Abdominal pain is one of the most common reasons for consultation in Emergency Departments (ED) worldwide. The challenge for physicians is to not misdiagnose a surgical emergency. The actual gold standard for diagnosis is computed tomography (CT). However with this procedure there is high radiation exposure and a risk factor of radiation-induced cancers, therefore alternative diagnostic techniques should be considered. The aim of this study is to evaluate the performance of measuring venous lactate in patients presenting with acute abdominal pain in ED.

In this single-center, prospective, non-interventional study, the diagnostic accuracy of venous lactate in order to detect surgical emergencies is evaluated. The hypothesis made here is that venous lactatemia is a positive predictive factor of surgical emergencies in patients with acute abdominal pain.

Abdominal pain is one of the most common reasons for consultation worldwide in Emergency Departments (ED). The challenge for physicians is to not misdiagnose a surgical emergency. The actual gold standard for diagnosis is computed tomography (CT). However with this procedure there is high radiation exposure and a risk factor of radiation-induced cancers, therefore alternative diagnostic techniques should be considered. The aim of this study is to evaluate the diagnostic performance of measuring venous lactate in patients with acute abdominal pain in ED.

A single-center, prospective, non-interventional study, will be conducted between June 2016 and January 2017 in the university emergency department of Nice, France. Inclusion criteria are patients aged 18 and over, suffering from abdominal pain for seven days or less and requiring a blood test to help with diagnosis.

The primary outcome is to determine if the value of venous lactate is a predictive factor of emergency surgery in patients with acute abdominal pain.

The secondary outcome is to determine if the "strong ion gap", first defined in "The Stewart Approach", is a predictive factor of emergency surgery in patients with acute abdominal pain.

A blood test will be performed when patients are admitted to the ED. Seven days after being admitted to the ED, patients' outcome will be assessed by consulting patients' medical records or by phone call.

Inclusion Criteria:

• Patients over 18 years old
• Patient presenting acute abdominal pain since 7 days or less
• Need of blood sample confirmed by physician
• Affiliation to french social security system
• Informed Consent

Exclusion Criteria:

• Post traumatic abdominal pain / occurrence of abdominal trauma in the 7 days before ED visit
• Patients with cirrhosis classified as Child-Pugh C

Patients presenting abdominal pain since seven days or less, older than 18 years old, and who need a blood analysis to perform diagnosis after physician's clinical evaluation.