Approach to third trimester bleeding: Clinical sciences

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Introduction0:00–0:44

Third trimester bleeding is defined as bleeding from 28 weeks of gestation through delivery, and is considered an obstetric emergency if severe or accompanied by maternal or fetal instability.
Bleeding at this stage of pregnancy can be classified based on the presence or absence of abdominal pain. Painless causes include cervical or vaginal lesions, placenta previa, and ruptured vasa previa; while painful causes include placental abruption, uterine rupture, or normal labor.
Severe third trimester bleeding requires rapid assessment and stabilization, along with timely management in order to prevent maternal and fetal morbidity and mortality.Your first step in evaluating a patient presenting with third trimester bleeding is to perform a CABCDE assessment along with a primary obstetric survey to determine if they are stable or unstable.

Acute Management 0:44–1:48

If the patient is unstable, control any life-threatening hemorrhage. Then stabilize the airway, breathing, and circulation.
Obtain IV access if not already present, and monitor maternal vital signs closely. Once the patient is stabilized, be certain to assess the fetal status by monitoring the fetal heart rate.
A labor evaluation may then be performed by testing for rupture of membranes and checking cervical dilation.Here’s a clinical pearl!
A digital cervical exam should never be performed prior to confirming placental location, either through a review of the patient’s prenatal records or on a bedside ultrasound if not previously documented.
Palpation of a placenta previa through a partially dilated cervix can result in life-threatening hemorrhage and should be avoided.
Alright, now let’s talk about stable patients. First, obtain a focused history and physical examination.

Stable Patient1:48–2:31

During history, characterize the bleeding and take notes of the quantity, the presence or absence of abdominal pain, and any associated precipitating events.
Specifically, question the patient regarding any recent history of trauma, and if reported, whether direct abdominal contact occurred.
Also assess if the patient has any prior uterine surgery that disrupted the myometrial layer of the uterus, such as a c-section or myomectomy.
Lastly, the presence or absence of abdominal pain will help narrow down your differentials, so be sure to assess for abdominal pain.First, let’s talk about patients who present with third trimester bleeding in the absence of any abdominal pain or contractions.

Painless Bleeding2:31–3:05

In these patients, the primary diagnoses to consider are a cervical or vaginal lesion, placenta previa, or ruptured vasa previa.
Once you have classified the bleeding as painless, your next step is to perform an obstetric ultrasound to assess the placenta for any abnormality.
Additionally, perform a speculum exam to evaluate for active bleeding versus old blood and to assess the amount of bleeding present.
Let’s start with cervical or vaginal lesions. Patients will report a history of light vaginal bleeding, sometimes occurring after recent intercourse.

Cervical or Vaginal Lesion3:05–3:59

In these patients, your physical examination will play a key role in confirming your diagnosis. On visual inspection of the cervix and vagina, you will see a lesion responsible for the painless bleeding, such as a friable cervix, cervical polyp, or other abnormality.
Ultrasound will show a normal placenta, supporting the diagnosis of a cervical or vaginal lesion. Here’s a clinical pearl!
Cervical friability refers to cervical tissue that’s easily irritated, making it more prone to inflammation, bleeding, or tearing.
This can be normal in pregnancy, but may also be related to cervicitis from infection, most commonly chlamydia, gonorrhea, or bacterial vaginosis.
Let’s move on to placenta previa, which occurs when the placenta partially or completely covers the internal cervical os.

Placenta Previa3:59–5:07

It’s most commonly detected on routine anatomy ultrasound around 18 to 20 weeks of gestation. If the patient reports abrupt onset vaginal bleeding in the context of a known placenta previa or history of a previa, your diagnosis is most likely bleeding from the placenta previa.
History might be significant for a previous cesarean delivery, which is one of the strongest risk factors. This finding may assist in diagnosis in cases where placental location is unknown.
On physical exam, you may observe either substantial or light bleeding. Typically, the uterus will not be tender nor have increased tone.
The fetal heart rate tracing may show a nonreassuring pattern depending on the quantity of bleeding and maternal vital signs.Finally, the ultrasound will show homogeneous placental tissue extending over the internal cervical os.
If this is present, you have your diagnosis of placenta previa.Okay, let’s go ahead and discuss the last cause of painless bleeding called ruptured vasa previa.

