Primary bloodstream infections associated with central venous catheter (CLABSI) represent an important challenge in intensive care units (ICUs), especially in oncology patients due to immunosuppression. Early identification of factors related to the increase in these infections is essential for prevention and control. The Affinity Diagram is a tool that organizes ideas by similarity, promotes collective reasoning, and facilitates identification of causes and action planning. This study aimed to describe the identification, based on the nursing team’s perceptions, of factors associated with the increase in CLABSI in an oncology ICU, using the Affinity Diagram to support preventive interventions.

A qualitative, descriptive, exploratory study conducted by the infection control nursing team and the oncology ICU nursing team, with participation of about 40 professionals (nurses and technicians), distributed across two shifts. After presentation of data showing increased CLABSI and an explanation of the pathophysiology, participants answered—via post-its—the question: “Which factors may be contributing to the increase in CLABSI?” Responses were grouped into categories by similarity on a flip chart, followed by group discussion to identify critical points related to infection prevention.

Analysis of the 51 contributions revealed six main categories: hand hygiene (33.3%)—low adherence and lack of supplies; connector disinfection (17.6%); dressing (15.7%)—failures in changing, maintenance, and protection; CVC insertion (15.7%)—breaks in sterile technique and management of the first dressing; workload overload (9.8%)—high work demand; medication preparation (7.8%)—inadequate disinfection of ampoules and use of dirty trays. Based on the nonconformities identified, a workshop on Healthcare-Associated Infections (HAIs) was conducted with a focus directed toward CLABSI prevention.

The Affinity Diagram proved to be a useful tool to stimulate collective critical thinking, identify factors related to the increase in CLABSI, and support targeted educational actions. Active listening and team involvement were fundamental to align perceptions, strengthen good practices, and improve infection prevention in the oncology ICU.