Postpartum Hemorrhage

Postpartum hemorrhage is one of the most common and deadly obstetric complications. Since 2017, postpartum hemorrhage has been defined as blood loss greater than 1,000 mL for both cesarean and vaginal deliveries, or excessive blood loss with signs of hemodynamic instability. Blood loss of more than 500 mL following a vaginal delivery is considered abnormal, though no longer classified as postpartum hemorrhage. The most common cause of postpartum hemorrhage is uterine atony. Retained products of conception, trauma, and coagulopathies may also cause postpartum hemorrhage. Appropriate management requires rapid identification of the cause of the hemorrhage, medical and/or surgical correction, and patient resuscitation.

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Definition and Epidemiology

Definition

Postpartum hemorrhage is defined as excessive blood loss following the delivery of an infant > 20 weeks gestational age.

  • The classic definition of postpartum hemorrhage was based on mode of delivery:
    • Blood loss > 500 mL following a vaginal delivery 
    • Blood loss > 1,000 mL following a cesarean section
  • The newer meaning of postpartum hemorrhage was defined by the American College of Obstetricians and Gynecologists in 2017:
    • Postpartum hemorrhage:
      • Cumulative blood loss ≥ 1,000 mL regardless of delivery route, OR
      • Bleeding associated with signs/symptoms of hypovolemia within 24 hours of delivery
    • While reducing cases labeled as postpartum hemorrhage, blood loss of > 500 mL following a vaginal delivery is still considered abnormal and should prompt investigation.
  • Postpartum hemorrhage can be primary or secondary:
    • Primary postpartum hemorrhage: occurs within 24 hours of delivery
    • Secondary postpartum hemorrhage: occurs between 24 hours and 12 weeks after delivery

Epidemiology

  • Incidence: 
    • 1%–10% of deliveries
    • Higher in sites using quantitative (compared to estimated) blood loss measurements
  • Leading cause of maternal mortality:
    • Approximately 11% of pregnancy-related mortality in developed countries
    • Up to 60% of maternal deaths in developing countries
  • Uterine atony accounts for 70%–80% of all postpartum hemorrhage

Etiology

Primary postpartum hemorrhage

The primary etiologies can be remembered as “the 4 Ts” (tone, tissue, trauma, and thrombin).

  • Tone (uterine atony):
    • Inability of the uterus to contract effectively following delivery
    • The most common cause of postpartum hemorrhage
    • Risk factors:
      • Prolonged labor (uterine muscle fatigue)
      • Intraamniotic infections (e.g., chorioamnionitis)
      • Uterine overdistension: a multiple pregnancy (e.g., twins), polyhydramnios, large for gestational age infants
      • Grand multiparity
      • Uterine inversion
      • General anesthesia
  • Tissue (retained products of conception):
    • Placenta tear during the 3rd stage of labor
    • Abnormal placentation:
      • Placenta accreta
      • Placenta previa
  • Trauma: 
    • Lacerations:
      • Vagina
      • Perineum
      • Cervix
    • Lateral extension of the uterine incision into the uterine arteries during cesarean section
    • Uterine rupture (during a vaginal birth after cesarean delivery through a prior uterine incision)
    • Hematomas
    • Risk factors:
      • Operative vaginal delivery
      • Precipitous delivery
      • Emergent cesarean delivery
  • Thrombin disorders (coagulopathies):
    • DIC, which is more likely to occur with:
      • Intrauterine fetal demise (IUFD)
      • Placental abruption
      • Amniotic fluid embolism
      • Sepsis
    • Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome
    • Gestational thrombocytopenia
    • Idiopathic thrombocytopenic purpura
    • Von Willebrand disease (von Willebrand factor rapidly decreases in delivery)
Postpartum hemrrhage placenta

Different types of placenta accreta

Image: “A diagram illustrating the different types of placenta accreta” by TheNewMessiah. License: Public Domain, edited by Lecturio.

