What is the role of atony in the etiology of postpartum hemorrhage (PPH)?

Updated: Jan 02, 2018
  • Author: Maame Yaa A B Yiadom, MD, MPH; Chief Editor: Bruce M Lo, MD, MBA, CPE, RDMS, FACEP, FAAEM, FACHE  more...
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Atony is by far the most common cause of postpartum hemorrhage. Uterine contraction is essential for appropriate hemostasis, and disruption of this process can lead to significant bleeding. Uterine atony is the typical cause of postpartum hemorrhage that occurs in the first 4 hours after delivery.

Risk factors for atony include the following:

  • Overdistended uterus (eg, multiple gestation, fetal macrosomia, polyhydramnios)

  • Fatigued uterus (eg, augmented or prolonged labor, amnionitis, use of uterine tocolytics such as magnesium or calcium channel blockers)

  • Obstructed uterus (eg, retained placenta or fetal parts, placenta accreta, or an overly distended bladder)

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