Definition Placenta previa: Abnormal location- of the placenta over,orin close proximity to the internal os. Incidence: approximately 1 /250 pregnancy nulliparas: 1/1000~1/1500 pregnancy grandmultiparas: 1/20
General Consideration Definition The separation of the placenta from its site of implantation after 20 weeks of gestation or during the course of delivery Frequency 0.51%0-2.33%(our country) 1%o(other countries) Incidence of fetal death
Must choose routes for various origin destination pairs(O/D pairs) or for various sessions - Datagram routing: route chosen on packet by packet basis Using datagram routing is an easy way to split paths Virtual circuit routing: route chosen a session by session basis Static routing: route chosen in a prearranged way based on O/D pairs Eytan Modiano