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Flashcards in Obstetric Physiology Deck (77)
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1
Q

What is the placenta formed from?

A

Trophoblast

2
Q

What happens to the placenta at day 6 of gestation?

A

Trophoblast interact with endometrial decidual epithelia –> invasion into maternal uterine cells

Invasion is interstitial and on the anterior and posterior walls of the body of the uterus

3
Q

What happens to the placenta at day 8 of gestation?

A

Differentiation into syncitiotrophoblast and cytotrophoblast

Syncitiotrophoblast send out projections to erode maternal tissue and produce HCG

4
Q

What happens to the placenta at day 9 gestation?

A

Lacunae form within syncitiotrophoblast and maternal blood enter from spiral arteries

Cytotophoblast begin to form villi

5
Q

What are the types of villi in the placenta?

A

Primary - projections of trophoblast
Secondary - invasion of a mesenchyme core
Tertiary - invasion of fetal vessels

6
Q

What happens to the maternal circulation in the formation of the placenta?

A

Spiral arteries remodel forming low resistance, high flow circulation

Cytotrophoblast invade the spiral arteries and replace maternal endothelium - 1 less barrier

7
Q

What are the key blood vessels in the fetus?

A

Umbilical vein - carry oxygenated blood

Umbilical artery - carry deoxygenated blood

8
Q

How do nutrients exchange at the placenta?

A

Maternal O2 and nutrients exchange at terminal villi into intervillous space

9
Q

What surrounds the fetal surface?

A

Chorionic membrane:

  • amnion
  • umbilical vessels
10
Q

What is the decidua?

A

Name given to the endometrium which is modified by progesterone in preparation for pregnancy

11
Q

What are the parts to the Decidua?

A

Basalis - where the implantation takes place and the basal plate is formed
Capsularis - Capsule around chorion
Parietalis - Lie on opposite uterus wall

12
Q

What forms the placental barrier in the first trimester?

A

Syncitiotrophoblast resting on cytotrophoblast

Relatively thick

13
Q

What is the placental barrier like in the third trimester?

A

Thin - cytotrophoblast lost

Huge SA

14
Q

What happens to the placenta around month 4-5?

A

Decidua form septal which project into intervillous lacunae

Has core maternal tissue and covered by syncitial cells

Septa divide placenta into cotyledons

15
Q

What is the function of HCG and what secretes it?

A

Maintain corpus luteum until placenta can secrete the pregnancy hormones

Secreted by syncitiotrophoblast

16
Q

What causes most maternal adaptations in pregnancy?

A

Progesterone

Oestrogen has some effect

17
Q

What changes are seen in pregnancy?

A
GI
Haematological
MSK
Renal
Biochemical
Respiratory
Nutrient
CVS
18
Q

What GI changes are seen in pregnancy?

A

Visceral displacement - appendicitis present as RUQ pain

SM relaxation - heartburn + gall stones

Reduced GI motility - constipation

19
Q

What haematological changes are seen in pregnancy?

A

Plasma volume increase - dilution anaemia

Raised fibrinogen and clotting factors and decreased fibrinolysis - Pro-thrombotic state

Immunosuppression - risk of infection

20
Q

What MSK changes are seen in pregnancy?

A

Ligament laxity - Pubic symphysis dysfunction

Back pain

21
Q

What renal changes are seen in pregnancy?

A

Renal plasma flow and GFR increase - increased creatinine and clearance

SM relax - stasis = UTI

Large uterus - Risk of obstruction

Bicarb excretion (compensate for hyperventilation) - low bicarb reserve so acidosis risk

22
Q

What biochemical changes are seen in pregnancy?

A

Calcium req. increase - Increased renal excretion (stones) and more GI absorption

TBG increase - free T3/4 = same but overall T3/4 increase for fetal neural development

23
Q

What respiratory changes occur in pregnancy?

A

Diaphragm displaced up - AP and transverse diameter increase to compensate

Increased CO2 from fetus and increased respiratory drive - hyperventilation

24
Q

What nutrient changes are seen in pregnancy?

