Combined Oral Contraceptive Pill - Essential GP Revision

Combined oral contraceptive pill for general practice exams.

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Transcript

SPEAKER_00 0:00

Hi, this is Tom, and welcome back to the Zero to GP Podcast. In this episode, I'm going to be going through the combined oral contraceptive pill, the key stuff you need to know for your GP exams. The format, as always, is I'm going to ask you questions. I want you to come up with your answer, ideally write it down, and then I'll go through an explanation. If you're preparing for your AKT exam at any point in the next 6, 12, 24 months, I recommend checking out the AKT revision book, the zero to gp.com website for a full question bank, fact trainer tool, flashcards, and notes. And my upcoming AKT revision course, which is a day-long course with me, Tom, in London on the 13th of September 2026 to prepare you for the AKT exam. But for now, let's get straight into this episode on the combined oral contraceptive pill. So let's start with our first case. It's a 21-year-old woman, and she comes into the GP practice because she's got heavy menstrual bleeding. These heavy periods that she's experiencing are not painful, and she wants contraception. She has one long-term exclusive partner, so you're not so worried about sexually transmitted infections. And she's otherwise well, no particular risk factors, nothing concerning, and she has regular periods with no red flags, no intermenstrual bleeding, and that kind of thing. You would organize or offer a full blood count to look for anemia. And the guidelines say every woman who has heavy menstrual bleeding should have a full blood count to exclude anemia. They actually recommend against checking the ferritin for iron deficiency anemia, just the full blood count, and that will pick up whether they're anemic or not. The next question I have is what would be the first line treatment that you would offer this particular patient? Now the main presenting symptom here is heavy menstrual bleeding, and the first line treatment to offer or consider is the levinogesteral intrauterine device, for example, the Myrena coil. This intrauterine device is the first line treatment for heavy menstrual bleeding in patients who want contraception. So my next question is what's the second line treatment? Let's say you offer her the Myrena coil and she says, Oh no, I don't like the sound of that, I want to try something else. What would be the second thing you'd offer this patient? The second line in this scenario is to offer the combined oral contraceptive pill. This is the second line for heavy menstrual bleeding in patients who want contraception. Let's say she didn't want contraception, there would be other options, which would include tranexamic acid and cyclical oral progestogens, but because she wants contraception, then the next option is the combined pill. My next question for you is what's the mechanism of action of the combined oral contraceptive pill? There are actually three things that the combined pill does. The primary mechanism of action is that it prevents ovulation. It stops ovulation from occurring. This obviously protects against pregnancy because if you have no ovulation, you can't get pregnant. The second is that it thickens the cervical mucus. So it causes the mucus within the cervix to thicken, meaning that sperm can't get through into the uterus. This is a progestogenic effect. And the third thing is that it inhibits endometrial proliferation. So it keeps the endometrial a bit thinner, which makes pregnancy less likely, and also causes lighter bleeding as opposed to heavy periods. My next question for you is what options would this patient have for taking the combined contraceptive pill? So let's say you offer her the pill and she she wants to go ahead with it. There are several ways that she could take it, not just the standard way. What options does she have? The most common three options that uh people offer are the standard way or the traditional way, which is 21 days of taking the pill, and then a seven-day hormone-free interval, which is where there's seven days off the pill. So 21 days on, seven days off. That's the traditional way, and during that seven-day hormone-free interval, there'll usually be a breakthrough bleed, which is like a period. It's not technically a period, it's a breakthrough bleed. The second option is what they call tricycling, which is where you take three packs of hormones back to back, which means 63 days on, and then you have a seven-day hormone-free interval, so seven days off. So 63 days on, seven days off, which means a breakthrough bleed every three months or so. And the third option is continuous use. So you can just go back to back to back to back to back with the pill packs, meaning there's no hormone-free interval and no breakthrough bleeding. All three options are perfectly safe. There's no need to have a breakthrough bleed because the hormones within the pill are balanced, so you won't have any complications like uh endometrial proliferation or hypertrophy. Um, so all three are safe. It just depends on the woman's preference. Some women, because of their normal menstrual cycles, will want to have a breakthrough bleed because that's feels more natural to them, but it's really their preference. Okay, on to the next case, or this same case, really. 