Overview
Shoulder Dystocia
1. Clinical Overview
Summary
Shoulder Dystocia is an Obstetric Emergency occurring when the fetal head delivers but the shoulders become impacted, preventing delivery of the body. The most common mechanism is the anterior shoulder impacting behind the maternal Pubic Symphysis, creating a bony obstruction. Time is critical – delivery must be achieved rapidly to prevent fetal hypoxia and death. It is unpredictable, with 50% of cases occurring in non-macrosomic babies. Management follows the HELPERR Algorithm. [1,2]
Definition
- Clinical Definition: Failure of the fetal shoulders to deliver spontaneously after the head, requiring additional obstetric manoeuvres beyond gentle downward traction.
- Objective Definition (Academic): Head-to-Body interval >60 seconds or need for ancillary manoeuvres.
Clinical Pearls
The "Turtle Sign": Pathognomonic. After the head delivers, it retracts tightly back against the perineum (like a turtle's head retracting into its shell). The head fails to restitute (rotate laterally).
50/50 Rule: 50% of shoulder dystocia occurs in babies who are NOT macrosomic. You cannot predict it reliably.
DO NOT PUSH FUNDUS: Fundal pressure increases impaction. It does NOT help. It risks uterine rupture.
5-6 Minutes: Serious fetal neurological harm becomes likely after ~5-6 minutes of head-to-body delivery.
2. Epidemiology
Incidence
- Frequency: 0.5-1.5% of vaginal deliveries (varies by population and birthweight).
- Recurrence: 10-15% recurrence risk in subsequent pregnancy.
Risk Factors
| Factor | Risk Increase |
|---|---|
| Fetal Macrosomia (>4kg) | RR 2-3 (but 50% occur in normal weight) |
| Maternal Diabetes (GDM/T1DM) | Macrosomic babies with different fat distribution |
| Previous Shoulder Dystocia | RR 10-15 |
| Prolonged Second Stage of Labour | Suggests disproportion |
| Instrumental Delivery (Forceps/Ventouse) | Associated |
| Maternal Obesity | Associated with macrosomia and GDM |
| Post-Dates Pregnancy | Larger baby |
Key Point
- Unpredictable: Most cases occur in women with NO risk factors. Routine induction for suspected macrosomia is NOT recommended (doesn't reduce shoulder dystocia).
3. Pathophysiology
Mechanism of Impaction
- Fetal Head Delivers: Passes through the pelvis normally.
- Shoulders Enter Pelvis: The bisacromial diameter (shoulder width) enters the pelvic brim.
- Anterior Shoulder Impaction: The anterior shoulder becomes lodged behind the Pubic Symphysis.
- Bony Obstruction: Unlike soft tissue dystocia (solved by episiotomy), this is a BONY problem. Cutting soft tissue does not solve it.
- Cord Compression: The umbilical cord is compressed between the fetal body and the pelvis, causing hypoxia.
- Need for Manoeuvres: Specific obstetric manoeuvres are required to dislodge the shoulder.
Why Diabetic Babies Are Different
- Infants of diabetic mothers have increased trunk fat and shoulder width relative to head size. The head may deliver normally, but the shoulders are disproportionately large.
4. Differential Diagnosis (Delayed Shoulder Delivery)
| Condition | Features |
|---|---|
| Shoulder Dystocia (Bony) | Turtle sign. Head retracts. Anterior shoulder stuck. Manoeuvres needed. |
| Tight Nuchal Cord | Cord wrapped around neck preventing descent. Somersault or cut cord. |
| Large Baby (No Dystocia) | Slow but progressive delivery without impaction. Gentle patience may suffice. |
| Uterine Atony / Slow Contractions | Delay in pushing phase. Not a mechanical obstruction. |
5. Clinical Presentation
Recognition
Timing is Critical
"Call for Help" Moment
Head delivers but body does not follow with the next contraction.
Turtle Sign
Head retracts tightly against the perineum.
No Restitution
Head does not rotate laterally to align with the shoulders.
Difficulty Extracting Chin
Difficulty extracting the chin/face.
6. Investigations
None Required During Emergency
- This is a clinical diagnosis managed in real-time.
- Post-Event: Document all manoeuvres, timing, and neonatal status (Apgar, blood gases).
7. Management
Management Algorithm: HELPERR Mnemonic
SHOULDER DYSTOCIA DETECTED
(Turtle Sign, Head-to-Body delay)
↓
H – CALL FOR HELP
(Senior Obstetrician, Midwife, Anaesthetist,
Neonatologist, Scribe for timing)
↓
E – EPISIOTOMY
(Creates access for hands. Does NOT solve bony
impaction. Optional – don't delay for it.)
↓
L – LEGS (McROBERTS MANOEUVRE) ← FIRST LINE
(Hyperflex hips onto abdomen. Flattens sacral
promontory, opens pelvis. **Solves 40-50%**)
↓
P – SUPRAPUBIC PRESSURE ← WITH McROBERTS
(Push DOWN on anterior shoulder from ABOVE pubis.
Adducts shoulders, dislodges from behind pubis.
**DO NOT PUSH FUNDUS!**)
↓
McROBERTS + SUPRAPUBIC = 90% SUCCESS
↓
STILL IMPACTED?
