Shoulder Dystocia

Question 1

Definition of shoulder dystocia. When does it occur

Answer 1

• A vaginal cephalic delivery that requires additional obstetric manoeuvres to deliver the foetus after the head has delivered and gentle traction has failed
• Occurs when either the anterior, or less commonly the posterior, foetal shoulder impacts on the maternal symphysis or sacral promontory respectively.

Question 2

What alternative definition exists

Answer 2

• An objective definition of prolongation of head-to-body delivery time of more than 60 seconds has been proposed, but is not widely used.

Question 3

Incidence of shoulder dystocia

Answer 3

Between 0.56-0.7% of births

Question 4

Risk factors for shoulder dystocia

Answer 4

• Pre-labour: previous shoulder dystocia, Macrosomia >4.5Kg, Diabetes Mellitus (2x increased risk), Maternal BMI >30Kg/m2, Induction of labour
• Intrapartum: Prolonged first stage of labour, secondary arrest, prolonged second stage of labour, oxytocin augmentation, assisted vaginal delivery

Risk assessments for the prediction of shoulder dystocia are insufficiently predictive to allow prevention of the large majority of cases- conventional risk factors only account for 16% of dystocias that result in infant morbidity.

Question 5

Presentation of shoulder dystocia

Answer 5

• Presents with difficulty delivering the face and head and obstruction in delivering the shoulders after delivery of the head
• There may be failure of restitution, where the head remains face downwards (occipito-anterior) and does not turn as expected
• Turtle-neck sign: head is delivered but then retracts back into the vagina

Question 6

Complications of shoulder dystocia

Answer 6

• A delay in delivery of the foetal shoulder leads to foetal hypoxia proportional to the time delay to complete delivery- associated with significant perinatal morbidity and mortality
• Traction applied to the foetal head can result In BRACHIAL PLEXUS INJURY (Erb’s Palsy- most common reason for litigation in O&G)- complicated 2.3-16% of shoulder dystocia deliveries. Most cases resolve without permanent disability, with fewer than 10% resulting in permanent neurological dysfunction
• Larger babies are more likely to suffer a permanent BPI
• Maternal: Increased incidence of PPH (11%) and third and fourth-degree perineal tears (3.8%)

Question 7

How can shoulder dystocia be prevented

Answer 7

• Induction of labour at term can reduce the incidence of shoulder dystocia in women with GDM, however it does not prevent it In suspected macrosomic foetuses
• Elective caesarean section should be considered to reduce the potential morbidity for pregnancies complicated by pre-existing or gestational diabetes, regardless of treatment, with an estimated foetal weight>4.5Kg
• Either C-section or vaginal delivery can be appropriate after a previous shoulder dystocia (should be a two-way decision)

In labour, should routinely observe for:
* Difficulty in delivery of the face or chin
* The head remaining applied to the vulva or retracting (turtle-neck sign)
* Failure of restitution or shoulder descent

Question 8

What manouvre can be used to diagnose shoulder dystocia

Answer 8

• Routine traction in the axial direction
• Any other traction should be avoided since associated with BPI (i.e traction in line with the foetal sign without lateral deviation)

Question 9

Immediate management of shoulder dystocia

Answer 9

• Immediately after recognition of shoulder dystocia, additional help should be called for
• Fundal pressure should not be used (associated with uterine rupture) and maternal pushing should be discouraged since this may exacerbate impaction of the shoulders
• McRoberts’ manoeuvre is a simple, rapid and effective intervention and should be performed first. (successful in 90% of cases)
• Woman should be laid flat, then legs hyperflexed- routine traction should then be applied
• May apply suprapubic pressure at the same time as McRobert’s. Suprapubic pressure should be used to improve the effectiveness of the McRoberts’ manoeuvre.
• Internal manoeuvres or ‘all-fours’ position should be used if the McRoberts’ manoeuvre and suprapubic pressure fail. Internal manourvres: RUBIN II (hand to anterior shoulder, press to babys chest), WOODS SCREW (pressure to posterior shoulder)

Question 10

When should an epiiotomy be considered in shoulder dystocia

Answer 10

• An episiotomy is not always necessary- but may be useful in allowing more space to facilitate internal vaginal manoeuvres

Question 11

When can third-line manouvres be considered in shoulder dystocia

Answer 11

Third-line manoeuvres should be considered very carefully to avoid unnecessary maternal morbidity and mortality, particularly by inexperienced practitioners
* These include cleidotomy (surgical division or bending of the clavicle with a finger)
* Symphysiotomy
* Zavanelli manoeuvre (vaginal replacement of the head for C-section)

Should bear in mind that the foetus likely has irreversible hypoxic-acidosis at this stage

Question 12

Postpartum management following shoulder dystocia

Answer 12

o Should be aware of the risk of PPH and severe perineal tears
o Should examine the baby for injury

Question 13

Summary of the management of shoulder dystocia

Answer 13