Case 8 Flashcards
What is the difference between epidural and spinal block ?
Epidural allows regional pain relief but with ability to mobilise (push) during vaginal delivery. Spinal block to subarachnoid space is more rapid used in Caesarean when mobilisation isn’t required.
What is the common rule for normal symphysis fundal height ?
The embryological week age -2 in cm.
What is the difference between the basal and chorionic plate ?
Basal = mum’s tissue , chorionic = fetal tissue. Pool of blood in between the two which is full of O2/nutrients/waste.
What are the diaphragmatic openings ?
I 8 10 Eggs At 12.
IVC = T8
Eosophagus = T10
Aorta = T12
The umbilical vein brings blood to the foetus. It divides at the liver to form what ?
IVC and portal vein.
What is the ‘shortcut’ pathway from the umbilical vein to the IVC ?
Ductus venosus
The umbilical arteries take blood to be pooled in the placenta for exchange. What structures feed into them ?
The two branches of the internal iliac arteries.
What are the two walls of the foramen ovale and which side are they on ?
Septum primum (LA side) Septum secundum (RA side)
What structures does the ductus arteriosus connect ?
Allows blood flow from pulmonary artery to aorta and then into circulation.
What substance causing contraction of the umbilical arteries and veins in response to decrease temperature immediately after birth ?
Wharton’s jelly. squeezes down on the vessels.
What causes the decreased resistance immediately after birth that allows blood into the lungs ?
Alveoli fluid is pushed into the capillaries by air. This causes arterioles to dilate. RA/RV pressure decrease.
What happens in response to increased blood flow into the left atrium?
The pressure increases in LA so it’s now higher than RA (which is dealing with O2 poor blood). Therefore the foramen ovale closes to stop contamination.
What does the foramen ovale become when closed ?
Fossa ovalis, more of a remnant of the fibrous sheet that covered the foramen ovale during development.
Post natal, what does the increase in pressure in the aorta cause ?
Pressure in aorta is now > pulmonary artery. This causes contraction of SM of ductus arteriosus from ^ O2.
Placental removal causes a decrease in what substance? This has the knock on effect of…
Increased prostaglandins
Ductus arteriosus responds by constricting to form the ligamentum arteriosum.
Blood flow through the umbilical artery stops causing what ?
pressure to increase therefore closes its branch with the internal iliac.
What are the two stages of labour in terms of pain ?
First, onset to full cervical dilation
Second, full cervical dilation to delivery.
What does the first stage of labour cause ? what substance has increased release ?
Repetitive uterine contractions and distension of lower uterine segment. Tissue stretches causing Prostaglandin release.
What is the required level of cervical dilation ?
10 cm.
What dermatome controls contraction and using what fibres ? What other structures might be affected ?
T10 - L1 in slow unmyelinated C fibres.
Adjacent pelvic structures (L2-S1) might be affected.
What pain sensation do the C fibres give?
Visceral crampy poorly localised pain, can be referred. Travel in paracervical ganglion up the lumbar sympathetic chain.
Which pain fibres are triggered in the second stage of labour ? What pain response do they produce ?
A delta fast fibres. Sharp and localised pain.
Why doesn’t blocking the pudendal nerve numb the region to pain ?
Pudendal nerve supplies the perineum and lumbo sacral plexus. But the perforating branch or post cut thigh, ilioinguinal and gentofemoral also give innervation therefore pain still felt.
What are the two major problems with maternal hyperventilation ?
decreased CO2.
1st, left shift of O2 Hb dissociation curve increasing maternal affinity Hb for O2. This then decreases O2 delivery to fetus.
2nd, causes maternal alkalosis which constricts uterine artery and decreases blood flow.
What are the three major types of analgesic options ?
non pharmacological (duala, birth partner etc) , Neuraxial (spinal cord) , nerve blocks (peripheral nerves).
What is the effect of C fibres in the spinal cord in inducing nociception ?
C fibres stimulate secondary afferents which suppress inhibitory interneurons causing pain gate to open. Therefore C fibres are only pain fibre so strong pain stimulus transmitted -> nociception.
What pain fibres modulate pain in the dorsal horn ? What sensations are they responsible for ?
