Shoulder dystocia: Clinical sciences

Chapters:

Watch video only

Introduction0:00–0:35

Shoulder dystocia is an unpredictable obstetric emergency! It most often occurs during a vaginal delivery when the anterior fetal shoulder becomes impacted behind the maternal symphysis pubis, thereby preventing spontaneous delivery of the fetal body after delivery of the head.
Less frequently, it may occur if the posterior shoulder becomes impacted by the sacral promontory. Once diagnosed, time is of the essence, as the longer a fetus remains impacted, the higher the risk of maternal and fetal morbidity.

Focused History and Physical0:35–2:27

Okay, when a patient presents with a chief concern suggesting shoulder dystocia, you should first obtain a focused history and physical exam.
The patient may have a history of prior shoulder dystocia, a pregnancy complicated by suspected fetal macrosomia, or they may have gestational or pregestational diabetes.
While these findings are associated with an increased risk of shoulder dystocia, it most often occurs in non-diabetic patients with normal-sized infants.
Additional risk factors that may increase the risk of shoulder dystocia include maternal obesity, as this is associated with maternal diabetes and fetal macrosomia; post term pregnancies, or those lasting beyond 42 weeks; an abnormal pelvic structure; or a short maternal stature.
Also, a prolonged second stage of labor should raise suspicion, although this alone is not a good predictor for shoulder dystocia.When it comes to the physical exam, you might see the delivered fetal head retracting against the perineum, which is called the “turtle sign.” Additionally, the fetal shoulders will not easily deliver despite gentle downward traction of the fetal head.
Basically, if you see a fetal head that delivers without spontaneous delivery of the body, you can diagnose shoulder dystocia.
Here’s a high-yield fact! Be sure to avoid forceful traction on the fetal head, as it may cause a brachial plexus injury!
Erb’s palsy, or injury to C5 through C7 causes the classic “waiter's tip” posture; whereas Klumpke’s paralysis, or injury to C8 through T1 results in a “claw hand” appearance of the infant’s extremity.
Generally, brachial plexus injuries are not permanent, and most resolve by 24 months.Okay, let’s move on to acute management.

Acute Management2:27–3:52

Remember, shoulder dystocia is an obstetric emergency, so your first step is to immediately call for help! This includes additional nurses, another obstetric care provider, anesthesia, and the neonatology team.
Next, instruct the patient to stop pushing, as further expulsive efforts may worsen the impaction of the shoulder. Also, start a timer and assign one person to record the events.
The recorder will note how long the dystocia lasts, as well as when a maneuver is started and for how long it is attempted.
Following this, you should evaluate the need for an episiotomy, which is a procedure that enlarges the vaginal opening by making a small incision at the introitus.
In this scenario, an episiotomy may provide additional space for you to better perform the maneuvers needed to deliver the fetus.
Speaking of maneuvers, the goal of these is to dislodge the impacted shoulder and allow for delivery by creating a larger space in the bony pelvis; by decreasing the fetal bisacromial diameter, which is the distance between the outermost parts of the fetal shoulders; or by altering how the bisacromial diameter is situated within the bony pelvis.First-line interventions consist of external maneuvers, specifically the McRoberts maneuver and suprapubic pressure.

External Maneuvers3:52–5:04

These are both easy and quick to perform and often are initiated together. The McRoberts maneuver involves hyperflexion of the maternal hips, or flexing the maternal knees and bringing them to her chest.
This straightens the maternal sacrum and lumbar spine, thereby increasing the anterior-posterior diameter of the pelvis, which may dislodge the dystocia.
McRoberts should be performed by two assistants, while another assistant uses the heel of their hand to apply suprapubic pressure in a downward and lateral motion on the posterior aspect of the fetal impacted shoulder.
The aim is to adduct the fetal shoulder thereby decreasing the fetal bisacromial diameter. Once completed, assess the response of these two maneuvers.
If there is an adequate response you will be able to deliver the neonate with gentle downward traction on the fetal head.
However, if the response is inadequate you will note a persistent dystocia and must proceed with additional maneuvers.Next, it’s time to employ internal maneuvers, which involve using your hands to manipulate the fetus and allow delivery.

