Radiologic and Arteriographic Features

The preoperative diagnosis of paraduodenal hernia can be established only by radiologic evaluation. Studies are best performed during a symptomatic period. Examination in intervals between recurrent internal herniation may be negative or may demonstrate mild degrees of dilatation, stasis, and perhaps edematous mucosal folds that may be falsely attributed solely to adhesions. Diligent serial filming is essential to diagnosis.

In patients with a small left paraduodenal hernia (Figs. 16-6 through 16-9) a circumscribed mass of a few loops—most typically, jejunal—may be seen in the left upper quadrant immediately lateral to the ascending duodenum. The herniated loops may depress the distal transverse colon and indent the posterior wall of the stomach. Stasis of barium within the hernial contents and mild dilatation of the duodenum may be associated findings. Small right paraduodenal hernias present a similar ovoid grouping of small bowel loops lateral and inferior to the descending duodenum (Figs. 16-10 and 16-11).

Large paraduodenal hernias can contain several or most of the small bowel loops. These form a circumscribed ovoid mass having its main axis lateral to the midline and its inferior border convex downward (Figs. 16-12 through 16-15). The encapsulation within the hernial sac prevents separation or displacement of the text continues on page 724

Tran

Srv*rSl

Fig. 16-3. Development of a left paraduodenal hernia.

(a-c) The small bowel loops herniate via the fossa of Landzert into the descending mesocolon. Note the position of the inferior mesenteric vein and ascending left colic artery in the anterior margin of the neck of the sac.

eJo,

Ascending left colic artery

Inferior mesenteric vein i;V £

Inferior mesenteric vein

•-Paraduodenal fossa

•-Paraduodenal fossa

Ascending left colic artery

--------Inferior mesenteric artery

Drawings Mesenteric Vein

Superior mesenteric artery

\ Duodenum

Mesentericoparietal fossa

Fig. 16—4. Lateral drawing of the mesentericoparietal fossa of Waldeyer showing its position behind the superior mesenteric artery and small bowel mesentery. Note also its infraduodenal position.

Left Paraduodenal Hernia

Fig. 16—5. Development of a right paraduodenal hernia via the fossa of Waldeyer toward the ascending mesocolon. Note the position of the superior mesenteric artery anterior to the hernia and in the leading edge of the sac.

Fig. 16—5. Development of a right paraduodenal hernia via the fossa of Waldeyer toward the ascending mesocolon. Note the position of the superior mesenteric artery anterior to the hernia and in the leading edge of the sac.

Paradudenum And Picture

Fig. 16—6. Small left paraduodenal hernia.

(a) Small bowel series shows a circumscribed ovoid mass of herniated jejunal loops immediately lateral to the ascending duodenum (arrows).

(b) Two-hour film demonstrates stasis of barium within these loops (arrows) and depression of the distal transverse colon. At surgery, the hernial sac contained only a couple feet ofjejunum. This was readily reduced, and the peritoneal defect was repaired.

(Reproduced from Meyers.17)

Fig. 16—6. Small left paraduodenal hernia.

(a) Small bowel series shows a circumscribed ovoid mass of herniated jejunal loops immediately lateral to the ascending duodenum (arrows).

(b) Two-hour film demonstrates stasis of barium within these loops (arrows) and depression of the distal transverse colon. At surgery, the hernial sac contained only a couple feet ofjejunum. This was readily reduced, and the peritoneal defect was repaired.

(Reproduced from Meyers.17)

Paradudenum And Picture

Fig. 16—7. Small left paraduodenal hernia.

(a) Prone oblique and (b) frontal projections demonstrate a proximal jejunal loop within the hernial sac (arrows) behind the stomach, rising above the duodenojejunal junction into the descending mesocolon and especially into the left half of the transverse mesocolon. Note the pressure of the loop on the posterior wall of the stomach. A chronically deformed duodenal bulb is also present. (Reproduced from Meyers. )

Fig. 16—7. Small left paraduodenal hernia.

(a) Prone oblique and (b) frontal projections demonstrate a proximal jejunal loop within the hernial sac (arrows) behind the stomach, rising above the duodenojejunal junction into the descending mesocolon and especially into the left half of the transverse mesocolon. Note the pressure of the loop on the posterior wall of the stomach. A chronically deformed duodenal bulb is also present. (Reproduced from Meyers. )

Paraduodenal Hernia Images

Fig. 16—8. Small left paraduodenal hernia.

