Shoulder Dystocia

Shoulder dystocia is an unanticipated, time-critical obstetric emergency in which delivery of the fetal shoulders fails after the head has been born, requiring additional manoeuvres beyond gentle downward traction. It is a classic NEET PG clinical-scenario topic: the examiner gives you a "turtle sign" and asks for the correct first manoeuvre or the correct sequence (HELPERR).

Definition

Shoulder dystocia is defined as a vaginal cephalic delivery that requires additional obstetric manoeuvres to deliver the fetus after the head has delivered and gentle traction has failed.

Mechanistically, it is the impaction of the anterior fetal shoulder behind the maternal pubic symphysis (the common variety). Less often, the posterior shoulder is impacted on the sacral promontory. The fundamental problem is that the bisacromial (shoulder-to-shoulder) diameter has failed to rotate into the wider oblique pelvic diameter and instead remains in the narrow anteroposterior diameter of the pelvic inlet.

A useful objective criterion sometimes used is a head-to-body delivery interval >60 seconds, or the need for ancillary manoeuvres.

High-yield: Shoulder dystocia is a clinical, bony obstruction at the inlet, not a soft-tissue problem. It is fundamentally a disproportion between the bisacromial diameter and the pelvic inlet AP diameter.

The "Turtle sign"

The pathognomonic clinical sign is the turtle sign (turtle-neck sign) — the fetal head delivers but then retracts tightly back against the perineum, like a turtle pulling its head into its shell, because the impacted shoulder prevents external rotation (restitution). Restitution often fails to occur.

Risk factors

Risk factors are heavily tested but the single most important examination point is that shoulder dystocia is largely UNPREDICTABLE and UNPREVENTABLE — over half of cases occur in women with NO identifiable risk factor, and most fetuses with risk factors deliver without dystocia.

Pre-labour (antepartum)	Intrapartum
Fetal macrosomia (>4–4.5 kg)	Prolonged first stage
Maternal diabetes (GDM / pre-gestational)	Prolonged second stage
Maternal obesity / excessive weight gain	Operative vaginal delivery (forceps/vacuum)
Previous shoulder dystocia (strongest predictor, recurrence ~10%)	Oxytocin augmentation / induction
Post-term pregnancy	Precipitate (very rapid) delivery
Short maternal stature / contracted pelvis

High-yield: Diabetes is the key associated condition because diabetic fetuses have shoulders and trunk disproportionately larger than the head (truncal/shoulder adiposity), so dystocia occurs at lower birth weights than in non-diabetics.

High-yield: Previous shoulder dystocia is the strongest single risk factor (recurrence ≈ 10–15%). Despite this, elective caesarean is not routinely recommended for all; it is individualised.

When is elective caesarean considered?

Prophylactic LSCS may be offered to reduce risk when estimated fetal weight is:

• > 4.5 kg in a diabetic mother, or
• > 5.0 kg in a non-diabetic mother.

Note that estimated fetal weight (clinical or ultrasound) is unreliable at term (error ±10–15%), which is why prediction fails so often.

Pathophysiology — why injury happens

When the anterior shoulder impacts behind the symphysis, continued excessive axial traction + downward pull on the head stretches the brachial plexus, producing nerve-root traction injury. Simultaneously the umbilical cord may be compressed within the pelvis, and the fetal chest is compressed, so there is a finite window before fetal hypoxia/acidosis develops.

Compression of the cord and inability to breathe → progressive fetal acidosis → this is why shoulder dystocia is a true emergency with a recommended resolution within minutes.

Clinical features / diagnosis

Diagnosis is clinical and intrapartum:

1. Head delivers, then retracts (turtle sign).
2. Failure of restitution (head does not spontaneously rotate).
3. Failure of the shoulders to descend with routine gentle downward traction and maternal pushing.

There is no investigation — recognition must be immediate. The moment routine traction fails, call for help and start the protocol.

