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Obstetrics and Gynaecology > Obstetric Physiology > Flashcards

Obstetric Physiology Flashcards

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1
Q

What is the placenta formed from?

A

Trophoblast

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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

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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

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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

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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

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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

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7
Q

What are the key blood vessels in the fetus?

A

Umbilical vein - carry oxygenated blood

Umbilical artery - carry deoxygenated blood

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8
Q

How do nutrients exchange at the placenta?

A

Maternal O2 and nutrients exchange at terminal villi into intervillous space

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9
Q

What surrounds the fetal surface?

A

Chorionic membrane:

  • amnion
  • umbilical vessels
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10
Q

What is the decidua?

A

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

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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

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12
Q

What forms the placental barrier in the first trimester?

A

Syncitiotrophoblast resting on cytotrophoblast

Relatively thick

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13
Q

What is the placental barrier like in the third trimester?

A

Thin - cytotrophoblast lost

Huge SA

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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

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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

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16
Q

What causes most maternal adaptations in pregnancy?

A

Progesterone

Oestrogen has some effect

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17
Q

What changes are seen in pregnancy?

A 
GI
Haematological
MSK
Renal
Biochemical
Respiratory
Nutrient
CVS
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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

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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

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20
Q

What MSK changes are seen in pregnancy?

A

Ligament laxity - Pubic symphysis dysfunction

Back pain

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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

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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

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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

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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

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25
What CVS changes occur in pregnancy?
Increased blood volume Increased CO, SV. HR Peripheral resistance and BP drop in 1st and 2nd trimester IVC compressed if flat on back
26
How is dyspepsia due to pregnancy managed?
Sleep propped up Small frequent meals Decrease spice, fruit, caffeine Most antacids can be used
27
How is constipation due to pregnancy managed?
Increase fluid intake High fibre food Plenty of exercise Laxatives
28
How is fatigue and insomnia due to pregnancy managed?
Rest and reassure Avoid sleeping tablets Peak in first trimester
29
Explain what must be considered when a pregnant lady has pruritus
Look for rash Exclude obstetric cholestasis - check LFT's Common in last 12 weeks
30
How is back pain due to pregnancy managed?
Light exercise Simple analgesia Physio referral
31
What happens in pubic symphysis dysfunction?
Pain in suprapubic and lower back area which radiates to thigh and perineum
32
How is pubic symphysis dysfunction managed?
Education Physiotherapy Belts Crutches
33
Why do pregnant women get carpel tunnel syndrome and how is it managed?
Fluid retention compresses nerve Wrist splints and steroid injections
34
What changes are seen in blood results in pregnancy?
Raised - WCC, ALP, TSH (in 3rd trimester) Lowered - Hb, Na+, K+, Urea, Creatinine, Ca2+, Albumin, Bilirubin, TSH (1st trimester)
35
When is the uterus usually palpable in the abdomen?
12 weeks
36
What could cause a large for date uterus?
Molar pregnancy Multiple pregnancy Polyhydramnios Fibroids and Cysts
37
When does the uterus normally reach the umbilicus?
20 weeks
38
How long does labour usually last?
8 hours in first pregnancy | 5 hours in subsequent pregnancies
39
How many stages are there to labour?
3
40
What is the latent first stage of labour?
Painful contractions and | Cervical change - effacement and dilatation upto 4cm
41
What is the established first stage of labour?
Regular painful contractions AND | Progressive cervical dilatation from 4cm to 10cm
42
What is considered if the first stage of labour is delayed?
Amniotomy | Oxytocin
43
What must happen to the cervix in labour?
Dilate Retract anteriorly Thin
44
What triggers cervical changes in labour?
Prostaglandins
45
What happens to the myometrium in labour?
Pacemaker smooth muscle cells generate AP's which spread across specialised gap junction --> co-ordinated contractions
46
What are Braxton-Hicks contractions?
High amplitude, low frequency contractions in third trimester
47
What is brachystasis in relation to pregnancy?
Uterus contract more than it relaxes meaning fibres shorten progressively - push presenting part into birth canal
48
When do prostaglandins increase and what are its effects?
Increased levels when oestrogen > progesterone Ripen cervix Increase forcefulness of contractions
49
What is the role of oxytocin in pregnancy?
Increase frequency of contractions Oxytocin receptors increase when oestrogen > progesterone
50
What are the parts of the second stage of labour?
Passive | Active
51
What is the passive second stage of labour?
Finding of full dilatation of cervix before or in absence of involuntary expulsive contractions
52
What happens in the active second stage of labour?
Baby is visible Expulsive contractions with full dilatation of cervix Active maternal effort following confirmation of full dilatation
53
What movements does the baby do when being delivered?
``` Head flex Head internally rotate Head delivered Head extend Head externally rotate Shoulders rotate and deliver ```
54
When is labour considered delayed?
Active stage lasting: Nulliparous - >2hr Multiparous - >1hr
55
What would you do if labour is delayed?
Refer to obstetrician - operative vaginal delivery
56
How quickly does the cervix dilate?
>0.5cm/hr in nulliparous | >1cm/hr in multiparous
57
What grip is used when delivering a baby and why?
Herrell/Finnish grip + hand on head to slow down Reduce risk of perineal tears
58
What happens in the third stage of pregnancy?
Uterus contract hard and shear off placenta and expel within 10 mins of delivering baby
59
What is the active management of the third stage of pregnancy and why?
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
What uterotonic drugs can be used?
Syntocinin Syntometronin Carboprost Ergometrine
61
What is the physiological management of the third stage of pregnancy?
No routine use of uterotonic drugs No clamping of cord until pulsation stopped Delivery of placenta by maternal effort
62
When is the third stage of pregnancy considered delayed?
Active management - >30 mins | Physiological management - >60mins
63
What happens to the breasts during pregnancy?
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
What is the purpose of sebum and pheromones?
Sebum - prevent cracking | Pheromones - Baby locate nipple
65
Why is there little milk secretion in pregnancy?
High progesterone:oestrogen ratio
66
What is the composition of breast milk?
``` Water - 88.1% Fat - 3.8% Protein - 0.9% Lactose - 7% Other - 0.2% ```
67
What is colostrum?
First secretion from mammary glands Low in water, fat and sugar High in protein, IgA,M,G and white cells
68
How much colostrum is produced?
40ml/day for first 3 days
69
What are the benefits to breastfeeding?
``` Baby gets less infections Bonding - oxytocin Reduced risk ovarian and breast cancer Further contract uterus Weight loss ```
70
How does milk production start post delivery?
Delivery of placenta remove large amount of progesterone Alveoli respond to Prolactin and produce milk within 24-48hrs
71
How is prolactin stimulated?
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
Why is some milk made in the first 24-48 hours?
Prolactin produced by decimal cells which aren't inhibited by dopamine
73
How is milk production regulated?
Suckling at one feed promote prolactin release which produces milk ready for next feed - it is a demand based production
74
Describe the milk let down reflex
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
What can stimulate/inhibit oxytocin release?
Stimulate - Cry, sight of infant, fondling, anticipation | Inhibited - Pain, embarrassment, alcohol
76
How does milk production stop?
If suckling stop, milk production gradually ceases This can be due to: Turgor induced damage to secretory cells Low prolactin levels
77
What drugs should be avoided while breastfeeding?
``` Antibiotics - cipro, tetracycline, chloramphenicol, sulphonamides Lithium and Benzo's Aspirin Carbimazole Methotrexate Sulfonylureas Cytotoxics Amiodarone Clozapine ```

Obstetrics and Gynaecology (21 decks)

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