21-year-old woman, and she's considering the combined oral contraceptive pill. My question next question to you is what are the criteria that we use to determine the suitability for the pill or any form of contraception? We use something called the UK Medical Eligibility Criteria, which is UK MEC. So my next question is what are the UK MEC grades? You'll get a grade, UK MEC something, but what what are those grades and what do they mean? So there's four. UKMEC 1 means there's no restriction of you on use of that contraception. Uh the benefits will far outweigh the risks. You can provide that contraception if somebody is UKMEC 1. UKMEC 2 means the benefits generally outweigh the risks. So on balance, there are some risks, but the benefits will be greater. UKMEC 3 means the risks generally outweigh the benefits, but um it's not an absolute contraindication. Potentially the patient could have it, but the benefits, uh the risks generally outweigh the benefits. And UKMEC 4 means that the risk is unacceptable. This means it's contraindicated if something's UKMEC 4, uh you shouldn't use it. On to the next question, which is what are the UKMEC BMI criteria for the combined oral contraceptive pill? So anytime someone's taking the pill, you need to check their BMI to make sure they're suitable. What how would the UKMEC uh grading change based on their BMI? So if someone has a normal BMI, um UKMEC 1, there's no problem there at all. If their BMI is 30 to 34 kilograms per meter squared, uh that's UKMEC 2. And if their BMI is over or 35 or above, that's UKMEC 3. My next question is when you're counseling a patient about the combined conceptive pill, what are the serious risks associated with the combined pill? So the biggest one is venous thromboembolism. So risk of uh DVT or deep vein thrombosis or pulmonary embolism. This is the one we're kind of most concerned about and what causes most of these higher UK MEC grades. So venous thromboembolism. Generally I warn patients if you do get some leg swelling or sharp chest pain and shortness of breath or any other kind of symptoms associated with a DBT or PE, you need to seek urgent medical attention. The next uh risk associated with it is there is a slight increased risk of breast cancer and cervical cancer. More so breast cancer, slight increased risk of cervical cancer. But this risk returns to baseline 10 years after stopping the combined pill. So it's an increased risk for the kind of 10 years after you take it, but once you're 10 years past the pill, the risk is back to normal. And there's a slight increased risk of myocardial infarction and stroke. Again, this is due to thrombosis formation, but that's kind of less of a concern. Okay, you've got a 21-year-old woman. She wants to start the combined oral contraceptive pill, but when you're taking a history and risk assessing her, turns out she has a history of migraines. My next question for you is what is the risk in a patient with migraines if they were to take the combined oral contraceptive pill? Why do we need to be cautious? Migraines plus the pill can increase the risk of ischemic stroke. That's the thing we're worried about. Ischemic stroke. My next question to you is what would be the UKMEC grading in a patient who has had recent migraines with aura. This would be UKMEC4 with the combined oral contraceptive pill. So this UKMEC4 means it's absolutely contraindicated, unacceptable risk. So any patient with migraines with aura can't have the combined oral contraceptive pill. Generally, they can uh they can have the progestogen-only uh forms of contraception. So the progestogen-only pill would be fine, uh, the myrena coil, the uh implant or injection would all be fine, but they can't have the combined pill. My next question is what about migraine without aura? So when we're talking about aura, we're talking about other kind of sensations, for example, sparks in the vision or flashes and floaters and things like that. Um but what about migraine where they have typical migraine symptoms but no visual aura or tingling or any other um aura kind of symptoms? What UK mech would that be? So there's a bit of nuance here because migraine without aura actually depends on whether you're initiating or continuing the combined pill. So if you've got somebody who's got occasional migraines without aura and you want to start the pill, that would be UKMEC2 to initiate the pill because they've established established migraines without aura. However, if they've started the pill and then they develop migraines without aura, at that point it would be UKMEC 3 to continue. So for example, let's say you have a patient, she's been on the pill for a while, then she develops migraines without any aura. She would then be UKMEC3, meaning the risks outweigh the benefits, and it it would be sensible to stop the pill, probably to convert her to something else like the progestogen-only pill. My next question is: what about if you've got a patient who wants to start the pill and you explore and there's a history of migraines with aura, but these migraines with aura were more than five years ago. So she hasn't had a migraine with aura for five, six, ten, fifteen years.

