Shoulder Dystocia is an unpredictable life-threatening obstetric emergency, with significant risk of harm to the infant if managed inappropriately. Certain risk factors have been identified but their predictive value is low. Consequently birth attendants must be prepared for the possibility of shoulder dystocia in all vaginal deliveries and have a prepared plan of management. Rehearsed protocols markedly enhance such preparation.
[CG] Shoulder dystocia
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Shoulder dystocia is the failure to deliver the shoulders with routine axial traction, i.e. the same degree of traction as is applied during a normal delivery, applied in line with the fetal spine. (RCOG Guideline no. 42, 2012).
- Soft tissue injury e.g. anal sphincter injury (3.8%) vaginal/cervical lacerations, neuropathy
- Postpartum haemorrhage due to trauma or atony (11%)
Fetal and Neonatal complications
- Brachial plexus injury: Erb’s Palsy (C5, C6), Klumpke’s Palsy (C8, T1). This complicates 2.3% - 16% of such deliveries, though fewer than 10% of brachial plexus injuries result in permanent neurological dysfunction. There is therefore an approximately 1% risk of permanent neurological dysfunction in the event of a shoulder dystocia.
- Fracture of clavicle or humerus
- Hypoxic brain injury
- Stillbirth/Neonatal death.
Conventional risk factor analysis only predicts 16% of shoulder dystocias that result in neonatal morbidity. Everyone is at risk. Some patients though are at even higher risk.
Pre-labour risk factors
- Previous shoulder dystocia
- Fetal macrosomia, i.e. estimated fetal weight >4500g
- Diabetes, whether gestational or pre-existing
- Maternal BMI >30kg/m2
- Induction of labour
Intrapartum risk factors
- Prolonged first stage or second stage of labour
- Syntocinon augmentation
- Assisted vaginal delivery. Beware in particular the parous woman requiring this
There is a correlation between fetal weight and shoulder dystocia but it is not a reliable one.
- The majority of infants with a birth weight >4500g do not experience should dystocia
- 50% of shoulder dystocias occur with infants who weigh <4000g
If risk factor(s) are present, consider performing episiotomy at delivery
Warning signs at delivery
Head tight against the perineum after its delivery
Failure to restitute
Only employ routine axial traction to the fetal head. If the shoulders do not deliver, this is shoulder dystocia.
Bear in mind throughout that there is a very low rate of hypoxic ischaemic injury if the head-to-body delivery time is <5 minutes.
Appoint a member of staff to record events to prompt the team as to steps that may have been missed or to move on to the next step. 30 seconds of each attempted manoeuvre is reasonable.
Stop pulling and pushing.
Stop pulling and instruct the patient to stop pushing.
Further efforts will not assist delivery and will expose the baby to the risk of brachial plexus injury.
Communicate with patient
Explain briefly to the patient that the baby’s shoulders are stuck and that you are going to need help from quite a few people to assist with delivery.
Call for help
Urgently request help: ensure that the most experienced available obstetrician and midwife are summoned immediately, along with sufficient staff to assist with the following manoeuvres and, very importantly, the neonatal team also. Given the significant possibility of associated maternal morbidity, it is prudent to request anaesthetic attendance. Issuing both an obstetric and neonatal emergency call is an effective and efficient way to achieve all of this. Enough help should be summoned so that someone present is able to document event contemporaneously. Documentation should include a clear description of which the fetal shoulder was the anterior one.
Position the patient
The bed should be flattened and lowered, the patient’s bottom brought to the edge of the bed to permit maximum access and her legs removed from stirrups (if present) in order to permit McRoberts’ positioning.
Legs should be placed in McRoberts position by assistants: hips maximally flexed with knees a little over shoulder-width apart. Remove legs from stirrups (if present). Once in this position, instruct the patient to push and attempt to deliver with routine axial traction. The majority of shoulder dystocias will resolve at this point; however stop pushing/pulling if there is no progress. McRoberts’ position is a treatment for shoulder dystocia and has no place as a “prophylactic” measure: this only confuses diagnosis and complicates counselling in the event of a future pregnancy.
