Uterine Motility

Question 1

What are the layers of the uterus called (from outward most layer inwards)?

Answer 1

• Perimetrium (serosa)
• Myometrium
• Endomrtrium

Question 2

What layer of the uterus is a single thin layer of epithelium?

Answer 2

Perimetrium (serosa) (not evident clinically)

Question 3

What does the endometrium become during pregnancy?

Answer 3

Decidua

Question 4

What is the cervix mostly made up of?

Answer 4

Connective tissue and blood vessels (a little bit of smooth muscle)

Question 5

What do uterine contractions depend on?

Answer 5

Gap junctions for phasic propagation of depolarisation

Question 6

What is the name of the gap junction present in the uterus?

Answer 6

Connexin 43

Question 7

How is uterine SM induced?

Answer 7

Hormones during pregnancy (connexin 43 not active after)

Question 8

What alpha-adrenoceptors cause?

Answer 8

Contraction

Question 9

What beta-adrenoceptors cause?

Answer 9

Relaxation

Question 10

What is the ratio of alpha and beta sympathetic receptor types influenced by?

Answer 10

Hormonal status

Question 11

How many amino acods make up oxytocin and ADH?

Answer 11

9 amino acid peptides (only 2 are different between them)

Question 12

What are the effects of oxytocin and ADH on the uterus?

Answer 12

They stimulate contraction

Question 13

What are oxytocin’s effect on the uterus dependant on?

Answer 13

Receptor numbers which is influenced by sex hormone levels

Question 14

What tissues does oxytocin affect?

Answer 14

• Uterine muscles

- Mammary glands

Question 15

What happens to the number of uterine receptors in the uterus at term?

Answer 15

Increases drastically (in order to induce contractions)

Question 16

What does oxytocin stimulate the biosynthesis of at term?

Answer 16

Prostaglandins

Question 17

What happens to progesterone levels at term?

Answer 17

They start to fall

Question 18

Describe the uterine contractions?

Answer 18

• Stimulated by oxytocin
• They increase in regularity towards parturition and are co-ordinated and travel from the fundus to the cervix (fundal dominance)
• Uterus relaxes completely between contractions

Question 19

What are uterine stimulants (oxytocics) used for?

Answer 19

• Induce abortion
• Induce and accelerate labour
• Contract the uterus after delivery to control postpartum haemorrhage (PPH)

Question 20

What are uterine relaxants (tocolytics) used for?

Answer 20

• Menstraul cramps / dysmenorrhoea
• Prevent or treat preterm labour
• Facillitate obstetric manoeuvres
• Counteract (iatrogenic) uterine hyperstimulation

Question 21

What do uterine stimulants (oxytocics) comprise of?

Answer 21

• Oxytocin
• Ergometrine
• E and F series prostaglandins

Question 22

What is the main purpose of ergometrine?

Answer 22

• To stop bleeding post partum (contract uterus)
• Causes sustained powerful contractions
• Also used for bleeding in early pregnancy (oxytocin not effective)

Question 23

When is ergometrine not advised?

Answer 23

HYpertension can cause nasea/vomitting

Question 24

Where are prostaglandins synthesised?

Answer 24

Endometrium and cervix

Question 25

What will prostglandins do for pregnancy?

Answer 25

Stimulates labour

Question 26

What do the F series of prostaglandins do?

Answer 26

Vasoconstrict (PGF2a)

Question 27

WHat do the E series of prostaglandins do?

Answer 27

Vasodilate (PGE2 - helps to ripen and soften cervix as well 20x more powerful)

Question 28

What is Dinoprostone used for?

Answer 28

To induce rapid uterine contractions (equivelant to PGE2)

Question 29

What is Carboprost used for?

Answer 29

- Analogue of PGF2a - Injected to uterus - Induces rapid uterine contractions (C-section)

Question 30

What are synthetic analogues of PGE1?

Answer 30

- Gemeprost | - Misoprostol (more widely used)

Question 31

What does misoprostol used for?

Answer 31

- Slow effect - Treat peptic ulcers - Medical abortion, myometrium sensitised by mifepristone (progesterone receptor antagonist) then misoprostol - Induction of labour - Control of PPH

Question 32

How is misoprostol administered?

Answer 32

- Oral - Vaginal - Sublingual - Rectal SLOWLY ABSORBED so NOT IV/IM

Question 33

Wha are some examples of types of Uterine relaxants (tocolytics)?

Answer 33

- B2-agonists - CCBs - NSAIDs - Oxytocin receptor antagonists - Nitrates

Question 34

What are some adverse effects of B2 agonists?

Answer 34

- Tachycardia - Hypertension - Hyperglycaemia

Question 35

What are some examples of B2 agonists?

Answer 35

- Ritodrine, terbutaline, salbutamol

Question 36

What are some examples of CCBs?

Answer 36

- Nifedipine (current choice of drug for preterm labour) | - Magnesium sulphate (also vasodilate so baby will not have compromised blood flow)

Question 37

What are some examples of NSAIDs used as tocolytics?

Answer 37

- Indomethacin (not in obstetrics used as it can cause ductus arteriosus to stay open) - Inhibit prostaglandin biosynthesis

Question 38

What is an example of a oxytocin receptor antagonist?

Answer 38

Atosiban

Question 39

What are some examples of Nitrates used as tocolytics ?

Answer 39

- Nitric oxide (NO) donors - Nitroglycerine patch - Weak

Question 40

What medication is used for dysmenorrhoea and can reduce period blood loss by almost 50%?

Answer 40

Antifibrinolytic i.e tranexamic acid enhances vit K pathway w/o increasing blood clots