Shoulder Dystocia

Definition
§ Difficulty in delivery of fetal shoulders
§ Failure to deliver fetal shoulder without utilizing facilitating maneuvers
§ Prolonged head-to-body delivery time
§ >60 seconds
§ Incidence: 0.2-3% of all live births




Pathophysiology


§ Size discrepancy between fetal shoulders and maternal pelvic inlet
§ Macrosomia
§ Large chest:BPD
§ Absence of truncal rotation
§ Fetal shoulders remain A-P or descent simultaneously


Risk Factors
§ Antepartum

§ Macrosomia (>4500g)
§ DM/GDM (increases overall risk by 70%)
§ Multiparity


§ Intrapartum

§ Prolonged deceleration phase of labor
§ Prolonged 2nd stage
§ Protracted descent
§ Operative delivery (vacuum>forceps)

§ No evidence based data:
§ Male
§ AMA
§ short maternal stature
§ abnormal pelvic shape/size

Unpredictable
§ 25-50% have no defined risk factor!
§ 50% of cases occur in infants whose birth weight is <4000g § 84% of patients did not have prenatal dx. of macrosomia by US
§ 82%of infants with brachial plexus palsy did not have macrosomia

Complications 
§ Maternal
 Hemorrhage § 4th degree laceration

§ Fetal

§ Fx of humerus or clavicle
§ Brachial plexus injury (Erb’s/Klumpke’s palsy)
§ Asphyxia/cord compression


Management 

§ Goal: safely deliver infant before asphyxia and/or cortical injury
§ 7 minutes!!!
§ Episiotomy
§ Suprapubic Pressure
§ McRoberts Maneuver
§ Woods or Rubin Maneuvers
§ Zavenelli McRoberts Maneuver
§ 42% success rate § + suprapubic pressure = 54-58% § Brings pelvic inlet and outlet into more vertical alignment § Flattens sacrum
§ Cephalad rotation of pubic symphysis
§ Elevates anterior shoulder and flexes fetal spine
§ Increases IUP by 97%
§ Increases amplitude of contractions
§ +31N of pushing force


Summary 
§ Cannot accurately predict
§ BE PREPARED!
§ Consider risk factors
§ Be prepared to perform various maneuvers
§ Diagnose and treat quickly
§ Obtain assistance from nursing staff and NICU