Patients with an unclear diagnosis or treatment plan often consider asking for a second opinion from another clinician. This systematic review found a limited body of literature addressing the outcomes of second opinions, but discovered evidence that some proportion of patients (ranging from 10% to 62% across studies) do receive different advice on diagnosis or treatment from a second clinician. According to another recent study (not included in this review), more than 40% of patient-initiated second opinions result in a change in diagnosis or treatment recommendations.