Ultrasound of Hernias

Introduction

I am Dr. Michael R. Williamson.

I practice at the University of New Mexico, Albuquerque, New Mexico.

The topic of my talk today will be ultrasound of hernias and I have no relevant financial relationships.

Anatomy of the Right Lower Quadrant

First, we're gonna talk about the anatomy of the right lower quadrant.

Most of our anatomy centers around the inguinal canal.

As you see in this diagram, the inguinal canal has a deep ring and a superficial ring.

One of the important markers for the location of the deep ring is the inferior epigastric artery.

So each time we do an ultrasound of the inguinal region, we have to find the inferior epigastric artery, and I will show you how to do that.

Other important landmarks here are the rectus abdom muscle at the midline.

The spermatic cord, which lies in the back of the inguinal canal and the femoral artery.

In vein, this cene shows you what happens embryologically when the testicle descends.

Embryology of Testicle Descent

So the right testicle slides into the inguinal canal through the deep ring and slides all the way down the canal and falls into the scrotum.

Testicle doesn't like to be in the abdominal cavity 'cause it's warm there, so the testicle wants to get down to the scrotum where it's a little bit cooler.

The problem is that that canal leads to a pathway for future hernia formation.

This is a view from the side.

It's the same al canal fall, and the testicle is falling through the al canal to land in the scrotum.

Usually the left inguinal canal closes first and the left testicle descends first.

So hernias are much less common on the left side.

The right testicle descends second, and it's more likely that the inguinal canal will remain patent and therefore there will be a pathway for future hernia formation.

Steps to Perform a Hernia Exam

Now this diagram shows you the 4.4 steps that I use to perform a hernia exam.

Number one is to look, find the femoral vein and look around the femoral vein as the patient performs a Val Salva and look for a femoral hernia.

The femoral hernia projects downward and will project all the way into the medial thigh.

In a worst case scenario, you should have the patient Val Salva.

You should be looking at a point where the saphenous vein comes into the femoral vein.

Have the patient val salva two or three times, and then slide your transducer more proximally.

Slide it north to find the inferior epigastric artery.

That will be the marker for your deep ring and will be the point where an indirect hernia comes into the inguinal canal and slides down the inguinal canal.

Slide on medially with your transducer into hasselbeck triangle.

Hasselbeck triangle is marked by the inferior epigastric artery, the inguinal ligament, and the rectus abdominis muscle.

You'll find a direct hernia in Hasselbeck triangle.

Look around there.

And finally, for your fourth spot, slide up the edge of the rectus abdominis muscle following the inferior epigastric artery and look for a spigel hernia, which can occur anywhere along that pathway.

A salia and hernia can occur all the way into the upper abdomen along the edge of the rectus abdominis muscle.

Hernia Terminology

So let's talk about terminology a minute.

The neck of a, of a hernia is a narrow part.

That's where it penetrates through a fascial plane.

It's where the defect is located.

You need to tell your surgeon what the neck size is.

The sac or body is the main part of the hernia.

That's the sac that contains the bowel or fat contents.

It's a sac made out of peritoneum.

A strangulated hernia is a hernia where there is ischemia caused by a narrow neck.

You really can't tell this well with ultrasound that I usually don't try and incarcerated hernia is a hernia that cannot be reduced.

The hernia contents, the fat or the bowel, are caught in the sac and cannot go back into their normal anatomic location.

So you should tell the surgeon if the hernia is reducible or non reducible.

That's important.

Quick Overview of Hernia Types

The quick version, once again, femoral hernia medial to the femoral vein.

Femoral hernia moves superior to inferior, mostly in females, wants to strangulate indirect hernia comes obliquely into the inguinal region.

From the anterior inferior IAC spine to the synthesis pubis tends to be congenital, occurs mostly in males, mostly on the right side.

Sits anterior to the spermatic cord and likes to strangulate.

This is called an indirect hernia because it comes to, into the surgeon's field of view, indirectly from above.

Direct hernia occur comes from medial and behind the cord and moves posterior anterior.

It moves directly toward your transducer.

It's also called an old man's Hernia.

Occurs in older males, doesn't tend to strangulate, has a wide neck and is pretty benign, but will get bigger as as time goes by.

Gelian hernia moves posterior to anterior at the linea semilunar along the edge of the rectus abdominis.

It can occur anywhere along that line.

There's no strangulation risk for the most part.

And umbilical hernia occurs in females may strangulate and may not be exactly in the umbilicus.

Layers of the Abdominal Wall

So here are the sagittal layers of the abdominal wall.

You have your external oblique muscle on the, uh, most outside the internal oblique muscles.

Next down transverse ADONs muscles, the third muscle down.

Then you run into transverse cous fascia.

And finally, peritoneum.

One of these layers has to be penetrated.

And of course, usually it's the transverse cous fascia because that's the deepest layer.

Causes and Associations of Hernias

Causes and associations of hernias.

