Abstract Background Chronic abdominal pain is occasionally caused by an abdominal wall entity such as Anterior Cutaneous Nerve Entrapment Syndrome (ACNES). This syndrome is thought to occur due to entrapped intercostal nerve branches (Th7-12) within the rectus abdominis muscles. This clinical diagnosis is based on subjective clues in patient history and physical examination. In contrast, in carpal tunnel syndrome an additional diagnostic test is used, which is referred to as the scratch collapse test (SCT). The SCT has shown positive results not only in other peripheral entrapment neuropathies involving the ulnar, peroneal, and long thoracic nerve, but also in three recently described ACNES patients. We investigated whether the SCT is of diagnostic use in patients suspected of having ACNES. Method A prospective, case-control study was performed among patients with ACNES (n = 20) and two control groups without ACNES (acute abdomen n = 20; healthy n = 20), all were consecutively included. ACNES was diagnosed based on previously published criteria. The SCT test was executed at the painful abdominal area in both patient groups and at a corresponding area in healthy controls. Predictive values, sensitivity, and specificity were calculated. Videos of tests were evaluated by blinded observers. Results SCT was judged positive in 19 of 20 ACNES patients, but not in any of the 40 controls. A 95% sensitivity (CI:75–99) and 100% specificity (CI: 83–100) were calculated. Conclusion This study provides strong evidence that ACNES should be considered as an entrapment neuropathy, while a positive SCT should be considered as a major diagnostic criterion.