Anaphylaxis is a severe and life-threatening complication during the perioperative period. Perioperative anaphylaxis is still associated with a significant mortality despite quick and efficient management using epinephrine, the mainstay of acute treatment. Experimental data and few case reports are suggesting that hemostasis, and more precisely platelets, could play a role in anaphylaxis. Our main hypothesis is that activation of the hemostatic system contributes to the severity of the reaction

Inclusion Criteria:

• Patient, male or female, adult
• In the perioperative period
• In whom the diagnosis of anaphylactic shock is suggested
• Patient is giving his consent to participate in the study

Exclusion Criteria:

• Subject under legal protection
• Subject under guardianship or guardianship
• Anemia less than 7 g /dl at the time of inclusion

The study will focus on any adult patient with a suspected diagnosis of perioperative anaphylactic shock