Diagnostic ultrasound ( PDFDrive )

490 PART II Abdominal and Pelvic Sonography
localized along the craniocaudal axis. Although diastasis usually
does not, epigastric hernias oten do cause tenderness.
Epigastric linea alba hernias are easier to diagnose than are
groin hernias as long as they are scanned with the proper
transducer and the sonographer or physician is actually visually
inspecting the linea alba. Epigastric hernias are usually supericial
enough in location that they are best shown with 10- to 12-MHz
linear array transducers. With these transducers, the defect
through the linea alba is usually quite conspicuous because it is
either isoechoic or hypoechoic compared with the extremely
hyperechoic linea alba. he defect is usually very near the midline,
but it may occur eccentrically toward the right or let side of the
linea alba (see Fig. 13.39D-E; Figs. 13.41 and 13.42, Video 13.14).
he most frequent reason for missing an epigastric linea alba
hernia is that the examination for abdominal pain was performed
with the standard 3-MHz curved linear array transducer, focused
too deep in the elevation axis to identify any structures except
large hernias in obese patients. he clinician must have an index
of suspicion to use the appropriate transducer.
Although clinically detected epigastric hernias tend to be quite
large and oten contain bowel and other intraperitoneal contents,
sonographically detected epigastric hernias are usually small to
moderate-sized and contain only preperitoneal fat (Video 13.15).
In hernias that contain only preperitoneal fat, the underlying
peritoneal membrane and transversalis fascia are intact and the
hernia cannot be seen or repaired laparoscopically. Epigastric
hernias always have a very narrow neck in comparison to the
size of the fundus and thus are usually not reducible and are at
increased risk for strangulation, even when small. Some epigastric
hernias that contain only preperitoneal fat are so small that it is
diicult to believe that herniation is the cause of pain (Fig. 13.43).
hese hernias are not palpable, and patients typically have pain,
which more likely results from the tear or tendinosis of the linea
alba than from herniation of a tiny amount of properitoneal fat.
A B C
FIG. 13.41 Epigastric Linea Alba Hernia. Mesenteric fat protrudes through a 1-cm defect (calipers) in the linea alba at midline just above the
umbilicus. Images were obtained in the transverse supine (A), transverse with patient sitting (B), and sagittal with patient sitting (C). Note the
change in the appearance of the hernia defect with change in patient position.
A
B
FIG. 13.42 Large Ventral Hernia. Large fat-containing hernia is visible just left of midline. (A) and (B) Transverse images show the hernia in
the region of patient’s pain in palpable abnormality. See also Video 13.14.