Paraduodenal Hernia

Published on 13/07/2015 by admin

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Last modified 22/04/2025

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 Left (75%): Protrusion of small bowel through paraduodenal mesenteric fossa of Landzert

image Right (25%): Protrusion of small bowel through jejunal mesentericoparietal fossa of Waldeyer
• CT features

image Left paraduodenal hernia

– Encapsulated “cluster” or sac-like mass of small bowel loops located between pancreatic body/tail and stomach to left of ligament of Treitz
– Hernia sac may exert mass effect on posterior wall of stomach, duodenojejunal junction inferiorly and medially, and transverse colon inferiorly/anteriorly
– Crowded, engorged mesenteric vessels supplying bowel loops within hernia sac
image Right paraduodenal hernia

– Clustered, encapsulated small bowel in right upper abdomen lateral/inferior to descending duodenum
– Unusual “looping” course of SMA and SMV to supply bowel in hernia sac
• Small bowel follow-through

image Abnormally crowded, clustered bowel loops to left or right side of colon
image Fixation, stasis, and delayed flow of contrast seen in bowel within hernia sac

– Right-sided paraduodenal hernias are often larger than on left with more “fixed” bowel loops
image Lateral film: Retroperitoneal displacement of herniated bowel loops

PATHOLOGY

• Usually result of congenital mesenteric anomaly

image Anomalies in mesenteric fixation of ascending or descending colon → abnormal openings → internal hernia
• Can very rarely result from complication of surgery or trauma

CLINICAL ISSUES

• Most often occurs in men during 4th-6th decades of life
• Smaller hernias clinically silent and reduce spontaneously
• Larger hernias more commonly symptomatic (i.e., vague discomfort, abdominal distension, postprandial pain)

image May present with symptoms of bowel obstruction
image Very high (∼ 50%) lifetime risk of strangulation or incarceration
image
(Left) Graphic shows a left paraduodenal hernia image containing dilated proximal jejunal loops in a peritoneal sac.

image
(Right) Small bowel follow-through demonstrates an ovoid cluster image of mildly dilated jejunal segments in the left upper quadrant. The outer confines of the hernia sac are well defined. The herniated bowel exerts mass effect on the greater curvature of the stomach, characteristic of a left paraduodenal hernia.
image
(Left) Abdominal radiograph shows an unusual cluster of dilated jejunal small bowel loops image in the left upper quadrant.

image
(Right) Axial CECT in the same patient shows the same cluster of dilated bowel image interposed between the pancreas and stomach. Note the displaced inferior mesenteric vein image that runs along the anterior edge of the hernia sac. This constellation of findings is characteristic of a left paraduodenal hernia.

TERMINOLOGY

Definitions

• Congenital internal hernia resulting from protrusion of bowel loops through abdominal mesenteric defect

IMAGING

General Features

• Best diagnostic clue

image CECT: Cluster of dilated bowel loops in right or left upper abdomen with distorted mesenteric vessels
• Location

image Left (75%): Protrusion of small bowel through paraduodenal (lateral to 4th part) mesenteric fossa of Landzert (located near ligament of Treitz)
image Right (25%): Protrusion of small bowel through jejunal mesentericoparietal fossa of Waldeyer (located inferior to 3rd portion of duodenum)

Radiographic Findings

• Radiography

image Supine abdomen: Distended, clustered loops of small bowel (SB) in right or left upper abdomen

CT Findings

• Left paraduodenal hernia

image Encapsulated “cluster” or sac-like mass of small bowel loops located between pancreatic body/tail and stomach to the left of ligament of Treitz

– Bowel loops herniate into sac created by descending and distal transverse mesocolon
– Hepatic flexure of colon usually located anterior to hernia sac
image Hernia sac may exert mass effect on posterior wall of stomach, duodenojejunal junction inferiorly and medially, and transverse colon inferiorly/anteriorly
image Crowded, engorged mesenteric vessels supplying bowel loops within hernia sac

– Inferior mesenteric vein (IMV) and left colic artery lie in anterior and medial border of hernia sac, with IMV often displaced to left
• Right paraduodenal hernia

image Clustered, encapsulated small bowel loops in right upper abdomen lateral and inferior to descending duodenum

– Ascending colon located lateral to hernia sac
– Mass effect from hernia sac displaces right ureter laterally
image Unusual “looping” course of superior mesenteric artery (SMA) and vein (SMV) to supply bowel in hernia sac