A delta fibres. They synapse inhibitory interneurones and stimulate them decreasing transmission of pain to 2ndry afferents which closes the pain gate.
Pressure and touch.
Why are NSAIDs avoided for pain relief when pregnant/labour ?
Causes permanent closure of ductus arteriosus. This affects renal and pulmonary vessels.
What is Pethidine and what is it’s route of administration ?
Commenest analgesic. IM injection. sedative that increases fatal blood plasma conc 2-5 hrs post injection.
What is the active metabolite of pethidine ?
Norpethidine, sedative.
What is Remifentanil ?
highly potent, rapid onset sedative. Acts 90 seconds after administration. Metabolised by tissue esterases.
What is the pathway of an epidural injection ? (6)
Skin, subcut tissue, supraspinous and intraspinous ligaments, ligamentum flavium, epidural space
What is the ligamentum flavium ?
Yellow layer full of elastic tissue
What are the general qualities of an epidural ? (3)
Catheter gives prolonged effect that can be monitored/changed/
Minimal fetal transfer of drugs
No sedation, still mobile.
What is an epidurogram ?
Contrast outlining epidural space. Use local anaesthetic and opiate.
What is the route of a spinal injection ? (7)
Skin, subcut tissue, supraspinous and intraspinous ligaments, ligamentum flavium, epidural space, dura
What is the conus ?
The conical lower extremity of the spinal cord
What level do spinal injections have to be done at and why ?
Below the conus (L1-L2) because it avoids the spinal cord. Could/will cause paralysis.
What are the major qualities of the spinal injection ? (3)
Minimal fetal transfer of drugs. No sedation. Have to reinfect whereas epidural you can ‘top up’ with catheter.
What are the common complications of neuraxial ? (2)
dural puncture -> headache, CSF leak decrease pressure.
Nerve damage; direct = conus nerve root, indirect = haemotoma, abscess.
Why can neuroaxial blocks increase the chance of instrumental delivery ?
They can temporarily paralyse delivery apparatus. Decrease urge to push due to decreased sensation. Prolongs 2nd labour stage.
What are the 3 major parts of the placenta?
The amnion (water bag) , the chorion (vast majority of weight, composed of villi) and the umbilical cord
What are cells in the placenta that have differentiated from maternal endometrium called ? Why do they change ?
Decidual cells.
Levels of progesterone increase.
What is a key component of early breast milk that helps boost an infants immune system?
Immunoglobulins
What are the action of myoepithelial cells ?
Surround the mammary glands, contract to squeeze out milk toward the nipple.
Why do the mammary glands expand ?
stimulation from Oestrogen and progesterone during pregnancy and puberty.
What area is the areola? what is it’s function?
Dark circular area that surrounds the nipple. Contains areolar glands which secrete oily lipid fluid to moisturise and prevent cracking/tearing during feeding.
Its colour and smell also attract the infant.
What is the pathway of milk from the mammary glands ?
glands , lactiferous ducts, nipple pores, nipple.
What pathway stimulates oxytocin release during lactation ? (6)
Infant starts to suckle on a teet.
Mechanoreceptors -> spinal cord -> hypothalamus -> oxytocin neurones in PPG -> Oxytocin ^
What is the negative pathway during lactation ?
Infant suckles on teet. -ve signals to prolactin neurones in APG that release prolactin inhibitory neurone therefore prolactin increases. Mammary glands produce more milk.
What are the inactive small areas called in breast histology? often shown as blue
Lobules
What is the significance of having more stroma than lobules ?
Women is not producing milk. Stroma are areas of CT (pink on histology)
What type of epithelium lines the small ducts within the lobules ?
Cubodial epithelium.
What adaptions do acini have in a milk producing breast ?
Much larger so they have a higher milk storing capacity.
Very loose CT, supported by oestrogen surrounding the lobules.
Between lobules skin has fat and CT.
What does necrosis within proliferated ducts in breast indicate ?
Malignancy, could be linked to chronic haemorrhage.
What is DCIS ? what’s the difference if ducts show infiltrating nests into surrounding tissue?
Intraductal carcinoma in situ.