Internal Maneuvers5:04–7:17

First, you can attempt delivery of the posterior arm of the fetus. This will similarly decrease the bisacromial diameter and allow delivery.
To perform this maneuver, you will insert your hand into the posterior vagina and slide it along the posterior fetal arm to grasp the hand or wrist.
Next, sweep the fetal arm anteriorly over the fetal chest and deliver the posterior arm. If this is unsuccessful, you will move on to rotational maneuvers, also known as Rubin and Wood Corkscrew maneuvers.
The Rubin maneuver is performed by placing pressure on the posterior aspect of the most accessible shoulder to adduct the fetal shoulder towards the chest.
This allows the impacted shoulder to inwardly rotate and dislodge from its impacted location. The Woods Corkscrew maneuver is performed by placing your hand anteriorly on the posterior fetal shoulder and rotating it towards the fetal back while rotating the fetus 180 degrees.
During the rotation, the fetus will hopefully descend and deliver. Another internal maneuver to try is posterior axillary sling traction.
This is helpful in cases where the fetal arm is extended. Here, you’ll place a urinary or suction catheter around the posterior shoulder and use it as a sling to pull outward and deliver the posterior shoulder.
If these are unsuccessful you should consider the Gaskin maneuver. This entails placing the patient on her hands and knees and attempting to deliver the posterior shoulder that is against the maternal sacrum.
As this maneuver involves the patient moving and holding a new position, it cannot reliably be accomplished in patients with an epidural.
If delivery still has not occurred, you should repeat the internal maneuvers. You can also ask the other obstetrical care provider present to attempt the maneuvers.
After this, reassess the response. If there’s an adequate response, you will deliver the neonate.

Methods of Last Resort7:17–9:20

But, if the response is inadequate with persistent dystocia, consider methods of last resort. Here the shoulders are so severely impacted that you must try options that will cause significant maternal and neonatal morbidity to allow for delivery.
This includes intentionally fracturing the fetal clavicle by pulling the anterior clavicle outward to decrease the bisacromial diameter.
With this, there’s a risk of damaging underlying pulmonary or vascular structures. You can also try the Zavanelli maneuver, also known as cephalic replacement.
Essentially, you’ll elevate and place the fetal head back into the vaginal canal and uterus, then immediately proceed to an operating room for a cesarean delivery.
If the Zavanelli maneuver is unsuccessful, you can try abdominal rescue. In this situation, you start performing a cesarean delivery, however, instead of delivering the fetus through the abdomen, you will attempt to manually rotate the fetal shoulders so the shoulder dislodges from above via the hysterotomy.
You will then proceed with vaginal delivery. The last option to try is symphysiotomy.
It should only be attempted if all other methods have failed or there’s no immediate access to an operating room to perform the Zavanelli maneuver or abdominal rescue.
You will place a urinary catheter to laterally displace the urethra then make an incision through the anterior fibers of the pubic symphysis, creating a larger opening to dislodge the shoulder and proceed with a vaginal delivery.
There’s a significant risk of injuring surrounding structures, such as the bladder and urethra, as well as ongoing chronic pain and difficulty ambulating for the patient.Alright, as a quick recap… Shoulder dystocia is an obstetrical emergency that occurs when the fetal head delivers but the shoulders do not.

Review9:20–10:33

Once diagnosed, you should immediately call for help and employ maneuvers to allow for delivery. External maneuvers include the McRoberts maneuver and suprapubic pressure.
If these don’t work, move on to internal maneuvers, meaning delivery of the posterior arm, rotational maneuvers, and posterior axillary sling traction.
In some situations, you can attempt the Gaskin maneuver as well. If these also fail, try methods of last resort, including fracture of the fetal clavicle, Zanelli maneuver, abdominal rescue, and in the most extreme cases,