– SMV rotated anteriorly and to left
– Twisted vascular jejunal branches behind SMA extend into hernia sac
– Main trunk of SMA and right colic vein located along anterior medial border of hernia sac
image Commonly associated with intestinal nonrotation
• Small bowel obstruction (SBO)

image Bowel loops within hernia sac may or may not be dilated depending on presence or absence of SBO, with transition point between dilated loops within hernia sac and decompressed distal small bowel
image Consider bowel ischemia if bowel within hernia sac appears thickened, inflamed, or abnormally enhancing

Fluoroscopic Findings

• Small bowel follow-through

image Abnormally crowded, clustered bowel loops in right or left upper abdomen with small bowel often absent from pelvis

– Left: Circumscribed ovoid mass of jejunal loops in LUQ lateral to ascending duodenum
– Right: Ovoid mass of small bowel loops lateral and inferior to descending duodenum
– Configuration of small bowel loops appears as sac-like “mass” with confining border
image In cases with bowel obstruction (either complete or partial), point of transition between dilated and nondilated bowel may be visualized
image Fixation, stasis, and delayed flow of contrast seen in bowel within hernia sac

– Right-sided paraduodenal hernias are often larger than on the left and herniated loops on right are typically more “fixed” than on left
image Lateral film: Retroperitoneal displacement of herniated bowel loops

Ultrasonographic Findings

• Dilated SB loops with no other distinguishing features

Angiographic Findings

• Superior mesenteric arteriogram: Normal jejunal branches arise from left margin of main trunk, abruptly course right, and pass behind to supply herniated loops

Imaging Recommendations

• Best imaging tool

image CECT, small bowel follow-through

DIFFERENTIAL DIAGNOSIS

Transmesenteric Internal Hernia

• Internal hernia that is most often acquired in setting of prior surgery (most commonly Roux-en-Y gastric bypass and liver transplantation)

image Rarely results from congenital mesenteric defect (usually in pediatric age group)
• Clustered loops of small bowel in periphery of abdomen, with loops of bowel abnormally contacting abdominal wall and located lateral to colon

image Most commonly occur in right hemiabdomen
image Unlike paraduodenal hernias, transmesenteric hernias do not appear encapsulated or enveloped in a sac
• Large transmesenteric hernias may present with bowel obstruction, strangulation, or ischemia

Closed Loop Obstruction

• Obstruction of small bowel at 2 separate points in single location forming “closed loop”
• Usually caused by adhesive band but rarely can result from internal or external hernia
• Dilated bowel loops appear abnormally tethered or clumped, with radiating configuration of bowel and stretched mesenteric vessels toward a central point

image Mesentery and vasculature may demonstrate whirl sign, with swirling of mesentery and stretched mesenteric vessels toward a central point
• High risk of volvulus, strangulation, and bowel infarction

Pericecal Internal Hernia

• Cluster of bowel loops (usually ileum) abnormally located posterior and lateral to cecum with extension into paracolic gutter
• Herniation of bowel through pericecal fossa (defect in cecal mesentery)
• Lies more inferiorly compared to right-sided paraduodenal hernia (right lower quadrant rather than right upper quadrant)

PATHOLOGY

General Features

• Etiology

image Most commonly results from congenital or developmental mesenteric anomaly

– Anomalies in mesenteric fixation of ascending or descending colon → abnormal openings → internal hernia
image Can also result from complication of surgery or trauma

– Abnormal mesenteric defect created during surgery or trauma → abnormal mobility of SB and right colon → internal hernia
image Left paraduodenal hernia: Herniation of small bowel via abnormal mesenteric fossa of Landzert 

– Discrete peritoneal opening lateral to distal duodenum found in 2% of population
– Bowel loop herniates into pocket of distal transverse and descending mesocolon, posterior to SMA
image Right paraduodenal hernia: Herniation via abnormal mesentericoparietal fossa of Waldeyer

– Fossa of Waldeyer seen in ∼ 1% of population
– Jejunal mesentery located immediately behind SMA and inferior to transverse duodenum
– Bowel loop herniates into pocket of ascending mesocolon
• Associated abnormalities

image Right-sided paraduodenal hernias often associated with intestinal nonrotation

