Case 8 Flashcards
What is the function of Cooper’s Ligaments?
Fibrous connective tissue which supports the breast.
What type of epithelium are acini cells?
Columnar
What is the function of acini cells?
Produce milk
What is the function of myoepithelial cells?
Contract to eject milk
What effect does puberty have on the breast?
Elongation and bifurcation (branching) of lactiferous ducts, formation of spherical masses at the end of each duct, development of immature alveoli, increased fat deposition.
Human Placental Lactogen
Reduces maternal insulin sensitivity.
Reduces maternal glucose utilisation.
Increased lipolysis with release of free fatty acids.
Increases availability of glucose for the foetus.
Why do women suddenly produce milk following miscarriage/abortion?
Large amounts of progesterone and oestrogen inhibit prolactin during pregnancy.
These hormone levels fall suddenly following miscarriage/abortion.
Where is milk stored during pregnancy?
Cannot be stored, it is absorbed into the blood.
How is milk production prevented in women following miscarriage/abortion?
Dopamine agonist
Which immunoglobulin is found in breast milk?
IgA
What is the effect of dopamine on prolactin?
Inhibitory
What is the effect of oxytocin on the lactating breast?
Contraction of myoepithelial cells
What stimuli cause release of oxytocin?
Suckling
Mother hearing the sound of crying
How does oxytocin cause contraction of myoepithelial cells?
Binding to its receptors causes an increase in intracellular calcium.
How long must suckling cease for, for milk production to stop?
2-3 weeks
Colostrum is high in…
Protein, minerals, vitamins A, D, E and K, immunoglobulins.
Meconium
Earliest stool
What important immunological effect does lactose have on the gut of the neonate?
Promotes growth of the intestinal flora.
What is the function of Alpha Lactalbumin?
Regulatory subunit of lactose synthase. Transfer of galactose moieties to glucose.
Promotes growth of bifidobacterium (intestinal bacteria)
Immunoglobulins found in breast milk:
IgA, IgG, IgM
What is the role of lactoferrin found in breast milk?
Iron Chelation
Blocks adsorption/penetration of viruses (rotavirus)
Blocks adhesion of bacteria (e.g. Vibriocholerae, E. Coli)
Promotes intestinal growth and repair
Immune modulation(reduces production of IL-1,2,6 and TNF-alpha
What is the function of lysozyme found in breast milk?
Inhibits endotoxin
Macrophage activation
Bacterial cell wall lysis
Increases IgA production
What is the function of casein found in breast milk?
Inhibits adhesion of bacteria
Promotes growth of bifidobacterium (intestinal bacteria)
What is the function of oligosaccharides in breast milk?
Prevent adhesion of common respiratory pathogens to respiratory epithelium (e.g. haemophilus influenzae, streptococcus pneumoniae)
What sort of fibres are involved in pain during Stage 1 of labour?
C fibres (slow, unmyelinated)
What vertebral levels are involved in pain during stage 1 of labour?
T10-L1
Which nerve plexi are involved in pain during stage 1 of labour?
Hypogastric
Paracervical
Lumbar sympathetic chain
What type of pain is felt during stage 1 of labour?
Cramping, poorly localised, Visceral pain
What type of pain is felt during stage 2 of labour?
Well localised, sharp, somatic pain
Which nerve plexi are involved in pain during stage 2 of labour?
Lumbosacral plexus and pudendal nerves
What vertebral levels are involved in pain during stage 2 of labour?
T10-L4
What sort of fibres are involved in pain during stage 2 of labour?
A delta fibres (fast, myelinated)
What are the effects of entonox?
Analgesia, euphoria, anxiolytic, sedatory
MOA of Pethidine
Mu-opioid receptor agonist
Why are NSAIDs contraindicated in pregnancy/labour?
