Obstetric Analgesia & Anaesthesia
Specific Learning Outcomes
Understand the Anatomy of Pain in labour
Internalize Techniques of Analgesia Without Drug Use
Comprehend Analgesic, Amnestic, Anaesthetic Agents
Understand general and regional anesthesia in Obstetrics
Regional (neuroaxial) Analgesia and its Techniques
Introduction
Many patients may request relief of labor pain
Pain of labor and delivery can be controlled by
Childbirth preparation techniques
Non-pharmacologic means or
Pharmacologic means (including labor epidural)
The choice depends on the
Circumstances of labor and delivery
Preferences of care provider and patient, and
Judgment of anesthesiologist
Controversial evidence exists that labour epidurals may
Increase a patient's risk for instrumental delivery
Early discussion of this issue between the patient and
Obstetrical care provider advised
Analgesia useful for patients with certain risk factors even
Without maternal request
Helps minimize need for emergency anesthesia where this
1
, Would be especially hazardous
Risk factor patients for early anaesthetic service requiring joint
management plan:
Marked obesity
Obstetric complications with potential for operative delivery e.g.,
Placenta praevia, high order multiple gestation
Severe preeclampsia
Bleeding disorders e.g, thrombocytopenia
Use of anticoagulants
Severe edema, trauma, surgery, or anatomical abnormalities of
The face, neck, or spine
Abnormal dentition, small mandible, or difficulty opening mouth
Extremely short stature, short neck, or arthritis of the neck
Goitre
Prior history of anesthesia complications, such as malignant
hyperthermia
Cardiovascular, neurological, or respiratory disease
Hyperreflexia in parturients with a high spinal cord lesion
Anatomy of Pain
Uterine contractions & cervical dilatation result in visceral pain
Pain impulses transmitted by afferent
Slow conducting, A-delta and C fibers that
Fibres accompany sympathetic nerves and
Enter spinal cord at the T10 to L1 level
As labor progresses, descent of fetal head and
2
, Subsequent pressure on pelvic floor, vagina, & perineum
Generates somatic pain, transmitted by the pudendal nerve
(S2-4)
Fibres rapidly conduct somatic pain hence relatively
difficult to block
NB: “Pain response” is a response of total personality
Presence of pain for 1st stage of labour involves spinal segments T10
– L1
Discomfort associated with uterine ischaemia during contraction
Dilation and effacement of the cervix
Sensory pathways include
Uterine plexus
Inferior hypogastric plexus
Middle hypogastric plexus
Superior hypogastric plexus
Lumbar and lower thoracic T10 – L, spinal segments
Pain in second stage of labour due to distension of vagina and
perineum sensory pathways conveyed mainly by:-
Branches of pudendal nerve via dorsal nerve of the clitoris
Labial nerves
Inferior haemorrhoidal nerves above branches conveyed
Along nerve roots S2, S3, & S4
Other nerves of perineal innervations
Ilioinguinal nerves
3
Specific Learning Outcomes
Understand the Anatomy of Pain in labour
Internalize Techniques of Analgesia Without Drug Use
Comprehend Analgesic, Amnestic, Anaesthetic Agents
Understand general and regional anesthesia in Obstetrics
Regional (neuroaxial) Analgesia and its Techniques
Introduction
Many patients may request relief of labor pain
Pain of labor and delivery can be controlled by
Childbirth preparation techniques
Non-pharmacologic means or
Pharmacologic means (including labor epidural)
The choice depends on the
Circumstances of labor and delivery
Preferences of care provider and patient, and
Judgment of anesthesiologist
Controversial evidence exists that labour epidurals may
Increase a patient's risk for instrumental delivery
Early discussion of this issue between the patient and
Obstetrical care provider advised
Analgesia useful for patients with certain risk factors even
Without maternal request
Helps minimize need for emergency anesthesia where this
1
, Would be especially hazardous
Risk factor patients for early anaesthetic service requiring joint
management plan:
Marked obesity
Obstetric complications with potential for operative delivery e.g.,
Placenta praevia, high order multiple gestation
Severe preeclampsia
Bleeding disorders e.g, thrombocytopenia
Use of anticoagulants
Severe edema, trauma, surgery, or anatomical abnormalities of
The face, neck, or spine
Abnormal dentition, small mandible, or difficulty opening mouth
Extremely short stature, short neck, or arthritis of the neck
Goitre
Prior history of anesthesia complications, such as malignant
hyperthermia
Cardiovascular, neurological, or respiratory disease
Hyperreflexia in parturients with a high spinal cord lesion
Anatomy of Pain
Uterine contractions & cervical dilatation result in visceral pain
Pain impulses transmitted by afferent
Slow conducting, A-delta and C fibers that
Fibres accompany sympathetic nerves and
Enter spinal cord at the T10 to L1 level
As labor progresses, descent of fetal head and
2
, Subsequent pressure on pelvic floor, vagina, & perineum
Generates somatic pain, transmitted by the pudendal nerve
(S2-4)
Fibres rapidly conduct somatic pain hence relatively
difficult to block
NB: “Pain response” is a response of total personality
Presence of pain for 1st stage of labour involves spinal segments T10
– L1
Discomfort associated with uterine ischaemia during contraction
Dilation and effacement of the cervix
Sensory pathways include
Uterine plexus
Inferior hypogastric plexus
Middle hypogastric plexus
Superior hypogastric plexus
Lumbar and lower thoracic T10 – L, spinal segments
Pain in second stage of labour due to distension of vagina and
perineum sensory pathways conveyed mainly by:-
Branches of pudendal nerve via dorsal nerve of the clitoris
Labial nerves
Inferior haemorrhoidal nerves above branches conveyed
Along nerve roots S2, S3, & S4
Other nerves of perineal innervations
Ilioinguinal nerves
3
