Antepartum Hemorrhage

Antepartum hemorrhage is defined as vaginal bleeding that occurs after 20 weeks of gestation and is unrelated to labor. The most important causes are placental abruption (most common), placenta previa (2nd most common), vasa previa, and uterine rupture. Placental abruption and uterine rupture are diagnosed clinically. Placenta previa and vasa previa are usually diagnosed as part of routine screening on a midtrimester ultrasound, and digital exams in these women must be avoided. All of these conditions can lead to maternal and/or fetal hemorrhage, necessitating emergency C-section and maternal and/or fetal resuscitation.

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Overview

Definition

Antepartum hemorrhage is defined as vaginal bleeding that occurs after 20 weeks’ gestation and is unrelated to labor.

Epidemiology and etiology

  • Incidence: occurs in approximately 5% of pregnancies 
  • Most common etiologies:
    • Placental abruption: 30%
    • Placenta previa: 20%
  • The etiology is often not determined.
Table: Causes of antepartum bleeding by location
Anatomic locationCauses of antepartum bleeding
Placenta
  • Placental abruption*
  • Placenta previa*
  • Vasa previa*
UterusUterine rupture*
Cervix
  • “Bloody show”: a small amount of bloody mucus discharge that often precedes labor as the cervix ripens
  • Cervicitis
    • STIs: gonorrhea, chlamydia
    • Secondary to vaginitis: candidiasis, bacterial vaginosis
  • Cervical ectropion: exposed cervical columnar epithelium that is prone to light bleeding when touched
  • Polyps
  • Carcinoma
Vagina and vulva
  • Varicosities
  • Vaginitis
  • Lacerations
  • Carcinoma
*Clinically important obstetric cause.

Placental Abruption

Overview

Placental abruption is the complete or partial premature detachment of a normally implanted placenta before the birth of the infant.

Clinical relevance:

  • With a detached placenta:
    • The infant is no longer able to get oxygen.
    • Maternal and fetal hemorrhage occurs through the placenta.
  • An obstetric emergency that usually requires immediate delivery

Epidemiology

  • Incidence: approximately 2–10 per 1000 births
  • Age: more common in women < 20 and > 35 years of age
  • Gestational age at abruption:
    • Term: 60%
    • 32–36 weeks: 25%
    • < 32 weeks: 15%

Risk factors

  • Previous abruption (strongest risk factor)
  • Hypertension
    • Preeclampsia
    • Poorly controlled chronic hypertension
  • Trauma to the abdomen
  • Cocaine or tobacco use
  • Quick decompression of the uterus
    • Rupture of membranes in a pregnancy with polyhydramnios
    • Delivery of the 1st infant in a multiple gestation
  • Fetal growth restriction (may suggest a small chronic partial abruption)
  • Uterine anomalies 
    • Leiomyomas
    • Bicornuate uterus

Etiology

  • Unknown, but likely related to: 
    • Chronic placental disease processes 
    • Abnormalities in the development of placental vasculature
  • Direct abdominal trauma (less common)

Pathophysiology

  • Rupture of maternal vessels in the decidua basalis → accumulation of blood splits the decidua → a thin layer of decidua is separated off with its placental attachment
  • Thrombin is a potent uterotonic agent → clotting in the decidua triggers uterine contractions
  • Complete abruption:
    • Caused by high-pressure arterial hemorrhage in the center of the placenta
    • Life-threatening for fetus and mother
  • Partial abruption:
    • Caused by low-pressure venous hemorrhage, usually at the periphery of the placenta
    • Often self-limited, with only a small area of separation
    • Can lead to “chronic abruption” throughout the remainder of pregnancy

Clinical presentation

  • Bleeding may be:
    • External with visible vaginal bleeding (80%) OR
    • Concealed (blood pools behind the placenta) without vaginal bleeding (20%)
  • Painful bleeding:
    • Abdominal and/or back pain
    • Bleeding can range from mild to life-threatening.
  • Contractions (often hypertonic or high-frequency)
  • Uterine tenderness
  • Fetal distress/decreased fetal movement
  • Small, partial abruptions may be less dramatic and present with:
    • Smaller amounts of bleeding over time (chronic abruptions)
    • Oligohydramnios
    • Intrauterine fetal growth restriction
Placental abruption

Placental abruption:
External versus concealed bleeding

Image: “Placental abruption” by BruceBlaus. License: Public Domain

Diagnosis

The diagnosis of placental abruption is usually clinical, based on the history, exam, and fetal monitoring.