So the indirect hernias have a congenital component.

All of these hernias are associated with collagen abnormalities.

There's an abnormal ratio of type three immature collagen to type one mature collagen.

The same thing that causes lousy collagen causes aortic aneurysms.

So other associations include cigarette smoking.

Cigarette smoking destroys the collagen mix up cigarette smoker look older.

The collagen won't keep their face, uh, looking young with good elasticity in the face.

And that same thing in cigarette smoke causes hernias, causes aortic aneurysms, aler Danlos syndrome, muco, polysaccharide os obesity, poor conditioning, ascites, peritoneal dialysis and COPD are all other associations.

Femoral hernias and umbilical hernias are associated with pregnancies and the more pregnancies, the greater the risk.

Femoral Hernia

A femoral hernia passes through the femoral ring at the entrance to the femoral canal.

It amounts to about 20% of hernias in females and about 5% in males.

It's usually just above the merger of the saphenous vein with the femoral vein.

And usually it's just medial to the vein.

There's a risk of strangulation and in, in a worst case, these will extend into the medial thigh and cause a lump in the thigh.

They can contain fat and or a bowel they need to be fixed.

The purple blob in this dr in this drawing, uh, is representing a femoral hernia sitting just below the inguinal ligament.

And, uh, may, as I say, project all the way down into the thigh.

This is an example of a femoral hernia.

The V marks the femoral vein.

The arrows mark a very small fatty femoral hernia.

As the patient performs a val salva, this hernia projects down into the thigh.

This is another larger femoral hernia.

The posterior arrow is marking the vein, the femoral vein, and the anterior arrow is marking a larger fat containing femoral hernia that is projecting down alongside that femoral vein, slightly anterior to it.

You need to look for these because these are more common than you think.

Indirect Hernia

Indirect hernia, as I said, indirect hernias come indirectly into the surgeon's field of view.

So they have an oblique course down the inguinal canal.

They enter the deep ring, which is marked by the inferior epigastric artery.

So we look for the inferior epigastric artery 'cause that, because that tells us where the deep ring is.

The hernia extends from the peritoneal cavity into the deep ring down the inguinal canal.

In a female, the inguinal canal is called the canal of nook.

These are often congenital because of a patent canal.

Usually these are repaired in when a, when a patient is in infant or in childhood, they're more common on the right than on the left.

They can contain fat or bowel the neck.

The tight spot is at the deep ring and they, these lie anterior to the spermatic cord.

So this is an example of where an indirect hernia would occur.

This is an a hernia that is just in this diagram, a hernia that is just starting down the inguinal canal.

They can go all the way down into the scrotum.

You can wind up with bowel in the scrotum.

This is an example of a, of a indirect hernia sliding down the inguinal canal.

There's a lot of fluid associated with it.

When the patient relaxes, the fat of the hernia pops back up and almost out of the canal, but doesn't quite reduce completely.

This is a second to example.

The arrow shows just a tiny hernia just starting down the inguinal canal at the deep ring.

The hypogastric vessels are posterior on this image and marked back there, marked by the word hypogastric.

And this is another example of an indirect hernia.

A stationary, a stationary image just showing the fat, extending down the inguinal canal.

Direct Hernia

Direct hernia called an old man's hernia.

It's 'cause of lousy muscle tone or incomplete coverage of the abdominal wall.

Uh, at the, uh, location of Hasselback triangle, there's a conjoin tendon between the internal oblique muscle, the transverses abdominus muscle, and the transverses abdominus aosis.

Oftentimes this is congenitally deficient, and then when a patient gets older, becomes less well conditioned, the patient is set up for a direct hernia.

These probably occur because of a tear in the transverses fascia and ultimately can tear the transverses muscle muscle and the other layers.

They usually have a wide broad neck and are completely reducible, especially when the patient is supine.

The hernia contents will just fall back into the abdominal cavity.

So this is a, an example of the location.

The purple blob shows you where a direct hernia occurs.

Oftentimes they're over closer to the rectus abdominus muscle, but they're generally in the lower part of that triangle.

This is a transverse shot showing the spermatic cord and how an indirect hernia comes down.

The val canal anterior to the cord, and a direct hernia starts out posterior to the cord.

The direct hernia will then protrude anteriorly.

This is a sagittal view or a side view of the layers of the abdominal wall showing what happens with a direct hernia.

The peritoneum is intact, but the transverse ous fascia has been breached and the peritoneum is protruding through it and making an indentation on the muscle layers.

And this is a cene of a direct hernia.

The this direct hernia contains fat and the hernia is protruding towards the transducer.

It goes posterior to anterior direct hernia is called a direct hernia because the hernia protrudes directly into the surgeon's field of view.

This is another direct hernia, posterior anterior towards the transducer.

The hernia, this hernia does not reduce completely.

So this is at risk for strangulation and a third direct hernia protruding towards the transducer.

Occasionally these can take a course that's obliquely through the muscles and can be very confusing.

