OBG Radiology Case - Placenta Previa Flashcards
In placenta previa, the placenta is located over or very near the ___.
Internal os
There are four degrees of placenta previa and one related condition - list them.
- Total placenta previa
- Partial placenta previa
- Marginal placenta previa
- Vasa previa
- Low-lying placenta
Define total placenta previa.
Placenta completely covers the internal os
Define partial placenta previa.
Placenta partially covers the internal os
Define marginal placenta previa.
Edge of the placenta is at the margin of the internal os
Define vasa previa.
Fetal vessels course through the membranes and present at the cervical os
Define low-lying placenta.
Placenta implanted in lower uterine segment so that the placenta edge does not actually cover the internal os but is close to it
What is the clinical setting when you will consider placenta previa?
Painless hemorrhage near the end of the second trimester or after. Antepartum bleeding typically refers to uterine bleeding after 20 weeks of gestation that is unrelated to L&D; usually ceases spontaneously and then recurs
List some major causes of painless hemorrhage in pregnancy.
- Placenta previa
- Placental abruption
- Uterine rupture
- Vasa previa
___ usually presents with pain and contractions.
Abruptio placenta
___ and ___ are rare causes of vaginal bleeding.
Uterine rupture; vasa previa
What is the gold standard imaging modality for evaluating placenta previa?
Transabdominal sonography - simple, precise, safe
Transabdominal sonography is ___% accurate at identifying placenta previa.
96-98
What can cause false positive results in transabdominal sonography evaluating for placenta previa?
Bladder distention (repeat after emptying the bladder)
What are the radiologic findings of placenta previa?
- Identification of echogenic placental tissue overlying or proximal to the internal cervical os
- A distance of greater than 2cm from the os excludes the diagnosis of previa, although the placenta may be low lying
