PBL 36 Flashcards
Pathophysiology of pre-eclampsia
- Cause/mechanism
- Signs/symptoms/clinical manifestation
- Risk factors
- Diagnosis
- Treatment
- Cause/mechanism
- Defective spiral artery remodelling causes the placenta to not develop properly
- Leads to ischaemia in the placenta, causing an imbalance in anti & pro-angiogenic factors. This imbalance leads to widespread endothelial dysfunction, affecting ALL maternal organ systems - Signs/symptoms/clinical manifestation
- High blood pressure >= 140/90 on two separate readings taken 4/6 hours apart
- Proteinuria
- Usually occurs in third trimester
- Peripheral oedema
- Vision problems
- If left untreated –> leads to seizures = eclampsia - Risk factors
- Diabetes
- Hypertension
- Kidney disease
- Lupus
- Having a condition during pregnancy
- First pregnancy
- Family history
- Over age of 35
- Obesity - Diagnosis
- Blood test for placental growth factor - low levels could be a sign but further tests needed
- Blood pressure taking
- Urine tests for protein - Treatment
- Delivering the baby
- LABETALOL for hypertension, used for pregnant women
- Having baby around 37-38th week, so labour may be artificially induced or you may need a caesarian section
Overview of the 3 stages of labour
Stage 1:
- Onset of contractions
- Dilation of cervix to 10cm
- Sometimes Braxton hicks can be felt for up to a week before labour (false labour contractions)
Stage 2:
- Time from full dilation to delivery of the baby
Stage 3:
- From delivery of the baby to delivery of the placenta
Hormone released during labour
- Progesterone
- Steroids
- Oxytocin
- Prostaglandins
- Corticotrophin releasing hormone
- Interleukins
- Calcium
Why can labour not begin until progesterone effects are diminished? How is this solved?
Because progesterone inhibits uterine contractions
- Oestrogen levels rise at the end of gestation, producing changes that overcome the inhibiting effects of progesterone
How do oestrogen levels rise towards the end of gestation?
- Oestrogen levels rise due to the placenta releasing corticotrophin releasing hormone
- This stimulates the anterior pituitary of the foetus to secrete adrenocorticotrophic hormone (ACTH)
- ACTH stimulates the foetal adrenal gland to secrete cortisol and DHEA (major adrenal androgen)
- The placenta then converts DHEA to oestrogen
Effects of oestrogen on the onset of labour
- High levels of oestrogen cause the number of receptors for oxytocin on the uterine muscle fibres to increase, and cause uterine muscle fibres to form gap junctions with one another.
- Oxytocin released by the posterior pituitary stimulates uterine contractions, and relaxin released by the placenta assists by increasing the flexibility of the pelvic symphysis and helping dilate the uterine cervix.
- Oestrogen also stimulates the placenta to release prostaglandins, which induce production of enzymes that digest collagen fibres in the cervix causing it to soften.
How are uterine contractions controlled?
- Control of labour contractions occur via a positive feedback cycle. Contractions of the uterine myometrium force the baby’s head or body into the cervix, distending it. Stretch receptors in the cervix send nerve impulses to neurosecretory cells in the hypothalamus, causing them to release oxytocin in the blood of posterior pituitary. Oxytocin stimulates myometrium to contact more forcefully.
Uterine contractions: true vs false labour
True labour: Uterine contractions are at regular intervals, producing pain, back pain on walking, dilation of the cervix, and show of blood discharge containing mucus.