Spigelian Hernia

Speg gallian hernia.

This is a defect in the aosis of the internal oblique muscle and the transverses abdo muscle can be anywhere along the linea simline, but it's usually in the lower abdomen where the inferior epigastric artery penetrates.

And, and the rectus abdominis muscle is less broad.

This projects posterior anterior, but also may move obliquely.

So this is a typical location, uh, at where the purple blob is seen.

Typical location for a spa and hernia.

Umbilical Hernia

Umbilical hernias occur at the umbilical ring.

They may increase in size with age, the hernia moves posterior to anterior.

Once again, these may occur because the round ligament, the obliterated umbilical vein doesn't reinforce the umbilical ring satisfactorily.

Or maybe they occur at the umbilicus because of late midgut return to the abdomen.

Most adults have a para umbilical hernia and are due to a weak linear elbow.

The hernia therefore does not come in directly, uh, from behind the umbilicus.

You need to repair umbilical hernias because of the tendency to strangulate.

This is an example of a non reducing umbilical hernia.

It's fat containing.

You can see at the arrows, the neck on the hernia and how the fat protrudes through the abdominal wall.

This is another umbilical hernia with a very narrow neck and a wider sack.

Also, non reducible

Complications of Hernia Repair

Complications of repair of hernias.

So most hernias are repaired by placing mesh.

Uh, you may be asked to look for a recurrent hernia after mesh has been been placed.

The hernia usually occurs along the edge of the mesh scan, the periphery of the mesh, having the patient Valsalva.

But I will tell you that the mesh is often difficult to see.

Sometimes you can see it secondary to vague shadowing, but many times you will have to guess where you think the mesh is.

Infection may have fluid, but fluid is normal in the post-op period.

For a month or so, the spermatic cord will also be thick in the post-op period and that does not necessarily mean infection.

Testicular ischemia will, can occur if the mesh is so tight that it obliterates the testicular artery as it goes down the the inguinal canal.

The patients will be pretty unhappy about this.

Uh, they will present with testicular pain.

I always look at the testicle.

When a patient comes back in following a hernia repair, I just wanna make sure that that testicle looks okay.

In a traditional repair where no mesh is placed, this tends not to happen because the patient, uh, will twist and move because of the discomfort and will eventually cause uh, just kind of a natural loosening in the repair.

Summary of Exam Steps

So the steps are, take the transducer, hold it transversely to the femoral artery and vein in the thigh.

Move up the femoral vein, find the saphenous vein entrance, and look for a femoral hernia.

Have the patient val salva.

Then move the transducer approximately on the femoral artery and vein.

Look for the superficial and deep iliac circumflex arteries.

These two arteries go laterally.

The next vessel up goes medial and is the inferior epigastric artery.

Rotate the transducer into the inguinal canal plane.

Look for an indirect hernia.

Move the transducer medially.

Look for a direct hernia.

Move it up down medial lateral.

Look in several spots for a direct hernia.

Then move the transducer superiorly along the edge of the rectus abdominis and along the inferior epigastric artery.

Look for a spag hernia.

Now you need to do it all again, standing.

Many of these patients are not in good condition.

They cannot generate enough pressure doing a al Salva while they are supine, but if you stand them up, their body weight will help them do a really good Val Salva and the hernia will pop out.

So you also need to do them supine.

You can't just do them standing because the an, the anatomy's easier to find supine.

And sometimes you will only see the hernia in a supine position.

Identifying Key Vessels

These are the vessels I referred to about two minutes ago.

You start on the femoral artery and vein, follow the femoral artery up to till you see the sup facial iliac circumflex artery.

It goes laterally.

Go up a little further.

The next laterally, uh, preceding artery is the deep circumflex iliac.

Go up a little more and you'll find the inferior epigastric artery.

That's the marker for your deep ring.

Final Steps Overview

Once again, it's four steps.

1, 2, 3, 4.

One is the femoral hernia adjacent to the femoral vein in the proximal thigh.

Number two, look for the indirect hernia at the deep ring where the inferior epigastric artery is your marker.

Number three, go medially look for the direct hernia.

Direct hernia comes posterior to anterior and direct hernias are the most common hernia that I see almost always in older males who smoke.

Number four, look for a spigel hernia at the location of the rectus abdominis and inferior epigastric artery.

Stand the patients up.

You've got to stand them up or you won't be able to find these hernias.

Recommended Reading

If you wanna read more about this, there is a very good article by Tom Stavros and Cynthia Rapp from Ultrasound quarterly in 2010.

When I was trying to figure all of this out, I used surgery textbooks to try to understand it.

This article gave me a great deal of insight and helped me kind of refine my technique.

I ultimately, with Jared Burleson, have written another article that was in the ultrasound clinics of North America in 2014.

Hopefully that will add something to your knowledge.

Also, with these two articles, you should be able to figure out how to do this.

Thank you very much.