Cause neonatal haemorrhage due to thrombocytopenia
Interfere with prostaglandin synthesis (important for uterine contraction)
MOA of Entonox
Stimulates endogenous endomorphin and endomorphin secretion
Composition of Entonox
50% N2O and 50% O2
ADRs of Entonox
Nausea and vomiting
B12 inactivation with prolonged use
may be neurologically toxic
Contraindications of Entonox
Pneumothorax or other air cavity injury
What is the name of the active metabolite in pethidine?
Norpethidine
ADRs of Pethidine
Biliary Spasm Bradycardia Confusion Constipation Dependence
MOA of Pethidine
Mu-opioid receptor agonist
+ Postsynaptic Potassium efflux, hyperpolarisation prevents pain transmission
Route of administration of Pethidine as a labour analgesic
I/M injection
Contraindications for Pethidine
Acute respiratory depression
Head injury
MOA of Bupivacaine
Sodium channel blocker in nociceptive axons - prevents transmission of action potential to CNS
Route of administration of Bupivacaine
IV injection
ADRs of Bupivacaine
Convulsions, cardiac arrhythmias, dizziness
Contraindications of Bupivacaine
Cardiac arrhythmia
What are the benefits of fentanyl over pethidine?
Same effect (mu-opioid R agonist) but with less potential for drug interaction
MOA of fentanyl
Mu-opioid receptor agonist - suppresses presynaptic GABA release
ADRs of fentanyl
Biliary Spasm Bradycardia Confusion Constipation Dependence
Contraindications of Fentanyl
Acute respiratory depression
Head injury
What is the negative impact of opiates on labour?
Prolongs labour time
Which structures are penetrated when providing an epidural?
Skin, Subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum –> epidural space
When is an epidural given?
When cervical dilatation has reached 4-5cm
Which drugs can be given epidurally?
Bupivacaine and some opiates
What are the benefits of epidural administration of analgesia?
Prolonged effect and can be topped up
Minimal foetal transfer of drugs
Continued mobility - still able to push
What is the disadvantage of epidural compared to spinal analgesia?
Slower - effects reached 15-20 minutes after administration (cf. 5-10 minutes)
At what vertebral level is a spinal analgesic given?
Below L1-2
When is a spinal anaesthetic indicated?
Elective surgery
Which drug is used in a spinal anaesthetic?
Fentanyl
What are the benefits of intrathecal administration of analgesia?
Quick pain relief (5-10 minutes)
Minimal foetal transfer of drugs
What are the disadvantages of intrathecal administration of analgesia?
Wears off after 1 hour and cannot be topped up
Loss of mobilisation (unable to push - used in C-section)
Contraindications for neuraxial analgesia:
Patient refusal
Abnormal spinal anatomy - Spina bifida (low clonus), Lumbar fusion
Impaired coagulation (risk of spinal haematoma)
Infection (risk of meningitis or abscess)
Fixed cardiac output state (unable to compensate for vasodilation) e.g. Severe Aortic Stenosis, Massive haemorrhage
What type of headache is a complication of nauraxial analgesia?
Low pressure headache - dural puncture causing leakage of CSF
When is a neuraxial block indicated?
When an instrumental delivery will take place (+ episiotomy)
Target for Neuraxial block
Pudendal Nerve (S2,3,4)
Neuraxial block increases risk of:
Prolonged stage 2 labour
Instrumental Delivery
(reduces urge to push due to reduced sensation)
Why might adrenaline be used with an local anaesthetic?
Causes peripheral vasoconstriction. Prolongs duration of effect of LA at site of injection by preventing is from dissipating out as quickly.
Less LA needs to be used.
(Also reduces bleeding at the wound/incision site = easier to manage)
When is adrenaline contraindicated in use with a local anaesthetic during labour?
Episiotomy - tissue surrounding the site must have collateral blood supply to remain viable. Pudendal and perineal nerves might be damaged by becoming ischaemic.
When should caution be taken when coadministering adrenaline with LA?
