Antepartum Bleeding
last authored: Aug 2011, David LaPierre
last reviewed: Nov 2011, Subani Selvarajah
Introduction
Antepartum bleeding or hemorrhage is defined as any vaginal bleeding that takes place after 20 weeks gestation until the start of labour. It occurs in approximately 2-5% of all pregnancies (Women's Hospital, 2011).
In the third trimester of pregnancy, the blood supply to the uterus increases dramatically to approximately 20% of cardiac output. Therefore, uterine bleeding, which can have various causes, can lead to profound blood loss and hemodynamic instability. It is one of the most significant causes of maternal death during the second and third trimester of pregnancy.
The Case of Meredith R
Meridith is a 44 year-old woman who is 32 weeks gestation. After an uneventful ride on a motorcycle she stood up to find she was sitting in a large pool of blood. There was no associated pain. Her husband immediately drove her to the hospital.
- How do you proceed?
- What might be causing her bleeding?
- What tests do you order?
Differential Diagnosis
Obstetrical causes of bleeding include:
- placental abruption or marginal placental separation (30%)
- placenta previa (20%)
- uterine rupture
- vasa previa (membrane vessels running across the cervical opening)
Other causes include cervical, vaginal, or uterine causes such as:
- intercourse (with vagnitis, polyp, neoplasia)
- genital tract trauma (MVA, abuse)
Also consider, in the differential diagosis:
- rectal bleeding (hemorrhoids, fissures, etc)
- genitourinary bleeding
Labour itself often results in bleeding, and must be considered.
History and Physical Exam
- history
- physical exam
History
Questions regarding the bleeding include:
- gestational age
- onset of bleeding
- amount and frequency of bleeding (how many pads, etc)
- pain (location, radiation), or contractions
- previous bleeding
- trauma or intercourse
- colour or consistency (water vs frank blood)
Ask for symptoms of shock
- dizziness, lightheadedness
- diaphoresis
- nausea
- confusion
- chest pain
Past obstetrical history
- history of placenta previa, abruption
- previous uterine surgery or Cesarian delivery
Medical history
- coagulopathy
- sexually transmitted diease
- fibroid polyps
- abnormal pap tests
- polyps
Physical Exam
Vitals (assess for shock)
- pulse
- blood pressure
- temperature
- respiration rate
Mental status exam (confusion, lethargy, loss of consciousness)
Abdominal exam:
- lie of the baby
- contractions
- uterine tenderness (abruption)
Avoid vaginal exam until placenta previa has been ruled out.
A sterile, gentle speculum exam may be done to assess for:
- visible source of blood (uterine vs vaginal)
- pooling of fluid or blood
- dilated cervix
Fetal monitoring should also be performed.
Investigations
If abdominal or back pain occurs with vaginal bleeding, abruption of the placenta should be ruled out.
- lab investigations
- diagnostic imaging
Lab Investigations
Bloodwork:
- CBC to assess hemoglobin and to set a baseline
- type and screen
- liver enzymes
- coagulation profiles (PTT, INR) to assess DIC
- Apt test to assess for maternal vs fetal blood
- Kleihauer-Betke test to assess abruption
A bedside clot test may be done by placing blood at room temperature for six minutes to assess for DIC.
Diagnostic Imaging
Ultrasound, including transvaginal doppler, can be done to assess for:
- placenta or vasa previa
- placenta accreta
- placental abruption (though of limited benefit)
- biophysical profile
- amniotic fluid volume
- fetal well-being
Electronic fetal monitoring, if available, can be used to assess the fetal status.
Management
Management depends on the suspected cause of hemorrhage, stability of mother and fetus, and viability of the fetus. A stable woman and fetus should be monitored for 12-24 hours, as the risk of recurrent bleeding is high. Transfer to an adequate facility with surgical treatment options and intensive premature neonatal care might be indicated.
Stabilization
If unstable, the patient needs vigorous intravenous fluid resuscitation. Vital signs and urine output can be used to monitor the hemodynamic status of the patient. Oxygen supplementation and pain management is also a part of acute management. Use of blood and blood products may be indicated. Continuous fetal monitoring should be provided.
Monitor for disseminated intravascular coagulopathy. If DIC is present, immediate correction is necessary.
Fetomaternal hemorrhage can be identified with a Kleihauer-Betke test. According to the test results, Rhogam should be given to all mothers who are of Rh negative bloodtype.
If the fetus is not viable (20- 24 wks of gestation), the goal is to stabilize the mother and monitor the progress. If fetus is between 24 weeks and 36 weeks of gestation, corticosteroids may be considered for fetal lung maturity, and the fetus should be monitored continuously.
If the gestational age is 36 weeks or more, treatment should depend on the cause:
- placenta previa - an elective C-section should be performed.
- abruption - if maternal and fetal state is stable, an expectant management could be considered and plan to induce at 37 weeks. If there is fetal or maternal compromise, the fetus should be delivered expeditiously by the quickest and safest method
- vasa previa, which is characterized by painless vaginal bleeding and can be confirmed with Doppler US, an expectant management is acceptable if mother and fetus are stable. If unstable, an emergency C-section should be performed.
Pathophysiology
The vasculature of the uterus is largely derived from the uterine and ovarian arteries. The uterine artery branches from the iliac artery, while the ovarian artery arises directly from the aorta. As mentioned in the introduction, the cardiac output to the uterus increases from 1% to 20% during pregnancy, meaning blood loss can quickly become catastrophic.
Uterine vessels terminate within the endometrial decidua to form spiral arteries. During the development of the placenta, spiral arteries are extensively modified by the placental trophoblasts. As their architecture is established, blood flows into the placenta and leaves spiral arteries to flow around the intervillous space, bathing the chorionic villi. Please visit placenta for greater detail.
Bleeding from placental abruption begins in the endometrial decidua, sometimes following rupture of spiral arteries.
Resources and References
Magann et al. 2005. Antepartum bleeding of unknown origin in the second half of pregnancy: a review. Obstet Gynecol Surv. 60(11):741-5.
Clinical Practice Guideline, Royal Women's Hospital, Australia
Current diagnosis and treament: Obstetrics and Gynecology, Decherney et al.
Topic Development
authors: Kim Colangelo, David LaPierre
reviewers:
 |