The Bleeding Pregnant Patient in the Third Trimester: Pearls and Pitfalls

Authors: Cynthia Peng, MD (EM Resident Physician, York Hospital) and Robert Stuntz, MD (Program Director and Vice Chair of Education, York Hospital) // Edited by: Jennifer Robertson, MD, MSEd and Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital)

You are working in the emergency department (ED) when a 30-year-old G2P0010 female presents with painless vaginal bleeding. She is 30 weeks pregnant. Vital signs are a temperature (T) 98.7° Fahrenheit (F), a heart rate (HR) 130 beats per minute (bpm/min), blood pressure (BP) 80/40 mmHg, and a respiratory rate (RR) of 14/min. The patient’s abdomen is soft and non-tender. What are the next steps?


On average, pregnant women lose about one liter (L) of blood during birth [6]. Immediately after delivery, a pregnant patient’s blood volume requirement decreases, and thus, this one liter loss is typically well tolerated. On the other hand, this amount of blood loss would be hemodynamically significant in a third trimester pregnant patient. In the patient with significant third trimester bleeding, the initial steps in management are just as in any patient with hemorrhagic shock. These steps include judicious crystalloid volume resuscitation and early treatment with blood products (packed red blood cells (PRBC), platelets, fresh frozen plasma (FFP), and cryoprecipitate). Indications for blood transfusion include signs of hemorrhagic shock, 30-40% blood volume loss, or severe thrombocytopenia with platelets <20,000 x 109/L.

One of the most important factors to evaluate is the amount of bleeding. In extreme situations, the patient may be in hypovolemic shock. For any hemorrhage greater than 750-1500 milliliters (mL), you may see vital sign changes consistent with a Class II hemorrhage. However, the traditional classes of hemorrhage are not always reliable. Pregnancy itself can be a complicating factor, as:

  1. HR increases 10-20 bpm and reaches a maximum throughout third trimester [4].
  2. BP reaches a nadir in 2nd trimester (5-10mm Hg below baseline), but increases in the 3rd trimester.
  3. Total blood volume, plasma volume, and RBC mass increases during pregnancy, and laboratory testing reflects physiological anemia from hemodilution [4].

Historically, in a Rhesus (Rh) alloimmunized pregnancy, there was a 25-30% chance of a fetus to contract mild to moderate hemolytic disease and a 25% of hydrops fetalis [5]. With Rho (D) immune globulin (RhoGAM), the maternal sensitization process can be temporarily prevented. In Rh negative patients, RhoGAM is typically administered in the 26-28 week period, then again within three days of delivery. In the setting of third trimester bleeding with an Rh negative mother, RhoGAM should be administered if not already given. It is imperative to maintain a level of passive anti-D every 12 weeks if given before [5]. The Kleihauer-Betke (KB) test is important to quantify transplacental hemorrhage. It also helps determine if the amount of fetal to maternal hemorrhage exceeds that which can be treated with a standard 300 microgram (mcg) dose of RhoGAM. The KB test is indicated in the setting of severe vaginal bleeding (as in this case) and maternal trauma. It is an acid elution test where the adult hemoglobin is dissolved and the fetal hemoglobin remains and stains. The test is positive if >0.01mL of fetal blood is detected.


The differential for third trimester bleeding includes placental abruption, placenta previa, and vasa previa. Vaginal speculum and bimanual exams are contraindicated with these diagnoses due to the risk of inciting massive hemorrhage. Therefore, always perform an ultrasound first in a third trimester bleeding patient.  Placental abruption occurs when the placenta detaches prematurely from the uterine wall, and can be seen in up to 30% of third trimester vaginal bleeding. Severe placental abruption can cause catastrophic vaginal bleeding and non-reassuring fetal heart rates. Complications of placental abruption include hypovolemic shock and disseminated intravascular coagulation (DIC) (occurs with 10-20% cases). Placenta previa (20% of cases) occurs when placental tissue covers the cervical os. At 24 weeks gestational age, placenta previa will be present in 1 in 20 pregnancies, but this typically resolves by the third trimester. Placenta previa usually presents as painless vaginal bleeding that is less severe in volume. Ultrasound is critical in differentiating between these placenta previa and placental abruption. In the absence of placenta previa or placental abruption, painless vaginal bleeding could be vasa previa. Vasa previa is a condition where the umbilical cord is trapped between the fetus and the cervix. This usually occurs in multiple gestations. If any of these diagnoses are present, an obstetrics/gynecology (OB-GYN) consultation is warranted for a possible Cesarean (C) section.  In any pregnant woman, the loss of 500 mL of bright red blood can be indicative of placental abruption [5]. These patients need to be taken to the operating room immediately. Other considerations include genital trauma and laceration, cervical cancer, cervicitis, foreign body, and bloody show.