In areas of poor collateralisation,
High value structures (nerves),
End extremity arteries (fingers and toes)
Storage of excess iron in the liver
Ferritin
Storage of excess iron in the bone marrow
Haemosiderin
Daily Iron requirement for a pregnant female:
4-7mg
Cause of low Hb and low MCV
Iron deficiency
Haemoglobinopathy (defect in Hb production)
Cause of low Hb and high MCV
B12/Folate deficiency
Haematological problem
What factors suggest iron deficiency during pregnancy?
Hb < 105g/L (still consider if <115g/L)
Increased MCV
Serum Ferritin <15mcg/L
Treatment of iron deficiency anaemia in pregnancy:
120-149mg of elemental iron/day given either orally or parenterally
Iron has a number of dose-related ADRs:
Nausea Abdominal Pain Constipation Diarrhoea Black stools
What is the function of B12 and Folate?
DNA synthesis - involved in remethylation
Daily Folate requirement during pregnancy:
300-400𝛍g/day (cf. 100 normally)
Thrombocytopenia
Low platelets
Fanconi Anaemia
Inherited condition - reduction in all blood cells produced by bone marrow
Myelodysplasia
Group of cancers in which immature blood cells in bone marrow do not become mature and healthy
HELLP
A variant of preeclampsia - Haemolysis, Elevated Liver Enzymes, Low Platelet Count
Platelet count (increases/decreases) throughout pregnancy
Decreases
For a vaginal delivery, platelet count must be:
> 30x10 9/L
For a C-section, platelet count must be:
> 50x10 9/L
Epidural cannot be given if platelet count is..
Less than 100x10 9/L
Spinal cannot be given if platelet count is…
Less than 50x10 9/L
Amniotic Fluid Embolism
Amniotic fluid enters bloodstream, activates coagulation cascade causing cardiac arrest.
Why does hypersplenism cause thrombocytopenia?
Larger spleen can store more platelets.
Pregnancy increases risk of venous thromboembolism by…
5-10x
Clinical Presentation of DVT
Initially cramping,
Followed by leg swelling, pain and tenderness.
Clinical Presentation of Pulmonary Embolism
Dyspnoea Pleuritic Chest Pain Cough Haemoptysis Syncope
Treatment for DVT/PE in pregnancy
Enoxaparin (1mg/kg/bd)
i.e. Low Molecular Weight Heparin
A type blood can receive
A or O
B type blood can receive
B or O
AB type blood can receive
Any other blood type
O type blood can receive
O only
What type of immunoglobulin are anti-D (anti Rhesus D)?
IgG - therefore able to cross the placenta
What percentage of the caucasian population are RhD Negative?
15%
When are RhD Negative, pregnant women given anti-D?
After each potential ‘sensitising’ event e.g. car accident
Prophylactically at 28 and 35 weeks
Within 72 hours of childbirth (If baby is RhD positive)
What action does anti-D have when given to the mother?
Destroys any foetal RhD antigens in the maternal bloodstream before she makes them herself.
Kleihauer Testing
Used to estimate volume of haemorrhage and allow correct dose of anti-D to be calculated.
Foetal Hb stains darkly whereas maternal Hb are light.
Size of bleed is estimated using proportion of foetal and maternal cells in blood.
Criteria for blood to be transfused:
CMV negative
Irradiated (prevents any residual lymphocytes from attacking patient as foreign)
Hep E negative
Indication for Red Blood Cell Transfusion
Anaemia
Perioperative blood loss
Indication for platelet transfusion
Thrombocytopenia:
Patients undergoing chemotherapy
Patients with aplastic anaemia
Patients with disseminated intravascular coagulation
What is the B antigen?
D-Galactose
What is the A antigen?
N-Acetyl-D-galactosamine
What type of immunoglobulins are ABO antibodies?
IgM
Clinical Presentation of Acute Transfusion-related Lung Injury
Acute dyspnoea with hypoxia
Bilateral pulmonary infiltrates
Within 6 hours of transfusion with no obvious cause
What is the cause of Transfusion-related Acute Lung Injury?
Antibodies in donor plasma reacting with ‘primed’ white blood cells in the lungs
What is the effect of falling progesterone in the initiation of labour?
