Parturition

Question 1

FORCES OF RETENTION
what do the following do to promote labour?
1. progesterone
2. cervix
3. hypervolaemia
4. adrenaline
5. relaxin
6. Corticotrophin releasing hormone

Answer 1

1. strengthens muscle in cervix
   Dampens down excitability of uterine smooth muscle
2. softens towards the end of the third trimester
3. suppresses the release of hormones
4. acts in similar way to progesterone
5. acts on chemical transmitters in uterine muscle to reduce its contractibility
6. inhibits the release of prostaglandins

Question 2

FORCES OF RELEASE

1. oestrogen
2. oxytocin
3. vasopressin
4. cortisol
5. prostaglandins
6. corticotrophin releasing hormones
7. uterine distension

Answer 2

1. promotes release of prostaglandins
   increases the number of oxytocin receptors on uterine myocytes
   causes myocytes to form gap junctions
2. increases contractibility of the uterus
3. promotes contraction of uterine muscle
4. blocks action of progesterone
5. sensitise uterine muscle to oxytocin and act to soften the cervix
   used synthetically to induce labour
6. increase the contractibility of the uterus towards term
7. distension promotes reflex contraction

Question 3

1. at the pelvic inlet, which diameter is greater?
2. at the pelvic outlet, which diameter is greater?
3. which pelvic shape is most favourable for giving birth?

Answer 3

1. tramsverse diameter
2. AP diameter
3. gynecoid - oval inlet, wide suprapubic arch, generous capacity

Question 4

name the 4 key characteristics of the uterus

Answer 4

1. tone - constant resting tone
2. contractility - increases during later stages of pregnancy due to increase in number of oxytocin receptors
3. fundal dominance - contractions start at fundus and move down
4. rhythmicity - inherent rhythm of contractions

Question 5

1. describe the positive feedback cycle of uterine contractions
2. what is the purpose of contractions in the third stage of labour?

Answer 5

1. contractions of uterine myometrium force baby down on the cervix, causing cervical distension
   stretch receptors in cervix send nerve impulses to the neurosecretory cells in the hypothalamus
   release of oxytocin from posterior pituitary
   oxytocin stimulates the myometrium to contract more forcefully
2. contract the uterus down and decrease blood flow to prevent haemorrhage

Question 6

Describe the following foetal head presentations

1. suboccipito-bregmatic
2. suboccipitofrontal
3. occipitofrontal
4. mentovertical
5. submental bregmatic

Answer 6

1. occiput is the leading part. Chin tucked into chest. Most favourable
2. partially deflexed. Wider diameter.
3. deflexed vertex. wider diameter
4. top of head is leading part. diameter wider than pelvic outlet. Difficult to deliver
5. face first.

Question 7

Describe the following cardinal movements of labour:

1. engagement
2. descent
3. flexion
4. internal rotation
5. extension
6. external rotation
7. expulsion

Answer 7

1. entry of head into pelvic inlet
2. head moves deep into pelvic cavity
3. resistance of head against soft tissues of pelvis causes baby’s chin to meet chest
4. foetus moves from transverse to anteroposterior position
5. extension of neck to turn corner of pubic arch so that head is born
6. rotation so that head is more transverse so that shoulders can be born
7. rest of body is born

Question 8

What occurs, and what is the duration of the following stages of labour?

1. latent
2. first
3. second
4. third

Answer 8

1. onset of contractions > regu;ar contractions. Cervix becomes fully effaced
   3-4 cm dilation. can take several days
2. regular contractions. 3-4cm > 10cm
3. 25 hrs in primiparous women; 5.5 hours in multiparous
4. full dilation > delivery
   1 hour in primiparous women; 0.25 hours in multiparous women
5. delivery of placenta and membranes. Involves contraction of uterus and haemostasis to prevent haemorrhage
6. 25 hours.

Question 9

1. what does foetal mammary gland development result in?
2. what hormone promotes branching of this structure?
3. describe breast development during puberty
4. describe breast development during pregnancy
5. what happens to the breasts following menopause?

Answer 9

1. rudimentary duct tree
2. oestrogen (and inhibited by testosterones)
3. High levels of oestrogen promote significant ductal development, plus the growth of stromal and fat tissue
4. progesterone and prolactin mediate lobuloalveolar development in oestrogen primed gland tissue
5. due to lower levels of oestrogen, mammary gland tissue atrophies and the mammary glands become smaller and replaced with adipose tissue

Question 10

FOETAL BREAST DEVELOPMENT

1. what is the name of the primitive structures that give rise to the breasts?
2. at what gestational age are the primary milk ducts formed?
3. describe breast development at 32-40 weeks

Answer 10

1. milk streaks
2. 32 weeks
3. lobular areolar structure containing colostrum develop
   ducts open onto the areola
   nipple and areola become pigmented

Question 11

1. Which hormones strongly affect breast growth in girls at puberty?

Describe the influence of the following hormones on the breast tissue during pregnancy:

2. oestrogens
3. progesterone
4. prolactin
5. serum placental lactogen
6. ACTH and HG

Answer 11

1. oestrogen and hGH
2. stimulates ductal system proliferation and differentiation
3. duct enlargement and widening. growth of lobes, lobules and alveoli
4. influences nipple growth.
   essential for complete lobular-alveolar development
5. areolar growth
6. combines synergistically with prolactin and progesterone to promote mammary growth

Question 12

describe breast changes in pregnancy at the following stages:

1. 6-8 weeks
2. 12 weeks
3. 12-16 weeks

Answer 12

1. fullness, tenderness, tingling. increased blood supply leads to more prominent veins
2. pigmentation of nipple and areola. Areola becomes enlarged, and nipple becomes more pronounced.
3. colostrum begins to be secreted

Question 13

1. between which intercostal spaces is breast tissue located?
2. what is the name given to the tail of tissue extending towards the axilla?
3. what is the areola?
4. what are the tubercles of montgomery?

