Perioperative testing is often approached differently by internists and anesthesiologists. While internists typically focus on long-term disease management, anesthesiologists interpret preoperative studies through the lens of acute perioperative physiology, anesthetic planning, and crisis preparedness. Surgery and anesthesia impose stressors such as hypovolemia, blood loss, arrhythmias, ischemia, and shifts in acid–base and electrolyte balance. Consequently, anesthesiologists emphasize how laboratory and imaging results will influence induction strategy, intraoperative monitoring, transfusion thresholds, and recovery planning. Key tests include a complete blood count, in which the hemoglobin level helps assess the likelihood of transfusion, while the platelet count informs the safety of neuraxial and certain regional anesthetic techniques. Electrolytes, renal function, and hepatic indices direct drug dosing, ventilation strategies, and coagulopathy assessment. Type and screen, along with coagulation studies, underpin transfusion planning and anesthetic technique selection, particularly for high-risk or coagulopathic patients. Ancillary testing, including electrocardiogram, echocardiography, arterial blood gas analysis, viscoelastic assays, and brain natriuretic peptide (BNP) measurement, provides valuable context for anticipating hemodynamic instability, arrhythmias, and potential challenges in achieving optimal intraoperative oxygenation and ventilation. Imaging studies such as chest X-ray, and computed tomography/magnetic resonance imaging may appear low yield in general medicine but are critical for anesthesiologists facing potential airway challenges or lung isolation requirements. Professional society guidelines consistently emphasize selective, indication-based preoperative testing rather than routine screening panels. However, anesthesiologists may appropriately request or prioritize certain tests that internists might otherwise defer, given that intraoperative decision-making and physiological management often differ substantially from chronic outpatient or general inpatient care. Recognizing this perspective enhances collaboration: small laboratory or imaging details can significantly affect anesthetic safety, especially in high-risk surgeries and patients with complex comorbidities.