Techniques and principles for shoulder extraction during shoulder dystocia and breech delivery

The shoulder width (width of the parascapular cross-section) is the greatest among various body widths and thus, it may complicate the passage of the fetus through the pelvis. The shoulder width is at its greatest when the arms are elevated in the breech presentation. It is important to understand three principles to deform or reduce the shoulder width, deliver a trapped shoulder, or align the shoulder axis with the wider diameter of the pelvis.: (1) elevation or descent of the unilateral shoulder joint (avoiding simultaneous entry of both shoulders into the pelvis); (2) internal rotation of the shoulder joint (reduction of the shoulder width and contact of the forearm with the chest wall); and (3) matching the shoulder axis to the pelvic oblique diameter or transverse diameter.In cases of shoulder dystocia, (1) the anterior shoulder is first guided into the pelvis to prevent the simultaneous entry of both shoulders (suprapubic pressure), however, advancement of the posterior (opposite) shoulder, is also possible (Schwartz method). (2) Pushing the shoulder forward (internal rotation of the shoulder joint: [Rubin method, Woods corkscrew method]) reduces the shoulder width. Internal rotation of the shoulder is induced by a forward-pushing maneuver from the fetal back. (3) As the oblique and transverse diameters are greater than the anteroposterior diameter in the plane of the pelvic inlet, the fetus should be guided for the shoulder axis to match the oblique or transverse diameter, rather than the anteroposterior diameter (Woods corkscrew method, reverse corkscrew method).The classical method of freeing the shoulders and arms in the breech presentation is performed as follows: (2) the posterior shoulder is first pushed forward and downward from the fetal back (internal rotation of the shoulder joint), with the fetal forearm closely contacting the chest wall. Then, (1) the shoulder is extracted downward by pulling the elbow joint of the posterior shoulder to deliver the arm. (3) The shoulder axis should match the oblique diameter. Freeing the arm leads to the advancement of the posterior shoulder, because this maneuver is performed while the fetal trunk is pulled upward. Freeing the shoulder and arm should always be performed from the fetal back with the same-side hand. In cases of arm elevation or a nuchal arm, internal rotation of the shoulder joint is particularly important. The upper arm and forearm should be made to descend in such a manner that they con