↓
E – ENTER (INTERNAL MANOEUVRES)
┌────────────────────────────────────────┐
│ RUBIN II: Push POSTERIOR surface of │
│ anterior shoulder → adducts shoulder │
├────────────────────────────────────────┤
│ WOODS SCREW: Rotate posterior shoulder│
│ 180° to become anterior (corkscrew). │
├────────────────────────────────────────┤
│ REVERSE WOODS: Rotate in opposite │
│ direction. │
└────────────────────────────────────────┘
↓
R – REMOVE POSTERIOR ARM
(Reach in, sweep posterior arm across chest,
deliver. Reduces shoulder diameter.)
↓
R – ROLL (GASKIN MANOEUVRE / ALL-FOURS)
(Mother on hands and knees. Gravity assists.
Changes pelvic dimensions.)
↓
LAST RESORT:
- Zavanelli Manoeuvre: Restitute head,
push back into pelvis, Emergency C-Section.
- Symphysiotomy: Rarely performed (Africa).
- Cleidotomy: Deliberate fracture of clavicle.
Key Manoeuvres Explained
| Manoeuvre | Technique | Success Rate |
|---|---|---|
| McRoberts | Hyperflex thighs onto maternal abdomen. Two assistants hold legs. | 40-50% (alone) |
| Suprapubic Pressure | Assistant pushes DOWNWARD and POSTERIORLY from above pubic bone (NOT fundal pressure). | (Used with McRoberts) |
| McRoberts + Suprapubic | Combined | ~90% |
| Rubin II | Hand behind anterior shoulder, push posteriorly to adduct. | Second line |
| Woods Screw | Rotate posterior shoulder 180° anteriorly (corkscrew). | Second line |
| Delivery of Posterior Arm | Sweep posterior forearm across chest and deliver hand first. Reduces diameter. | Highly effective but higher fracture risk. |
| Gaskin (All-Fours) | Mother onto hands and knees. Changes pelvic dynamics. | Variable |
DO NOT Do
- DO NOT apply Fundal Pressure: Worsens impaction. Risks uterine rupture.
- DO NOT apply excessive lateral traction on head: Risks Brachial Plexus Injury.
8. Complications
Fetal Complications
| Complication | Incidence | Notes |
|---|---|---|
| Brachial Plexus Injury (Erb's Palsy) | 10-15% | Upper plexus (C5-6). "Waiter's Tip" position. 70-90% recover. |
| Clavicle Fracture | 5-10% | Usually heals well. May be iatrogenic (deliberate) or accidental. |
| Humerus Fracture | less than 5% | Rare. |
| Hypoxic Ischaemic Encephalopathy (HIE) | ~1-2% | Brain damage if prolonged. |
| Stillbirth | less than 1% (If managed promptly) | Risk if >10 mins head-to-body. |
Maternal Complications
| Complication | Notes |
|---|---|
| Postpartum Haemorrhage (PPH) | Due to prolonged labour, manoeuvres. |
| 3rd/4th Degree Perineal Tears | Especially with episiotomy + manoeuvres. |
| Psychological Trauma | Debriefing essential. |
9. Prognosis and Outcomes
- Majority deliver safely with prompt, trained management.
- Brachial Plexus Injury: Most (70-90%) resolve within 1 year. Permanent injury in ~5-10%.
- Mortality: Rare with prompt management (less than 1% asphyxial death).
- Recurrence: 10-15% in subsequent vaginal delivery. Counsel about options (Elective C-Section vs Supervised Vaginal).
10. Evidence and Guidelines
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Green-Top Guideline No. 42 | RCOG | HELPERR algorithm. No fundal pressure. Simulation training. |
| ACOG Practice Bulletin | ACOG | Unpredictable. McRoberts first line. Document all steps. |
Landmark Evidence
- UK Confidential Enquiries: Highlighted the importance of training and teamwork.
- ALSO/PROMPT Training: Simulation training reduces neonatal injury rates.
11. Patient and Layperson Explanation
What is Shoulder Dystocia?
It is a rare but serious emergency during childbirth where the baby's head is born, but the shoulders become stuck. We need to act quickly to deliver the rest of the baby safely.
Why does it happen?
The baby's shoulder gets caught behind the mother's pelvic bone. It can happen to any baby but is more common if the baby is very large.
What will you do?
We will call for help and perform specific manoeuvres (like moving your legs into a special position) that open your pelvis and help free the baby's shoulder. Most babies are delivered quickly and safely.
Could my baby be hurt?
There is a chance the baby's arm or collarbone could be injured, but most injuries heal completely. More serious harm is rare when we act quickly and correctly.
12. References
Primary Sources
- RCOG Green-Top Guideline No. 42. Shoulder Dystocia. 2012 (Updated 2017).
- Gherman RB, Chauhan S, et al. Analysis of McRoberts' maneuver by x-ray pelvimetry. Obstet Gynecol. 2000;95:43-47.
13. Examination Focus
Common Exam Questions
- Emergency: "Baby's head delivers, retracts against perineum, doesn't restitute. Diagnosis?"
- Answer: Shoulder Dystocia (Turtle Sign).
- Management: "First manoeuvre?"
- Answer: McRoberts Manoeuvre (Hyperflex thighs).
- Contraindication: "What must you NOT do?"
- Answer: Fundal Pressure.
- Complication: "Most common fetal injury?"
- Answer: Brachial Plexus Injury (Erb's Palsy).
Viva Points
- HELPERR Mnemonic: Be able to recite and explain each step.
- Zavanelli Manoeuvre: Last resort. Push head back in, Emergency C-Section. Very rare.
- Why NOT fundal pressure?: Increases impaction of anterior shoulder. Risks uterine rupture.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.