A dilated jejunal loop resides abnormally high lateral to the fourth portion of the duodenum and mildly displaces the duodenojejunal junction medially. Its degree of dilatation and encapsulation is sufficient to produce pressure deformity on the posterior wall of the adjacent stomach. Although no hernia was present at the time of autopsy, a paraduodenal fossa admitting three to four fingers was found. This would readily allow intermittent herniation of jejunum as illustrated. (Reproduced from Meyers.17)

Paraduodenal Hernia Images

Fig. 16—9. Left paraduodenal hernia.

(a and b) Filled and postevacuation barium enema study demonstrates refluxed proximal ileal loops forming a circumscribed ovoid mass (arrows) with stasis within the left paraduodenal fossa.

Fig. 16—9. Left paraduodenal hernia.

(a and b) Filled and postevacuation barium enema study demonstrates refluxed proximal ileal loops forming a circumscribed ovoid mass (arrows) with stasis within the left paraduodenal fossa.

Fig. 16—10. Small right paraduodenal hernia.

A circumscribed grouping ofjejunal loops (arrows) has herniated into the ascending mesocolon and the right portion of the transverse mesocolon. The dilated afferent jejunal limb shows a localized constriction (arrowheads) at the hernial orifice behind the superior mesenteric artery. (Reproduced from Ghahremani and Meyers.32)

Ileal OrificeIleal Orifice

Fig. 16—11. Right paraduodenal hernia.

(a) The afferent and efferent limbs, which lie close together, both appear obstructed.

(b) Later the small intestinal loops within the circumscribed ovoid hernial sac (arrows) into the ascending mesocolon are still dilated but with a smaller degree of obstruction. The alternating sites of narrowing represent adhesions between loops.

(Reproduced from Meyers.17)

Fig. 16—11. Right paraduodenal hernia.

(a) The afferent and efferent limbs, which lie close together, both appear obstructed.

(b) Later the small intestinal loops within the circumscribed ovoid hernial sac (arrows) into the ascending mesocolon are still dilated but with a smaller degree of obstruction. The alternating sites of narrowing represent adhesions between loops.

(Reproduced from Meyers.17)

Paraduodenal Hernia Images

Fig. 16—12. Large left paraduodenal hernia.

Upper GI series (LAO position) shows an encapsulated cluster of multiple small bowel loops in the fossa of Landzert, with a mild impression upon the posterior wall of the stomach (black arrows). A typically tapered efferent limb is demonstrated (white arrows). (Reproduced from Schlaffer et al.33)

Fig. 16-13. (Right) Large left paraduodenal hernia in a 42-year-old female with persistent postprandial pains despite multiple abdominal operations.

(a) Most of the small bowel loops are gathered in the left side of the abdomen, forming a circumscribed mass with a convex inferior margin. Internal adhesions within the sac narrow bowel loops at multiple sites.

(b) Lateral projection shows retroperitoneal displacement of the herniated intestine.

(c) A serial film demonstrates that the efferent loop (arrows) leads from the hernial sac to the normally situated distal ileum. Despite multiple postural changes, the grouped position of the small bowel loops remained unchanged. (continued on pages 721 and 722)

Images Herniated Small IntestineMesenteric Margin Small Intestine

Fig. 16-13. Continued. (d and e) Aortogram shows that the upper jejunal arteries are redirected medially and posteriorly just beyond their origins from the superior mesenteric artery (arrows). This characteristic reversal of their course indicates the posteromedial border of the hernial orifice, beyond which the intestinal loops herniate. (f) Horizontal diagram of anatomic relationships of jejunal arteries redirected medially and posteriorly to left paraduodenal hernia into the descending mesocolon. (Reproduced from Meyers.27)

Fig. 16-13. Continued. (d and e) Aortogram shows that the upper jejunal arteries are redirected medially and posteriorly just beyond their origins from the superior mesenteric artery (arrows). This characteristic reversal of their course indicates the posteromedial border of the hernial orifice, beyond which the intestinal loops herniate. (f) Horizontal diagram of anatomic relationships of jejunal arteries redirected medially and posteriorly to left paraduodenal hernia into the descending mesocolon. (Reproduced from Meyers.27)

Paradudenum And Picture

Fig. 16-14. Large right paraduodenal hernia.