Secondary postpartum hemorrhage

  • Uterine infection (postpartum endometritis)
  • Retained products of conception
  • Subinvolution of the uterus
  • Inherited coagulation defects

Pathophysiology

Postpartum hemorrhage due to a nontraumatic etiology results when 1 or both of the primary mechanisms required for normal postpartum hemostasis are disrupted. The 2 primary mechanisms are mechanical hemostasis and hemostatic factors.

Mechanical hemostasis

  • Normal contraction of the myometrium → compression of myometrial vasculature in the crisscross latticework of the smooth muscle fibers of the uterus
  • Disrupted in:
    • Uterine atony:
      • Failure of myometrial contraction → continued uterine blood flow → hemorrhage from the exposed vessels supplying the placental bed
      • Anything impairing postpartum contraction of the uterus leads to postpartum hemorrhage.
    • Retained products of conception:
      • Blood flows into the maternal side of the placenta and out through the placental fragment
      • Retained products prevent the uterus from fully contracting → uterus fills up with blood → uterine atony

Hemostatic factors

  • Clotting is facilitated by:
    • Factors released from the uterine decidua (i.e., tissue factor)
    • Systemic, circulating coagulation factors and platelets
  • Disrupted in coagulopathies (inadequate hemostatic factors to stop the bleeding of the placental bed)

Clinical Presentation and Diagnosis

Most patients present with heavy bleeding and/or signs of hemodynamic instability. Diagnosis is usually clinical.

Clinical presentation

  • Heavy vaginal bleeding (often dramatic)
  • Hemodynamic instability:
    • Tachycardia
    • Tachypnea
    • Hypotension
    • ↓ Urine output 
    • Skin findings: 
      • Cool and clammy
      • Delayed capillary refill
      • Pale
    • Mental status changes

Diagnosis

  • On exam look for:
    • Uterine atony: soft, boggy uterus
    • Uterine inversion: firm, round mass in the vagina
    • Retained products of conception: 
      • Visible trailing membranes
      • Palpable irregularities within the uterus
    • Lacerations/trauma
  • Monitor vital signs for signs of hemodynamic instability.
  • Measure blood loss:
    • Clinical estimate of blood loss by visual assessment 
    • Quantitative blood loss measurements:
      • Volumetric assessment of blood is collected via suction or in graduated drapes.
      • Weight assessment of blood is collected on surgical sponges.
      • Efforts are made to collect and quantify all blood lost.
  • Imaging:
    • Ultrasound is the modality of choice.
    • May be help identify retained products of conception (especially in secondary postpartum hemorrhage)
  • Laboratory tests:
    • Useful for management, but not diagnosis
    • The following should be ordered once postpartum hemorrhage is diagnosed:
      • Type and crossmatch to prepare for a blood transfusion
      • CBC
      • Coagulation panel: PT, PTT, fibrinogen

Classification of hemorrhage

The 4 classes of hemorrhage are described by the Advanced Trauma Life Support manual, which can also classify postpartum hemorrhage.

Table: 4 classes of hemorrhage (Advanced Trauma Life Support manual)
ClassPercentage of blood volume lostClinical findings
Class IUp to 15%Mild tachycardia
Class II15%–30%
  • Tachycardia
  • Tachypnea
  • Cool and clammy skin
Class III30%–40%
  • Marked tachycardia
  • Marked tachypnea
  • Hypotension
  • Mental status changes
  • Diminished urine output
Class IV> 40%
  • Marked tachycardia
  • Marked tachypnea
  • Hypotension
  • Mental status changes
  • Minimal or absent urine output
  • Cold, pale skin

Management

Prevention and preparation

  • Active management of the 3rd stage of labor:
    • Give oxytocin immediately after delivery of the infant.
    • Continuous uterine massage with gentle traction on the umbilical cord until placental delivery
    • Always inspect placenta after delivery for missing cotyledons.
  • Quantitative measurement of blood loss:
    • Better assessment of blood loss
    • Providers consistently underestimate visible blood loss.
  • Be prepared for postpartum hemorrhage in high-risk patients:
    • Appropriate personnel are nearby during delivery.
    • Ensure adequate IV access.
    • Uterotonic agents are immediately available.
    • Ensure the patient has a current type and screen (consider converting it to type and crossmatch if blood transfusions are likely).
    • Considered high risk:
      • Low-lying placenta or placenta previa
      • Active bleeding
      • Hematocrit < 30%
      • Known coagulopathy
      • Platelet count < 100,000
    • Important note: Postpartum hemorrhage can occur in anyone (e.g., a postterm, pregnant patient with prolonged induction of labor may develop an intraamniotic infection).

Emergency stabilization

  • Call for help
    • Other colleagues (e.g., obstetrician, nurse, anesthesiologist)
    • Alert the blood bank.
    • Consider holding an OR on standby if equipment and personnel would not otherwise be immediately available.
  • Call for blood.
  • IV access:
    • Start 2, large-bore IV needles. 
    • Give IV fluids. 
    • IV access becomes increasingly difficult as a patient continues to bleed.
  • Tranexamic acid, an antifibrinolytic agent, is given to control bleeding; however, the benefit is reduced if postpartum hemorrhage is diagnosed more than 3 hours postdelivery.
  • Get labs to assist in resuscitation: 
    • CBC
    • Coagulation studies: PT, PTT, INR, fibrinogen
  • Red top tube test (if a concern for DIC): 
    • Place 2–3 mL of the patient’s blood in a test tube and let the blood sit for 6 minutes. 
    • If the blood does not clot within 6–10 minutes, suspect DIC.
  • Consider the etiology (therapy is directed at the underlying cause).

Treatment for uterine atony

  • Step 1: uterine massage:
    • Instruct patient to empty the bladder to increase effectiveness.
  • Step 2: Give additional oxytocin.
  • Step 3: If uterine atony persists, give other uterotonic agents:
    • Methylergonovine
    • PGF 
    • Misoprostol
  • All 4 medications may be given if the patient has no contraindication.
  • Step 4: uterine packing:
    • Place balloons, sponges, etc. in the uterus to provide compression.
    • Carefully count all foreign bodies placed inside the uterus.
  • Step 5: surgery:
    • Surgical compression of the uterus:
      • Surgically placed sutures cinch down and/or compress the uterus 
      • Example: B-lynch sutures 
    • Arterial ligation:
      • Ligate the vessels supplying the uterus.
      • 1st: uterine artery ligation
      • 2nd: utero-ovarian artery ligation
    • Hysterectomy (last resort)
  • Alternative option: uterine artery embolization:
    • An interventional radiologist identifies the uterine artery via fluoroscopy and performs an embolization.
    • Requires the patient to be stable enough to undergo the procedure (uncommon)
Table: Uterotonic agents used in postpartum hemorrhage
Medication (generic)ClassRouteContraindications
OxytocinNatural hormoneIV, IMNone
MethylergonovineErgot alkaloidIMHypertension
Carboprost (PGF)Prostaglandin analogueIMSevere hepatic, renal, and cardiovascular disease, and asthma
MisoprostolProstaglandin analogueOral, rectalNone
Uterine massage

Uterine massage/manual compression for uterine atony

Image by Lecturio.

Treatment for retained products of conception

  • Suspect retained products of conception if the placenta is not delivered intact.
  • Management:
    • Manual exploration of the uterus to remove any retained pieces of membrane or placenta
    • Dilation and curettage
    • Uterine packing may be helpful

Treatment of trauma

  • Careful assessment for lacerations: 
    • Adequate lighting and equipment for pelvic exam
    • Inspect the entire cervix (often difficult due to active bleeding and full dilation).
  • Management:
    • Suture repair of any bleeding lacerations
    • Surgical repair of uterine rupture
    • Apply compression to hematomas to prevent expansion of bleeding.

Treatment for thrombin disorders

Activate the hospital’s massive transfusion protocol and administer blood products:

  • Packed RBCs: 1 unit should ↑ hemoglobin by 1 g/dL and hematocrit by 3%
  • Platelets: 1 unit should ↑ platelet count 5,000–10,000
  • FFP: 
    • Contains all coagulation factors and plasma proteins 
    • 1 unit should ↑ fibrinogen 10 mg/dL
  • Cryoprecipitate: 
    • Contains fibrinogen (factor I), factor VIII, factor XIII, and von Willebrand factor
    • 1 unit should ↑ fibrinogen 10 mg/dL
Management of Postpartum Hemorrhage

Management of postpartum hemorrhage

Image by Lecturio.

Complications

  • DIC
  • Acute renal failure
  • Adult respiratory distress syndrome
  • Loss of fertility (hysterectomy)
  • Pituitary necrosis (Sheehan syndrome)

Clinical Relevance

  • Cesarean section: The operative delivery of 1 or more infants through surgical incision into the maternal abdomen, surgical opening of the uterus, and delivery of the infant(s). 
  • Prolonged labor: longer-than-normal rate of labor progression. Prolonged labor increases the risk for obstetric complications including postpartum hemorrhage, intraamniotic infection, and fetal distress. 
  • Rapid labor: shorter-than-normal rate of labor progression. The normal duration of labor is usually at least 3 hours. Rapid labor increases the risk for postpartum hemorrhage.
  • Chorioamnionitis: an infection of the chorion and amnion. An infected uterus does not contract well, which leads to prolonged labor and significantly increases a patient’s risk for postpartum hemorrhage. Chorioamnionitis is a common complication of prolonged rupture of membranes. Chorioamnionitis may lead to maternal sepsis and/or postpartum endometritis.
  • Multiple pregnancy: a pregnancy with more than 1 fetus (e.g., twins, triplets, quadruplets). Multiple pregnancy leads to overdistension of the uterus, which is a risk factor for several obstetric complications, including postpartum hemorrhage and prelabor rupture of membranes.
  • Abnormal placentation: placental implantation occurring in an abnormal site within the uterus. Abnormal placentation also includes placenta accreta, which is an invasion of the placenta into the myometrium. Abnormal placentation increases the risk of postpartum hemorrhage due to retained products of conception.
  • Antepartum hemorrhage: obstetric bleeding during the 3rd trimester. Common causes include placenta previa, placental abruption, and preterm labor. Bleeding due to abnormal placentation may increase the risk of postpartum hemorrhage due to retained products of conception.
  • Disseminated intravascular coagulation (DIC): a serious medical disorder in which multiple clots form and can lead to permanent organ damage. Systemic activation of blood coagulation occurs and results in the generation and deposition of excess fibrin. The systemic activation of the coagulation cascade uses many coagulation factors, which result in uncontrolled bleeding.
  • Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome: a preeclampsia complication involving a triad of hemolysis, elevated liver enzymes, and low platelets (thrombocytopenia). Thrombocytopenia represents a hemostasis abnormality and increases the risk of postpartum hemorrhage.

References

  1. Belfort, M. A. (2021). Overview of postpartum hemorrhage. In Barss, V.A. (Ed.), UpToDate. Retrieved March 11, 2021, from https://www.uptodate.com/contents/overview-of-postpartum-hemorrhage
  2. Wormer, K. (2020). Acute postpartum hemorrhage. In Bryant, S. (Ed.), StatPearls. Retrieved March 11, 2021, from https://www.statpearls.com/articlelibrary/viewarticle/27638/ 
  3. The American College of Obstetrics and Gynecology Committee on Obstetrics. (2017). Practice Bulletin No. 183: Postpartum hemorrhage. Retrieved March 11, 2021, from https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2017/10/postpartum-hemorrhage 
  4. The American College of Obstetrics and Gynecology Committee on Obstetrics. (2019). Committee Opinion No. 794: Quantitative blood loss in obstetric hemorrhage. Retrieved March 11, 2021, from https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2019/12/quantitative-blood-loss-in-obstetric-hemorrhage 
  5. Tobian, A. (2021). Clinical use of Cryoprecipitate. UpToDate. Retrieved May 15, 2021, from https://www.uptodate.com/contents/clinical-use-of-cryoprecipitate

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