Page 195 - كتاب تمريض نسا الاكتروني

193

 (Placental stage) Third Stage
Definition:
Starts with delivery of the fetus and ends with expulsion of the placenta, cord and
membranes, takes about 10-20 minutes ( average 10 minutes) and is painless.

 Note : Labour is prolonged when it lasts more than 18 hours.
 Mechanism of the third stage of labor:

Schultz Mechanism:

Commonest, occurs in 80% of cases. The central part of the placenta separates first as

the placenta is firmly attached at its edges. A retroplacental hematoma forms and the placenta

is delivered by its fetal surface followed by the membranes containing the blood clot. This

mechanism is lees liable to be followed by bleeding or retained fragments. Actually, the

placenta is delivered like inverted umbrella.

Duncan Mechanism:

In 20% of cases. The placenta separates at its lower edge, and is delivered sideways with

the maternal and fetal surfaces appearing together. There is no retro placental hematoma. It

is more liable to be followed by bleeding and retained fragments.

Placenta Expulsion:

After separation of the placenta from the uterine wall, continued uterine contractions cause

the placenta to be expelled and the placenta is delivered either by the natural bearing down

effort of the mother or by gentle pressure on the contracted fundus by a physician or nurse.

 N.B :

- Contraction means temporary shortening of the muscle fibre.

- Retraction means permanent shortening of the muscle fibre.

Table of Content