Shoulder Dystocia

Article Author:
Donald Davis
Article Author:
Afghani Roshan
Article Author:
Christinne Canela
Article Editor:
Matthew Varacallo
Updated:
6/23/2020 7:46:54 PM
PubMed Link:
Shoulder Dystocia

Introduction

Shoulder dystocia is, by definition, a mechanical problem occurring during a vaginal delivery characterized by one of the following parameters:

  • failure to deliver the fetal shoulders using solely gentle downward traction 
  • the requirement of additional delivery maneuvers are needed to successfully deliver the baby
  • a documented head-to-body interval of greater than 1 minute

Unpredictable and often unavoidable obstetric emergencies complicate 0.6% to 1.4% of all vaginal deliveries. All obstetric providers are required to be knowledgeable regarding the risk factors and management of shoulder dystocia.[1][2]

Furthermore, shoulder dystocia can lead to obstetric brachial plexopathies such as Erb's or Klumpke's palsies. Injuries to the brachial plexus during birth can be categorized as upper lesions, involving C5-6, lower lesions, involving C8-T1, or total plexopathies involving C5-T1. 

Etiology

Several risk factors for shoulder dystocia have been identified. Fetal macrosomia is the most significant risk factor for shoulder dystocia. Other known risk factors include pregestational and gestational diabetes, prior history of shoulder dystocia and operative vaginal delivery, particularly with the use of the vacuum. Other risk factors such as maternal obesity, excessive maternal weight gain, and labor dysfunction are controversial since studies have had conflicting results. Attempts to predict shoulder dystocia based on these risk factors have shown poor reliability and poor predictive value.[3]

Of the obstetric brachial plexopathies, upper lesions are the most common. Upper lesions result from a lateral flexion of the head away from the affected shoulder, with depression of the ipsilateral shoulder resulting in a C5-6 deficiency.  Lower lesions are caused by traction with the shoulder in full abduction at the time of delivery. Total brachial plexopathies are the rarest form of obstetric plexopathies, and are caused by a severe stretch or avulsion type injury.[4]

Epidemiology

There are potential maternal and fetal consequences following shoulder dystocia. Maternal consequences include postpartum hemorrhage and an increased risk of third or fourth-degree lacerations. Certain "heroic maneuvers" such as the Zavanelli maneuver is associated with significant maternal morbidity. Fetal consequences include fetal brachial plexus injuries, fetal clavicular or humeral fracture, Hypoxic Ischemic Encephalopathy syndrome, and even fetal death. Most brachial plexus injuries are transient and resolve with time and physical therapy. Fetal fractures typically heal without consequences.[5][6][7]

The anterior fetal shoulder may become impacted behind the maternal pubic symphysis. Rarely, the posterior fetal shoulder may be obstructed on the sacral promontory.[7][8]

During a 2 year prospective study by Lagerkvist et al, obstetric plexopathies occurred in 2.9 per 1000 births in total, and 3.6 per 1000 vaginal births.  Of the 114 infants included, 70 were males and 44 were females (p ~.015).[4]

History and Physical

The comprehensive history and physical examination components hinge on critically detailed documentation of the entire vaginal delivery.  A comprehensive maternal history should be obtained.  Documentation of the delivery process should be thorough and focused on all potential elements that would be considered consistent with a shoulder dystocia presentation.  Shoulder dystocia is, by definition, a mechanical problem occurring during a vaginal delivery characterized by one of the following parameters:

  • failure to deliver the fetal shoulders using solely gentle downward traction 
  • the requirement of additional delivery maneuvers are needed to successfully deliver the baby
  • a documented head-to-body interval of greater than 1 minute

Retraction of the fetal head toward the perineum may be noted following the delivery of the fetal head. This is called the "turtle sign".  The latter is a risk factor for shoulder dystocia.

In the evaluation of obstetric plexopathies, a full neurovascular examination is warranted. Upper lesions results in a classic "waiter's tip" palsy, with the extremity adducted, internally rotated at the shoulder, extended at the elbow, and pronated at the forearm secondary to deficiencies of the axillary, suprascapular, musculocutaneous, and radial nerves (C5-C6 innervation). 

Lower lesions result in a classic "claw hand" palsy, with the wrist in extreme extension, hyperextension of the metacarpophalangeal joints, and flexion of the interphalangeal joints. This plexopathy has a high association with Horner's syndrome, and therefore evaluation for ipsilateral miosis, ptosis, and anhidrosis is an important component of the physical evaluation.

Total plexus palsies result in a flaccid extremity with both motor and sensory deficits.  These injuries have the lowest chance of recovery and the highest incidence of associated phrenic nerve injuries. 

All children with a suspected brachial plexopathies should undergo evaluation for Horner's Syndrome as mentioned above, and pulmonary examination with chest radiograph in evaluation for phrenic nerve injury, as these disorders frequently present in concomitantly with obstetric plexopathies.

