Shoulder Dystocia

Last updated 20.09.12

 

Definition

-  Impaction of fetal anterior shoulder behind pubic symphysis preventing delivery

 

Shoulder Dystocia

 

Features

-  Obstetric emergency

-  Fetal head delivered to chin w body still in pelvis

-  Incidence 1-2%

-  Increases w advancing gestation

-  Cause of 8% intrapartum deaths

-  50% in normal fetuses

-  98% large fetuses not effected

-  Mechanism

-  Large shoulder diameter

-  Cephalic diameter smaller than shoulders

-  Failure of shoulders to internally roatate to oblique from AP from anterior shoulder impacts above pubic symphysis

-  Precipitate delivery

-  Poor fetal tone (anencephaly, hypoxia)

-  Instrumental delivery

 

Risk Factors

-  50% unpredictable

-  Macrosomnia

-  5% if >4kg

-  10% if >4.25kg

-  15% if >4.5kg

-  20% if >5kg

-  Past Hx of dystocia

-  DM x2 risk

-  Post dates

-  Obese mother: BMI>30

-  High parity: twins

-  Male fetus

-  Short stature

-  Abnormal pelvic anatomy

-  Epidural

-  IOL

-  1st Stage of Labour

-  Prolonged

-  Secondary arrest > 8cm

-  Mid-cavity arrest

-  Forceps/ventouse delivery

-  2nd Stage of Labour

-  Difficulty delivering chin

 

Complications

-  Fetal

-  Cord may become trapped & occluded

-  Rapid hypoxia & fetal death

-  50% of death within 5 minutes

-  Horners syndrome

-  Facial nerve palsy

-  Brachial plexus damage 10%

-  90% transient, 10% permanent

-  C5-T1, C5-C6: Erbs Palsy

-  C7-T1: Klumpskys Palsy

-  Complete

-  Fractures

-  Clavicle 10%

-  Humerus  12.5%

-  Death 1 in 250-300

-  pH falls 0.04 per min from delivery of head

-  Maternal

-  Trauma to genital tract

-  Uterine rupture

-  PPH >10%

-  Symphyseal separation

 

Mx

-  Prevention

-  Consideration of IOL/LUSCS if known macrosomia

-  GDM

-  EFW >4.25Kg consider LUSCS

-  IOL (controversial)

-   40/40 if diet controlled

-   38/40 if Insulin

-  Anticipate when in labour

-  Disimpact shoulder & deliver fetus

-  Series of manoeuvres tried in sucession, 30 sec each

-  Outcome based on speed of resolution

-  Prepare to manage compromised infant: Neonatal resus

-  HELPERR

-  Help: call for assistance

-  Accoucher

-  Neonatal resus

-  Documentation

-  +/- Episiotomy

-  Provides additional room for manouvres in vagina

-  Only performed if deemed of benefit

-  Legs: McRoberts Manoeuvre

-  Pressure: Suprapubic Pressure

-  Both hands as if for CPR

-  Constant pressure for 30 sec

-  Pulsated pressure for 30 sec

-  Enter vagina

-  Rubins 2 & Woods Manoeuvres

-  Remove posterior arm/shoulder

-  Hand enters vagina to babys front

-  Feel for & grasp posterior hand

-  Pull & sweep hand across babys face

-  Humeral fracture common

-  Reduces bisacromial diameter by 2cm+/-

-  Roll onto all 4s: Gaskin Manouvre

-  If above fails

-  Anterior clavicle fracture

-  +/- Symphysiotomy

-  Zavanelli Manoeuvre

-  Push head back into cervix head & deliver by Caesarean

-  Last resort to save mother

 

 

 

References