9.2 Shoulder Dystocia: Recognition, Risk Factors & HELPERR Emergency Sequence

Shoulder Dystocia: Recognition, Risk Factors & HELPERR Emergency Sequence

Shoulder dystocia is an unpredictable, time-critical intrapartum obstetric emergency. Following the birth of the fetal head, the anterior fetal shoulder becomes impacted behind the maternal symphysis pubis (or less commonly, the posterior shoulder becomes impacted on the sacral promontory). Rapid clinical identification, avoidance of dangerous traction or fundal pressure, and immediate execution of structured relief manoeuvres are essential to avoid permanent fetal hypoxic-ischaemic injury or death. UK clinical practice is defined by RCOG Green-top Guideline No. 42 (Shoulder Dystocia).

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Clinical Definition & Diagnostic Recognition

Shoulder dystocia is formally defined as a vaginal cephalic birth that requires additional obstetric manoeuvres to release the fetal shoulders after gentle downward traction on the fetal head has failed.

Clinical Presentation & The "Turtle Sign"

Midwives must recognize the key clinical signs that announce shoulder dystocia immediately:

• The "Turtle Sign": Upon delivery of the head, the fetal chin retracts tightly and firmly back against the maternal perineum, as if withdrawing into a shell.
• Failure of Restitution: The fetal head fails to undergo spontaneous restitution (external rotation into the oblique or transverse plane).
• Failure of Descent: The shoulders remain arrested at the pelvic brim despite maternal expulsive effort.
• Resistance on Gentle Traction: Standard, gentle downward axial traction fails to deliver the anterior shoulder.

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Risk Factors: Antenatal & Intrapartum Predictors

While shoulder dystocia can occur in any labour, specific maternal, fetal, and intrapartum factors elevate the statistical probability:

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Potential Complications

Shoulder dystocia carries substantial risks of severe maternal and neonatal morbidity:

Neonatal Complications

1. Brachial Plexus Injury (BPI): Stretching or avulsion of the cervical nerve roots (C5–T1). The classic manifestation is Erb's Palsy (C5–C6 damage), causing the characteristic "waiter's tip" posture (internally rotated, adducted arm with extended elbow and pronated forearm). Less commonly, Klumpke's Palsy (C8–T1 damage) involves paralysis of intrinsic hand muscles. BPI complicates 2% to 16% of shoulder dystocia cases; while ~90% resolve within one year, permanent neurological deficit can result.
2. Fractures: Fractures of the clavicle and humerus.
3. Hypoxic-Ischaemic Encephalopathy (HIE) & Asphyxial Perinatal Death.

Maternal Complications

1. Obstetric Anal Sphincter Injuries (OASIS): Third- and fourth-degree perineal lacerations occur in up to 4% of cases.
2. Major Postpartum Haemorrhage (PPH): Secondary to uterine atony and extensive genital tract trauma.
3. Uterine Rupture and bladder or urethral trauma.
4. Psychological Trauma: Post-traumatic stress disorder (PTSD) and fear of future pregnancy.

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Immediate Actions & Absolute Contraindications

Upon clinical recognition of shoulder dystocia, the attending midwife must institute immediate emergency command:

1. Declare the Emergency: State aloud clearly: "This is shoulder dystocia!"
2. Call for Help Immediately: Activate the emergency call bell and dial 2222 for the multidisciplinary obstetric emergency team (consultant/senior obstetrician, senior midwife, paediatrician/neonatologist, and anaesthetist).
3. Instruct the Mother to STOP PUSHING: The mother must immediately cease pushing and pant. Continued maternal pushing wedges the impacted anterior shoulder tighter behind the pubic symphysis, exacerbating impaction and increasing brachial plexus tension.
4. Move Mother to the Edge of the Bed: Bring the maternal buttocks to the very edge of the delivery bed to permit full downward mobility of the fetal head during manoeuvres.

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The HELPERR Emergency Sequence

The HELPERR mnemonic, standardized by the Advanced Life Support in Obstetrics (ALSO) curriculum and mirrored in RCOG guidelines, provides a systematic, sequential clinical algorithm:

                  ┌──────────────────────────────────────────┐
                  │       HELPERR EMERGENCY SEQUENCE         │
                  └────────────────────┬─────────────────────┘
                                       │
    ┌──────────────────────────────────┴──────────────────────────────────┐
    ▼                                                                     ▼
┌──────────────────────┐                                       ┌──────────────────────┐
│ H - Help (Call 2222) │                                       │ E - Enter Manoeuvres │
│ E - Evaluate for     │                                       │   • Rubin II         │
│     Episiotomy       │                                       │   • Woods Screw      │
│ L - Legs (McRoberts) │                                       │   • Rev Woods Screw  │
│ P - Pressure         │                                       │ R - Remove Post. Arm │
│     (Suprapubic)     │                                       │ R - Roll (All-Fours) │
└──────────────────────┘                                       └──────────────────────┘

H — Help (Emergency Call)

Activate the obstetric emergency team via 2222. Designate a midwife to record timestamps (head delivery time, initiation of each manoeuvre, and final birth time).