The mother is not your only patient in this setting. Remember to document a fetal heart rate, and perform constant fetal monitoring. In the setting of a 24 to 34 week gestation pregnancy, consider steroids to expedite lung maturity. Tocolytics can also be used in preterm patients with third trimester bleeding. Evidence has not shown any increased morbidity or mortality associated with tocolytic agent use [2].


  1. Normal physiological changes in pregnancy are important to consider. Heart rate increases by about 10-20 bpm, and peaks in the third trimester. Blood pressure may be 5-10 mm Hg lower than baseline, but usually rebounds in the third trimester.
  2. RhoGAM should be administered in any Rh-negative mother who presents with vaginal bleeding or trauma. The Kleihauer-Betke test can quantify the amount of fetal blood. The standard RhoGAM dose is 300mcg of Rho(D) immune globulin for 15mL of fetal red cells.
  3. The most concerning causes of third trimester bleeding include placental abruption, placenta previa, and vasa previa. Any pregnant woman presenting with a loss of 500cc of bright red blood should be taken to the operating room immediately, as this can be indicative of placental abruption [5].


  1. Do not perform a speculum or bimanual genital exam until after an ultrasound has been performed. This will rule out placental abruption, placenta previa, and vasa previa and decrease the chance for causing an obstetrical emergency.
  2. Do not forget the rest of your differential diagnoses. Other considerations include genital trauma and laceration, cervical cancer, cervicitis, foreign body, and bloody show.
  3. Remember, you have two patients! Do not forget to document fetal heart rate, and maintain fetal monitoring. Consider steroids and tocolytics.

References / Further Reading

[1] Balderston KD1, Towers CV, Rumney PJ, Montgomery D. Is the incidence of fetal-to-maternal hemorrhage increased in patients with third-trimester bleeding? Am J Obstet Gynecol. 2003 Jun;188(6):1615-8; discussion 1618-21.

[2] Towers CV1, Pircon RA, Heppard M. Is tocolysis safe in the management of third-trimester bleeding? Am J Obstet Gynecol. 1999 Jun;180(6 Pt 1):1572-8.

[3] Shakuntala Chhabra, Preetindar Kaur, Chandan Tickoo, Prashant Zode. Transplacental haemorrhage in women having third trimester bleeding and perinatal outcome. Open Journal of Obstetrics and Gynecology, 2011, 1, 149-152

[4] Monika Sanghavi, MD; John D. Rutherford, MB ChB, FRACP. Cardiovascular Management in Pregnancy. Circulation.2014; 130: 1003-1008

[5] Prevention of Rh D Alloimmunization. ACOG Practice Bulletin. Number 4, May 1999. Clinical management guidelines for obstetrician-gynecologists. American College of Obstetricians and Gynecologists.

[6] “3rd Trimester Bleeding.” Brookside Associates, N.D. Web. 14 June 2016

3 thoughts on “The Bleeding Pregnant Patient in the Third Trimester: Pearls and Pitfalls”

  1. Speculum exam is fine, it’s a bimanual with a digit in the cervix that’s problematic until you have a sono that shows no previa. This is of course, only for folks who are presenting at these late dates- prior to 10-11 wks. most don’t have any sono and there’s no issue to avoid either exam.

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