American Society for Clinical Pathology (ASCP) Histotechnician Certification Practice Exam

The correct duration for leaving iodine on the venipuncture site when preparing for blood culture collection is 20 seconds. This timing is crucial because it allows the iodine sufficient time to effectively disinfect the skin surface and reduce the microbial load at the site. Leaving iodine for 20 seconds ensures that it penetrates the skin and works against a wide range of bacteria, minimizing the risk of contamination during the blood culture process. This period strikes a balance between effective disinfection and practical application, making it a standard practice in clinical settings. In contrast, shorter durations like 10 or 15 seconds may not provide adequate disinfection, potentially leading to contamination of the blood culture. Leaving the iodine on for a full 30 seconds might not be necessary and could extend the procedure unnecessarily without significantly increasing the disinfection efficacy. Thus, 20 seconds is the recommended guideline in this scenario.