If you're seeing this message, it means we're having trouble loading external resources on our website.

如果你被网页过滤器挡住,请确保域名*.kastatic.org*.kasandbox.org 没有被阻止.

主要内容
当前时间:0:00总时长:10:12

视频字幕

you know it's not unheard of for a guy to have a UTI or urinary tract infection but still it's pretty reasonable to say that UTSA are way more common in women in fact there's a statistic that I once read that said that one in five women will have a UTI at some point in their life so yeah I guess you could say it is pretty common in women and to understand why this infection is so common in women you have to understand the female anatomy and I know that's not an easy thing to do female urinary Anatomy is a bit complicated so so let's simplify it so okay if this is a woman's body what we're gonna do is kind of slice it down the middle and take a look down the midline so if we do that towards the back towards the back of the body we have the digestive system right so we have the rectum and that's what I'm drawing here the rectum and the rectum ends with the anus so this is the anus right here and almost immediately in front of the anus is the vagina also the vagina and the vagina is this canal that leads up to the uterus so this is the uterus uterus and and this canal is the vagina okay and then immediately in front of the vagina is the urethra and the urethra urethra is the end or the outlet for the bladder so this is a bladder bladder and this is the urethra and the bladder stores urine right we know that and that urine is made up in the kidney which is then carried through the ureter x' and into the bladder so this is the kidney the kidney and these are the you readers or a you reader leading up to the bladder so it's really apparent from this diagram that there's a lot cramped into a pretty small space okay so back to urinary tract infection so the term urinary tract really implies anything from the kidney down to the urethra but to be a little bit more specific infection of the urethra or this part right here this part I'm coloring in a different color is called urethritis so infection of this part right here the urethra is called urethritis infection or the latter right so this portion right here this portion is called cystitis infection of the bladder is called cystitis and then finally infection of the kidneys from right here so infraction of a kidney is called pyelo nephritis it's called pyelonephritis and the fact is that when most people talk about UTIs they're actually talking about societics or infection of the bladder and the word infection implies some sort of pathogen some bacteria of sorts the bacteria in this case is usually e.coli which comes from contamination from feces from back here in the anus and that actually explains why UTIs are so common in women the anus and the urethra are so close together in women then it makes contamination a lot more likely and the urethra and women is also a lot shorter than it is in men so the bacteria have a much shorter climb on their way to the bladder also contributing to the fact that UTIs are more common in women and that brings me to kind of a random but important point so like I said most UTI something like 80% of them are caused by e.coli and one of the most important reasons for that is that a coli have these things on them called pili that actually enable them to stick to the urinary tract and to climb up the urinary tract so the piller kind of like those suction cup things that ninjas and spies use in those movies to climb up the outside of buildings that's how I like to think of them and a pill are important because when urine comes rushing down the urinary tract that you call I aren't washed away like other bacteria without pill I would be so so then why are we talking about UTIs in pregnancy well it turns out that they're even more common in pregnant women and a lot of that has to do with the uterus becoming larger throughout the course of the pregnancy with the growing baby so the large uterus does a couple of different things firstly it makes it pretty difficult to maintain hygiene in the area making contamination more likely and secondly the uterus pushes on the bladder making it hard to empty the bladder completely so that means that each time the woman urinate some urine is left behind you aren't sitting around for a long time serves as a good medium for bacteria to grow and to thrive in and another thing that happens in pregnancy is that the GFR the glomerular filtration rate or the rate at which blood is filtered through the kidneys increases so the GFR increases in pregnancy and so what that means is that things like glucose are filtered a lot more out of blood and into the urine and more glucose in the urine means more food for bacteria to grow all right and finally pregnancy especially if the the very end of pregnancy is is a sort of state of immune suppression right and so that predisposes the mom to all sorts of infections infections including UTIs so so then let's talk about some of the symptoms of cystitis right so some of the symptoms that you get when you have an infection of the bladder burning and discomfort with urination right that's called dysuria occurs pretty commonly with cystitis also symptom called urinary frequency or feeling like you have to urinate really frequently occurs pretty commonly and urinary urgency or feeling like you have to urinate immediately is another common symptom and occasionally you can also have something called hematuria and hematuria refers to blood in the urine and this constellation of symptoms all of this group of symptoms they're really important to know because a person has to have these symptoms in order to be treated for the UTI is to say that they can't be treated if they have only evidence of bacteria in their urine but they don't have any symptoms of the UTI but one of the important exceptions to that rule is pregnancy so so a pregnant woman who has bacteria in her urine without any symptoms of UTI which is called asymptomatic it's called asymptomatic so without symptoms bacteria bacteria urea so when you have bacteria in the urine but don't have any symptoms right in a pregnant woman that needs to be treated and the reason for that is is something like 25% of pregnant women with asymptomatic bacteriuria end up with pyelonephritis and that's dangerous very dangerous in fact because pyelonephritis and a pregnant woman can lead to sepsis it can lead to kidney dysfunction premature labor and even death of the fetus so that's why we always always collect a sample of urine in the very first trimester even if a woman has absolutely no symptoms of a UTI to look for a bacteria in the urine and if there's evidence of bacteria in the urine again even if she has no symptoms we go ahead and treat and and that brings me to what it takes to diagnose a UTI so when we're trying to diagnose a UTI we collect a sample of urine and what we're looking for is a is a urine culture in which we have more than 100,000 colony-forming units so more than 100,000 colonies of one type of bacteria that's known to cause a UTI now I want to mention one other important difference in UTIs in non pregnant versus pregnant women and that is treatment so in a non pregnant woman or or even a man for that matter your choice of treatment is is pretty diverse it could be something like trimethoprim let's just try methyl trimethoprim sulfur-sulfur myths ox sulfamethoxazole phone myth ox is all right I know it's a mouthful another and that's a very popular treatment another popular treatment is nitro nitro whew ran nitro Fira and toen right and a third popular choice is cipro ciprofloxacin ciprofloxacin okay and there are other less commonly used antibiotics also available for your choice but your treatment choice in a pregnant woman is very different from that in a non pregnant woman because a lot of these choices are dangerous to the fetus trimethoprim for example is a foley antagonist so it blocks the use of foley by the baby and we know that Foley is really important for neural tube development so for that you for that reason it's usually avoided in the first trimester and sulfamethoxazole can increase bilirubin levels in the baby which can be pretty dangerous so for that reason it's avoided and ciprofloxacin is also avoided in pregnancy due to problems with bone development so it leads to problems with bone development so if you can't have those options available to you some of the options that are available in pregnant women for the treatment of societies include amoxicillin where you may have heard of that one before amoxicillin it's used for a bunch of different things you can also use nitro for Antone's so nitro fair and tone is one of those drugs that you can use safely in both pregnant and non-pregnant women another popular option is cephalexin cephalexin and also phospho fosfomycin so there's those are some of the options that you have available to you for the use in pregnant women so there you have it that's quite a bit of information on a very common disorder urinary tract infection