Introduction to Estimated Placental Volume (EPV)

Transcript

• 00:00Hi, this is Harvey Kliman.
• 00:02I'd like to talk to you about
• 00:05estimated placental volume epv.
• 00:07Why should we measure the placenta volume?
• 00:09Well, the placenta is the entire
• 00:11support system for the fetus.
• 00:13You can think of the placenta
• 00:14as the roots of a tree.
• 00:16I have here a little model of a placenta.
• 00:19This would be the fetal surface.
• 00:21You can see the umbilical cord and the fetal
• 00:23vessels branching over the fetal surface.
• 00:25And this is the maternal surface,
• 00:27the side that is attaching
• 00:29to the mother's uterus.
• 00:31So I wanted to go over some basic concepts,
• 00:34dos and don'ts about measuring epv O.
• 00:37This placenta can be any place in space.
• 00:40If you imagine a patient lying here on the
• 00:43table, this can be an anterior placenta.
• 00:46It can be a posterior placenta.
• 00:48Those are relatively easy to measure,
• 00:50but of course it can be lateral on either
• 00:53side fundle at the top of the uterus.
• 00:56Of course,
• 00:57a dangerous situation is placenta previa.
• 00:59It's probably going to be
• 01:00very difficult to measure.
• 01:01Percent of volume in this position.
• 01:04But I want to talk about the ideal
• 01:07way to measure placental volume epv.
• 01:10The way that you want to do it is think of
• 01:13the placenta as a π that you're cutting,
• 01:15and if you can see these lines here,
• 01:17you want to find the widest cross
• 01:20section axis of the placenta.
• 01:23Here, let me take this apart and show you
• 01:25what it looks like when you've made that
• 01:27cross section with the ultrasound device.
• 01:29It basically looks like a Crescent.
• 01:32And if you imagine this in space,
• 01:34what we need to do to measure epv is
• 01:37draw a line from this tip to this tip.
• 01:40This is the width.
• 01:42Measurement.
• 01:42Then you find the apex of the placenta.
• 01:45Drop a line down to this width line
• 01:48and make sure it's 90 degrees.
• 01:50Fix it,
• 01:51and then draw another line from
• 01:53your exact starting point here
• 01:54down to the bottom of the placenta.
• 01:57This is the thickness measurement with the.
• 01:59With the height and the
• 02:01thickness measurements,
• 02:02you have the three numbers you need to
• 02:05calculate estimated posando volume E PV.
• 02:08Now,
• 02:08what are some of the things that
• 02:10you shouldn't do?
• 02:10One is.
• 02:11Not finding the complete center
• 02:13axis of the placenta.
• 02:16If you were to cut across here
• 02:18this part of the placenta,
• 02:19you would not get an accurate
• 02:22estimation of placental volume,
• 02:23and I'll show you a cross section
• 02:25here that I can take apart.
• 02:27So this cross section is much less than
• 02:29the major cross section I showed you.
• 02:32So if you were to make these measurements,
• 02:34you would have an artificially small number.
• 02:36The other thing that you can do
• 02:39incorrectly is not holding the probe.
• 02:42Perpendicular to the surface.
• 02:44So it's very important.
• 02:45Let me just put this back together
• 02:48here to hold your ultrasound probe
• 02:50directly perpendicular to the surface.
• 02:531 does not want to be oblique
• 02:55in that measurement
• 02:56because you can artificially make
• 02:59the thickness measurement larger
• 03:01by being oblique to the surface.
• 03:03OK, so that's a basic overview how to do EPV.
• 03:07Let's go see how it's actually done
• 03:09with a real patient and a real maternal
• 03:11fetal medicine physician. Doctor Rad.