If McRoberts’ alone has been unsuccessful, pressure should be applied by an assistant just above the pubic symphisis, from the direction on which the fetal back is suspected to lie, while maintaining McRoberts’. Either steady or “rocking” pressure may be applied. If it is not known on which side the fetal back is lying, attempt with pressure first from one side, then from the other. Fundal pressure should never be employed as this risks uterine rupture. Once appropriate pressure is established, again attempt delivery and again abandon the attempt if there is no progress.
Evaluate for episiotomy.
Maintain McRoberts’ and Suprapubic pressure and attempt internal manoeuvres. If vaginal entry proves impossible, an episiotomy must be cut. This is though both difficult and dangerous to perform at this juncture, hence the recommendation to consider it at the time of delivery.
Internal manoeuvres – Rotation of the shoulders
The options are either to attempt to rotate the fetal shoulders or to deliver the posterior arm. A suggested means of proceeding is to insert your right hand into the vagina if the fetal back is on the right and/or if the baby has, prior to delivery, been ROA/ROT/ROP, and the left hand if left LOA/LOT/LOP. In any event, your hand must be reduced to its smallest size and the whole hand (not just two or four fingers) inserted posteriorly into the sacral hollow, as this is where there will be most space. It may then be possible, by applying pressure to the anterior aspect of the posterior shoulder, to assist the person applying Suprapubic pressure in facilitating rotation into the oblique diameter and thence delivery. This may be assisted by applying pressure vaginally to the posterior aspect of the anterior shoulder. If there is any progress, instruct the patient to push. If a degree of rotation is achieved but delivery does not result, further rotation in the same direction may be attempted in an effort to make the anterior shoulder the posterior one and vice versa.
Delivery of posterior arm
If this is unsuccessful or if no rotation is possible, search the fetal chest for the posterior wrist and attempt to deliver this by grasping it and pulling it directly in the direction of the introitus. Humeral fracture is an acceptable risk, the rate of this being between 2% and 12%. If it proves difficult to locate the wrist, locate the posterior elbow first by tracing the course of the humerus, then trace the forearm to the wrist. Once the posterior forearm delivers, delivery of the posterior shoulder will follow easily, after which the anterior shoulder will be easily with routine axial traction. An alternative to delivery of the posterior arm is to move your hand up and apply pressure to the anterior aspect of the anterior shoulder, having first instructed the person applying Suprapubic pressure to stop. You can further assist this attempt at rotation by inserting your other hand posteriorly and applying pressure to the posterior aspect of the posterior shoulder. Rotation either to the oblique diameter or further, such that the anterior shoulder becomes posterior, may be successful in effecting delivery.
All fours position
If all this fails and a more experienced obstetrician/midwife has not arrived, assist the patient on to all fours (with hips maximally flexed and knees a little over shoulder width apart) with her bottom at the edge of the bed and go back to Step 7.
If all of above fails, more experienced help is not arriving and the time since delivery of the head is over 5 minutes, consider applying pressure to the most accessible fetal clavicle in order to break this with the aim of thereby reducing the bisacromial diameter. The remaining options are the Zavanelli manoeuvre or symphysiotomy. The former – replacement of head in the vagina followed by caesarean section – may be a reasonable course of action if one is already in theatre. Replacement may require a tocolytic such as terbutaline 0.25mg administered subcutaneously. (Contraindications to terbutaline include: significant active cardiac disease, significant hypovolaemia and abruption). Symphysiotomy could be considered under other circumstances but is associated with significant maternal morbidity.
- Obtain cord bloods for pH and base excess
- Anticipate PPH
- Determine extent of and repair maternal trauma
- Baby to be examined by Neonatologist
- Record all events accurately in the shoulder dystocia proforma included below, including which was the anterior shoulder, the manoeuvres used, cord blood results, personnel present and the timing of events, particularly of delivery of head and delivery of trunk, and neonatal condition
- Debrief patient and partner as soon as is reasonably possible. Complete DATIX form
- Patient and partner debrief by consultant before discharge
- Notes to consultant for letter and postnatal review decision.