Acute calculous cholecystitis (ACC) is the second most frequent surgical condition in emergency departments. The recommended treatment is surgical treatment (ST) and the accepted mortality is <1%, but in severe and/or fragile patients is higher. Despite the Tokyo Guidelines, there no consensus on who is the unfit patient for ST. A recent study has identified 4 risk factors that predicts the mortality in a 92% of patients (ACME) and could help to develop new guidelines in ACC. The aim of this study is to perfom an external validation of the new simplified scoring system for mortality in ACC.

This is a prospective multicenter observational study of 10.000 adults with ACC during 2 consecutive years (2025/2026), including baseline demographic characteristics, comorbidity severity defined as Charlson Comorbidity Index (CCI), ASA Score, Tokyo Guidelines severity classification and the new ACME Scoring system. The primary outcome is to study the prediction of mortality of ACME score. Secondary outcomes include complications following Clavien-Dindo's classification, C-statistic, and ROC Curves.

Inclusion Criteria:

• Acute Calculous Cholecystitis

Exclusion Criteria:

• Acute Cholangitis
• Chronic Cholecystitis
• Neoplasia
• Acute Pancreatitis
• Pregnant

All the consecutive admisions with an acute calculous cholecystitis, independent on the treatment indicated, during 2025 and 2026.