Main d’accoucheur, or carpopedal spasm, is a posture of the hand with wrist flexion in which the muscles are rigid and painful. Main d’ac-coucheur is so called because of its resemblance to the posture of the hand adopted for the manual delivery of a baby ("obstetrical hand").
This tetanic posture may develop in acute hypocalcemia (induced by hyperventilation, for instance) or hypomagnesemia, and reflects muscle hyperexcitability. Development of main d’accoucheur within 4 minutes of inflation of a sphygmomanometer cuff above arterial pressure (Trousseau’s sign) indicates latent tetany. Mechanosensitivity of nerves may also be present elsewhere (Chvostek’s sign).