<prompt> Which one of the following is not a cause of secondary postpaum hemorrhage?Placenta preRetained bits of placentavon Willebrand diseasePlacental polyp  <response>: - Placenta pre causes APH Secondary postpaum hemorrhage is bleeding after 24 hours to 12 weeks after delivery. Causes of PPH : Uterine atonicity most common cause of primary PPH Injury to any pa of genital tract Coagulopathy von Willebrands disease Retained tissues - most common cause of secondary PPH Usually, retained products undergo necrosis with fibrin deposition and may eventually form a so-called placental polyp. 