E — Evaluate for Episiotomy

Shoulder dystocia is a bony impaction, not a soft-tissue obstruction. An episiotomy does not release the impacted bone. Therefore, routine episiotomy is not required for first-line manoeuvres (McRoberts and suprapubic pressure). However, an episiotomy must be evaluated and performed if additional soft-tissue space is required for the clinician's hand to enter the vagina to execute internal manoeuvres.

L — Legs: The McRoberts Manoeuvre

• Execution: Two assistants stand on either side of the mother. Each assistant grasps a maternal leg, deeply hyperflexing and abducting the maternal hips, pressing her thighs firmly against her lateral abdomen ("knees to nipples").
• Biomechanical Mechanism: This manoeuvre straightens the lumbosacral angle, flattens the sacral promontory, and rotates the maternal pubic symphysis cephalad (upwards towards the maternal head). This dynamic pelvic tilt utilizes the normal mobility of the sacroiliac joints to widen the functional anteroposterior diameter of the pelvic outlet.
• Efficacy: RCOG GTG42 describes McRoberts as simple, rapid and effective, and it resolves many cases on its own; reported success rates vary widely between studies.

P — Pressure: Suprapubic Pressure (Rubin I Manoeuvre)

• Execution: An assistant places their hands on the maternal lower abdomen, just above the symphysis pubis, over the posterior aspect of the anterior fetal shoulder (determined by fetal back position). Firm, continuous or rocking downward and lateral pressure is applied at an angle of 45° towards the fetal chest.
• Biomechanical Mechanism: Suprapubic pressure adducts the anterior shoulder (pushes the shoulder forward onto the chest), collapsing the fetal bisacromial diameter and nudging the anterior shoulder down under the pubic symphysis into the wider oblique pelvic diameter.
• Combined First-Line Measures: Suprapubic pressure improves the effectiveness of McRoberts, and together they resolve the majority of cases; if they fail, move promptly to internal manoeuvres or delivery of the posterior arm.

E — Enter: Internal Rotational Manoeuvres

If first-line manoeuvres fail, the clinician introduces their gloved hand into the vagina to perform internal manipulation:

1. Rubin II Manoeuvre: Insert fingers of the examining hand into the vagina onto the posterior surface of the anterior shoulder, pushing it forwards towards the fetal chest to induce adduction and rotation into an oblique diameter.
2. Woods Screw Manoeuvre: Keeping fingers behind the anterior shoulder, place two fingers of the other hand on the anterior surface of the posterior shoulder. Apply simultaneous pressure in the same rotational direction, rotating the shoulders through 180 degrees like turning a screw.
3. Reverse Woods Screw Manoeuvre: If Woods screw fails, place fingers on the posterior aspect of the posterior shoulder and rotate the fetus in the opposite direction.

R — Remove the Posterior Arm

• The clinician slides their hand deeply along the curve of the sacrum into the posterior pelvic cavity, identifying the posterior fetal arm.
• Follow the humerus down to the elbow joint; apply gentle pressure into the antecubital fossa to flex the fetal forearm.
• Sweep the fetal forearm across the fetal chest and face, grasping the fetal wrist or hand to deliver the arm out through the vulva.
• Delivering the posterior arm instantly reduces the impacted shoulder diameter from the bisacromial diameter (approx. 12 cm) to the significantly narrower axillo-acromial diameter (approx. 9.5 cm), immediately resolving the impaction.

R — Roll onto All-Fours (The Gaskin Manoeuvre)

• Assist the woman onto her hands and knees (all-fours position).
• This position utilizes maternal gravity and pelvic mobility to expand pelvic outlet dimensions (increasing conjugate pelvic diameters by up to 10 mm). Gentle downward traction can deliver the posterior (now upper) shoulder first.

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Tertiary / Third-Line Manoeuvres

In rare instances where all first- and second-line manoeuvres fail, catastrophic third-line interventions are considered:

• Intentional Clavicle Fracture (Cleidotomy): Direct upward digital pressure against the mid-shaft of the anterior fetal clavicle to fracture it, collapsing the shoulder girdle.
• Zavanelli Manoeuvre: Cephalic replacement. The fetal head is rotated back into the direct occiput-anterior position, flexed, and pushed back upward through the cervix into the uterine cavity, followed by an immediate emergency Category 1 caesarean section.
• Symphysiotomy: Surgical division of the maternal pubic symphysis cartilage under local anaesthesia.