Postpartum Hemorrhage Flashcards
How is postpartum hemorrhage defined?
a cumulative blood loss of more than 1 L or blood loss accompanied by signs and symptoms of hypovolemia within 24 hours of delivery
How do we define primary and secondary postpartum hemorrhage?
- primary is within 24 hours of delivery
- secondary is delayed, usually between 24 hours and 12 weeks after delivery
What are the most significant risk factors for postpartum hemorrhage?
- prolonged, augmented, or rapid labor
- history of PPH
- pre-eclampsia
- over distended uterus
- abnormal uterine placentation
- operative delivery
- chorioamnionitis
Describe the symptomatic progression following blood loss.
- signs are first apparent with 15-20% of blood loss, including tachycardia, tachypnea, and delayed capillary refill
- orthostatic changes and narrowed pulse pressure follow
- with 30% blood loss, overt hypotension develops
What is the most common cause of PPH?
uterine atony
What does the differential include for PPH?
- uterine atony is most common
- retained placenta, genital tract trauma, lacerations, and coagulation disorders are less common
- ruptured uterus and inverted uterus are rare but serious
One unit of packed RBCs is expected to have what effect on a patient’s CBC? What about one unit of random donor platelets?
- pRBCs increase Hct by 3% and hemoglobin by 1 g/dL
- RDPs increase platelet count by 5K-10K
What normally prevents excessive bleeding after delivery?
uterine contraction, which constricts the spiral arteries, more so than coagulation
Uterine Atony
- a failure of the uterus to contract and constrict the spiral arteries following delivery
- risk factors include enlargement of the uterus, abnormal labor, and conditions that interfere with contraction such as uterine leiomyomata or magnesium sulfate
- risk is reduced by active management of the third stage of labor, usually with oxytocin infusion, uterine massage, and gentle traction on the cord
- diagnosis is based on palpation of the uterus which is softer and boggy rather than firm
- treated first with bimanual uterine massage; then attempt uterotonic agents, uterine compression with packing or balloon compression, or surgical management
- these include oxytocin, methylergonovine maleate, misoprostol, B-lynch sutures, sequential arterial ligation, arterial embolization, or hysterectomy
How is the third stage of labor actively managed and why do we do this?
- normal management includes 20 units oxytocin in 1L normal saline at 200-500 mL/hour initiated after delivery of the infant along with gentle cord traction and uterine massage
- used to prevent atony
What uterotonic agents are available for the treatment of uterine atony?
- oxytocin
- methylergonovine maleate
- misoprostol (PGE1)
- dinoprostone (PGE2)
- 15-methyl prostaglandin F2a
What surgical options are available for treating uterine atony?
- uterine compression sutures, either B-lynch or multiple squares
- sequential arterial ligation of the ascending or descending branches of the uterine, utero-ovarian, then internal iliac arteries
- selective arterial embolization
- hysterectomy
Describe a B-lynch suture.
- a stitch is placed inferior to the c-section cut and comes out superior to the cut
- the suture is run over the top and around to the back of the uterus and comes through on the posterior uterine surface opposite the c-section incision
- the suture is run out the back of the uterus, horizontally across the posterior surface of the uterus
- the suture is run over the top and around to the front of the uterus where it is run through superiorly and the inferiorly to the c-section incision
- there, it is tied
What is the advantage and disadvantage of methylergonovine maleate as a uterotonic agent?
- it works very fast, inducing contraction within minutes
- it can lead to dangerous hypertension and is avoided in those with hypertensive disorders
What risk factors exist for lacerations of the lower genital tract which may then lead to postpartum hemorrhage?
- instrumented delivery
- manipulative delivery such as a breech extraction
- precipitous labor
- presentations other than occiput anterior
- macrosomia
The placenta and uterus separate between what layers?
the zona basalis and zona spongiosa
What risk factors exist for retained placenta?
previous cesarean delivery, uterine leiomyomata, prior uterine curettage, accessory placental lobe
What finding would indicate the presence of a retained accessory placental lobe?
sheared or abruptly ending surface vessels on the delivered portion of the placenta
Why is retained placental tissue problematic?
it can interfere with contractions, leading to atony and excessive bleeding, and is a nidus for infection
What are placenta accreta, increta, and percreta?
- accreta: placenta attaches to the myometrium without penetrating it
- increta: placenta penetrates into the myometrium
- percreta: placenta penetrates through the myometrium and into the uterine serosa
Placenta Accreta
- improper implantation of the placenta onto the myometrium with little or no intervening decidua
- placenta increta and percreta are varying degrees of penetration
- risk factors are placenta previa, previous uterine surgery, prior endometrial ablation, Asherman’s syndrome, and maternal age greater than 35
- presents with difficult delivery of the placenta and life-threatening postpartum hemorrhage
- typically managed with planned preterm cesarean hysterectomy with the placenta left in situ
Retained Placental Tissue
- risk factors include previous cesarean delivery, uterine leiomyomata, prior uterine curettage, accessory placental lobe
- retained accessory lobe may be indicated by sheared or abruptly ending surface vessels on the delivered portion of the placenta
- presents with inadequate uterine contraction and postpartum hemorrhage
- often requires hysterectomy if the tissue can’t be removed manually or via curettage
How does lower genital tract hematoma present?
it is a possible cause of postpartum hemorrhage which is likely to presents with exquisite pain with or without signs of shock
What obstetric conditions are associated with DIC?
- placental abruption
- amniotic fluid embolism
- acute fatty liver
- sepsis
- severe pre-eclampsia
Amniotic Fluid Embolism
- a potential cause of postpartum hemorrhage
- presents with a sequence of respiratory distress, cyanosis, cardiovascular collapse, hemorrhage, and coma
- often also results in a severe coagulopathy or DIC
Uterine Inversions
- a potential cause of severe postpartum hemorrhage
- likely to occur if more than gentle traction is applied to the cord before the placenta has separated from the uterus
- avoid by applying suprapubic counterpressure while delivering the placenta to secure the fundus
- initial treatment includes manual replacement, typically after administering a medication to relax the uterus such as sublingual nitroglycerine
- surgical management may be required
What is the difference between a uterine rupture and uterine dehiscence?
- rupture is a frank opening between the uterine cavity and abdominal cavity
- dehiscence is a window covered by the visceral peritoneum
What risk factors exist for uterine rupture?
- abnormal labor
- operative delivery
- placenta accreta
Uterine Rupture
- a frank opening between the uterine cavity and the abdominal cavity; in contrast to a dehiscence which is a window covered by the visceral peritoneum
- risk factors include abnormal labor, operative delivery, and placenta accreta
- presents with acute abdominal pain, change in abdominal contour, non reassuring fetal heart patterns, and loss of fetal station
- surgical repair is required
