Shoulder Dystocia

Definition and Incidence

Vaginal cephalic birth that requires additional obstetric manoeuvres to assist the birth of the infant after gentle traction has failed. Shoulder dystocia occurs when either the anterior shoulder impacts behind the maternal symphysis pubis or, less commonly, the posterior shoulder impacts over the sacral promontory. Manoeuvres are designed to imporve the relative dimensions of the maternal pelvis (MsRoberts' position, all-fours position), reduce the diameter of the fetal shoulders (suprepubic pressure, delivery of the posterior arm) and/or move the fetal shoulders into a wider pelvic diameter (suprapubic pressure, internal rotation),

Incidence

1985-2016 0.1%- 3%

Recent reports that in USA 1.4% out of USA 0.6%

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Litigation

  • Can result in long-term morbidity for both mother and baby
  • USA second most litigated complication of childbirth
  • Saudi Arabia most commonly litigated problem
  • England 2000-2009 paid more than £100 million in legal compensation for preventable harm associated with shoulder dystocia
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Risk Factors- Pre-labour

Because shoulder dystocia is not clinically predictable, all staff should be prepared for its occurence at any vaginal birth.

  • Previous shoulder dystocia: 6-30 times more likely. Reported rates of 12-17%
  • Macrosomia: Greater the fetal birth weight, higher the risk of shoulder dystocia and brachial plexus injury. 
  • Gestational age; Likelihood ingreases as gestational ages increases. Likely to be related to increasing fetal size.
  • Maternal diabetes mellitus: Infants of diabeteic mothers have a twofold increased risk of shoulder dystoca compared to infants born at the same weight to non-diabetic mothers. Probably due to different body shape i.e broader not just heavier 
  • Operative vaginal birth: Infants born in this way are more likely to be macrosomic and/or shoulder more likely to be brought down directly into the narrower direct anteriorposterior diameter. 
  • Obesity: More likely to be diabetic and have larger babies
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Risk Factors- Intrapartum

  • Prolonged first stage
  • Prolonged second stage
  • Labour augmentation
  • Operative vaginal birth: Infants born in this way are more likely to be macrosomic and/or shoulder more likely to be brought down directly into the narrower direct anteriorposterior diameter. 

The majority of cases of shoulder dystocia occur in women with no risk factors. 

Shoulder dystocia is an unpredictable and largley unpreventable event.

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Prevention and antenatal counselling

Caesarean Birth

Shoulder dystocia can be prevented by caesarean section, however elective section is not routinely recommended as a method of reducing potential morbidity from possible shoulder dystocia.The risk of a still birth in a future pregnancy following a c-section is 0.4% whereas permentant brachial plexus injury following shoulder dystocia is 0.03%. This is just one point that should be mentioned in the discussion as to whether a c-section is more appropriate. 

The option of c-section is recognised by the RCOG for women with GDM and an estimated fetal weight of over 4500g or where the estimated fetal weight is over 5000g in woman without diabetes as there is a higher incidence of shoulder dystocia and BPI in pregnancies effected by diabetes.

Induction of labour

IOL to reduce the risk of shoulder dystocia in maternal diabetes and suspected fetal macrosomia.The incidence of shoulder dystocia is reduced by early induction of labour for these women.

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Management of shoulder dystocia

Four basic shoulder dystocia manoeuvres:

  • McRoberts' position/all-fours position
  • Suprapubic pressure
  • Delivery of the posterior arm
  • Internal rotation

Recommend that McRoberts and suprapubic pressure should be attemped first as they are less invasive. However it may be appropriate to move straight to an internal manouvre, for example in a morbidly obese woman it may be difficult to achieve McRoberts' and suprapubic pressure therefore going striaght for delivery of the poserior arm may be more appropriate.

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Recognition of shoulder dystocia

  • May be difficulty with birth of the face and chin
  • When the head is born, it remains tightly applied to the *****
  • The chin retracts and depresses the perineum (turtle-neck sign)
  • The anterior shoulder fails to release with maternal effort and/or when routine axial traction is applied 

If in pool:

Asked to get out as soon as soon as the midiwfe identifies a delay in the birth of the shoulders. No manouvres should be attempted in the pool. 

