Diagnosis of pregnancy

- [Voiceover] In ancient Egypt, women who questioned whether they were pregnant or not were told to urinate on bags of wheat and barely over the course of several days. And if the wheat sprouted, the woman was having a girl and if the barley sprouted, she was having a boy, and if neither sprouted, she wasn't pregnant. So I guess you could say that the question of "Am I pregnant?" is as old as time. And the craziest thing about that story is that they tested it in the 60s and they found out that it worked 70% of the time. Okay, so how do we tell if a woman is pregnant in the age of modern medicine, so today? Well, there are a few different signs of pregnancy and the signs of pregnancy are divided into three different groups. So first, there are the presumptive, the presumptive, the presumptive signs of pregnancy and these are changes that are experienced by the woman that make her think that she might be pregnant. And then the second group of signs are the probable signs. The probable, probable signs of pregnancy, which are changes that are seen on physical exam that make the examiner suspect that the woman might be pregnant. And then finally, there are the positive signs of pregnancy. The positive signs of pregnancy, or signs that can only and only be explained by pregnancy. Alright, so let's start with the presumptive signs. So we're talking about signs that make the woman think she's pregnant. And the number one sign has to be a missed period. And the medical term for that is amenorrhea. The medical term for a missed period is amenorrhea. And if you've heard enough of these Latin words, you may have picked up that putting an A in front of a word means lack of. So this is lack of menses. And you know I think it's really important that you understand why the period is missed in pregnancy. So really briefly, over here you have a uterus and the uterus has layers. but the inner most layer, the endometrium, is what we're concerned with right now. And off to the side we have the ovary, which has lots of different follicles in it, and inside each follicle is an egg. So really, just as 50,000 foot view of things, the whole purpose of the menstrual cycle is to select one of these follicles, one of these follicles every menstrual cycle for development. So one of these follicles is selected to grow and develop. And as it does that, as it grows and develops, it secretes hormones, specifically estradiol, so it specifically secretes estradiol, which is a type of estrogen. And that estradiol acts on the uterus and it causes this inner lining of the uterus, the endometrium to proliferate and to become thicker. And then, in the middle of the menstrual cycle, this one mature follicle ruptures and it releases the egg that's inside it. And that event, that event where the follicle ruptures and releases the egg inside of it, is referred to as ovulation. After ovulation, the egg that's released travels down the fallopian tube, hopefully to find a sperm to fertilize it. But meanwhile, this ruptured follicle that's left behind over here, which is now referred to as the corpus luteum, so the corpus luteum takes this sort of waiting period while it's sitting around waiting for the egg to be fertilized to start producing lots of progesterone. So progesterone is another hormone that the corpus luteum produces. And again, the progesterone acts on the endometrium of the uterus to increase the growth of glands and cause the storage of glycogen. And all of this is done to prepare the endometrium, to prepare it for the implantation of an embryo. Alright, so what does any of this have to do with a period? Well, if that egg that's hanging out over there doesn't get fertilized, the corpus luteum recognizes that and it says, "Well, I guess there's no reason "to prepare this endometrium for implantation." So it stops making progesterone. And without the progesterone, the endometrium starts to slough off. And that sloughing off of endometrium is what's referred to as a period. But, if instead the egg does become fertilized, it will implant into the uterus. And when it implants into the uterus, it makes this hormone called human, called human, human chorionic chorionic gonado, gonadotropin, human chorionic gonadotropin. Usually it's just referred to as HCG. And human chorionic gonadotropin tells the corpus luteum to stay alive and to keep making progesterone, and that progesterone in turn keeps the endometrium alive and healthy so that it doesn't slough off and you don't end up with a period. So that is why, when an egg becomes fertilized, when you become pregnant, you miss a period. So that's a lot of information. Now, a lot of the hormones that I just talked about account for the other presumptive signs of pregnancy. So nausea and vomiting, for example. Lots of people wonder why do you become so nauseous during pregnancy and one of the reasons for the nausea is progesterone. So progesterone is really good at relaxing smooth muscle. And that's smooth muscle throughout the entire body, including the smooth muscle of the GI tract. And if you can imagine, if the smooth muscle of the GI tract is relaxed instead of contracting, food isn't gonna make it's way down the GI tract like it should. It kinda just