(a) An ovoid grouping ofjejunal loops in the right midabdomen resides within a hernial sac.

(b) Selective superior mesenteric arteriogram. The jejunal branches originate normally from the left side but abruptly change their direction (arrow) behind and toward the right of the parent vessel to accompany the herniated jejunal loops.

(Courtesy of Gary Ghahremani, M.D., Evanston, IL.)

(c) Diagram of the course of jejunal arteries accompanying the herniation via the mesentericoparietal fossa.

Direction Superior Mesenteric Artery

Fig. 16—15. Large right paraduodenal hernia.

(a) The right midabdomen is occupied by a circumscribed grouping of virtually all of the intestinal loops, representing a total herniation into the ascending mesocolon and right portion of the transverse mesocolon. The cecum was normally positioned.

(b) On aortography, the jejunal arteries are demonstrated to course to the right, accompanying the circumscribed herniated loops and their mesentery.

(Reproduced from Lechner and Gebhardt.34)

Fig. 16—15. Large right paraduodenal hernia.

(a) The right midabdomen is occupied by a circumscribed grouping of virtually all of the intestinal loops, representing a total herniation into the ascending mesocolon and right portion of the transverse mesocolon. The cecum was normally positioned.

(b) On aortography, the jejunal arteries are demonstrated to course to the right, accompanying the circumscribed herniated loops and their mesentery.

(Reproduced from Lechner and Gebhardt.34)

individual loops from the rest of the hernial contents during fluoroscopic manipulation. Stasis of the contrast material and dilatation of the herniated loops may also be evident. At the hernial orifice, the efferent loop of the left paraduodenal hernia shows an abrupt change of caliber (Figs. 16-12 and 16-13c). In a right paraduo-denal hernia, however, both the afferent and the efferent loops appear closely apposed and narrowed. Lateral films are particularly useful for detection of retroperitoneal displacement of the hernial content, showing the loops projecting well over the spine.17,20 On barium enema examination, the descending colon may be seen to be anterior, to the left, or posterior to a left paraduodenal hernia. The ascending colon always lies lateral to a right paraduodenal hernia, however, and the cecum is found in its normal position.17

The position of the major mesenteric vessels in the anterior margin of the neck of the paraduodenal hernial sac is important embryologically, surgically, and radio-logically. Not only the intestinal loops, but their mesentery and vessels are incorporated into the hernia. Arteriography visualization of these vessels, particularly of the position of their branches supplying the small bowel loops, can assist in the radiologic diagnosis of paraduodenal hernias.17,27 In a right paraduodenal hernia, the jejunal arteries that normally arise from the left side of the superior mesenteric artery reverse their direction and course behind the parent vessel to supply the her-niated jejunal loops within the fossa of Waldeyer (Figs. 16-14b,c and 16-15b). In a left paraduodenal hernia, I have noted that the proximal jejunal arteries show an abrupt change of course along the medial border of the hernial orifice, where they are redirected posteriorly behind the inferior mesenteric vessels to accompany the herniated loops (Fig. 16-13d-f). A line connecting the points at which these arteries suddenly change their course indicates the medial border of the hernial orifice beyond which the small intestinal loops herniate.17,27

The computed tomography findings in left paradu-odenal hernia involve (a) encapsulation of bowel loops at the level of the duodenojejunal unction or interposed between the stomach and pancreas, or behind the descending colon; (b) dilatation and air-fluid levels in the trapped loop; and (c) narrowing of the efferent limb35-38 (Figs. 16-16 through 16-19). Normal vascular relationships, although perhaps with mild displacement by the herniated loops, are useful landmarks.

In right paraduodenal hernia, the major CT findings are (a) looping of jejunal branches of the superior mes-enteric artery and vein to the right and posterior in a

Paradudenum And Picture

Fig. 16—16. CT findings in small left paraduodenal hernias, in three separate cases.