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Call for help

  • Emergency buzzer or 999 if in community
  • Call for: Senior midwife, additional maternity staff, experience obstetrician, neonatal team and consider calling anaesthetist 
  • In community call for paramedic abulance 
  • Clearly state the problem. Announce SHOULDER DYSTOCIA as help arrives
  • Note the time that head was born. Start the clock on the resuscitaire or mark on CTG
  • Ask mother to stop pushing, as this may increase impaction and therefore the risk of neurological and orthopaedic complications and will not resolve dystocia.
  • Lie woman flat and move buttocks to edge of mattress if on bed
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McRoberts' Manoeuvre

  • Reported success of 90% but recent study found to be less than 50%
  • Low rate of complication and one of the least invasive manoeuvres
  • Lie mother flat, move any pillows
  • One assistant either side
  • Hyperflex the mothers legs against her abdomen so that her knees are up towards her ears
  • If in lithotomy position, legs need to be removed from the supports
  • If in theatre, may be possible to adjust the supports to achieve McRoberts position with legs remaining in boots
  • Maternal buttocks are lifted off the bed during the hyperflextion of the hips, thereby rotating the pelvis

McRoberts' position increases the relative anteroposterior diameter of the pelvic inlet by rotating the maternal pelvis cephaloid and straightening the sacrum to the lumbar spine.

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Routine Axial Traction

The same degree of traction as applied during a normal birth and in an axial direction (in line with the axis of the fetal spine) should be applied to the babys head to assess whether the shoulders have been released.

If the anterior shoulder is not released with McRoberts' position- Move on to next manouvre.

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All-Fours Position

Positioning women in a flexed all-fours position with thighs against the abdomen has a similar effect on the maternal pelvis as McRoerts. 

For a slim, mobile woman with a lone midwifery birth attendant, all-fours may be more appropriate than McRoberts.

To achieve all-fours, ask woman to roll over so that she is supporting herfelf on her upper arms and knees, with her hips and knees flexed. 

This simple change in position may release the fetal shoulders.

Routine axial traction should be applied to the fetal head to see if the shoulder dystocia has been resolved.

If not, internal manouvres should be attempted (if lone birth attendant)

Remember that when woman is in all-fours position, the maternal sacral hollow and the fetal posterior shoulder will both be uppermost..

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Suprapubic Pressure

Suprapubic pressure aims to ressolve the shoulder dystocia by:

  • Reducing the fetal bisacromial diameter (shoulder to shoulder)
  • Rotating the anterior fetal shoulders into the wider oblique diameter of the pelvis. The anterior shoulder is freed to slip underneath the symphysis pubis with the aid of routine axial traction
  • Assistant should apply suprapubic pressure from the side of the fetal back, which will reduce the diameter of the fetal shoulders by 'scrunching' (adducting) the shoulders in towards the fetal chest
  • Pressure should be appled just above the symphysis pubis in a downward and lateral direction, to push the posterior aspect of the anterior shoulder towards the fetal chest.
  • If there is uncertaity abour fetal position, suprapubic pressure should be applied to the side where the fetal back is most likely to be and if this is unsuccessful, can be attemoted from the other side.
  • No evidence that rocking is better than continuos pressure, nor that pressure should be performed for 30 seconds for it be effective. If anterior shoulder is not released after attempting suprapubic pressure and routine axial traction, go on to another manouvre
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Evaluate Need For An Episiotomy

  • Will not relieve the bony obstruction of shoulder dystocia but may be required to allow more space to facilitate internal vaginal manouvres (delivery of posterior arm, internal roatation)
  • Often perinium already torn or episiotomy already been performed, almost always enough room to gain internal access without performing an episiotomy 
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Internal Manoeuvres

2 types of internal manouvres that can be performed:

  • Delivery of the posterior arm
  • Internal rotational manouvres

No evidence saying that either should be attempted before the other, just depends on the clinical circumstances. 

