Placenta Previa Flashcards
The number of cases of placenta previa and its complications are increasing due to
The rising incidence of cesarean sections, and increasing maternal age
What is vasa previa?
It describes a fetal vessels coursing through the membranes between the internal os, and the fetal presenting part. Unprotected by placental tissue or the umbilical cord.
Type one vasa previa
A velamentous cord inserted in a single, or bilobed placenta
What is the type 2 vasa preview?
Fetal vessels running between lobes of a placenta with accessory lobes
What is the incidence of vasa previa?
1/2000 to 1/6000 pregnancies
Mortality rate of vasa previa
60%
Presentation of vasa previa
- Fresh vaginal bleeding at the time of membrane rupture
- Fetal heart rate abnormalities like decelerations, bradycardia, Sinusoidal trace, or fetal demise
Fetal blood volume
80-100 ml/kg
Risk factors of vasa previa
- Placental anomalies such as bilobed placenta or succenturiate lobes
- History of low lying placenta in the second trimester
- Multiple pregnancy
- IVF. As high, as 1/300.
Definition and grades of PLACENTA PREVIA
lacenta develops within the lower uterine segment and graded according to the distance between the lower placenta edge and internal os
Grade 1: minor lower edge
Grade 2: marginal lower edge reaches the internal ps
Grade 3: partial previa ….partially cover os
Grade 4: complete previa
AIUM grading of placenta previa
Placenta praevia - Placenta directly over the os
Low-lying - when lower edge is <20 mm from the os
Normal - lower edge 20 mm or more from the os
This is for pregnancies more than 16 weeks
Incidence of PP ?
1/200 pregnancies
Risk factors of placenta previa
Increased maternal age
Smoking
ART
Prior CS - increases as the number of C sections increase, increased risk if the prior CS was Elective or prelabour, increased risk if the CS to current pregnancy interval is less than 1 year
when to do screening for placenta previa
midpregnancy routine fetal anomaly
when to use the term low-lying placenta
if >16w, when placental edge is less than 20 mm from internal os
if lowlying or previa at routine fetal anomaly scan (18-22w), when to follow up
dollow-up u/s including tvs at 32 w