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UTIs in pregnancy | Reproductive system physiology | NCLEX-RN | Khan Academy



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- [Voiceover] 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 UTIs are way more common in women.

And 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 let's simplify it.

So, okay, if this is a woman's body,

what we're going to 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,

so we have the rectum.

And that's what I'm drawing here, the rectum.

The rectum and with the anus,

so this is the anus right here.

And almost immediately in front of the anus

is the vagina.

Okay, so the vagina.

And the vagina is this canal that leads up

to the uterus.

So this is the uterus, the uterus,

and this canal is the vagina.

Okay. And then immediately in front of the vagina

is the urethra.

Now, urethra, urethra is the end or the outlet

for the bladder.

So this is the bladder, the 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 ureters

and into the bladder.

So this is the kidney, all right, the kidney.

And these are the ureters or a ureter,

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, and I'm coloring it a different color,

is called urethritis.

So the infection of this part right here,

the urethra, is called the urethritis.

Infection of the bladder, right, so this portion

right here, this portion, is called cystitis.

So the infection of the bladder is called cystitis.

And then finally, infection of the kidneys, right here,

so infection of the kidney is called pyelonephritis.

It's called pyelonephritis.

And the fact is when most people talk about UTIs,

they're actually talking about cystitis

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 that it makes contamination

a lot more likely.

And the urethra in 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 UTIs, something like 80%

of them, are caused by e-coli.

And one of the most important reasons for that

is that e-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 pili are 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 pili are important because when urine

comes rushing down the urinary tract,

the e-coli are washed away like other bacteria

without pili would be.

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 urinates,

some urine is left behind.

And that urine 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 or 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, right?

And finally, pregnancy,

especially the very end of pregnancy,

is a sort of state of immune suppression, right?

And so that predisposes the mom to all sorts

of infections, infections including UTIs.

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 a 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 consolidation of symptoms

or 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.

That 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 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, bacteriuria,

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 something like 25%

of pregnant women with asymptomatic bacteriuria

end up with pyelonephritis.

And that's dangerous, very dangerous.

In fact, because pyelonephritis in 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 the sample

of urine in the very first trimester,

even if a woman has absolutely no symptoms of UTI,

to look for 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 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 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 even a man, for that matter,

your choice of treatment is pretty diverse.

It could be something like Trimethoprim,

Trimethoprim,

Sulfamethoxazole, right?

I know it's a mouthful.

And that's a very popular treatment.

Another popular treatment is Nitrofurantoin, right?

And a third popular choice is

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 folate antagonist,

so it blocks the use of folate by the baby.

And we know that folate is really important

for neural tube development.

So 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 cystitis include Amoxicillin, right?

You may have heard of that one before.

Amoxicillin is used for a bunch of different things.

You can also use Nitrofurantoin.

So Nitrofurantoin 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 Fosfomycin.

So 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.