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Gaining Vaginal Access

  • As the anterior shoulder is trapped above the symphysis pubis, there will be no room for a hand anteriorly
  • The most spacious part of the pelvis is the sacral hollow and therefore vaginal access can be gained more easily posteriorly into the sacral hollow
  • Should scruch up hand as if reaching for last pringle in tube or putting on a right bracelet
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Delivery Of The Posterior Arm

  • Delivering the posterior arm will reduce the diameter of the fetal shoulders by the width of the arm. This usally provides enough room to resolve the shoulder dystocia
  • Often possible to feel hand and forearm of posterior arm as babies often lie with arms flexed across their chest.
  • Take hold of fetal wrist and gently release the posterior arm in a straight line. 
  • Once posterior arm is delivered, gentle traction may be applied to the fetal head 
  • If shoulder dystocia has been ressolved, baby should be born easily
  • If baby is lying with posterior arm straight down its body, may be possible to apply pressure with thumb to the antecubital fossa and flex the posterior arm, so that wrist can be grasped and arm can be delivered.
  • However this can be difficult and it may be easier to attempt internal rotation of the fetal shoulders instead
  • If you pull on upper arm rather than the wrist, this is likely to result in a humeral fracture
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Internal Rotation Manoeuvres

The aim of internal rotation is:

  • To move the fetal shoulders (the bisacromial diameter) out of the narrowest diameter of the mothers pelvis (the anterior-posterior) and into the wider pelvis (the oblique or transverse)
  • Internal roattation of the fetal shoulders can be most easily achieved by pressing on the anterior aspect (front) or posterior aspect (back) of the posterior (lowermost) shoulder.
  • Pressure on the posterior aspect of the posterior shoulder has the added benifit of reducing the shoulder diameter by adducting the shoulders (scrunching the shoulders together)
  • Rotation should move the shoulders into the wider oblique diameter of the maternal pelvis
  • Aided by routine axial traction
  • It is not necessary to place fingers from both hands into the vagina or to move the shoulders more than 20-30 degrees
  • If pressure in one direction has no effect, try to rotate the shoulders in the opposite direction by pressing on the other side of the fetal posterior shoulder
  • While attempting to rotate shoulder, instruct someone to apply suprapubic pressure, pushing with you and not against
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Additional Manoeuvres

  • It is very rare that these are required if all previous manoeuvres are performed correctly.

Zavanelli Manoeuvre

  • Vaginal replacement of the head and subsequent birth by c-section, but success rates vary.
  • High proportion of fetuses have irreversible hypoxia-acidosis by the time zavanelli is attempted
  • As uterus now have retracted following birth of fetal head, the uterus is now smaller and a tocolytic (e.g. terbutaline 0.25mg subcutabeously) should be given prior to any attemots to replace the fetal head inside the vagina, to reduce risk of uterine rupture

Symphysiotomy

  • Partial surgical division of the maternal symohysis pubis ligament
  • High incidence of serious maternal mobidity and poor neonatal outcomes

Other techniques include the use of a posterior axillary sling, but there is few data avalible to recommend their use. There is also cleidotomy which is cutting one or both clavicals on the fetus to reduce to width of the shoulders

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How Much Time?

  • Not possible to recommend an absoulte time limit for the management of shoulder dystocia as the head-to-body birth interval that each individual fetus can withstand without hyposixa occuring will vary depending on clinical circumstances and the vulnerability of the infant
  • The condition of the baby at eventual birth is dependent on the head-to-body interval and the fetal condition at the start of the dysctocia 
  • If the baby is good condition before the should dystocia, the risk of hypoxia-ischaemic encephalopathy (HIE) due to prolonged head-to-body interval will be minimised.
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What To Avoid

