Mechanism

1. MECHANISM OF
LABOUR

2. FETAL LIE
 The relation of the long axis of the fetus to
that of the mother
 Longitudinal lie is found in 99% of labours
at term
 Predisposing factors for transverse
lie/oblique lie
 multiparity
 placenta previa,
 hydramnious
 uterine anomalies

3. FETAL PRESENTATION
 The presenting part is the portion of the
body of the fetus that is foremost in the
birth canal
 The presenting part can be felt through the
Cx on vaginal examination
 Longitudinal lie  cephalic presentation
breech presentation
 Transvrse lie  shoulder presentation

4. CEPHALIC PRESENTATION
 Head is flexed sharply  vertex / occiput
presentation
 Head is extended sharply  face presentation
 Partially flexed  bregma presenting (sinciput
presentation)
 Partially extended  brow presentation
BREECH PRESENTATION
 Frank breech
 Complete breech
 Footling breech

5. ATTITUDE
 Posture of the fetus folded on itself to
accommodate the shape of the uterus
 Flexed head, thighs, knees &feet
 The arms crossed over the chest
 Face presentation extended concave
contour of the vertebral column

6. .
'
"
'
I
!
1
1
1
A
B
i
i
F
c
D
Longitudinal lie. Cephalic presentation. Differences in
attitude of fetal body,
(A) vertex (B) sinciput (C) brow (D) face

7. Longitudinal lie. Frank
breech presentation.
I
I
Longitudinal lie. Complete
breech presentation.

8. Longitudinal lie. Incomplete, or
footling, breech presentation.

9. POSITION
The relation of an arbitrary chosen point of the fetal
presenting part to the Rt or Lt side of the maternal
birth canal
The chosen point
 Vertex presentation  occiput
 Face presentation  mentum
 Breech presentation Sacrum
Each presentation has two positions Rt or Lt
Each position has 3 varieties : Ant, transverse, post
OA
OP
LOT
ROT
LOA
ROA
LOP
ROP

10. ~
'
t
J
LONGITUDINAL LIE VERTEX PRESENTATION
LOA LOP

11. s
A
Longtitudinal Lie.Vertex Presentation
A. Right occiput posterior (ROP) Right occiput transverse (ROT)

12. J
3
~
S
f
a
!
w
C
c
h
t
p
(
f
i
t
t
b
f
e
w
c
a
l
Right occiput anterior
(ROA).

13. Longitudinal lie. Face presentation. Left
and right anterior and right posterior
positions.
Rt mento-post
Rt mento-ant
Lt mento-ant

14. ~
Longitudinal lie Breech presentation LSP

15. Transverse lie. Right acromiodorsoposterior position
(RADP). The shoulder of the fetus is to the mother's right,
and the back is posterior.

16. Lever action producing FLEXION of the head; conversion
from occipitofrontal to suboccipitobregmatic diameter
typically reduces the anteroposterior diameter from nearly
12- to 9.5 cm.

17. Left lateral
a. Knee chest

18. a. Squatting
a. Standing

20. Types of episiotomy
1. Medio-lateral
2. Median
3. Lateral
4. J shaped

30. 3
0
2
2.Engagement;descent,
flexion
6. Restitution (external
rotation)
3. Further descent,
internal rotation
4. Complete rotation,
Cardinal
movements in
the mechanism
of labor and
delivery, left
occiput anterior
position.

31. Mechanism of labor for right
occiput posterior position,
anterior rotation.
,
.
,
0