Third Trimester Bleeding Flashcards
What is the differential for third trimester bleeding?
- intercourse
- trichomonad cervicitis
- recent pelvic examination
- bleeding from hemorrhoids
- labor
- cervical polyp
- ectropion
- cervical carcinoma
- uterine rupture
- placenta previa, vasa previa
- placental abruption
What are the two most common causes of significant third trimester bleeding?
placenta previa and placental abruption
Why is intercourse likely to lead to third trimester bleeding?
because the cervix is more vascular and friable in pregnancy
When evaluating third trimester bleeding, one should never do what before performing an ultrasound?
never perform a bimanual pelvic exam without first confirming the placental position
Ectropion
- an area on the ectocervix where columnar epithelium has been exposed to vaginal acidity due to eversion of the endocervix
- may present as mild third trimester bleeding
- on exam, the tissue may appear reddened and raw looking
What baseline studies should be performed to evaluate third trimester bleeding?
- CBC with platelets
- PT, PTT, and fibrinogen
- type and cross
- ultrasound to identify the placental location
What is a Kleihauer-Betke test?
a test used to determine the amount of immunoglobulin needed to prevent alloimmunization, which assesses the amount of fetal blood to which the mother was exposed using differences in osmotic fragility
Placenta Previa
- implantation of the placenta in the lower uterine segment with the placenta overlying the cervical os; classified as complete, partial, marginal, or low-lying placenta
- risk factors include placenta previa in prior pregnancy, prior uterine surgery, multiparty, advanced maternal age, cocaine use, and smoking history
- in many cases partial, marginal, or low-lying will resolve spontaneously by 32-25 weeks gestation as the lower uterine segment stretches
- presents as third trimester bleeding, typically between 29-30 weeks gestation, without abdominal pain, which resolves in 1-2 hours and is associated with a normal fetal heart rate pattern
- diagnosed with transvaginal ultrasound as transabdominal has a high false positive rate
- increases the risk of preterm delivery and vaginal delivery is associated with compression of the cord, so management involves planned cesarean between 36.0-37.6 weeks gestation
- also associated with abnormal placental implantation, raising the risk for emergent hysterectomy
What is the difference between complete placenta previa, partial, marginal, and low-lying placenta?
- complete previa covers the os entirely
- partial covers some portion of the os
- marginal refers to a placenta with an edge within 2 cm of the os
- low-lying refers to a placenta in the lower uterine segment
What is the preferred treatment for suspected accreta?
planned cesarean hysterectomy with the placenta left in situ to avoid significant hemorrhage
Placental Abruption
- separation of an otherwise normally implanted placenta from the decidua prior to delivery; classified as complete, partial, or marginal
- risk factors include trauma, smoking, hypertension, and cocaine abuse, multiple gestation, advanced maternal age, chorioamnionitis, and multiparity
- presents with abrupt pain and third-trimester bleeding (bleeding may be concealed if the separation doesn’t extend to the cervical os) that doesn’t resolve within 1-2 hours as previa does
- fetal monitoring is likely to show tachycardia and then bradycardia, loss of variability, and non-reassuring decelerations
- may cause DIC, maternal shock, or fetal distress; life threatening to both the mother and fetus
- manage with monitoring vitals, administering fluids, and delivery if severe hemorrhage is present (vaginal or cesarean)
What is couvelaire uterus?
a complication of placental abruption in which blood penetrates the uterus to such an extent that the serosa becomes blue or purple is color
What is the most common cause of coagulopathy in pregnancy?
placental abruption
Vasa Previa
- a complication of pregnancy in which the fetal vessels run over or in close proximity to the cervical os, below the presenting part of the fetus
- more likely with velamentous insertion or when there is an accessory lobe of the placenta across the os from the main lobe
- vessels may rupture when the performing artificial ROM or spontaneously, presenting with membrane rupture, painless vaginal bleeding, and fetal bradycardia
- this source of bleeding can be differentiated form maternal bleeding using the Apt test
- requires an emergency C-section
What is a velamentous insertion?
insertion of the umbilical cord into the chorioamniotic membrane rather than the placenta