False labour: Braxton Hick contractions. Contractions with no pain on walking etc… No cervical dilation
Effects of late pregnancy on the mother: Cardiovascular changes
- Heart rate - Steady rise in heart rate and stroke volume, which required cardiac remodelling (size of the heart increases by 12%), from about 64bpm to about 76bpm
- Blood pressure - Remains largely unchanged, small drop mid gestation, hypotension develops more readily during pregnancy
- Blood volume - Increases steadily from week 6-8 to about week 32, physiological remodelling occurs to support this (increased venous return, increased atrial size)
- RBC increase not as high so fall in haematocrit
Effects of late pregnancy on the mother: Respiratory changes
- VC is maintained but TC is reduced, causing a decrease in RV
- Respiratory effort increased
- Diaphragm elevated
- Ribcage displaced upwards
- Breathing becomes thoracic
- Responsiveness to pCO2 increases - action of progesterone, increased TV
Effects of late pregnancy on the mother: Renal and urinary changes
- Kidneys enlarge: caused by increased excretion of waste products, increased Na+ reabsorbtion, increased blood flow
- Ureters displaced and enlarged
- Decreased bladder tone
- Urinary reflux from bladder to ureters
- Urinary stasis - increased UTI risk
Effects of late pregnancy on the mother: breast changes
- Stroma increases in bulk
- Lobules increase in size
- Areolar darken
- Nipples more pronounced
- Lactiferous ducts expand and branch for milk delivery
Effects of late pregnancy on the mother: overview
- CV changes
- Respiratory changes
- Renal changes
- Breast changes
- Weight gain (11kg average)
Which hormone stimulates growth and development of milk ducts?
Oestrogen
Which hormone stimulates growth of alveoli and lobules
Progesterone
Which hormone mimics prolactin and GH, causing breast, nipple and areola to enlarge?
Human placental lactogen
Causes and consequences of intrauterine growth restrictions
Causes:
- Issues with the placenta, so the foetus does not receive the necessary nutrients and oxygen
- Smoking
- Drinking alcohol
- Drug use
- Infection such as: cytomegalovirus, rubella, toxoplasmosis or syphillis
- Medical condition such as lupus, anaemia or clotting issues
Consequences:
- Limited body and organ growth
- Decrease O2 levels at birth
- Meconium aspiration
- Hypoglycaemia
- Difficulty maintaining body temperature
- Polycythaemia (>RBCs)
Where are the breasts located? Where do they span vertically?
Anterior thoracic wall
- Span between 2nd and 6th IC
Which muscles lies posterior to the breasts? How do they attach to each other?
Pectoralis major
Serratus anterior
- They attach by means of a layer of fascia composed of dense irregular connective tissue
Two regions of the breast?
- Circular body = largest and most prominent
- Axillary tail = smaller part, runs along the inferior lateral edge of the pectoralis major towards the axillary fossa
Quadrants of the breast
- Upper inner
- Lower inner
- Upper outer (towards axillary)
- Lower outer (towards axillary)
- Axillary tail of spence (towards axillary in armpit crest)
Which gland types are found within the areolae?
Sebaceous glands
- Secrete oily substance acting as a protective lubricant for the nipple
What are the spaced openings of ducts called on the nipple? What emerges from these ducts?
Lactiferous ducts
- Milk
Mammary glands are modified versions of which gland type?
Sweat glands
Mammary glands consists of 15 - 20…X… which consists of many alveoli embedded in connective tissue
Lobes
Each lobe contains several…X…, each one consists of many alveoli embedded in connective tissue
lobules
…X… cells surround the alveoli, when these contract…Y… is propelled towards the nipple
Myoepithelial cells
Milk
What is the connective tissue stroma?
- A supporting structure surrounding the mammary glands
- Contains a fibrous and fatty component
What is the function of the fibrous stroma?
Condense to form suspensory ligaments of Cooper, these have two main functions:
- Attach and secure the breast to the dermis and underlying pectoral fascia
- Separate the secretory lobules of the breast
What is the pectoral fascia? Its role?
The base of the breast lies on the pectoral fascia, a flat sheet of connective tissue associated with the pectoralis major muscle
- It acts as an attachment point for the suspensory ligaments
What is the retromammary space? Significance?
A layer of loose connective tissue between the breast and pectoral fascia
- Used in reconstructive plastic surgery
Blood supply to and from the breast?
- Medial aspect = internal thoracic artery (branch of the subclavian)
- Lateral aspect:
1. Lateral thoracic and thoracoacromial branches - from axillary
2. Lateral mammary branches - from posterior intercostal arteries
3. Mammary branch - from anterior intercostal artery - Venous drainage = axillary and internal thoracic veins
Lymphatic drainage of the breast tissue?
