This document discusses internal hernias, which occur when abdominal organs protrude through openings within the abdominal cavity. It describes several types of internal hernias, including paraduodenal, foramen of Winslow, intersigmoid, pericecal, transmesenteric, and retroanastomotic hernias. For each type, it provides details on location, risk factors, and radiographic findings such as clustering of bowel loops and abnormalities of mesenteric vessels. The document emphasizes the importance of recognizing abnormal bowel positioning and configurations, signs of obstruction, and vessel abnormalities on imaging studies to diagnose internal hernias.

1. Dr/Ahmed Bahnassy
Consultant radiologist
PSMMC

2. Importance of subject
Although internal hernias have an
overall incidence of less than
1%, they constitute up to 5.8% of
all small-bowel obstructions,
which, if left untreated, have been reported
to have an overall mortality exceeding 50%
if strangulation is present

3. Types of hernias
Hernias are of two main types, external and
internal . External hernias refer to prolapse
of intestinal loops through a defect in the wall
of the abdomen or pelvis, and internal hernias
are defined by the protrusion of a viscus
through a normal or abnormal peritoneal or
mesenteric aperture within the confines of the
peritoneal cavity. The orifice can be either acquired,
such as a postsurgical, traumatic, or
postinflammatory defect, or congenital, including
both normal apertures, such as the foramen
of Winslow, and abnormal apertures
arising from anomalies of internal rotation
and peritoneal attachment.

4. Clinical presentation
Clinically, internal hernias can be
asymptomatic or cause significant
discomfort ranging from constant vague
epigastric pain to intermittent colicky
periumbilical pain.
symptoms include nausea, vomiting
(especially after a large meal), and
recurrent intestinal obstruction

7. Fluoroscopy
General radiographic
features with barium studies include
apparent encapsulation of distended
bowel loops with an abnormal location, arrangement
or crowding of small-bowel loops
within the hernial sac, evidence of obstruction
with segmental dilatation and stasis, with additional
features of apparent fixation and reversed
peristalsis during fluoroscopic evaluation

8. CT
On CT, additional findings include
mesenteric vessel abnormalities,
with engorgement, crowding, twisting,
and stretching of these vessels commonly
found and providing an important clue to the
underlying diagnosis

9. Diagrammatic
illustration shows
various types of internal
hernias:
A = paraduodenal,
B = foramen of Winslow,
C = intersigmoid,
D = pericecal,
E = transmesenteric, and
F = retroanastomotic.
Review of Internal Hernias:Radiographic and Clinical Findings:Lucie C. MartinElmar M.
Merkle,William M. Thompson,Martin LC, Merkle EM, Thompson.AJR 2006; 186:703–717

10. Paraduodenal fossae
Drawing (coronal view) shows the
locations
of duodenal fossae. Arrows
indicate the directions
of hernias through these fossae.
The frequency with
which each fossa is found at
autopsy is given in parentheses.
1. superior duodenal fossa (50%),
2.inferior duodenal fossa (fossa of
Treitz) (75%),
3.paraduodenal
fossa (fossa of Landzert) (2%),
4.intermesocolic fossa (fossa of
Broesike),
5.mesentericoparietal fossa
(fossa of Waldeyer)

11. Left paraduodenal hernia
Landzert's fossa
Review of Internal Hernias:Radiographic and Clinical Findings:Lucie C. MartinElmar M.
Merkle,William M. Thompson,Martin LC, Merkle EM, Thompson.AJR 2006; 186:703–717

12. Left paraduodenal hernia
Left paraduodenal hernias have an overall
incidence of approximately 40% of internal
hernias. They occur when bowel prolapses
through Landzert’s fossa, an aperture
present in approximately 2% of the population
These hernias therefore can be
classified as a congenital type, normal aperture
subtype. Landzert’s fossa is located behind
the ascending or fourth part of the
duodenum and is formed by the lifting up of
a peritoneal fold by the inferior mesenteric
vein and ascending left colic artery as they
run along the lateral side of the fossa.
Small bowel loops prolapse
posteroinferiorly through the fossa
to the left of the fourth
part of the duodenum into the left
portion of the transverse
mesocolon.