  • Fetal nonstress test:
    • Measures fetal heart rate and uterine contractions (tocometry)
    • Used to assess fetal status
    • Signs of fetal distress: bradycardia, ↓ heart rate variability, late decelerations
    • Tocometry: frequent and/or hypertonic contractions
  • Ultrasonography:
    • Exclude placenta previa
    • May show a retroplacental hematoma
    • Low sensitivity, but decent specificity 
  • Laboratory: helpful in managing acute resuscitation, rather than diagnosis of abruption itself
    • Kleihauer-Betke test: can detect fetal RBCs in maternal circulation
    • Type and cross
    • CBC → evaluate degree of anemia
    • Coagulation panel: PT, PTT, fibrinogen → evaluate for DIC

Management

  • Severe abruption:
    • Needed in individuals with DIC, hypovolemic shock, or nonreassuring fetal status
    • Step 1: stabilization
      • Establish 2 large-bore IV lines.
      • Initiate IV fluids.
      • Transfuse blood products as needed.
    • Step 2: emergent cesarean delivery
  • Mild or chronic abruption:
    • Monitor and observe the mother to ensure the abruption remains stable.
    • Frequent assessments of fetal well-being
    • Corticosteroids (betamethasone) for fetal lung maturity in premature infants
    • Deliver if mother or infant decompensates.

Complications

  • Maternal complications:
    • DIC 
    • Renal failure
    • ARDS
    • Peripartum hysterectomy
    • Complications associated with blood transfusions
    • Increased risk of cardiovascular disease later in life
  • Fetal complications:
    • Complications of hypoxemia (e.g., neurologic impairment)
    • Complications of prematurity (e.g., respiratory distress, intraventricular hemorrhage, retinopathy of prematurity)
    • Fetal growth restriction (chronic partial abruption)

Placenta Previa

Overview

Placenta previa is a condition in which the placenta implants in the lower uterine segment, near or covering the internal cervical os.

Definitions:

  • Low-lying placenta: the placental edge is < 2 cm from (but not covering) the internal os (managed in the the same way as placenta previa)
  • “Marginal” and “partial” placenta previa are older terms that should be avoided.

Clinical relevance: 

  • As the cervix dilates beneath the placenta, it exposes the placenta → bleeding (both maternal and fetal blood loss)
  • Never perform a digital cervix exam on a woman with placenta previa; you will stick your finger into the placenta and cause severe hemorrhage.
Location of the placenta in placenta previa

Location of the placenta in placenta previa

Image: “Placenta previa” by OpenStax College – Anatomy & Physiology. License: CC BY 3.0

Epidemiology

  • Prevalence: 4 per 1000 births
  • In up to 6% of women, a midtrimester ultrasound will show placenta previa.
  • Approximately 90% of placenta previas identified at < 20 weeks resolve by delivery.
    • The lower uterine segment lengthens from 0.5 cm at 20 weeks to over 5 cm at term.
    • This lengthening “moves” the placenta away from the os.
  • Complete placenta previa is unlikely to resolve.

Risk factors

  • Most important risk factors:
    • Previous placenta previa
    • Previous C-section
    • Multiple gestation
  • Other risk factors:
    • Previous curettage
    • Previous or recurrent abortions
    • Infertility treatment
    • Advanced maternal age (> 35 years old)
    • Multiparity
    • Uterine structural anomaly 
    • Smoking 
    • Cocaine use

Clinical presentation

  • Painless vaginal bleeding
  • Fetal distress
  • Usually asymptomatic until cervical dilation begins after 30 weeks

Diagnosis

  • Transvaginal ultrasonography:
    • Shows placenta near or covering the cervical os
    • Usually diagnosed on routine midtrimester ultrasound
    • Assessing placental location is a recommended part of routine obstetric care.
  • Avoid digital exams on a woman with placenta previa.
Placenta previa on ultrasound

Transabdominal ultrasound showing placenta previa
P = placenta
CX = cervix

Image: “Placenta previa” by Haiyan Yu et al. License: CC BY 4.0

Management

  • Asymptomatic antenatal management:
    • Pelvic rest (no intercourse)
    • Plan to deliver at 36 weeks, prior to the onset of labor.
    • When exam is required, visual assessment with a speculum only
  • If bleeding: emergency C-section to prevent fetal death

Vasa Previa

Overview

Definitions:

  • Velamentous cord: portion of the umbilical cord lacks the protective Wharton’s jelly near the placental insertion site, making the cord prone to rupture:
    • Known as “membranous vessels” because they are attached to the chorion
    • Length of unprotected cord may be several centimeters long
  • Vasa previa: condition in which fetal vessels run across the internal cervical os

Clinical significance:

  • A digital exam may rupture these vessels, causing fetal exsanguination within minutes.
  • Rupture of membranes may rupture the vessels.
  • These vessels may also become compressed by the fetal head.
Vasa previa

Vasa previa

Image: “Vasa previa” by Sigrid de Rooij. License: CC BY-SA 4.0, edited by Lecturio.

Epidemiology

  • Prevalence: 
    • 1% of singleton gestations
    • Up to 15% of monochorionic twin gestations
  • Risk factors: 
    • Accessory (succenturiate) placental lobes
    • Multiple gestation
    • Placenta previa
    • Velamentous cord insertion

Clinical presentation

  • Painless vaginal bleeding (often after rupture of membranes)
  • Fetal distress
  • Women are often asymptomatic until cervical dilation or disruption due to mechanical trauma.

Diagnosis

  • Transvaginal ultrasound with Doppler: 
    • Demonstrates fetal vessels traversing the internal cervical os
    • Assessing the umbilical cord vessels and insertion site at around 20 weeks is a recommended element of routine prenatal care.
  • Avoid digital exam on a woman with vasa previa.
Doppler ultrasound of vasa previa

Transvaginal ultrasound showing a vasa previa:
The color Doppler shows blood flowing through the vasa previa vessel over the internal cervical os. The cervical canal is marked with the yellow asterisks on each end.

Image: “Doppler ultrasound of vasa previa” by Division of Reproductive Endocrinology & Infertility, Beth Israel Deaconess Medical Center/Boston IVF, Harvard Medical School, Boston, MA, USA. License: CC BY 3.0

Management

  • Asymptomatic antenatal management:
    • Pelvic rest (no intercourse)
    • Plan to deliver at 36 weeks, prior to the onset of labor.
    • When exam is required, visual assessment with a speculum only
  • If bleeding: emergency C-section to prevent fetal death

Uterine Rupture

Definition

Uterine rupture is a clinically significant disruption in all layers of the uterus, usually through a previous uterine scar.

Epidemiology

  • Incidence in individuals with a prior cesarean delivery: 
    • 0.3%
    • More common in women undergoing a trial of labor after cesarean (TOLAC) compared to planned repeat cesarean deliveries
  • Incidence in individuals without a prior uterine scar: 
    • Rare
    • Estimated at 1 per 20,000 pregnancies
  • Perinatal death rate associated with uterine rupture: 5%–25%

Risk factors

  • Prior uterine incision:
    • C-section (most common)
    • Classical (high vertical or fundal) uterine incision (highest risk)
    • Myomectomy
  • TOLAC
  • Induction and augmentation of labor (excessive oxytocin stimulation)

Clinical presentation

  • Abdominal pain (often severe and with sudden onset)
  • Vaginal bleeding (may be light if a majority of blood is lost intraabdominally)
  • Nonreassuring fetal heart rate patterns:
    • Bradycardia
    • Late decelerations
    • Minimal or absent fetal heart rate variability
  • Loss of uterine tone
  • Sudden loss of station of the presenting fetal part
  • Maternal hemodynamic instability
  • May be diagnosed postpartum after a TOLAC with a postpartum hemorrhage that does not respond to uterotonic agents

Diagnosis

  • The diagnosis is clinical, based on presentation and risk factors.
  • Usually, significant fetal distress necessitates immediate action.
  • Diagnosis is confirmed on laparotomy.

Management

  • Immediate emergency cesarean delivery
  • Concurrent maternal stabilization with IV fluids and blood products, as needed
  • Surgical repair of the uterine rupture, following delivery of the infant and maternal stabilization
  • Hysterectomy (last resort in cases of persistent hemorrhage and/or nonrepairable uterus)
Uterine rupture photograph

Uterine rupture:
This woman has undergone a laparotomy through a vertical midline incision. Within the abdominal cavity, a bulging amniotic sac is noted through a large defect in the anterior uterine wall.

Image: “Silent uterine rupture” by Department of Obstetrics and Gynecology, Michigan State University/Sparrow Hospital, Lansing, MI 48912, USA. License: CC BY 3.0

Comparison of Diagnoses

Table: Comparison of causes of antepartum bleeding
ConditionTypical presentationImportant risk factorsManagement
Placental abruption
  • Painful bleeding
  • Contractions
  • Nonreassuring fetal status
  • Hypertension
  • Rapid uterine decompression
  • Trauma
  • Cocaine or tobacco use
Emergent delivery
Placenta previaPainless bleeding OR asymptomatic
  • Prior placenta previa
  • Prior cesarean delivery
  • Multiple gestation
  • No digital exams
  • Pelvic rest
  • Deliver with bleeding, or at 36 weeks.
Vasa previaPainless bleeding OR asymptomatic
  • Accessory placental lobe
  • Current placenta previa
  • Multiple gestation
  • Velamentous cord
  • No digital exams
  • Pelvic rest
  • Deliver with bleeding, or at 36 weeks.
Uterine rupture
  • Painful bleeding
  • Loss of fetal station
  • Nonreassuring fetal status
  • Prior uterine incision (especially vertical or fundal incisions)
  • TOLAC
  • Induction of labor
  • Emergent delivery
  • Surgical repair of rupture

References

  1. Ananth, C.V., Kinzler, W.L. (2021). Placental abruption: Pathophysiology, clinical features, diagnosis, and consequences. In: Barss, V.A. (Ed.), UpToDate. Retrieved March 12, 2021, from https://www.uptodate.com/contents/placental-abruption-pathophysiology-clinical-features-diagnosis-and-consequences
  2. Deering, S. (2018). Abruptio placentae. Medscape. Retrieved March 12, 2021, from https://emedicine.medscape.com/article/252810-overview 
  3. Lockwood, C.J. (2019). Placenta previa: Epidemiology, clinical features, diagnosis, morbidity, and mortality. UpToDate. Retrieved March 11, 2021, from https://www.uptodate.com/contents/placenta-previa-epidemiology-clinical-features-diagnosis-morbidity-and-mortality
  4. Bakker, R. (2018). Placenta previa. Medscape. Retrieved March 12, 2021, from https://emedicine.medscape.com/article/262063-overview#a4 
  5. Anderson-Bagg, F. (2020). Placenta previa. StatPearls. Retrieved March 11, 2021, from https://www.statpearls.com/articlelibrary/viewarticle/27262/ 
  6. Lockwood, C.J. (2020). Velamentous umbilical cord insertion and vasa previa. UpToDate. Retrieved March 12, 2021, from https://www.uptodate.com/contents/velamentous-umbilical-cord-insertion-and-vasa-previa 
  7. Landon, M.B. (2020). Uterine rupture: after previous cesarean delivery. UpToDate. Retrieved March 12, 2021, from https://www.uptodate.com/contents/uterine-rupture-after-previous-cesarean-delivery

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