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DR MOHIT GOEL
Sonography of Inguinal Region Hernias
The inguinal ligament, the folded
and thickened lower border of the
external oblique aponeurosis,
attaches at the anterior superior
iliac spine and pubic tubercle and
medially forms the inferior floor of
the inguinal canal.
The deep inguinal ring is an
anatomic defect in the transversalis
The superficial inguinal ring is a
triangle-shaped anatomic defect in
the external oblique aponeurosis
immediately superior and lateral to
the pubic tubercle.
Condensation of the internal oblique and trans-versus abdominis aponeuroses
forms the conjoint tendon, and a reflection of the inguinal ligament forms the
The inferior epigastric artery
originates from the external iliac
artery proximal to the inguinal
ligament, initially passing along
the medial boundary of the deep
inguinal ring, and ascends
obliquely and medially to the
rectus abdominis muscle.
When the posterior abdominal
wall is viewed from within---
• inferiorly by the inguinal
• medially by the lateral margin
of the rectus abdominis and
• superiorly by the inferior
Illustration of right inguinal
region from anterior view
shows transducer position to
spigelian hernia (1),
indirect inguinal hernia (2),
direct inguinal hernia (3),and
femoral hernia (4).
Inguinal ligament (curved arrow),
rectus abdominis muscle (R),
lateral boundary of Hesselbach's
triangle (H) defined by inferior
epigastric artery (open arrow), and
spermatic cord (arrowhead).
40-year-old man with right inguinal anatomy. Sonogram of inguinal region
parallel and cranial to inguinal ligament corresponding to transducer position 2
shows spermatic cord (C), external iliac artery (A), inferior epigastric artery (E),
femoral vein (V), and superior pubic ramus (curved arrow).
Patients with groin hernias typically present with an obvious lump or
bulge and are often diagnosed clinically and infrequently require
On the other hand, patients with hernias who present with pain but
without a lump or bulge are more often referred for diagnostic
More recently, CT and MRI have been used to identify and describe
However, real-time ultrasound has advantages over other imaging
• The ability to scan the patient in both upright and supine positions.
• To use dynamic manoeuvres such as Valsalva and compression.
--in areas of natural weakness
--in areas where vessels penetrate the abdominal wall (femoral and spigelian)
--where fetal migration of testis, spermatic cord, or round ligament have
occurred (indirect inguinal)
--through broad flat tendons called aponeuroses (direct inguinal).
Hernias do not occur through the belly of abdominal wall muscles unless they
have been surgically
Why does hernia occurs ?
Most Sonographically detected hernias do not contain bowel.
In fact, most hernias contain only fat.
The fat may be intraperitoneal (mesenteric or omental)
or preperitoneal in origin.
Generally, it is not possible sonographically to distinguish whether the
hernia contains intraperitoneal or preperitoneal fat.
Hernias that contain intraperitoneal fat may contain bowel later and thus
may be a greater risk than those that contain only preperitoneal fat
Hernias that contain bowel are considered higher risk because
strangulation may lead to infarction of bowel.
Hernia showing bowel as its contents
Spigelian hernias that present clinically are rare.
Sonographically detected spigelian hernias are more common than the
literature would suggest.
All hernias occur along the course of the spigelian fascia, the complex
aponeurotic tendon that lies between the oblique muscles laterally and
the rectus muscles medially.
However, almost all spigelian hernias occur where the posterior rectus
sheath is absent, and where the spigelian fascia is penetrated and
weakened by the inferior epigastric vessels.
Almost all spigelian hernias
arise from the inferior end
of the spigelian fascia just
lateral to where
it is penetrated by the
inferior epigastric vessels,
lateral to the lateral edge of
the rectus abdominis
Image 1 -The inferior epigastric artery and its paired veins lie along the midlateral posterior
surface of the rectus abdominis muscle.
Image 2 - IEVs lie more laterally.
Image 3 - is obtained at a level where the IEVs (arrow)lie at the edge of the rectus muscle.
This is the level at which most spigelian hernias occur.
25-year-old man with right spigelian hernia. Pre-Valsalva maneuve over linea
semilunaris in axial plane corresponding to transducer position 1 in Figure 4
(hernia not visible) showing right rectus abdominis muscle (R), inferior
epigastric artery (curved arrow), peritoneal fat stripe (straight arrows), and
lateral abdominal muscles (M).
Post-Valsalva maneuver sonogram in same location showing peritoneal fat stripe
distorted by fat-containing spigelian hernia (arrows) at linea semilunaris.
