Endo

Question 1

How does the combined oral contraceptive pill prevent pregnancy?

Answer 1

1. The combined oral contraceptive pill contains artificial versions of oestrogen and progesterone.
2. It suppresses ovulation by interfering with GnRH by the pituitary via negative feedback on the hypothalamus.
3. This prevents the mid cycle rise of LH which triggers ovulation.
4. It also causes the endometrium to become thinner, which prevents the likelihood of an egg implanting successfully.
5. In addition, the cervical mucus becomes thicker making it more difficult for sperm to reach an egg.

Question 2

Young lady has episodes of severe diarrhoea, how would you advise her regarding her combined oral contraceptive pill?

Answer 2

Whilst she is having severe diarrhoea she should count this as though she has missed her pills on those days, and she will need to take additional contraceptive precautions for the following 7 days.

Question 3

How is metformin excreted?

Answer 3

Metformin is cleared by active tubular secretion and is excreted unchanged in the urine

Question 4

What precautions do you need to take if a patient on metformin is undergoing a radiological investigation with iv contrast?

Answer 4

(1. ) There is a risk of lactic acidosis in patients given iv contrast who are on metformin.
(2. ) If a patient taking metformin requires IV contrast, serum creatinine must be measured within the preceding month.
(3. ) If the creatinine is normal and a low volume of contrast (up to 100ml) is to be administered no special precaution is required.
(4. ) If more than 100ml of contrast is used iv or is given intra-arterially then the metformin should be withheld for 48h prior to contrast.
(5. ) If serum creatinine is raised = metformin should be withheld for 48h prior to and post contrast and serum creatinine should be measured prior to restarting the metformin.