(a) CT at the level of the superior mesenteric artery shows a rounded, encapsulated cluster of small bowel loops behind the transverse colon, caudal to the tail of the pancreas and immediately anterior to the left adrenal gland. (Reproduced from Olazabal et al.39)

(b) CT reveals a horseshoe appearance of an encapsulated bowel loop within a well-defined hernial sac. Some stasis is evident. The jejunal vessels are sharply deviated to the left to accompany the herniated loops and radiate inside the hernial sac to accompany them.

(c) CT demonstrates several mildly dilated jejunal loops encapsulated behind the stomach with pressure effect upon its posterior wall. Sites of angulation and narrowing involving the small bowel loops reflect adhesions within the hernial sac.

Fig. 16—16. CT findings in small left paraduodenal hernias, in three separate cases.

(a) CT at the level of the superior mesenteric artery shows a rounded, encapsulated cluster of small bowel loops behind the transverse colon, caudal to the tail of the pancreas and immediately anterior to the left adrenal gland. (Reproduced from Olazabal et al.39)

(b) CT reveals a horseshoe appearance of an encapsulated bowel loop within a well-defined hernial sac. Some stasis is evident. The jejunal vessels are sharply deviated to the left to accompany the herniated loops and radiate inside the hernial sac to accompany them.

(c) CT demonstrates several mildly dilated jejunal loops encapsulated behind the stomach with pressure effect upon its posterior wall. Sites of angulation and narrowing involving the small bowel loops reflect adhesions within the hernial sac.

Paradudenum And Picture

Fig. 16—17. Left paraduodenal hernia.

(a) Small bowel series demonstrates ovoid encapsulation of jejunal loops adjacent and to the left of the fourth portion of the duodenum.

(b) CT shows a cluster of mildly dilated small bowel loops with air-fluid levels behind the stomach on the left adjacent to the duodenojejunal junction. The superior mesenteric vessels are normally positioned.

(Reproduced from Warshauer and Mauro.37)

Fig. 16—17. Left paraduodenal hernia.

(a) Small bowel series demonstrates ovoid encapsulation of jejunal loops adjacent and to the left of the fourth portion of the duodenum.

(b) CT shows a cluster of mildly dilated small bowel loops with air-fluid levels behind the stomach on the left adjacent to the duodenojejunal junction. The superior mesenteric vessels are normally positioned.

(Reproduced from Warshauer and Mauro.37)

Paraduodenal Hernia Images

Fig. 16-18. Left paraduodenal hernia: CT findings.

CT shows encapsulated bowel loops with typical smooth convex lateral border of the hernial sac within the fossa of Landzert (large arrows). Normal relationships of the superior mesenteric artery and vein (small white arrows) with lateral and posterior displacement of their branches caused by the herniated bowel loops. There is anterior and superior displacement of the inferior mesenteric vein (open white arrow).

(Reproduced from Schaffler et al.33)

Hernia Paraduodenal

Fig. 16—19. Left paraduodenal hernia: CT findings.

(a and b) Two sections of the upper abdomen demonstrate a jejunal loop (open arrows) extending deep between the descending colon and left kidney. Focal narrowing of the loop occurs at its exit from the hernial sac, as delineated by the left colic branch of the inferior mesenteric artery (solid arrows). (Reproduced from Ghahremani.38)

Fig. 16—19. Left paraduodenal hernia: CT findings.

(a and b) Two sections of the upper abdomen demonstrate a jejunal loop (open arrows) extending deep between the descending colon and left kidney. Focal narrowing of the loop occurs at its exit from the hernial sac, as delineated by the left colic branch of the inferior mesenteric artery (solid arrows). (Reproduced from Ghahremani.38)

fashion analogous to the artériographie findings, and (b) clustering or encapsulation of small bowel loops in the right midabdomen37 (Fig. 16-20). If the hernia is associated with small bowel malrotation, two CT findings of malrotation will also be present: (a) rotation by which the superior mesenteric vein is located more left and ventral in relation to the superior mesenteric artery than normal,41-44 and (b) absence of the normal horizontal duodenum37 (Fig. 16-21). These vascular changes can be distinguished from volvulus superimposed upon malrotation. A characteristic CT sign of small bowel volvulus is the whirl sign, in which the bowel and mes-

enteric folds encircle the superior mesenteric artery and vein45-49 (Fig. 16-22). Typical vascular alterations may be readily illustrated by ultrasonography50,51 (Fig. 1623), and arteriography documents a twirled pattern of the superior mesenteric artery, producing the appearance of a barber pole48,52,53 (Fig. 16-24).