Note rectus abdominis muscle (R) and lateral abdominal muscles (M).
The spigelian fascia is composed of several different layers of loosely
apposed aponeurotic tendons.
From external to internal lie the aponeurosis of the external oblique,
internal oblique, and transverse abdominis muscle.
Internal to the aponeurosis lie the transversalis fascia and
In spigelian hernias the transverse abdominis tendon is always torn.
In most cases the internal oblique aponeurosis is also torn
The external oblique tendon is always intact and usually forces the
hernia sac to extend either medially over the anterior aspect of the
rectus abdominis muscle or laterally over the external oblique muscle,
forcing it into the shape of an anvil or mushroom.
Small, spigelian hernia in which the aponeuroses of both the transverse
abdominis and internal oblique muscles are torn, but in which the external
oblique aponeurosis, is intact.
Nonreducible left spigelian hernia contains bowel and has a narrow neck
and broad fundus, the typical shape for spigelian hernias.
In indirect inguinal hernia - herniated structures enter the inguinal
canal lateral to the inferior epigastric artery and superior to the
inguinal ligament, and extend for a variable distance through the
A second site of herniation is at the inferior aspect of the
Hesselbach's triangle, where a direct inguinal hernia usually occurs.
This weakened area is just lateral to the conjoint tendon and medial
to the inferior epigastric artery, in contrast to the indirect inguinal
hernia that originates lateral to the inferior epigastric artery.
30-year-old man with sonogram of right indirect inguinal hernia with transducer
positioned parallel to and cranial to inguinal ligament corresponding to
transducer position 2.
Pre-Valsalva maneuver sonogram (hernia not visible) shows external iliac artery
(A), inferior epigastric artery (E), and superior pubic ramus (curved arrow).
Post-Valsalva maneuver sonogram shows external iliac artery (A), inferior
epigastric artery (E), dilated external iliac vein (V), superior pubic ramus (curved
arrow), and indirect inguinal hernia (H) originating from lateral to external iliac
artery (arrowhead) and traversing inguinal canal from lateral to medial. (Left =
Indirect inguinal hernia.
Long-axis view shows that neck
of the hernia lies in the internal inguinal ring (IIR),
which lies superior and lateral to the proximal inferior epigastric artery (IEA).Hernia sac
then courses horizontally in an inferomedial direction within the inguinal canal (IC).Indirect
inguinal hernias always pass superficial to the IEA.
Left, Drawing shows that indirect inguinal hernia sac tends to lie anterior to spermatic cord,
whereas direct inguinal hernia sac lies posterior to the cord.
Center, Short-axis view shows fat-containing direct inguinal hernia (H)posterior and medial
to the spermatic cord (SC).
Right, Short-axis view shows fat-containing indirect inguinal hernia (H)lying anterior and
lateral to the spermatic cord (SC).
Left, Image shows the right direct inguinal hernia sac lying posterior to the
spermatic cord (SC).
Right, Image shows the left indirect inguinal hernia sac lying anterior to the
spermatic cord (SC).
Indirect inguinal hernia.
Short-axis view shows
indirect inguinal hernia
displacing and compressing
the hyperechoic spermatic
Direct inguinal hernia.
Short-axis view shows
direct inguinal hernia
displacing and compressing
the hyperechoic spermatic
cord anteriorly and laterally.
Femoral hernias are rare, because they are difficult to diagnose
clinically unless strangulated, and in fact are much less common that
Unlike inguinal hernias, femoral hernias are more common in
women than men.
It is thought that the increased intrapelvic pressure that occurs
during the third trimester of pregnancy together with the
Softening of tissues, predisposes to the development of
Femoral hernias arise within the femoral canal inferior to the inguinal
canal and ilioinguinal crease. The femoral canal lies just medial to the
common femoral vein (CFV) and just superior to the saphenofemoral
The saphenofemoral junction, similar to the origin of the inferior
epigastric artery for inguinal hernias, is the key landmark for identifying
Femoral hernias arise within
the femoral canal, which lies
medial to the common
femoral vein just superior to
the saphenofemoral junction
and inferior to the inguinal
31-year-old woman with femoral hernia. Sonogram of right inguinal
region parallel to and caudad to inguinal ligament corresponding to
transducer position 4.
Pre-Valsalva maneuver sonogram shows (hernia not visible) femoral
artery (A), femoral vein (V), and superior pubic ramus (curved
Post-Valsalva maneuver sonogram shows dilated femoral vein (V)
lateral to femoral hernia (arrows). Superior pubic ramus (curved
arrow) is also seen.