- Axillary nodes (75%)
- Parasternal nodes (20%)
- Posterior intercostal nodes (5%)
Innervation of the breast
Anterior and lateral cutaneous branches of the 4th and 6th IC nerves
Principal hormone in promoting milk production?
Prolactin
Where is prolactin secreted from?
Anterior pituitary gland
Which hormone inhibits the effects of prolactin, even though prolactin levels rise during pregnancy?
Progesterone
- After delivery, progesterone and oestrogen levels drop, allowing the inhibition of prolactin to be relieved
Explain how breast feeding increases prolactin release?
Suckling action of the infant during lactation is the principal stimulus for maintaining prolactin
- Suckling initiates nerve pulses from stretch receptors in the nipples to send signals to the hypothalamus
- The impulses DECREASE hypothalamic release of prolactin-inhibiting hormone (PIH) and INCREASE release of prolactin-releasing hormone (PRH)
- This causes more prolactin to be released by the anterior pituitary
Which cells do prolactin act on?
Glandular cells in breast
Which hormone causes release of milk into the mammary ducts? How does milk ejection occur?
Oxytocin
- Milk formed by glandular cells of breast are stored until the baby begins suckling
- Touch receptor stimulation in the nipple initiates sensory nerve impulses that are relayed to the hypothalamus
- In response, secretion of oxytocin from the POSTERIOR pituitary increases.
- Oxytocin is carried in the blood stream to the mammary glands, and stimulates contraction of the myoepithelial cells surrounding the glandular cells and ducts
- Resulting compression moves the milk from the alveoli of the mammary glands into the mammary ducts, where it can be suckled = MILK EJECTION
What is colostrum?
A cloudy fluid released from the mammary glands during late pregnancy and first few days after birth
- Serves adequately until the appearance of true milk on about the 4th day
- Colostrum and maternal milk contain important antibodies that protect the infant during the first few months
Effect of lactation on ovarian cycle
Lactation often blocks ovarian cycles for the first few months following delivery, but the effect is inconsistent
Pathophysiology of mastitis:
- Causes
- Signs and symptoms
- Risk factors
- Causes
- Milk stasis: build up of milk within the breast. Can occur due to baby not properly attaching, baby having problems sucking, infrequent feeds, favouring one breast, pressure on the breast, and a knock or blow to the breast
- Milk stasis can cause the milk ducts to become blocked
- Milk stasis can cause the milk to stagnate and become infected. S. Aureus live on the skin and may enter through a small crack/break in the skin, or bacteria present in a baby’s mouth and throat being transferred during breastfeeding
- In non-breastfeeding women, it is often caused by bacterial infection, THIS IS PERIDUCTAL MASTITIS
- Can also occur due to duct ectasia, this is where the milk duct gets shorter and wider as the breasts age
- Signs and symptoms
- Breast tenderness or warmth
- General malaise
- Pain continuously or while breast-feeding
- Redness
- Fever
- Nipple discharge - Risk factors
- Diabetes
- Corticosteroid use by mouth
Which breastmilk proteins bind to nutrients that many bacteria need to grow and survive?
Bacteria need B12 and iron. Breast milk contains B12-BP and lactoferrin to support the foetus
B12 binding protein - binds B12
Lactoferrin - binds to iron
Which antibodies are found in breast milk?
IgA
Which WBCs does breast milk contain?
Neutrophils
Macrophages
B-lymphocytes
- They serve as phagocytes in the baby’s GI tract
- B-lymphocytes differentiate into plasma cells which produce antibodies and T-lymphocytes to kill microbes directly
Breastmilk vs bottle feeding
Breast:
- Contains antibodies
- Perfect for baby’s digestive system
- Always available
- Free
- Less likely to have allergic reaction
- Skin-to-skin contact
- Beneficial for mother
Bottle:
- More convenient
- More flexible - partner or caregiver can feed the baby too
- Mother can eat what she wants without worrying
- Breast feeding can be unsafe if mother has medical conditions or takes medicines
- Formula feed babies usually need to eat less often because it is less digestible