Then it’s not DCIS (intra), actually more dangerous.
How would you identify the fundus of the uterus on palpation?
Start at the top and curve fingers into the belly downwards. Feels like a hard ball under the skin.
How would you palate the foetal vertebral column ?
Move hand over ‘the bump’ until you feel the ridges
From which two points would you measure the symphysis fundal height from ?
Top of the pubic bone to the top of the uterus.
What are the stages to the mechanism of labour ? Do Frogs In Cardiff Ever Ride A Pink Limousine
Descent , Flexion, internal rotation, crowning, Extension, Restitution, Internal rotation of the shoulders, Ant shoulder, Post shoulder, Lateral flexion.
Label the anatomy practical diagram on desktop
- Umbilical Vein
- Umbilical artery
- Amnion
- Pool of blood
- Chorionic plate
- Uterine wall
- Basal plate
- Trophoblasts
- Intervillus space
What is a cotyledon and what would be your concern if it was missing from delivered placenta ?
One of the ‘cobbles’ on the fatal side of placenta. If missing then still attached to mother so will bleed. Uterus can’t contract BVs can’t go back to former state, mum bleeds out.
What is the difference between wall thickness in arteries and veins ?
Arteries = thick , Veins = thin
The umbilical vein is obliterated to form…. it divides what structures ?
Round ligament/ligamentum teres. Divides the left part of liver and connects it to the abdominal wall.
Picture of the umbilical cord, it forms a face. What are the ‘two eyes’ , ‘the mouth’ , ‘the skin’ and the ‘spots’ ?
Two eyes = the two umbilical arteries.
The mouth = the one umbilical vein
The skin = Wharton’s jelly
Spots = embryonic remnant (allantois)
What do the umbilical arteries become ?
Medial umbilical ligament and a branch of the sup cervical artery
How does a true knot occur and what can it cause ?
Placenta growth ^ or its too long, causes increased movement allows foetus to slip through creating knot.
Intrauterine fatal death because O2 supply cut off.
How are false knots created, why are they often missed ?
Varices or dilations of umbilical veins
Not usually visible antenatally.
What is the condition called where the fossa ovalis fails to form postnatally?
Patent foramen ovale. Usually occurs when the septum primum and secundum don’t divide the atria completely.
What are the 3 major causes of the ductus arteriosus becoming the ligamentum arteriosum apart from pressure ?
Increased bradykinins in the lungs
increase O2 sat of blood
Decrease in circulating prostaglandins and their receptors
What are the function of the Cooper’s ligaments ? What happens during Carcinoma?
CT that attach lobules of gland to the overlying skin. If Carcinoma occurs, may result in puckering of nipple or dimpling of the skin.
List some major risk factors for breast cancer… (5)
Obesity, high alcohol intake, ^ intake of COCP, HRT (hormone replacement therapy), family history
What adaptions do the secretory cells have of a lactating breast ? (what type of epithelium, components of cell)
Depending on the amount of material in the lumen, they can have tall columnar or cuboidal shaped epithelium
Many microvilli on luminal surface
Abundant endoplasmic reticulum and large mitochondria.
What type of gland is the mammary gland ?
Compound tubular. Heavily branched with duct portions throughout. Contains secretory and duct cells.
What are the possible causes of px presenting with lactation who is not, and has not recently been pregnant?
Shows hormone imbalance. Possibly from pituitary gland, tumours, thyroid gland etc.
What are the methods of preventing lactation following birth ?
Not allow the baby to suckle Use Cabergoline (dopamine agonist) this can also be used to treat conditions with high levels of prolactin.
Px is diagnosed with fibrocystic change, what would you expect to see; microscopic description, histology
Can include mystically dilated normal structures and deposition of fibrous tissue.
More denser CT, may not be abnormal
Why might fibrocystic change be difficult to pick up/diagnose?
Similar to young adult breast tissue in appearance (dense). Appears as bright white.
Which nodes do the lateral and medial sides of the breast tissue drain to ?
Lateral = axillary nodes Medial = Parasternal (they have ^ mortality)
What are the pelvic floor muscles ?
Levator ani and bulbospongeous.