sits there and it's... and that piling up of food, that stasis of food, causes nausea. And, in addition to all of the estrogen and progesterone, the placenta makes a hormone called melanocyte stimulating hormone. It's not the most important hormone of pregnancy, but it makes this hormone called melanocyte stimulating hormone which does exactly what the name implies, it stimulates the melanocytes, which are the pigment cells in your skin. So hyper pigmentation is not an uncommon sign in pregnancy. So darkening of the skin can also occur as a sign in pregnancy. And that could be hyper pigmentation of the face. So the hyper pigmentation of the face is called melasma, and a lot of people refer to it as the mask of pregnancy. So you can see dark, blotchy spots on the face which typically go away within a year after the pregnancy is over, but still it can be a sign early on in the pregnancy. Linea nigra is another manifestation of that hyper pigmentation. So linea means line and nigra means black, right? So it's a dark line that tends to appear down the middle of the abdomen. And also you can see darkening of the areola of the breasts. So that's another manifestation of the hyper pigmentation. And speaking of the breast, many women early on in the pregnancy experience breast tenderness. And again, that's due to the effects of estrogen and progesterone causing growth of the glands inside the breast. And then somewhere around 12 to 14 weeks into the pregnancy, women can start to experience fetal movements for the very first time and they're commonly described as being flutter-like, so it feels like a flutter. And those movements are referring to as quickening. Quickening. Right, so quickening. So those are the presumptive signs of pregnancy. So what about the probable signs of pregnancy? Well first there's uterine enlargement. So if the examiner feels an enlarged uterus, that's a pretty big clue that the woman might be pregnant. And of course a positive pregnancy test is another big sign. So most pregnancy tests, whether they're blood tests or whether they're urine tests, detect beta HCG, they detect that human chorionic gonadotropin. And beta HCG is remember, made after the implantation occurs and it can be detected in the urine or in the blood anywhere between 10 to 14 days after conception. And I think there tends to be this thought that blood pregnancy tests are way more accurtate than urine tests that are done at home. But that's not necessarily true. So there have been a few studies that have shown that a urine pregnancy test is pretty much as accurate as a blood test, but it's improper usage or not correctly following instructions at home that tend to result in an inaccurate home pregnancy test. And you might be wondering why a positive pregnancy test isn't a positive sign of pregnancy. Why is it a probable sign of pregnancy? And it's because you can actually have a false positive pregnancy test. And because there are certain types of cancer that also produce HCG, so as you can imagine that would also lead to a positive pregnancy test in the absence of a pregnancy. Alright, now as far as the remainder of the probable signs of pregnancy, keep in mind that during pregnancy the blood flow to the entire reproductive tract, including the uterus and the vagina drastically increases. There are more blood vessels growing in these organs and more of mom's blood is being directed this way. And that makes these tissues really quite loose and swollen and elastic. So, for example, the tip of the cervix becomes soft and swollen and that can be seen or it can be felt by an examiner. And that softening of the tip of the cervix is referred to as Goodell's sign. It's referred to as Goodell's sign, so it's something an examiner can see that would sort of indicate that the woman might be pregnant. And all of those blood vessels give the cervix and the vagina a violet, bluish color which again can be seen during an exam. And that's referred to as Chadwick's sign. It refers to the bluish tinge of the vagina and the cervix. And eventually, actually, an examiner can feel the presence of the fetus. So, there is this maneuver where the examiner can insert their finger through the vagina and gently tap upwards, which causes the fetus to rise. And then the fetus sinks and then the examiner feels a gentle tap back on their finger. And that technique of gently, sort of bouncing the floating fetus is referred to as ballottement. It's referred to as ballott, as ballottement. So those are the probable signs of pregnancy, leaving us with the positive signs of pregnancy, which are signs that can only and only be explained by pregnancy. So they include visualizing the fetus, so direct visualization of the fetus either through ultrasound, x-ray. Also hearing fetal heart tones. Hearing fetal heart tones and feeling fetal movements. Feeling fetal movements. So visualizing the fetus, hearing the fetal heart tones, and feeling fetal movements are signs that are absolutely diagnostic of pregnancy. They can't be explained by anything else. Alright, so those are some of the different ways we can tell if a woman is pregnant, which just shows you that we've come a pretty far way from the days of urinating on bags of barley and wheat.