1. Management of a Low Lying Placenta
Max Brinsmead MB BS PhD
August 2018

2. Routine 2nd Trimester Ultrasound
Will warn of a placenta that is implanting in the lower segment of the uterus
Anatomically defined as below the peritoneal reflection from uterus to bladder
Internal cervical os is the other major landmark

3. If the placenta reaches or covers the internal os at 20 weeks…
Follow up Vaginal Ultrasound is required
Because the placenta will “migrate” in up to 80% of instances of low placenta identified by routine abdominal ultrasound in the 2nd trimester
But this is less likely if the placenta is posterior

4. If the degree of previa is minor and there is no APH…
Follow up ultrasound can be deferred until 36 weeks gestation
But any APH requires further immediate evaluation
As does any major encroachment or “central placenta previa”

5. Vaginal delivery is possible
If the leading placental edge is >3 cm from the internal os on vaginal ultrasound
Vaginal delivery is possible
Maybe even 2 cm if the placenta is anterior
But major encroachment closer than 2 – 3 cm will require Caesarean delivery

6. Patients with Major Placenta Previa
Re evaluate with vaginal ultrasound at 32 weeks
Warn about risk of APH and take all suitable precautions
Hospital care may be required in order to reduce risk to the mother but prolong the pregnancy as long as possible

7. Placental implantation extends through decidua to the myometrium
Placenta Accreta
Placental implantation extends through decidua to the myometrium
Is more common after a previous Caesarean and with an anterior placenta previa
Major haemorrhage at the time of deliver may require hysterectomy

8. Any Questions or Comments?
Please leave a Note on the Welcome Page to this Website