A

Raised lactogen, prolactin and cortisol - increased insulin resistance so maternal FA and glucose saved for fetus

Lipolysis to increase FA as metabolic substrate - risk of ketoacidosis

25
Q

What CVS changes occur in pregnancy?

A

Increased blood volume
Increased CO, SV. HR
Peripheral resistance and BP drop in 1st and 2nd trimester
IVC compressed if flat on back

26
Q

How is dyspepsia due to pregnancy managed?

A

Sleep propped up
Small frequent meals
Decrease spice, fruit, caffeine
Most antacids can be used

27
Q

How is constipation due to pregnancy managed?

A

Increase fluid intake
High fibre food
Plenty of exercise
Laxatives

28
Q

How is fatigue and insomnia due to pregnancy managed?

A

Rest and reassure
Avoid sleeping tablets
Peak in first trimester

29
Q

Explain what must be considered when a pregnant lady has pruritus

A

Look for rash
Exclude obstetric cholestasis - check LFT’s

Common in last 12 weeks

30
Q

How is back pain due to pregnancy managed?

A

Light exercise
Simple analgesia
Physio referral

31
Q

What happens in pubic symphysis dysfunction?

A

Pain in suprapubic and lower back area which radiates to thigh and perineum

32
Q

How is pubic symphysis dysfunction managed?

A

Education
Physiotherapy
Belts
Crutches

33
Q

Why do pregnant women get carpel tunnel syndrome and how is it managed?

A

Fluid retention compresses nerve

Wrist splints and steroid injections

34
Q

What changes are seen in blood results in pregnancy?

A

Raised - WCC, ALP, TSH (in 3rd trimester)

Lowered - Hb, Na+, K+, Urea, Creatinine, Ca2+, Albumin, Bilirubin, TSH (1st trimester)

35
Q

When is the uterus usually palpable in the abdomen?

A

12 weeks

36
Q

What could cause a large for date uterus?

A

Molar pregnancy
Multiple pregnancy
Polyhydramnios
Fibroids and Cysts

37
Q

When does the uterus normally reach the umbilicus?

A

20 weeks

38
Q

How long does labour usually last?

A

8 hours in first pregnancy

5 hours in subsequent pregnancies

39
Q

How many stages are there to labour?

A

3

40
Q

What is the latent first stage of labour?

A

Painful contractions and

Cervical change - effacement and dilatation upto 4cm

41
Q

What is the established first stage of labour?

A

Regular painful contractions AND

Progressive cervical dilatation from 4cm to 10cm

42
Q

What is considered if the first stage of labour is delayed?

A

Amniotomy

Oxytocin

43
Q

What must happen to the cervix in labour?

A

Dilate
Retract anteriorly
Thin

44
Q

What triggers cervical changes in labour?

A

Prostaglandins

45
Q

What happens to the myometrium in labour?

A

Pacemaker smooth muscle cells generate AP’s which spread across specialised gap junction –> co-ordinated contractions

46
Q

What are Braxton-Hicks contractions?

A

High amplitude, low frequency contractions in third trimester

47
Q

What is brachystasis in relation to pregnancy?

A

Uterus contract more than it relaxes meaning fibres shorten progressively - push presenting part into birth canal

48
Q

When do prostaglandins increase and what are its effects?

A

Increased levels when oestrogen > progesterone

Ripen cervix
Increase forcefulness of contractions

49
Q

What is the role of oxytocin in pregnancy?

A

Increase frequency of contractions

Oxytocin receptors increase when oestrogen > progesterone

50
Q

What are the parts of the second stage of labour?

A

Passive

Active

51
Q

What is the passive second stage of labour?

A

Finding of full dilatation of cervix before or in absence of involuntary expulsive contractions

52
Q

What happens in the active second stage of labour?

A

Baby is visible
Expulsive contractions with full dilatation of cervix
Active maternal effort following confirmation of full dilatation

53
Q

What movements does the baby do when being delivered?