Evaluation

Shoulder dystocia remains a subjective diagnosis. All providers should recognize the limitations in the objective evaluation and limitations regarding establishing objective diagnostic criteria. Moreover, the sole objective element in making the diagnosis is the presence of a head-to-body delivery interval of greater than 60 seconds.  

Treatment / Management

Once the diagnosis of shoulder dystocia is made, it is important to recognize the situation and inform other team members about the dystocia. This allows other members of the team to assist with the maneuvers as well as call for help. The provider can then attempt maneuvers to assist with relieving the shoulder dystocia. Maneuvers are typically divided into first-line and second-line maneuvers.[9][10][7]

Shoulder dystocia is an obstetric emergency that requires preparation and training for proper management by delivering providers. Not only does the baby need to be delivered quickly, but care must also be taken to mitigate the risk of injury to the mother and the infant

First-Line Maneuvers

  • McRoberts Maneuver: This is commonly the first maneuver performed along with suprapubic pressure. The patient's thigh is hyper flexed towards the abdomen. This will straighten the maternal sacrum on the lumbar spine.
  • Suprapubic pressure: the goal of suprapubic pressure is to decrease the fetal bisacromial diameter by adducting the anterior fetal shoulder. Pressure is applied to the suprapubic area in a downward fashion or a rocking motion from the fetal back toward the front.

Second-Line Maneuvers  

Rotational Maneuvers (Rubin or Woodscrew)

  • Rubin’s maneuver: performed by placing a hand into the vagina and applying pressure to the posterior aspect of the most accessible fetal shoulder towards the fetal chest. This will lead to the adduction of the fetal shoulder which would then allow the anterior shoulder to rotate and deliver from behind the pubic bone where is it impacted. 
  • Woods corkscrew maneuver: the obstetrician places a hand on the anterior aspect of the posterior fetal shoulder and rotates the shoulder toward the fetal back. The goal is to attempt to rotate the fetal shoulder 180 degrees. This allows the fetus to descend while the rotation is occurring. 
  • Delivery of the posterior arm: the obstetrician slides a hand along the fetal posterior shoulder and arm, and the fetal forearm or wrist is grasped and swept across the anterior fetal chest to effect delivery of the posterior arm. If the fetal forearm is not easily accessible, one can follow the posterior fetal arm and put pressure on the antecubital fossa, and this will typically lead to flexion of the fetal arm, allowing access to the fetal forearm. With the successful delivery of the posterior arm, the axillo-acromial diameter becomes the presenting part, and it is typically about 3 centimeters shorter and leads to delivery of the anterior shoulder.
  • Gaskin Maneuver: with the patient on her hands and knees (all fours position) or in a racing start or sprinter position, gentle downward traction is applied to the posterior shoulder (the shoulder against the maternal sacrum) or upward traction is applied on the anterior shoulder (the shoulder against the maternal symphysis).

Posterior Axillary Traction (Menticoglou or posterior axillary sling traction) - may be especially helpful in situations where the fetal arms are extended. With each method, the assistant should hold the fetal head and flexes it upward toward the anterior shoulder.

  • Menticoglou maneuver: the obstetrician, places their middle fingers under the posterior fetal axilla and applies downward and outward traction which leads to delivery of the posterior shoulder; this is then followed by delivery of the posterior arm.
  • Posterior axilla sling traction: a suction catheter or firm urinary catheter is used as a sling. Traction is applied to the sling to deliver the posterior shoulder followed by the arm. Alternatively, the sling can be used to rotate the shoulders by applying lateral traction towards the baby’s back while the other hand is placed on the anterior shoulder putting pressure towards the fetal chest.

Heroic Measures

  • Intentional clavicular fracture: the fetal clavicle is intentionally fractured by pulling the anterior clavicle outward. If successful, this will decrease the bisacromial diameter. Disadvantages: difficult to execute, the possibility of injury to underlying vascular and pulmonary structures.  
  • Zavanelli maneuver: the fetal head is rotated to its pre-restitution attitude, flexed and elevated up to the vagina and back into the uterus. A Cesarean section then achieves delivery. 
  • Abdominal rescue: If a cephalic replacement or the Zavanelli maneuver is unsuccessful, a low transverse hysterotomy is performed, and the fetal shoulders are manually rotated to an oblique diameter through the transabdominal incision. Once the fetal shoulders are rotated, vaginal delivery is then attempted.
  • Symphysiotomy: with the patient in the lithotomy position, a Foley catheter is placed. The urethra is retracted laterally with the Foley catheter. The skin and subcutaneous tissues are incised with a scalpel to the level of the pubic symphysis as well as the anterior fibers of the pubic symphysis. Recommended only as a last resort when all the other measures have failed or in cases where immediate access to an operating room facility for Zavenelli or abdominal rescue is not available.

Obstetric Plexopathy Treatments

Any suspected brachial plexopathy should undergo a trial of observation and daily passive exercises to await the return of function. The most important consideration in early non-operative management is maintaining the passive motion of the extremity while awaiting nerve function return.