Management — HELPERR (the most tested item)

Once dystocia is recognised, STOP pulling, STOP pushing, STOP fundal pressure, and proceed stepwise. The classic mnemonic is HELPERR:

Letter	Step	Key point
H	Help — call for help	Senior obstetrician, neonatologist, anaesthetist, extra nurses; note the time
E	Evaluate for Episiotomy	Episiotomy alone does NOT relieve a bony obstruction; it only makes room for internal (vaginal) manoeuvres
L	Legs — McRoberts manoeuvre	FIRST manoeuvre of choice; hyperflex maternal thighs onto the abdomen
P	Pressure — suprapubic pressure	Press just above symphysis to adduct/dislodge anterior shoulder (NOT fundal pressure)
E	Enter — internal rotational manoeuvres	Rubin II, Woods corkscrew, reverse Woods
R	Remove the posterior arm	Deliver the posterior arm/shoulder
R	Roll — all-fours (Gaskin) manoeuvre	Roll mother onto hands and knees

High-yield: McRoberts manoeuvre is the FIRST step and resolves the majority (>50%) of cases. It is simple, fast, and non-invasive — always the answer to "what is the initial/first manoeuvre?"

Stepwise flow (memorise this sequence)

Recognise turtle sign → Call for help + note time + stop traction/pushing → McRoberts (hyperflex hips) → Suprapubic pressure (Mazzanti/Rubin I) → Episiotomy to allow access → Internal rotation: Rubin II → Woods screw → reverse Woods → Deliver posterior arm → All-fours (Gaskin) → Last-resort: Zavanelli / symphysiotomy / cleidotomy

The manoeuvres in detail

1. McRoberts manoeuvre — Sharp hyperflexion of the maternal thighs onto the abdomen. This does NOT increase the actual pelvic dimensions; it straightens the lumbosacral angle, rotates the symphysis cephalad, and flattens the sacral promontory, freeing the impacted anterior shoulder. Combined with suprapubic pressure it resolves the great majority of cases.

2. Suprapubic pressure (Mazzanti / Rubin I) — An assistant presses just above the symphysis pubis, directed downward and laterally onto the posterior aspect of the anterior shoulder, to adduct the shoulders (reduce the bisacromial diameter) and push the anterior shoulder under the symphysis into the oblique diameter.

High-yield: Fundal pressure is CONTRAINDICATED — it worsens impaction and risks uterine rupture and brachial plexus injury. Use suprapubic, never fundal.

3. Rubin II manoeuvre — Fingers placed on the posterior aspect of the anterior shoulder, pushing it toward the fetal chest (adduction) to rotate it into the oblique diameter and decrease the bisacromial diameter.

4. Woods (corkscrew) manoeuvre — Pressure on the anterior aspect of the posterior shoulder, rotating the fetus 180° "like a screw" to bring the posterior shoulder anteriorly and free the impaction. Rubin II + Woods together is a common combined rotation.

5. Reverse Woods (Woods reverse screw) — Rotation in the opposite direction.

6. Delivery of the posterior arm (Jacquemier / Barnum manoeuvre) — Hand passed into the sacral hollow, flex the posterior elbow, sweep the forearm across the chest, and deliver the posterior arm/hand. This reduces the diameter from bisacromial to axillo-acromial and is highly effective, especially when rotational manoeuvres fail.

7. All-fours / Gaskin manoeuvre — Mother moved onto hands and knees; gravity and the increased true conjugate/sacral mobility help dislodge the shoulder. Useful in low-resource or single-attendant settings.

Last-resort manoeuvres (failed everything above)

• Zavanelli manoeuvre — Cephalic replacement: the fetal head is rotated back to occipito-anterior, flexed, and pushed back into the uterus, followed by emergency caesarean section. Used when all else fails. (High-yield eponym.)
• Symphysiotomy — surgical division of the symphyseal cartilage to widen the pelvis.
• Cleidotomy — deliberate surgical/manual fracture of the fetal clavicle to reduce the shoulder diameter (usually in a dead fetus).
• Abdominal rescue / hysterotomy — rotation through a uterine incision.

High-yield: Zavanelli = cephalic replacement followed by LSCS. It is the classic "last-resort" answer.

Complications

Fetal/neonatal

Complication	Notes
Brachial plexus injury — Erb's palsy (C5–C6)	Most common; "waiter's tip" / "policeman's tip" — arm adducted, internally rotated, forearm pronated, wrist flexed. Most resolve.
Klumpke's palsy (C8–T1)	Rarer; claw hand, may have ipsilateral Horner syndrome (T1)
Fracture of the clavicle	Common; usually heals well, can be deliberate (cleidotomy)
Fracture of the humerus	Less common
Hypoxic-ischaemic encephalopathy	From cord compression / delay
Perinatal death	Rare but recognised

High-yield: Erb's palsy (Erb–Duchenne, C5–C6 upper trunk) is the commonest neurological injury — classic "waiter's tip" posture. Most brachial plexus palsies are transient and resolve, and importantly can occur even with correct technique (some are antenatal/in-utero), which is medico-legally significant.