A
Head flex
Head internally rotate
Head delivered
Head extend
Head externally rotate
Shoulders rotate and deliver
54
Q

When is labour considered delayed?

A

Active stage lasting:
Nulliparous - >2hr
Multiparous - >1hr

55
Q

What would you do if labour is delayed?

A

Refer to obstetrician - operative vaginal delivery

56
Q

How quickly does the cervix dilate?

A

> 0.5cm/hr in nulliparous

>1cm/hr in multiparous

57
Q

What grip is used when delivering a baby and why?

A

Herrell/Finnish grip + hand on head to slow down

Reduce risk of perineal tears

58
Q

What happens in the third stage of pregnancy?

A

Uterus contract hard and shear off placenta and expel within 10 mins of delivering baby

59
Q

What is the active management of the third stage of pregnancy and why?

A

Routine use of uterotonic drugs
Deferred clamping and cutting of cord
Controlled cord traction after signs of separation of placenta

Decrease risk of PPH

60
Q

What uterotonic drugs can be used?

A

Syntocinin
Syntometronin
Carboprost
Ergometrine

61
Q

What is the physiological management of the third stage of pregnancy?

A

No routine use of uterotonic drugs
No clamping of cord until pulsation stopped
Delivery of placenta by maternal effort

62
Q

When is the third stage of pregnancy considered delayed?

A

Active management - >30 mins

Physiological management - >60mins

63
Q

What happens to the breasts during pregnancy?

A

Hypertrophy of ductular-lobular-alveolar system with prominent lobules forming

Alveolar cells differentiate to be able to produce milk from mid gestation

Areolar enlarge and darken

Montgomery tubercles produce sebum and pheromones

64
Q

What is the purpose of sebum and pheromones?

A

Sebum - prevent cracking

Pheromones - Baby locate nipple

65
Q

Why is there little milk secretion in pregnancy?

A

High progesterone:oestrogen ratio

66
Q

What is the composition of breast milk?

A
Water - 88.1%
Fat - 3.8%
Protein - 0.9%
Lactose - 7%
Other - 0.2%
67
Q

What is colostrum?

A

First secretion from mammary glands

Low in water, fat and sugar
High in protein, IgA,M,G and white cells

68
Q

How much colostrum is produced?

A

40ml/day for first 3 days

69
Q

What are the benefits to breastfeeding?

A
Baby gets less infections
Bonding - oxytocin
Reduced risk ovarian and breast cancer
Further contract uterus
Weight loss
70
Q

How does milk production start post delivery?

A

Delivery of placenta remove large amount of progesterone

Alveoli respond to Prolactin and produce milk within 24-48hrs

71
Q

How is prolactin stimulated?

A

Suckling

Mechanical stimulation of receptors in nipple inhibit dopamine secretion in hypothalamus. Dopamine inhibit prolactin. Suckling also increase vasoactive intestinal protein which promotes prolactin.

72
Q

Why is some milk made in the first 24-48 hours?

A

Prolactin produced by decimal cells which aren’t inhibited by dopamine

73
Q

How is milk production regulated?

A

Suckling at one feed promote prolactin release which produces milk ready for next feed - it is a demand based production

74
Q

Describe the milk let down reflex

A

Oxytocin released from posterior pituitary in response to suckling

Myoepithelial cells stimulated and contract squeezing milk out of breast (Milk is ejected not sucked out)

75
Q

What can stimulate/inhibit oxytocin release?

A

Stimulate - Cry, sight of infant, fondling, anticipation

Inhibited - Pain, embarrassment, alcohol

76
Q

How does milk production stop?

A

If suckling stop, milk production gradually ceases

This can be due to:
Turgor induced damage to secretory cells
Low prolactin levels

77
Q

What drugs should be avoided while breastfeeding?

A
Antibiotics - cipro, tetracycline, chloramphenicol, sulphonamides
Lithium and Benzo's
Aspirin
Carbimazole
Methotrexate
Sulfonylureas
Cytotoxics
Amiodarone
Clozapine