At 3-9 months of age, surgical intervention may be considered. Nerve grafting is indicated for patients without antigravity biceps function if the nerve injury is post-ganglionic, while pre-ganglionic nerve injures are better treated with nerve transfer or neurotization.

To prevent glenohumeral dysplasia from persistent internal rotation of the humerus, tendon transfers or tendon lengthening procedures may be considered.  The Hoffer procedure is a transfer of the latissimus dorsi and teres major to external rotators of the humerus.  Pectoralis major and subscapularis tendon lengthening procedures can serve to lessen the internal rotation forces that remain unopposed in upper lesions.  Alternatively, practitioners may consider a Wickstrom osteotomy, which serves as a proximal humeral derotation osteotomy to combat the internal rotation contracture present in such plexopathies.[11][12]  

Serial nighttime elbow extension splinting is the mainstay of treatment for elbow flexion contractures, but operative capsular release and biceps tendon lengthening may be considered for persistent contraction.[13]

A number of tendon transfers distally may be employed to treat deficiencies in the hand and wrist.  Wrist drop is most frequently treated with pronator teres to extensor carpi radialis brevis (ECRB) transfer.  Loss of finger extension may be treated with the transfer of flexor carpi radialis or ulnaris (FCR or FCU) to extensor digitorum communis (EDC). Loss of thumb abduction may be treated with extensor indicis proprius (EIP) to abductor pollicis brevis (APB) transfer.

Differential Diagnosis

The differential diagnosis for shoulder dystocia includes, but is not limited to umbilical cord prolapse, breech delivery, or other elements consistent with an emergent delivery and/or perimortem cesarean section (c-section) delivery.

A clear understanding of the anatomy of the brachial plexus will help diagnosticians to correctly distinguish the common brachial plexopathies from one another. Upper lesions cause Erb's palsy, with weakness in the axillary, suprascapular, musculocutaneous, and radial nerve distributions.  Lower lesions cause Klumpke's palsy, with a claw hand deformity.  And total plexus palsies result in a flaccid arm with both sensory and motor deficits.  Practitioners must also consider the possibility of spinal pathology and peripheral nerve injury as well.  Careful physical examination and observation are the most important tools for correct diagnosis and management.

Prognosis

Simulation-based training has decreased the overall rate of shoulder dystocia and other obstetric-related complications.[14][15][16]

Lagerkvist et al determined that by 3 months of age, 50% of children regain full function, and by 18 months 82% of children regain full function.  All children who required surgical intervention had diminished use of the affected extremity, with fine motor skills being the most severely diminished.[17]

Complications

Complications of shoulder dystocia can include, but are not limited to the following:

  • Obstetric brachial plexopathies
    • shoulder dystocia is a known risk factor for developing an OBBP injury
    • the incidence rate of 3% to 17% in the setting of shoulder dystocia diagnosis
    • phrenic nerve palsy
    • Horner's syndrome
  • Clavicular fracture (1.7 to 9.5%)
  • Humerus fracture (0.1 to 4.2%)
  • Permanent brachial plexus palsy (0.5 to 1.6%)
  • Hypoxic-ischemic encephalopathy (0.3%)
  • Death (0 to 0.35%)

Deterrence and Patient Education

Patients should be educated regarding the known risk factors for putting the infant at risk of shoulder dystocia.  In the setting of a history of prior delivery complicated by shoulder dystocia, it is important to convey to the mother that she has a 6- to 30-fold increased risk of shoulder dystocia recurrence with any subsequent vaginal deliveries.[18]

Pearls and Other Issues

Avoid applying fundal pressure as this only serves to impact the anterior fetal shoulder into the pubic bone further, making the shoulder dystocia worse. When performing the Zavanelli, tocolytics such as halogenated inhalational anesthetics, or Nitroglycerin may be given to assist with cephalic replacement. Following any shoulder dystocia, counseling the patient about the event and the 15% recurrence risk is important. The event should be properly documented in the medical record.

Enhancing Healthcare Team Outcomes

An interprofessional team must coordinate care to ensure optimal outcomes. The nurse is often required to apply fundal pressure or administer medications. The pharmacist is responsible for ensuring adequate stocks of analgesics, anesthetics, and other medications are available.

Children who suffer from obstetric brachial plexopathies have a generally good outcome with non-operative management and observation.  Still, some require more drastic intervention, which greatly reduces the child's long term functional outcome. In these cases it is important for orthopaedic surgeons, pediatricians, and therapists to work closely in concert with one another to achieve the most optimal outcomes for the patient.


References

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[2] ACOG practice bulletin: Shoulder dystocia. Number 40, November 2002. (Replaces practice pattern number 7, October 1997)., Sokol RJ,Blackwell SC,, International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics, 2003 Jan     [PubMed PMID: 12578001]
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