00:01
Let's now talk about confirming
and dating pregnancy.
00:05
So here's a case.
00:07
A 19 year old presents to
the emergency room with
complaint of nausea,vomiting
and right lower quadrant pain.
00:13
She states the pain has becoming
increasingly worse over the last
12 hours.
00:18
She has no medical problems
and no surgical history.
00:21
She has never been pregnant.
00:23
Her last menstrual
period was 10 weeks ago.
00:25
But she reports
cycles are irregular.
00:28
On physical exam her vital signs
are stable and she is afebrile.
00:32
She is tender in the right lower
quadrant on abdominal exam.
00:36
On pelvic exam, there is no
cervical motion tenderness
but she has fullness
and tenderness
in the lower right quadrant.
00:45
What is the next best
step in her management?
A. Ultrasound
B. Urinary analysis.
00:51
C. Urine pregnancy test.
00:53
or D. Serum pregnancy test.
00:56
Let's go through the lecture to
figure out what the answer is.
00:58
So there are several ways that
we can confirm pregnancy
and we can establish
gestational age.
01:05
We're going to talk about each
of these and talk about
the risks and the benefits
and why one test is better
than the other.
01:12
So first of all let's talk
about last menstrual period.
01:15
If we know a patient's last
menstrual period and cycles
are regular, we can't determine
the gestational age.
01:21
And we use something
called Naegele's rule.
01:24
So what we do is we take
the last menstrual period
subtract 3 months
and we add 7 days.
01:30
So if a patient tells us
her last menstrual period
is April 1st,
we subtract 3 months,
giving as January at 7 days
giving as the 8th.
01:41
And we would know that her
due date is January the 8th.
01:44
Okay, again this is based on an
accurate last menstrual period.
01:47
We can also confirm pregnancy
through a urine pregnancy test.
01:52
Now the urine pregnancy
test is a qualitative test.
01:56
That means that it either tells
that the patient is pregnant
or the patient is not pregnant.
02:02
So there are some benefits to
that and that we can tell
the patient such is in our case
that we discuss when we're
trying to figure out what may
be a differential diagnosis.
02:10
But this does not tell us how
far along the pregnancy is.
02:13
Next is the serum
pregnancy test.
02:17
Now this is a quantitative test.
02:19
So this tells us exactly how
much beta-hcg is in the blood.
02:23
Different than the urine
pregnancy test if we remember,
that one is qualitative so just
as the patient is pregnant
or the patient is not pregnant.
02:31
With that serum test,
because we can determine
the amount of hcg,
we can use that to help us
with our ultrasound to determine
if we should or should not see
something in the uterus to help
establish gestational age.
02:44
When the beta-hcg is at least
2000,
we should see something in
the uterus on
transvaginal ultrasound.
02:51
When the beta-hcg is 6000, we
should be able to see something
in the uterus on
abdominal ultrasound.
02:57
Speaking of ultrasound this
is the most accurate way to
determine the gestational age.
03:03
We expect with ultrasound in
the 1st trimester that
when we measure the fetus
from the crown-rump length
that it will be within one week
of the last menstrual period.
03:13
We'll talk about that in
a little bit more detail
as we go throughout this slide.
03:16
This is a high yield amount of
information remembering how we
confirm pregnancy and establish
the gestational age
using these 4 tests.
03:26
So back to our patient.
03:27
She's A 19 year old presents
in an emergency room.
03:30
Again complaining of nausea,
vomiting and right lower
quadrant pain.
03:34
And last menstrual period
was about 10 weeks ago.
03:37
And on exam we felt some
fullness on the right.
03:39
Now when we again think about
these options of what
we should do next.
03:44
What do you think the answer is?
The answer is D.
03:48
We want to do a
serum pregnancy test.
03:50
Remember that with the urine
pregnancy test
this is qualitative.
03:55
So this just tells that
the patient is pregnant
or if the patient is not pregnant.
03:59
That serum pregnancy test
is more important
because it actually tells
what the beta-hcg is.
04:04
So that when we do our
ultrasound, we'll know if we
should see something in
the uterus or if it's too early.
04:10
That helps with our
differential diagnosis.