Pneumomediastinum during the fourth stage of labor.

Postpartum spontaneous pneumomediastinum (Hamman's syndrome) is a very rare event with an estimated incidence of 1 in 100,000 deliveries. It occurs mainly in the second stage of labor and is potentially lethal. We report the case of a 29-year-old primiparous woman during the immediate puerperium (Leff's fourth stage of labor) presenting with acute chest pain, dyspnea and petechiae.