When a person openly regrets their gender transition or detransitions this bolsters within the medical community an impression that transgender and non-binary (trans) people require close scrutiny when seeking hormonal and surgical interventions. Despite the low prevalence of regretful patient experiences, and scant empirical research on detransition, these rare transition outcomes profoundly organize the gender-affirming medical care enterprise. Informed by the tenets of institutional ethnography, we examined routine gender affirming care clinical assessment practices in Canada. Between 2017 and 2018, we interviewed 11 clinicians, 2 administrators, and 9 trans patients (total n = 22), and reviewed 14 healthcare documents pertinent to gender affirming care in Canada. Through our analysis, we uncovered pervasive regret prevention techniques, including requirements that trans patients undergo extensive psychosocial evaluations prior to transitioning. Clinicians leveraged psychiatric diagnoses as a proxy to predict transition regret, and in some cases delayed or denied medical treatments. We identified cases of patient dissatisfaction with surgical results, and a person who detransitioned. These accounts decouple transition regret and detransition, and no participants endorsed stricter clinical assessments. We traced the clinical work of preventing regret to cisnormativity and transnormativity in medicine which together construct regret as life-ending, and in turn drives clinicians to apply strategies to mitigate the perceived risk of malpractice legal action when treating trans people, specifically. Yet, attempts to prevent these outcomes contrast with the material healthcare needs of trans people. We conclude that regret and detransitioning are unpredictable and unavoidable clinical phenomena, rarely appearing in life-ending forms. Critical research into the experiences of people who detransition is necessary to bolster comprehensive gender affirming care that recognizes dynamic transition trajectories, and which can address clinicians' fears of legal action-cisgender anxieties projected onto trans patients who are seeking medical care.