Maternal

• Postpartum haemorrhage (commonest maternal complication, from atony/trauma)
• Third- and fourth-degree perineal tears
• Vaginal/cervical lacerations, symphyseal separation
• Uterine rupture (especially with fundal pressure)

Key differentials / look-alikes

Distinguish the bony shoulder dystocia from conditions that also delay delivery after the head emerges:

Condition	Distinguishing feature
True shoulder dystocia	Turtle sign, failed restitution, anterior shoulder behind symphysis; relieved by McRoberts/internal manoeuvres
Short umbilical cord / cord around neck	Head delivers but does not retract tightly; shoulders descend normally once cord managed
Fetal abdominal/thoracic mass (e.g., ascites, large tumour)	Body bulky below shoulders; shoulders deliver but trunk obstructs
Locked twins / conjoined twins	Twin pregnancy context
Bandl's ring / obstructed labour	Obstruction occurs before the head delivers, not after

Documentation & medicolegal note

Because brachial plexus injury is a frequent source of litigation, careful documentation is essential: time of head delivery, time of shoulder delivery, sequence and timing of each manoeuvre, which shoulder was anterior, traction applied, staff present, and neonatal condition with cord gases.

Recently asked / exam angle

• "First manoeuvre in shoulder dystocia?" → McRoberts manoeuvre (with suprapubic pressure). Single most repeated MCQ.
• "Which pressure is contraindicated?" → Fundal pressure (use suprapubic).
• HELPERR sequence ordering questions — match each letter to its step; note L = Legs/McRoberts, second P/E = Enter/internal rotation.
• Rubin II vs Woods — Rubin II pushes the posterior surface of the ANTERIOR shoulder (adduction); Woods pushes the anterior surface of the POSTERIOR shoulder.
• Zavanelli manoeuvre — definition (cephalic replacement + caesarean) is a favourite one-liner.
• Commonest fetal complication / nerve injury → Erb's palsy (C5–C6, waiter's tip); Klumpke + Horner for C8–T1.
• Diabetes link — disproportionate shoulder/truncal growth; dystocia at lower birth weight.
• EFW cut-offs for elective LSCS → >4.5 kg diabetic, >5 kg non-diabetic.
• Scenario style: post-term diabetic primigravida, prolonged second stage, vacuum used, head retracts → identify dystocia and pick the first step.

Rapid revision

1. Definition: delivery needing extra manoeuvres after the head delivers and gentle traction fails — impacted anterior shoulder behind symphysis.
2. Turtle sign = head retracts against perineum; restitution fails.
3. It is largely unpredictable and unpreventable — >50% have no risk factor.
4. Diabetes and previous shoulder dystocia are the most important associations; prior dystocia is the strongest single predictor.
5. Mnemonic: HELPERR — Help, Evaluate episiotomy, Legs (McRoberts), Pressure (suprapubic), Enter (rotation), Remove posterior arm, Roll (all-fours).
6. McRoberts is the FIRST manoeuvre and resolves the majority of cases — works by straightening the lumbosacral angle, not enlarging the pelvis.
7. Suprapubic pressure is correct; fundal pressure is contraindicated (worsens impaction, risks uterine rupture).
8. Rubin II = adduct anterior shoulder (push its posterior surface); Woods screw = push anterior surface of posterior shoulder, rotate 180°.
9. Delivery of the posterior arm (Jacquemier) is very effective when rotation fails.
10. Zavanelli = cephalic replacement + emergency caesarean (last resort); others = symphysiotomy, cleidotomy.
11. Erb's palsy (C5–C6, "waiter's tip") = commonest nerve injury; Klumpke (C8–T1) + Horner = claw hand; clavicle fracture common; most palsies are transient.
12. Elective LSCS may be offered if EFW >4.5 kg in diabetics / >5 kg in non-diabetics; commonest maternal complication is PPH.