1.6 Labour Pain Pathways

Question 1

1. Describe different pain pathways during labour

Answer 1

Comprises of Uterine and Extra Uterine

1 - First Stage

2 - Second Stage

Question 2

First Stage

Answer 2

Pain source uterine + extra
eg - Cervical dilatation and uterine contraction

Impulses are transmitted via uterine sympathetic axons in T10-T12
located in :
superior + inferior hypogastric plexuses

Minor input
Vessels in tub ovarian ligament

Displacement other abdominal viscera
gravid uterus
Manifest during labour
Transmitted via coeliac plexus

Diaphragm receives sensory innervation
phrenic N.

Question 3

Second stage

Answer 3

Extra Uterine pain
Vaginal Perineal origin
Impulses via:

Pudendal N S2-S4

variable input Genitofemoral N L1-L2

Extra uterine compression
adjacent structures
related fetal position
OP Lie

Causes compression of viscera
a/w low backache
L5-S1

Question 4

Indications for Regional Analgesia Labour

Answer 4

Maternal

Labour

Fetal

Question 5

Maternal

Answer 5

1. Non obstetric surgery
   allow avoidance GA
   Non essnetial best postponed til post partum
2. Obstetric surgery
   C section
   Repair tear
   MROP
3. Pre eclampsia
   Increase placenta flow
   reduces catecholamine
4. Cardiac disease
   Regurg valve - benefit afterload reduction
   promotion forward flow

Stenotic lesions - caution to maintain SVR

Question 6

Maternal indications for RA

Answer 6

5. Respiratory disease
   Optimise ventilation in patients w/ reduced Vent capacity

Caution high block
loss intercostal accessoyies

6. Obesity
   Increase incidence prolonged labour
   comoribed disease
   postop complications

= Regional desirable in cohort

7. CNS
   Prevent large swings in ICP wit abnormal anatomy
   arnold chiari malfor

S.Cord injury
high prob autonomic dysreflexia during labour
good regional block can obtund

Question 7

Indications for regional Labour

Answer 7

1. Maternal Request
2. Labour analgesia

3, Labour with complications

• Multip gestation
• Malpresentation
• Induction or augment labour
• anticipated long labour - primup

Question 8

Indications for Regional - Fetal

Answer 8

Babies high risk complcations

Promotes blood flow
** severe PET