13. Left paraduodenal hernia
lt adrenal
stretched IMV

14. Left paraduodenal hernia
engorged vessels

15. Right paraduodenal henia
Right paraduodenal hernias have an overall
incidence of approximately 13% and
occur when bowel herniates through
Waldeyer’s fossa (representing a defect in
the first part of the jejunal mesentery), behind
the superior mesenteric artery and inferior
to the transverse or third portion of the
duodenum .
This type of hernia occurs more frequently in the
setting of nonrotated small bowel .

16. Right paraduodenal henia
waldeyer fossa
Review of Internal Hernias:Radiographic and Clinical Findings:Lucie C. MartinElmar M.
Merkle,William M. Thompson,Martin LC, Merkle EM, Thompson.AJR 2006; 186:703–717

17. Right paraduodenal henia
On a standard barium
gastrointestinal
examination,
a larger and more fixed,
encapsulated,
ovoid collection of bowel
loops is noted lateral and
inferior to the descending
duodenum, in the right
half of the transverse
mesocolon.

18. Right paraduodenal henia..CT
SMA

19. Additional vascular
findings include the presence of the
superior mesenteric artery, ileocolic artery,
and right colic vein in the anterior margin of
the neck of the hernial sac, displaced anteriorly
if there is sufficient mass effect by the
encased small-bowel loops . Again, vessel
engorgement may also be present and
provide a clue to the diagnosis.
SMA

20. Lesser sac hernia
foramen of winslow
Review of Internal Hernias:Radiographic and Clinical Findings:Lucie C. MartinElmar M.
Merkle,William M. Thompson,Martin LC, Merkle EM, Thompson.AJR 2006; 186:703–717

21. Lesser sac hernia
Risk factors for this type of hernia include
an enlarged foramen of Winslow, an
abnormally long small-bowel mesentery,
persistence of the ascending mesocolon
allowing marked mobility of bowel,

22. Lesser sac hernia
bowel loops posterior to stomach

23. Transmesenteric hernia

24. Transmesenteric hernia
swirled mesenteric vessels
clusters of bowel loops
stretched vessesl

25. Transmesenteric hernia
cluster of bowel
most common in pediatrics

26. Pericecal hernia
paracaecal
recesses
Review of Internal Hernias:Radiographic and Clinical Findings:Lucie C. MartinElmar M.
Merkle,William M. Thompson,Martin LC, Merkle EM, Thompson.AJR 2006; 186:703–717

27. Retro-caecal

28. Para-caecal

29. Para-cecal hernia

30. Intersigmoid hernia
sigmoid mesocolon
defect
Review of Internal Hernias:Radiographic and Clinical Findings:Lucie C. MartinElmar M.
Merkle,William M. Thompson,Martin LC, Merkle EM, Thompson.AJR 2006; 186:703–717

31. Intersigmoid hernia
IMV
Psoas major

32. Intersigmoid hernia

33. Trans-Omental hernia

34. Trans-Omental hernia

35. Pelvic internal hernia

36. Broad ligament hernia

37. Broad ligament hernia

38. Peri-rectal fossa hernia

39. Trans-mesocolic internal hernia
no omentum
directly on ABW
dilated bowel
transition point

40. the only statistically significant signs
were relatively nonspecific
findings of small-bowel dilatation with
transition point, clustering of small-bowel
loops, and mesenteric
vessel abnormalities (including
displacement of the main mesenteric
trunk to the right).
Occasionally, there may even be
evidence of ischemia with ascites and
bowel wall thickening present .
“closed loop”sign,
twisting of the mesenteric vessels
and
whirl sign .

41. Post operative Retro-anastomotic

42. Advices
• locate the abnormal position of bowel.
• clustering , +/- encapsulation,dilatation.
• any transitional point
• Relation to other organs.
• Study vessels status.
• is it obstructed (surgical emergency)or not.
• discuss with the referring physician (an
abnormality is present i.e.:follow up ,and
presence of data in patient file is important)