MEASURES TO RELIEVE SHOULDER DYSTOCIA

Shoulder dystocia is most often recognized after delivery of the fetal head, when gentle downward traction on the head fails to accomplish delivery. The so-called “turtle sign” is often noted – after the delivery of the head, the head is pulled back against the external vagina (perineum). Once dystocia is recognized, the mother should be stopped from pushing until the shoulders have been freed. If the umbilical cord is wrapped around the neck (nuchal cord), an attempt should be made to pull it over the head. If this fails, the cord should not be cut, but rather left intact until complete delivery has been accomplished.  Fetal shoulder dystocia is considered an obstetrical emergency, and steps should be rapidly instituted to relieve the problem. A delay of more than several minutes between head and shoulder delivery increases the chance of brain damage due to hypoxia.

McRoberts maneuver

The McRoberts maneuver is generally the first step taken once dystocia is recognized. The maneuver consists of flexion of both maternal thighs into the abdomen. This action causes a flattening of the lower spine and a subsequent increase in the front-to-back dimension of the pelvis. This change is often enough to permit the shoulders to slip through the pelvic inlet. Care must be taken not to be too aggressive in the maneuver as this may result  in maternal injury as described previously.

McROBERTS MANEUVER

Suprapupic pressure

Suprapubic pressure is often performed in conjunction with the McRoberts maneuver, or shortly thereafter if the McRoberts is unsuccessful. It consists of downward pressure applied with the heel of the hand directly above maternal pubic bone. The intended effect is to push the impacted shoulder below the pubic bone, thus freeing it to move forward through the inlet. Proper positioning of the hands at a point directly above the pubic bone is critical, as pressure applied at a higher level will compress the uterus and may aggravate brachial plexus stretch or umbilical cord compression and fetal hypoxia.

SUPRAPUBIC PRESSURE

Woods screw

If McRoberts and suprapubic pressure fail, a variety of additional techniques may be attempted, including the Woods Screw and Rubin maneuvers. The Woods Screw consists of application of the operator hands to the anterior and posterior shoulders. Pressure is then applied to rotate the shoulders, moving them into an oblique position, thus relieving the impaction. The Rubin maneuver (reverse Woods) involves application of pressure to the back (posterior) of whichever shoulder is most accessible, again with the goal of rotation into the oblique position.

WOODS SCREW MANEUVER

Posterior Arm Delivery

Delivery of the posterior arm has the effect of pulling the posterior shoulder into the pelvic inlet.  When successful, this has the effect of dropping the anterior shoulder beneath the pubic bone. The operator reaches in along the maternal spine, flexes the posterior arm at the elbow, and then delivers the arm with a sweeping motion along the fetal chest.

POSTERIOR ARM DELIVERY

Zavanelli, Symphisiotomy, Hysterotomy

When the above measures have failed to relieve dystocia, more aggressive, so-called “heroic” measures may be required. The Zavanelli maneuver consists of an attempt to replace the fetal head back into the labor canal, thus disimpacting the shoulders, and relieving stress on the brachial plexus and umbilical cord.  Once accomplished, the decision can be made whether to re-attempt vaginal delivery or proceed to an emergency caesarian section.

ZAVANELLI MANEUVER