LOP/ROP
Criteria for ROP (long rotation):
Lie- longitudinal
Attitude-head is deflexed
Presentation-vertex/ cephalic
Position - Right occipito posterior
Denominator-occiput
Presenting part: middle or anterior area of the left (right- in case
of LOP) parietal bone
·
The head engages
through the right oblique diameter (ie.,Occipitofrontal diameter) in R.O.P and
left oblique diameter in L.O.P.
·
The engaging
transverse diameter of the head is bi parietal (9.5cm) and that of antero-posterior
diameter is either suboccipito frontal ( 10 cm ) or occipito frontal (11.5 cm )
Because of deflexion, engagement is delayed.
·
The engaging antero
posterior diameter lies in the oblique diameter of the pelvic brim.
·
The occiput points to
the right sacroiliac joint and sinciput to the left iliopectineal eminence.
Flexion: Descent takes place with increasing flexion. The
occiput becomes the leading part.
Internal rotation of the head: The occiput reaches the
pelvic floor first and rotates forward 3/8th of a circle along the right side
of the pelvis to lie under the symphysis pubis. The shoulders follow, turning
2/ 8 th of a circle to from the left to the right oblique diameter.
Crowning: The occiput escapes under the symphysis pubis and
the head is crowned
Extension: The sinciput, face and chin sweeps the perineum and the
head is born by a movement of extension
Restitution: takes place and occiput turns 1/ 8 th of a circle to
the right and now the head is in alignment with the shoulders.
Internal rotation of the shoulders and external
rotation of the head :
The shoulders enter into the pelvis in the right
oblique diameter, the anterior shoulder reaches the pelvic floor first and
rotates forward 1/ 8th of a circle to lie under the symphysis pubis.
Lateral flexion: The anterior shoulder escapes under the symphysis pubis,
the posterior shoulder sweeps the perineum and the rest of the body is born by
a movement of lateral flexion.
Some cirumstances, the occiput fails to rotate and
causes incomplete toward rotation- deep transverse arrest.
Non rotation- oblique posterior arrest
Malrotation- occipito-sacral arrest.
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