Excessive and/or downward traction

  • Traction alone will not resolve the dystocia and excessive traction MUST be avoided because it is strongly associated with neonatal injury
  • Traction is a downward direction is also strongly associated with obstetric brachial plexus injury.
  • Evidence that traction applied with a 'jerk' rather than applied slowly may be more damaging to the nerves of the brachial plexus (like trying to break a bit of cotton, much easier to do with a quick pull).
  • DO NOT PULL QUICKLY, DO NOT PULL HARD, DO NOT PULL DOWNWARDS

Fundal Pressure

  • Fundal pressure is associated with a high rate of brachial plexus injury and rupture of the uterus. Therefore should NOT be applied during shoulder dystocia
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Documentation

  • Write clear explanation of the manouvres that were preformed 
  • Pro-forma to aid accurate record keeping

Important to record:

  • Time of birth of head
  • Manouvres performed, the timing and sequence
  • Traction applied 
  • Time fo birth of body
  • Staff in attendance and what time the arrived
  • Conditon of the baby
  • Umbilical cord blood acid-base measurements (cord pH or lactate)
  • Direction baby was facing at birth, i.e. which fetal shoulder was anterior at the time of the shoulder dystocia 
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After The Birth

  • Debreif parents, staff
  • Neonatologist to review any baby with suspected injury following shoulder dystocia
  • For babies suspected to have brachial plexus injury, early intervention key to a good outcome. Babies should commence physiotherapy at 5 days old and progress should be reviewed regularly. If arm function remains unequal by 8 weeks of age a referral should be made to a specialist centre for assessment.
  • If neonate has no active biceps movement by 12 weeks of age it is more likely that the injury is severe and will be permanent, option of surgery will be offered
  • Erbs palsy group recommended for families
  • Referred to connultant in any subsequent pregnancies
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Consequences of Shoulder Dystocia

Shoulder dystocia has a high perinatal mobidity and martality rate.

Perinatal:

  • Stillbirth 
  • Hypoxia
  • Brachial Plexus Injury
  • Fractures

Maternal:

  • Postpartum Haemorrhage
  • Third and fourth degree tears
  • Uterine rupture
  • Psychological distress
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Acidosis

Shoulder dystocia is an acute life-threatening event. A healthy fetus will compensate during shoulder dystocia, but only for an infite amount of time. Babies will be born with sevre metabolic acidosis or may develp HIE, with or without long-term neurological damage. Necessary resuscitation equipment should be perpared and neonatal staff called. 

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Brachial Plexus Injury

The brachial plexus is one of the most complex structures in the peripheral nervous system, conveying motor, sensory and sympathetic nerve fibres to the arm and shoulder. It contains 5 roots that terminate in 5 main peripheral nerves. Injuries can be divided into upper (Erbs palsy), lower (Klumpkes palsy) and total brachial plexus injury.

Erb's Palsy: Most common. Upper arm is flacid and lower arm is extended and rotated towards the body, with hand in classic 'waiters tip' posture. Up to 90% recover by 12 months,

Klumpke's Palsy: Less common. Hand is limp, no movement of fingers. Recovery rate is lower, 40% ressolving by 12 months.

Total brachial plexus injury: Occurs in appox 20% of brachial plexus injuries. Total sensory and motor deficit of the entire arm, making it completely paralysed with no senstation. Full function recovery rare without surgery. 

Brachial plexus injury occurs through excessive traction of the fetal head during shoulder dystocia.

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Humeral and Clavicular Fractures

Humeral and clavicular fractures can also occur following shoulder dystocia and may be related to poor care and/or inaccurate execution of the release manoeuvres. Incidence of bony fractures have been reduced after training. Fractures usally heal quickly.

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Shoulder Dystocia

Shoulder Dystocia Is An UNPREDICTABLE OBSTETRIC EMERGENCY

PROBLEM: Clearly state the problem

PAEDIATRICIAN: immediately call the peadiatrican/neonatologist

POSITION: McRoberts' or All-fours

PRESSURE: Suprapubic Pressure

POSTERIOR: Vaginal access gained posteriorly

PRINGLE: Get the whole hand in

PULL: Don't keep pulling if manoeuvre has not worked

PRO FORMA: Documentation should be clear and concise

PARENTS: Communication and explanation are essential

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