In the rare developmental anomaly known as peritoneal encapsulation, characterized by a delicate membrane enveloping a fixed cluster of nondilated intestinal loops, vascular relationships are maintained.54,55

A unique case of bilateral paraduodenal hernias has been recently reported56 (Fig. 16-25).

Fig. 16—20. Right paraduodenal hernia: CT findings.

CT demonstrates a saclike collection of dilated intestinal loops with thickened walls, entrapped within the right paraduodenal fossa.

(Courtesy of Sakae Nagaoka, MD, Takeshi Arita MD, and Naofumi Matsunaga MD, Japan.)

Paraduodenal Hernia ImagesParadudenum And Picture

Fig. 16-21. Right paraduodenal hernia.

(a) Small bowel series shows spherical encapsulation of jejunal loops in the right midabdomen.

(b) CT demonstrates absence of the normal horizontal duodenum consistent with nonrotation of the small bowel, multiple loops of which are encapsulated in the right midabdomen (open arrows). The normally rotated ascending colon lies lateral to these small bowel loops. The superior mesenteric vein (arrowhead) is rotated anterior and to the left of its normal position, and there is looping of arterial and venous jejunal branches (curved arrow) behind the superior mesenteric artery (long arrow) and into the hernial sac.

(Reproduced from Warshauer and Mauro.37)

Fig. 16-21. Right paraduodenal hernia.

(a) Small bowel series shows spherical encapsulation of jejunal loops in the right midabdomen.

(b) CT demonstrates absence of the normal horizontal duodenum consistent with nonrotation of the small bowel, multiple loops of which are encapsulated in the right midabdomen (open arrows). The normally rotated ascending colon lies lateral to these small bowel loops. The superior mesenteric vein (arrowhead) is rotated anterior and to the left of its normal position, and there is looping of arterial and venous jejunal branches (curved arrow) behind the superior mesenteric artery (long arrow) and into the hernial sac.

(Reproduced from Warshauer and Mauro.37)

Volvulus Newborn Lateral Ray

Fig. 16-22. The whirl sign of small bowel volvulus.

CT demonstrates a whirling appearance in which small bowel loops, mesenteric folds, and intestinal branches encircle the superior mesenteric artery and vein. Surgery revealed a 360-degree volvulus of the ileum. (Reproduced from Izes et al.48)

Fig. 16—23. Midgut volvulus in an infant.

Gray scale reproduction of color flow Doppler ultrasonogram in the transverse plane demonstrates the superior mesenteric vein (SMV) wrapping around the superior mesenteric artery (SMA). (Reproduced from Hayden.51)

Long Scale Contrast Radiography

Fig. 16-24. Midgut volvulus.

Selective superior mesenteric arteriogram demonstrates a twirled appearance of the superior mesenteric artery. (Reproduced from Izes et al.48)

Paraduodenal Hernia ImagesParadudenum And Picture

Fig. 16—25. Bilateral paraduodenal hernias.

(a) Oblique projection from a small bowel series demonstrates a large right (arrows) and small left (arrowheads) circumscribed, ovoid cluster of small intestine. The individual loops could not be separated from this mass with compression.

(b) CT after the administration of intravenous contrast and (c) axial T1-weighted MR image demonstrate right (arrows) and left (arrowheads) circumscribed groups of dilated small bowel loops. On CT, the hernial sacs clearly enhance. On MRI, motion artifacts are limited since these hernias are fixed to the retropentoneum and are often adhered to the hernia sac.

(Reproduced form Oruchi et al.56)

Fig. 16—25. Bilateral paraduodenal hernias.

(a) Oblique projection from a small bowel series demonstrates a large right (arrows) and small left (arrowheads) circumscribed, ovoid cluster of small intestine. The individual loops could not be separated from this mass with compression.

(b) CT after the administration of intravenous contrast and (c) axial T1-weighted MR image demonstrate right (arrows) and left (arrowheads) circumscribed groups of dilated small bowel loops. On CT, the hernial sacs clearly enhance. On MRI, motion artifacts are limited since these hernias are fixed to the retropentoneum and are often adhered to the hernia sac.

(Reproduced form Oruchi et al.56)

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