Failure of spontaneous
restitution after delivery
of head
Shoulder Dystocia: Risk factors, mechanisms and complications
Macrosomia
Post-dates
(>42 weeks)
Previous
shoulder
dystocia
Size discrepancy between fetal
shoulders and maternal pelvis
Multiparity
Maternal
diabetes
Inadequate
uterine tone (over
distension of
uterus, prolonged
2nd stage) and
birth canal trauma
from complicated
delivery
**Attempts to
disimpact and/or
deliver a
macrosomic fetus
Traction to head
can lead to
stretching and
tearing of
brachial plexus
nerves
Intentional or
incidental
fracture of the
fetus’:
Dysfunctional
or prolonged
labour and/or
contractions
↓ oxygenation
to fetus
Authors:
Danielle Hubbert
Risk Factors: *Up to 50% have no risk factors = Obstetrical Emergency that is challenging to predict Mark Diaz
Fetal death
Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published March 12, 2019 on www.thecalgaryguide.com
Prolonged
2nd stage of
labour
Maternal
obesity
Operative
vaginal
delivery
Fetal anterior shoulder becomes impacted
against maternal pubis symphysis and
fails to deliver spontaneously with normal efforts
Clavicular fracture
Erbs palsy (C5-6)
Klumpke palsy (C8-T1)
(rarely permanent)
Episiotomy or
3rd-4th degree
perineal tears Postpartum
hemorrhage
Hypoxia/asphyxia (see PPH slide)
Turtle sign – fetal head
retracts tight against
perineum
Uterine
rupture
Antepartum Risks Intrapartum Risks
Cord
Compression
Weakened and
distended
musculature
Fetal Complications Maternal Complications
Clavicle, to
↓ diameter
of shoulders
Humerus, when
sweeping
posterior arm
across chest
Humeral
fracture
Reviewers:
Dalynne Peters
Angela Deane
Ingrid Kristensen*
*MD at time of publication