Delivery of the posterior arm can be achieved by
inserting the hand in the vagina posteriorly and applying
gentle pressure at the antecubital fossa to flex
the fetal forearm, which is then grasped and swept
across the fetal chest. Following delivery of the posterior
arm, the anterior arm rotates posteriorly or
descends behind the symphysis pubis, as the shoulder dimensions are reduced by 2.5 cm with this
maneuver especially in larger fetuses.51
Rubin’s maneuver: rotation of the shoulders is attempted
by inserting two fingers behind the anterior
shoulder. The shoulder is pushed forward and the
bisacromial diameter rotates into an oblique position.
If unsuccessful, this can then be combined with
the Woods’ screw maneuver.
Woods’ screw: pressure is applied with two fingers
on the anterior aspect of the posterior shoulder
aiming to rotate the fetus toward the same direction
as Rubin’s maneuver.
Reverse Woods’ screw: with two fingers behind
the posterior shoulder, rotation is attempted in the
opposite direction to the original Woods’ screw.
All these maneuvers aim to rotate the shoulders
and enable delivery by bringing the anterior
shoulder posteriorly. Insertion of the whole hand
instead of two fingers in the vagina may enable better
thrust on the shoulder and facilitate rotation
(Fig. 3).49
All-fours: the woman is on her hands and knees
and gentle traction is applied aiming to deliver the
posterior shoulder, which may descend because of
gravity and to a possible increase of the anteroposterior
diameter of the maternal pelvis.
Clavicular fracture: although the bisacromial diameter
is reduced with this maneuver, there is an
increased risk of iatrogenic brachial plexus injury,
vascular, and fetal soft tissue trauma.