Page 65 - 2023 Elctronic Book (3) Normal Labor_Neat

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.

A-Schultze Mechanism B-Duncan Mechanism

• Signs of placental separation

o Uterus becomes smaller, globular, harder, higher and more mobile.

o Suprapubic bulge is noticed due to the presence of placenta in the lower uterine
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