What is the cause of postpartum hemorrhage in a 24-year-old woman, gravida 1 para 1, with a boggy uterus, despite uterine massage and high-dose oxytocin, following a forceps-assisted vaginal delivery of a 4.4 kg infant at 41 weeks gestation, with symptoms of dizziness, nausea, and tachycardia?

Differential Diagnosis for Postpartum Hemorrhage

• Single most likely diagnosis
  • Uterine atony: This is the most common cause of postpartum hemorrhage, especially given the patient's symptoms of heavy vaginal bleeding, a boggy and palpable uterine fundus, and the failure of uterine massage and high-dose oxytocin to resolve the bleeding. The large size of the infant (4.4 kg) may have contributed to uterine distension and subsequent atony.
• Other Likely diagnoses
  • Retained placental tissue: The passage of large clots and the failure of uterine massage and oxytocin to control the bleeding raise the possibility of retained placental tissue, which can cause bleeding due to incomplete placental separation.
  • Laceration of the lower uterine segment or cervix: Although the pelvic examination did not reveal any visible lacerations, a laceration of the lower uterine segment or cervix could still be present and contributing to the bleeding.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
  • Uterine rupture: Although less likely given the patient's forceps-assisted vaginal delivery, uterine rupture is a life-threatening condition that requires immediate attention. The patient's symptoms of dizziness, nausea, and heavy bleeding could be indicative of a rupture.
  • Amniotic fluid embolism: This rare but potentially fatal condition can cause sudden onset of bleeding, hypotension, and respiratory distress. Although the patient's oxygen saturation is currently normal, the increasing frequency of albuterol use throughout pregnancy could be a sign of underlying respiratory issues.
  • Coagulopathy: A coagulopathy, such as disseminated intravascular coagulation (DIC), could be contributing to the patient's bleeding. This condition requires prompt recognition and treatment to prevent further complications.
• Rare diagnoses
  • Placenta accreta spectrum (PAS) disorders: Although less likely given the patient's symptoms and the fact that the placenta is not mentioned as being adherent to the uterine wall, PAS disorders can cause severe postpartum hemorrhage.
  • Uterine inversion: This rare condition can cause severe bleeding and requires prompt recognition and treatment to prevent further complications.