Synthesis of PGE2 - uterine contractions
Where is oxytocin released from?
Posterior pituitary
During initiation of labour, oxytocin is released in response to:
Stretching of uterine tissues
How does increased oestrogen bring about initial contractions?
Increases expression of oxytocin receptors on myometrium.
Causes production of PGE2 and PGF2 by chorion and decidua
–> Increased calcium influx –> CONTRACTION
Labour: Stage 1, Latent
Up to 3cm dilatation
3-8 hours
Contractions every 10 minutes lasting 20 seconds
Labour: Stage 1, Active
3-10cm dilatation
2-6 hours
3 Contractions every 10 minutes, lasting 40 seconds
Labour: Stage 2
Passive Vs Active?
From full dilatation to onset of involuntary expulsive contractions
Passive - No maternal urge to push, foetal head is high in pelvis
Active - Maternal urge to push, foetal head is low in pelvis (longer in primiparous than multiparous)
Labour: Stage 3
Delivery of placenta and membranes
Should be less than 30 minutes
Changes occurring in neonate on delivery:
Closure of foramen ovale
Closure of umbilical arteries
Closure of umbilical vein and ductus venosus
Closure of ductus arteriosus
Foramen ovale becomes…
Fossa ovale
How does the foramen ovale close?
Inflation of lungs during first cry
Increase in pressure in the left atrium
How are the umbilical arteries closed during childbirth?
Wall contraction - due to thermal/mechanical stimuli and change in O2 tension
Ductus venosus becomes….
Ligamentum venosum
Umbilical vein becomes…
Ligamentum teres hepatis
Ductus arteriosus connects…
Pulmonary vein and aorta
How is the ductus arteriosus closed during childbirth?
Muscle wall contraction AND bradykinin release by lung inflation
Ductus arteriosus becomes…
Ligamentum arteriosum
How is blood volume increased during pregnancy?
Progesterone and Oestrogen cause a decrease in resistance and pressure.
Kidneys retain more water as a result.
Why does pregnancy cause dyspnoea on exertion?
Reduced total lung capacity
Explain why voice quality may change during pregnancy.
Progesterone causes an increase in red blood cells.
Oedema of respiratory tract (fluid moves into lungs from blood)
Nasal stiffness and obstruction of Eustachian tube
Cutaneous changes during pregnancy:
Linea nigra (pigmentation from umbilicus to pubic symphysis)
Chloasma Gravidarum (butterfly-like pigmentation of face)
Falling of hairs and increased brittleness of nails.
What is the effect of increased thyroid function during pregnancy?
Increased thyroxine
- Increased basal metabolic rate
- Increased heart rate
- Increased GI activity
What causes morning sickness?
Progesterone reduces contractility of GI smooth muscle. Nausea and vomiting for first 12 weeks.
Why might a pregnant woman become constipated?
Compression of rectum
Why are pregnant women at an increased risk of UTIs?
Pressure on ureters increases risk of backflow of urine
Why do pregnant women have increased micturition?
Increased cardiac output Increased GFR Decreased concentration of urea and creatinine (removed quicker) Decreased plasma osmolality More urine produced.
i.e. Increased renal function
Cervical Cerclage
Stitching together of cervix if it begins dilating prematurely during 2nd trimester
Where is the mucus plug located in a pregnant woman?
Between vagina and uterine contents
Relaxin
Hormone produced by placenta causing relaxation of pelvic ligaments and pubic symphysis
Therefore, woman will have a waddling gate
Decidua
Uterine lining during pregnancy. Forms the maternal part of the placenta
Initiation of labour
Ageing placenta - less progesterone to inhibit uterine contractions.
Uterine stretching causes oxytocin release from p.pituitary - causes uterine contractions
Increased oestrogen - increased expression of oxytocin receptors on myometrium
How does oxytocin cause uterine contraction?
Oxytocin binds to its receptors.
Chorion and decidua synthesise PGE2 and PGF2
PGs cause calcium influx
Uterine contraction