Ruptured vasa previa5:07–6:31

This one is the least common cause, but requires the most rapid action to prevent fetal compromise. Vasa previa occurs when unprotected umbilical vessels run through the amniotic membranes and pass over the cervix.
If a patient reports an abrupt onset of vaginal bleeding, which occurred at the time of membrane rupture, think about ruptured vasa previa as the cause.
Additionally, a patient may have a known vasa previa or abnormal placentation, such as a velamentous cord insertion, bilobed placenta, or a placenta with a succenturiate lobe.
Physical exam reveals substantial bleeding, and the fetal heart rate tracing most commonly shows fetal bradycardia. Other tracing abnormalities could include a sinusoidal pattern secondary to fetal anemia or other nonreassuring features, as bleeding from a vasa previa represents active fetal blood loss.
Given the acuity, bedside ultrasound often can’t be performed, as a ruptured vasa previa requires rapid delivery in order to prevent fetal morbidity and mortality.
However, if the patient is stable, an ultrasound showing fetal vessels present in the membranes covering the internal cervical os would confirm the diagnosis of a ruptured vasa previa.
Alright, let’s shift our focus to patients who present with third trimester bleeding that’s associated with abdominal pain or uterine contractions.

Painful Bleeding6:31–7:12

In these patients, you should consider placental abruption, uterine rupture, or normal labor-associated bleeding. After your history and physical, perform an obstetric ultrasound to assess for any placental abnormalities.
In addition, monitor the fetus and consider a speculum exam to rule out membrane rupture and quantify the amount of bleeding.
If normal placentation is confirmed, you may also perform a digital cervical exam to assess for spontaneous labor. Okay, let’s start with placental abruption.

Placental Abruption7:12–8:14

The patient would report abrupt onset vaginal bleeding with mild to moderate abdominal pain. In fact, this is the most common cause of painful bleeding in the third trimester.
Uterine contractions are typically present.Additional findings can include a recent history of trauma, especially direct abdominal trauma; as well as substance use, such as cocaine or tobacco.
On physical exam, the patient may have substantial or light bleeding; and uterine tenderness or increased uterine tone can often be appreciated.
Fetal heart rate tracing may show a nonreassuring pattern, along with high frequency, low amplitude contractions, which are pathognomonic for an abruption.
Lastly, bedside ultrasound shows a normal placenta, but in cases of more severe abruptions, a retroplacental hemorrhage is observed.
With these clinical findings, placental abruption can be diagnosed. Moving on to uterine rupture.

Uterine Rupture8:14–9:31

If the patient reports abrupt onset vaginal bleeding and describes their abdominal pain as sudden, intense, and constant, your primary diagnosis is a uterine rupture.
The likelihood of rupture increases significantly if the patient has a history of a prior cesarean delivery or other uterine surgery that disrupted the myometrium.
On physical exam, there might be substantial or light bleeding. A nonreassuring fetal heart rate tracing or fetal bradycardia may also be noted.
If your patient is in labor, tocometry can show a sudden cessation of contractions, and on exam you may notice recession of the presenting fetal part.
In addition, maternal vital signs can show sudden hypotension representing hemodynamic instability. If the fetal heart rate tracing is stable, perform a bedside ultrasound, which may show a uterine wall defect, sometimes even with fetal parts outside the uterine cavity.
But, if the patient is unstable or if the fetal heart rate tracing is critical, proceed with cesarean delivery. In the operating room, you will find the uterus to be open, confirming your diagnosis of a uterine rupture.
Our last cause of painful bleeding is actually normal labor! If a patient presents with a bloody show or light vaginal spotting, along with regular uterine contractions that increase in frequency and intensity, consider spontaneous labor as the bleeding source.

Normal Labor 9:31–10:09

Physical exam typically reveals light bleeding, often mixed with mucus or amniotic fluid. Additionally, progressive cervical dilation is noted, along with regular uterine contractions on the tocometer.
Ultrasound is not typically necessary, but if performed, it will show a normal placenta, confirming your diagnosis of normal labor.
Alright, as a quick recap… Third trimester bleeding in pregnancy can be classified based on the presence or absence of abdominal pain.

Review10:09–10:28

Painless bleeding can be due to cervical or vaginal lesions, placenta previa, or a ruptured vasa previa. Causes of painful bleeding include placental abruption,