Diagnostic ultrasound ( PDFDrive )

498 PART II Abdominal and Pelvic Sonography
FIG. 13.56 Recurrent Inguinal Hernia. Short-axis view shows small,
fat-containing, reducible (dotted line) hernia arising from inferomedial
edge of the mesh (m), where recurrent inguinal hernias most often
arise. See also Video 13.21.
A
FIG. 13.57 Detached Mesh With Hernia. Transverse extended–ieldof-view
image shows that a large piece of mesh used to repair a large
ventral hernia has become detached along its right edge (arrowhead),
allowing a recurrent hernia to protrude from under the detached edge
(arrows).
demonstrating signs of strangulation. Gray-scale sonography,
however, is sensitive. Doppler ultrasound shows arterial low
within hernias with some success (Fig. 13.60), but oten is not
sensitive enough to demonstrate venous low and cannot show
lymphatic low at all. Lymphatic and venous vessel walls are very
thin and easily compressed within by the tissues surrounding
the neck of the hernia. Arteries, on the other hand, are relatively
thick walled and incompressible and in general are not compressed
by the surrounding tissues. hus in strangulated hernias the
lymphatics and veins become obstructed long before arterial
low decreases. Blood can still supply the strangulated hernia
long ater venous and lymphatic outlow stops. he continued
inlow in the presence of obstructed outlow (1) increases
intravascular pressure, (2) causes increased transudation and
exudation of luid into the extracellular spaces, and (3) changes
the gray-scale appearance of the hernia even when Doppler
ultrasound can still detect arterial inlow. When both arterial
and venous low are seen in an otherwise unremarkable ventral
hernia, emergency surgery may not be indicated. 54 However, in
B
FIG. 13.58 Spiral Clips. (A) Anteroposterior radiograph of the pelvis
shows spiral clips in both inguinal areas from bilateral inguinal herniorrhaphies.
(B) Characteristic sonographic appearance of a spiral clip
(arrows).
a study by Rettenbacher, the absence of blood low in the contents
of a hernia could not be taken as a sign of incarceration because
most incarcerated hernias in his series (78%) had detectable
blood low on color Doppler sonography. 34
In a retrospective study of sonographically examined hernias
(predominately ater indeterminate surgical physical examination)
149 abdominal wall hernias (in 131 patients) were found and
underwent surgery (Table 13.2). he most sensitive indings of
incarceration were free luid in the hernia sac, bowel wall thickening
in the hernia, luid in the herniated bowel loop, and dilated
bowel loops in the abdomen. 34 All 23 incarcerated abdominal
wall hernias were correctly interpreted preoperatively as incarcerated
by the investigating radiologists, whereas 2 of 126 nonincarcerated
hernias were considered incarcerated and were
therefore falsely positive for incarceration on sonography. 34
Strangulation of the hernia, which implies compromise of
blood low, has additional indings including the following: