaringología (Dpto. Cirugía,Ginecol.Obstetr.) Área (Departamento): Área Cirugía (Dpto. Cirugía,Ginecol.Obstetr.)