Linea Alba Hernias
Linea alba hernias are anterior abdominal wall hernias that protrude
through the linea alba.
Those that occur superior to the umbilicus are called epigastric hernias,
and those that occur inferior to the umbilicus are called hypogastric
Hypogastric hernias are much less common than epigastric hernias
because the linea alba is much narrower and shorter, inferior to the
umbilicus than superior to the umbilicus.
The linea alba is a thick layer of aponeurosis that separates the rectus
abdominis muscles. It is formed by fusion and interlacing of fibers of
the anterior and posterior sheaths of the right and left rectus muscles.
A, Normal, thick linea alba.
B, Thinner but wider linea alba, possibly resulting from fewer decussations of rectus
sheath fibres or representing diastasis recti.
C, Marked thinning and bulging of the linea alba that occurs in diastasis recti.
D, Typical small, epigastric linea alba hernia with its neck near the midline of the linea
E, Small linea alba hernia with neck occurring eccentrically near the right edge of the
Any cause of prolonged increased intra-abdominal pressure
can predispose toward weakening of the linea alba.
The first step is often diastasis recti abdominis.
Epigastric linea alba hernias are easier to diagnose than are groin hernias.
The defect through the linea alba is usually quite conspicuous because it is
either isoechoic or hypoechoic compared with the extremely hyperechoic
The defect is usually very near the midline.
Umbilical hernias occur through a widened umbilical ring.
Umbilical hernias can, however, develop at any time during life.
Any cause of chronically increased intraabdominal pressure or connective
tissue weakness can lead to dilation of the umbilical ring and formation of
an umbilical hernia.
Umbilical hernias contain intraperitoneal contents, but smaller umbilical
hernias usually contain only intraperitoneal fat.
Untreated umbilical hernias tend to increase in size over time.
They are usually reducible but may become non-reducible and can also become
Small, non-reducible, strangulated umbilical hernia.
Incisional hernias occur through surgical scars.
Herniation can occur through any type of surgical scar, including
laparoscopy ports and stomal sites.
Incisional hernias can occur in any area along the anterior abdominal wall
where an incision is made.
Incisional hernias resulting from thinning and stretching of the scar have
wide necks and are reducible, whereas those resulting from tears in the
scar are more likely to have narrow necks and to be nonreducible.
Incisional hernias can occur where natural hernias cannot, through the
bellies of muscles that have been incised.
Narrow-necked, fat containing ventral incisional hernia that is incompletely
reducible, with no compression on the right, but with compression on the left.
Hernia complications include incarceration, obstruction, and
Incarcerated hernias are simply hernias that are nonreducible.
Obstructed hernias contain incarcerated bowel loops that have become
Strangulated hernias contain incarcerated contents with compromised
Not all strangulated hernias contain bowel loops; even preperitoneal fat
can become strangulated.
Most incarcerated hernias are neither obstructed nor strangulated,
but all obstructed and strangulated hernias are also incarcerated.
It is prefered not to use the term “incarcerated” because many referring
clinicians confuse incarceration with obstruction and strangulation, often
believing that incarceration is a surgical emergency when it is not.
Even strangulated hernias that contain only pre-peritoneal fat may not
It is the presence of bowel loops within strangulated hernias that
makes them emergent.
The shape of hernias affects their reducibility and their likelihood of
becoming obstructed or strangulated in the future.
Hernia types that typically have narrow necks and are at
high risk for strangulation include
• linea alba
• indirect inguinal hernias.
Although vascular compromise is the hallmark of strangulation ,
Doppler ultrasound is not the most sensitive modality for
demonstrating signs of strangulation.
Doppler ultrasound shows arterial flow within hernias with some
success, but generally is not sensitive enough to demonstrate venous
flow and cannot show lymphatic flow at all.
Thus, in strangulated hernias, the lymphatics and veins become
obstructed long before arterial flow decreases.
The most sensitive findings of strangulation are the presence
of the following:
• Hyperechoic fat
• Isoechoic thickening of the normally thin and echogenic hernia sac
• Fluid within the sac
• Thickening of bowel wall in bowel-containing hernias.
The sac normally appears thin and echogenic.
The sac wall is isoechoic and thickened, and a small bowel loop (b) has a
thickened wall and is aperistaltic.
Abnormal hyper-echogenicity of the fat within this umbilical hernia
indicates that it is strangulated.
Color Doppler and pulsed Doppler spectral ultrasound analysis shows
normal flow within the hernia, despite it being strangulated.