SPEAKER_01 14:37

What would be the UK MEC um grade for that?

SPEAKER_00 14:50

A history of migraines with aura five or more years ago would be UKMEC 3. So the risk would still outweigh the benefits, but it's not an absolute contraindication. My next question is: what would be the UK MEC criteria for severe tension headaches? Not migraines, but severe tension type headaches. Here it depends on whether you're initiating or continuing. It's UKMEC 1 to start the combined oral concept of pill or initiate it in someone with severe tension headaches, but if somebody develops severe tension headaches while taking the pill, it's UK MEC2 to continue. So the benefits still probably outweigh the risks, but you need to be more cautious if they develop while taking the pill. Okay, onto a new case. We've got a 36-year-old woman and she's a smoker. She wants to start the pill. So what would be the uh what would be the UK mech for the combined concept of pill for smokers? Here the criteria are a little bit nuanced. If the patient is under 35 and a smoker, it's UKMEC 2. If the patient is over 35 and they smoke 50 uh less than 15 cigarettes per day, it's UKMEC 3. And if they're above 35 and they smoke more than uh 15 or more cigarettes per day, then it's UKMEC 4. A new case, let's say you've got a 28-year-old woman who's recently giving birth, uh recently given birth. So she comes to see you after having a baby, and she wants to know when is it safe to start the combined oral contraceptive pill? She's been on it before, she wants to restart it so she doesn't get pregnant again. When would it be safe to start it? Here it's a little bit nuanced, um, and it depends particularly on whether she's breastfeeding or not. If she's not breastfeeding, when it's three weeks or more since she's given birth, it's UKMEC 2. When if she's not breastfeeding, when it's six or more weeks after giving birth, it becomes UKMEC 1. So if someone's not breastfeeding uh and it's more than six weeks since they've given birth, it's UK MEC 1. That's fine. This is assuming that she's got no other risk factors for venous thrombembolism. If she has um other risk factors for VTE, the UK MEC grade goes up. Um if she's breastfeeding from six weeks onwards after giving birth, it's UKMEC two. And if she's breastfeeding um and it's more than six months since she's given birth, then it's UKMEC 1. So to get to UKMEC 1, if you're breastfeeding, it's going to be six months or more. The key thing, the one thing I would encourage you to remember is that if somebody's breastfeeding, it becomes UKMEC 2 from six weeks after giving birth onwards. Okay, another case, we got a 24-year-old woman and she'd had she's had a recent termination of pregnancy. When would it be safe for her to start the combined pill? After a termination of pregnancy, you can start the combined pill immediately. It's UKMEC 1. Termination of pregnancy doesn't particularly increase the risk. As soon as the termination is is uh complete, then you can start the pill. Okay, just a general question. What would be the timing of starting the combined oral conceptive pill? Let's say you've you've sat down with a woman, agreed to start the pill, she's she's taken the prescription away, when should she take the first tablet? Now this is assuming she's taking it for contraception. If she starts it on day one to five of her cycle, so the first day she starts bleeding on her period, um up to day five of the period, so day one to five, if she starts taking the pill, she's immediately protected uh from pregnancy. So it's immediately effective. If she starts taking it after day five, she can do this, she can start at any time, but she won't be protected for the next seven days. So she needs an extra protection, meaning condoms or avoiding sex, for the next seven days of taking the pill until she's been on the pill for seven days correctly in a row. Now let's move on to talking about missed uh patients who've missed pills. So let's say you've got a woman, she's missed one pill, but she says she's been taking the other pills in her pack correctly, everything else has been fine, but she's missed one pill. My question to you is what action should this woman take. So if someone's missed one pill and they've taken all the rest correctly, they should take the missed pill as soon as they remember, even if that means taking two on the same day, and then carry on as usual. Um she remains protected, she shouldn't get pregnant, provided she's been taking the others correctly, and um she just continue the pill pack as she would have done if she hadn't missed that pill. Now let's say somebody's missed several pills, and it's been more than 72 hours since the last pill was taken. The other pills leading up to that point have been taken correctly, and uh she's already taken the latest missed pill. She heard about the missed pill rules, she took the latest missed pill, and we need to know what to do next. So, my question to you is when would you consider emergency contraception? In a patient who's missed several pills and it's been more than 72 hours since the last pill.

