In the emergency department (ED) setting, prioritizing triage and patient care may lead to challenges in capturing detailed documentation necessary for specific International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) coding in medical records. Consequently, the prevalent use of the "unspecified head injury" code poses concerns about the precision of ED-based administrative billing claims data when analyzed for public health surveillance of nonfatal traumatic brain injuries (TBIs). Understanding the perspective of medical coders can illuminate coding processes and opportunities to enhance coding accuracy for TBI and other head injuries in the ED. This evaluation explores medical coders' perspectives and challenges when assigning ICD-10-CM codes to head injuries in the ED. This qualitative evaluation utilized a phenomenological approach, which employed semi-structured interviews to understand medical coders' perspectives, processes, and coding determinations for head injuries in the ED. Interviews were conducted using a HIPAA-compliant video-based platform between July 2022 and January 2023. Seventeen medical coders with ED coding experience were interviewed. Their backgrounds were diverse, though most had more than 15years of experience. Four qualitative themes emerged, which highlighted challenges with lack of detailed documentation, defaulting to unspecified codes, time, and productivity pressure, and additional insights into coders' assumptions and code determination processes. Medical coders expressed challenges assigning ICD-10-CM codes to the highest level of specificity, citing issues including insufficient documentation by ED providers and terminology variations. Workplace time constraints and pressure for expedited claims also led to defaulting to unspecified codes. This evaluation highlights the need for improved documentation consistency and detail in ED records to facilitate accurate ICD-10-CM coding. Alleviating time pressures, improving algorithms, and offering specialized training opportunities to medical coders could be helpful steps to improve coding specificity and data accuracy for head injuries in the ED.