Answer 13

1. 2nd and 6th
2. tail of spence
3. circular area of pigmented skin in the centre of the breast, containing sebaceous glands
4. sebaceous glands in the areola, surrounding the nipple

Question 14

1. what are the basic units of the mature glandular breast tissue?
2. what are these structures lined with?
3. what are these structures surrounded by? What is the significance of this?

Answer 14

1. alveoli/acini
2. lactocytes - produce milk
3. myoepithelial cells - contract to eject milk into the lobules

Question 15

1. name the 2 arteries that supply the breast
2. what is the venous drainage of the breast?
3. which nodes drain the breast?
4. what is the innervation of the breast?

Answer 15

1. internal thoracic artery (branch of subclavian) and lateral thoracic artery (branch of the axillary)
2. internal and external mammary veins and axillary veins
3. axillary nodes
4. 2nd - 6th intercostal nerves

Question 16

Describe the following:

1. mammogenesis
2. lactogenesis 1
3. lactogenesis 2
4. lactogenesis 3
5. involution

Answer 16

1. growth and proliferation of the ductal tree and development of new lobules
2. occurs from mid to late pregnancy to 48 hours after birth. Production of low volume, high concentration colostrum.
   - colostrum encourages baby to remove mycelium and harmful bilirubin and has high IgA concentration.
3. 3-8 days post partum. Copius milk production due to reduction in levels of progesterone
4. from days 8-9 post partum to the beginning of involution. Established lactation, with milk synthesis controlled at the breast.
5. approximately 40 days after last breast feeding

Question 17

1. what happens to the alveoli during lactogenesis 1

2. what inhibits milk secretion in late pregnancy?

Answer 17

1. expanded through accumulation of colostrum; epithelial cells differentiate into secretory cells; milk droplets cross the cell membrane into the lumen of the alveoli
2. high levels of progesterone and oestrogen

Question 18

1. what triggers lactogenesis 2?
2. what changes occur in the breast milk?
3. lactation switches to what type of process?

Answer 18

1. completion of third stage of labour - abrupt withdrawal of progesterone in the presence of prolactin
2. sodium levels fall; lactose and milk lipids rise
3. from endocrine to autocrine

Question 19

Describe the following theories of autocrine control in lactogenesis 3:

1. prolactin receptor theory
2. feedback inhibitor of lactation
3. prolactin inhibitory factor

Answer 19

1. the more milk that is removed, the more prolactin receptors are expressed in lactocytes
2. substance in milk itself is removed on feeding; lack of feeding leads to accumulation of this substance, which inhibits action of prolactin
3. hypothalamic substance inhibits prolactin production when breast milk is not removed

Question 20

1. Where is prolactin produced?
2. what inhibits the release of prolactin?
3. what is the function of prolactin?
4. where is oxytocin produced?
5. what is the role of oxytocin?
6. describe the letdown reflex?

Answer 20

1. anterior pituitary
2. dopamine
3. promotes mammary growth, milk secretion, and maintains milk production
4. posterior pituitary
5. contracts myoepothelial cells
6. sucking stimulates nerve endings; signals transmitted to hypothalamus
   - release of oxytocin which enters the systemic circulation in the posterior pituitary
   - inhibition in dopaine release; relief of inhibition of prolactin
   Prolactin stimulates milk production
   oxytocin promotes milk ejection

Question 21

1. what is mastitis?
2. describe signs and symptoms
3. how can poor attachment lead to non-infective mastitis?
4. describe management of non-infective mastitis
5. which bacteria are the likely cause of infective mastitis
6. what is the management of infective mastitis?

Answer 21

1. inflammation of the breast
2. breast tenderness or warmth to touch; general malaise; breast swelling; pain or burning sensation; fever; flu like symptoms
3. inadequate milk removal > milk stasis > back pressure > leakage of milk into interstitial tissues > inflammation
4. treat case; support mother in correct positioning; encourage mother to increase frequency of breastfeeding; analgesics; check bra fitting
5. S. aureus; E. coli; Streptococcus
6. same self help measures as non-infective
   analgesics plus antibiotivs
   bed rest
   increased fluid intake

Question 22

What do the following drugs in labour do?

1. Dinoprostone
2. Oxytoxin
3. Ergometrine

Answer 22

1. PROGESTERONE - cervical ripening, and induces contraction of smooth muscle
2. Induces uterine contractions if cervix is already ripe. Reduces risk of postpartum haemorrhage
3. Reduces risk of postpartum haemorrhage