SPEAKER_01 22:05

When would she need emergency contraception?

SPEAKER_00 22:19

So the key time here is in week one of the pill pack. So days one to seven of the pills. So this would mean she's just completed the hormone-free interval, where she's had no pills for seven days, and then started that first week of the pill pack, and within that first week of the pill pack, she's had the several missed pills. And if she's had unprotected intercourse during the hormone-free interval or the first seven days of that pack where she's missed those pills, at that point she needs emergency contraception. She doesn't necessarily need emergency contraception, or it shouldn't need to be considered if she's missed a pill in week two or three of the pill pack. So provided she's had that set following the seven-day hormone-free interval, she's had all seven as prescribed. She took all seven of that first week of pills, and then she missed several pills in the second or third week of the pack, then she should still be covered, and you don't need to worry about emergency contraception. My next question for you is let's say she's missed several pills within the pack, and it's been 72 hours since the last pill. What are you gonna tell her about using additional contraception while she's getting back onto the normal cycle of the pills? So the advice is if she's missed several pills, then she's gonna need additional contraception for the next seven days until seven days of correctly taking the pill and being back on the pill. So she needs to be taking the pill every day for seven days until and and taking additional contraception during that time, and then after that, uh she's protected by the pill. But for those first seven days, she isn't. Next question I have is let's say she's missed several pills in the third week of the pill pack, so days 15 to 21 of the pack. What additional advice are you going to give this patient? So as well as the other precautions like taking the latest missed pill as soon as possible, uh additional contraception for seven days, you should also advise to skip the hormone-free interval of this pack. So if she's missed uh several pills and it's more than 72 hours since the last pill in days 15 to 21 of the pack, when she takes that 21st pill of the pack, then she should carry on straight to the next pack. So skip the hormone-free interval, go back to back with the packs. And again, she needs to take additional contraception until she's been taking it seven days in a row. So generally, if the if the patient theoretically is taking the pill seven days in a row, at least seven days in a row, and at most seven days off, cycling between those, she should she should remain um protected. So if she has more than seven days off the pill, so let's say she has the seven-day hormone-free interval, then misses the eighth, uh, misses the first pill of the pack, so she has eight days without the pill. At that point, she's no longer protected. She may ovulate and could become pregnant. But if she uh and then if she's had less than seven days in a row of taking the pill, so let's say she has the hormone-free interval, then five or six days of the pill, and then misses one, at that point she could also become theoretically uh wouldn't be protected and could become pregnant. So let's say you miss a pill in the third week of the pack, and then you go on to the hormone-free interval, you could have eight days without taking the pill, at which point she could ovulate and become pregnant. So that's why you need to go back to back with the pill, uh, with the packs if you miss the pill in the third week of the pack. Hopefully that makes sense. Bit complicated. And it's always tricky to explain these missed pill rules. But anyway, that's the end of the episode. Hopefully it was helpful. And uh do leave me a comment in the uh comment section below. Let me know any topics you want me to cover, and I'll see you in the next episode.