Anaesthesia of Labour Flashcards
what is the function of the female reproductive motor system
uterine ‘cramping’ - menstruation
Uterine contraction (eg. labour)
Pelvic floor muscle contraction eg. during sneezing
what is the functions of the female reproductive sensory system
Pain from the adnexae (ovaries+ Fallopian tubes)
Pain from uterus
Pain from vagina
Pain from perineum
what nerves innervate structures in the pelvis
Sympathetic
Parasympathetic
Visceral afferent
(as it is a body cavity)
what nerves innervate structures in the perineum
somatic motor
somatic sensory
(body wall)
what do parasympathetic and sympathetic nerves to the uterus control
uterine ‘cramping’ - menstruation
Uterine contraction - labour
what do somatic motor nerves to the female reproductive system control
pelvic floor muscle contraction
what pain do visceral afferents to the female reproductive system sense
pain from adnexae (ovaries+Fallopian tubes)
Pain from uterus
pain from pelvic part of the vagina
what female reproductive pain is sensed by somatic sensory nerves
perineal part of the vagina
pain from the perineum
where is pain from the superior pelvic organs that touch the peritoneum perceived
suprapubic
visceral afferents run along sympathetic fibres which enter the spinal cord at T11-L2
where is pain from the inferior aspect of the pelvic organs perceived
S2,3,4 dermatome (perineum)
visceral afferents run alongside parasympathetic fibres
enter spinal cord at levees S2, S3 and S4
where is pain perceived for structures which cross the pelvis into the perineum (eg. urethra, vagina)
Above the elevator ani - visceral afferent, S2,3,4
Below elevator ani - pudenal nerve S2,3,4, somatic sensory
where does sympathetic innervation to the pelvis come through
Sacral sympathetic trunk
T11-L2
Superior hypogastric plexus
where does parasympathetic innervation to the pelvic organs come from
Pelvic splanchnic nerves
S2,3,4
emerge from spinal rotes
mix with sympathetics in the interior hypogastric plexus
what 3 types of anaesthesia are used for the female reproductive system
Spinal anaesthetic
Epidural anaesthetic
Pudenal nerve block
when does the spinal cord become the caudate Aquinas
L2
what level does the subarachnoid space end at
S2
what level is anaesthetic injected for spinal or epidural
L3-L4 region
how do you work out where the L4 spinous process is
lies just above the most superior point of the iliac crests
what layers does the needed pass through for an epidural anaesthetic
supraspinous ligament
interspinous ligament
ligamentum flavum
epidural space (fat and veins)
what layers does the needle pass through for a spinal anaesthetic
supraspinous ligament interspinous ligament ligamentum flavum epidural space dura matter arachnoid matter finally reaches the subarachnoid space
where do sympathetic nerves exit the spinal cord
T1-L2
then travel to sympathetic chains running the length of the vertebral column
pass into all spinal nerves (in the anterior and posterior rami / named nerves)
how do sympathetic nerves travel further down than L2
sympathetic ganglia receive fibres from L2 via the sympathetic chain and distribute them via connections with lumbar, sacral and coccygeal spinal nerves
why are flushing of lower limbs, warmer lower limbs and reduced sweating all signs that spinal anaesthetic is working
because it blocks sympathetic fibres in all spinal nerves
sympathetic fibres supply all arterioles (sympathetic tone)
blockade of sympathetic tone causes vasodilation
can lead to vasodilation
what does the pudenal nerve do
provides somatic motor and somatic sensory innervation to the structures of the perineum
motor control of external anal and external urethral sphincters
comes from S2,3,4 (sacral plexus)
what does a pudenal nerve block do
anaesthetises the majority of the perineum
where does the pudenal nerve exit the pelvis then re-enter the pelvis/perineum
exits - greater sciatic foramen
re-enters- loser sciatic foramen
what does the pudenal nerve travel in
the pudenal canal
passageway within obturator fascia
travels with internal pudenal artery and vein
what landmark can be used to locate the pudenal nerve
ischial spine - located via internal vaginal examination
pudenal nerve runs along the lateral aspect of the sacrospinous ligament (ends at the ischial spine)
when is a pudenal nerve block used
can be used during labour
- forceps delivery
- painful vaginal delivery
- episiotomy inscision
perineal suturing post delivery
how can labour effect the pudenal nerve and perineal structures
branches can be stretched leading to weakness
fibres within the elevator ani or external anal spinchtor can be torn and cause muscle weakness
can lead to faecal incontinence and weakened pelvic floor
what is an episiotomy
a posterolateral incision
made into the ‘safe; fat filled ischoanal fossa to avoid incision extending into rectum
prevents tearing of the anal spinchter during pregnancy
