Progestogen only injections

Question 1

How do progestogen only injections work?

Answer 1

Prevent ovulation
Thickening of cervical mucus

Makes endometrial lining thinner so that it cannot support fertilised egg

Question 2

What is the failure rate of depo provera?

Answer 2

0.2% perfect failure rate

Question 3

When to initiate depot injection?

Answer 3

If you have it within first 5 days of cycle, immediate production.

Otherwise not protected for up to 7 days.

Before 21 days after giving birth, although if breastfeeding wait 6 weeks.

Straight after abortion/miscarriage or within 5 days (otherwise unprotected for 7 days)

Question 4

Side effects of depo injection?

Answer 4

Disruption of periods (heavy, light, irregular)
Can take months for fertility to return
Weight gain
Headache
Acne
Loss of libido

Reversible thinning of bones (because it lowers oestrogen) - CI in patients at risk of osteoporosis

Question 5

What are the risk of depot injection?

Answer 5

Allergic reaction (incredibly rare)
Chance of infection at site of infection

Question 6

What are the benefits of depot injection?

Answer 6

Lasts 8, 12, 13 weeks
Good if cannot use oestrogen-based
Safe in breastfeeding
No drug interactions (eg. enzyme inducers)

Some protection from PID and endometrial cancer