Our goal is to develop metrics that quantify the translation of performance from cadavers to patients. Our primary objective was to develop steps and error checklists from a Delphi questionnaire. Our second objective was to show that our test scores were valid and reliable. Sixteen UK experts identified 15 steps conducive to good performance and 15 errors to be avoided during interscalene block on the soft-embalmed cadaver and patients. Thereafter, six experts and six novices were trained, and then tested. Training consisted of psychometric assessment, an anatomy tutorial, volunteer scanning, and ultrasound-guided needle insertion on a pork phantom and on a soft-embalmed cadaver. For testing, participants conducted a single interscalene block on a dedicated soft-embalmed cadaver whilst wearing eye tracking glasses. We developed a 15-step checklist and a 15-error checklist. The internal consistency of our steps measures were 0.83 (95% confidence interval CI: 0.78–0.89) and 0.90 (95% CI: 0.87–0.93) for our error measures. The experts completed more steps (mean difference: 3.2 95% CI: 1.5–4.8; P<0.001), had less errors (mean difference: 4.9 95% CI: 3.5–6.3; P<0.001), had better global rating scores (mean difference: 6.8 95% CI: 3.6–10.0; P<0.001), and more eye-gaze fixations (median of differences: 128 95% CI: 0–288; P=0.048). Fixation count correlated negatively with steps (r=–0.60; P=0.04) and with errors (r=0.64; P=0.03). Our tests to quantify ultrasound-guided interscalene nerve block training and performance were valid and reliable.