Staging, Grading, & Classification

• Hernias classified based on anatomic location

image Internal or intraabdominal: Herniation of bowel loops via defect within abdominal cavity
image External: Prolapse of bowel loops via defect in wall of abdomen or pelvis
image Diaphragmatic: Protrusion of bowel loops via hiatus or congenital defect
• Subclassification of internal hernias

image Paraduodenal hernia
image Transmesenteric postoperative hernia
image Foramen of Winslow, pericecal hernias
image Intersigmoid and transomental hernias
• Subclassification of paraduodenal hernias based on location

image Left (75%), right (25%)

Gross Pathologic & Surgical Features

• Dilated bowel loops herniating via mesenteric defect

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Smaller hernias clinically silent and reduce spontaneously
image Larger hernias can produce vague discomfort, abdominal distension, periumbilical colicky pain, palpable mass, and localized tenderness

– Nonspecific symptoms make clinical diagnosis virtually impossible, making role of imaging critical
image Both right and left paraduodenal hernias may present with postprandial pain, often with symptoms present (in retrospect) since childhood
image May present with symptoms of bowel obstruction (nausea, vomiting, abdominal pain, distension)

Demographics

• Age

image All ages, but most common between 4th and 6th decades
• Gender

image M:F = 3:1
• Epidemiology

image Most common subtype of internal hernia, accounting for > 50% of all internal hernias
image Usually congenital and only rarely acquired due to surgery or trauma
image Rare cause of SBO, accounting for only 0.5 – 4.1% of all small bowel obstructions
image Very high (∼ 50%) lifetime risk of strangulation or incarceration

Natural History & Prognosis

• Complications

image Volvulus, ischemia, strangulation
image Bowel gangrene, shock, death
• Good prognosis with early surgical correction, but risk of poor outcomes in patients who present with bowel obstruction and other complications

Treatment

• All paraduodenal hernias should be surgically repaired (with closure of mesenteric defect)

image Most often performed with open laparotomy, although laparoscopic approach may be possible

DIAGNOSTIC CHECKLIST

Consider

• Consider incarceration with ischemia if bowel loops within hernia appear thickened or abnormally enhancing

Image Interpretation Pearls

• Cluster of dilated SB loops lateral to ascending/descending duodenum with crowded/twisted mesenteric vessels

image
(Left) Axial NECT demonstrates a cluster of encapsulated small bowel image in the left abdomen. Notice the location of these loops, immediately adjacent to the distal duodenum, posterior wall of the stomach, and colon, in keeping with a paraduodenal hernia.
image
(Right) Axial CECT demonstrates a cluster of mildly dilated small bowel loops image in the left upper quadrant, displacing the stomach forward. Mesenteric vessels supplying the herniated bowel segments converge toward the center of the cluster.
image
(Left) Axial CECT shows an oval cluster of jejunum image in the left upper quadrant. Note the sharply defined outer margin of the peritoneal sac around the herniated bowel, and the mesenteric vessels converging toward the sac center, compatible with a left paraduodenal hernia.

image
(Right) Delayed film from an upper GI series in the same patient shows a tight cluster of dilated jejunum image and delayed passage of contrast to the normal caliber distal small bowel.
image
(Left) Axial CECT shows a right paraduodenal hernia causing small bowel obstruction. Note the U-shaped configuration of the bowel loop within the right paraduodenal hernia sac image.

image
(Right) Coronal CECT demonstrates the characteristic “encapsulated” morphology of a left paraduodenal hernia image. Note the engorged mesenteric vessels extending directly into the hernia sac.
image
Axial CECT shows a cluster of mildly dilated small bowel segments image in LUQ, displacing the stomach forward. Mesenteric vessels and herniated bowel segments converge toward the center of the cluster.

image
Axial CECT shows a cluster of dilated jejunal loops in the RUQ image.
image
Axial CECT in the same patient demonstrates a peculiar twist of blood vessels image supplying the constricted segments of bowel.
image
Axial CECT shows a left paraduodenal hernia with a cluster of bowel image between the pancreas and stomach.
image
Small bowel follow through shows a cluster of jejunal bowel loops image that seem to lie within a confining sac, characteristic of a left paraduodenal hernia.
image
Axial CECT of LUQ shows a cluster of moderately dilated jejunal segments in the left upper and mid abdomen. Note the significantly dilated bowel image near the pancreatic body, displacing the stomach ventrally.
image
Axial CECT again shows clustered jejunal segments in the left upper and mid abdomen. Note the subtle crowding and distortion of the mesenteric vessels as they enter and leave the hernia sac image.
image
Axial CECT shows a left paraduodenal hernia image with inward-directed mesenteric vessels.
image
Axial CECT shows a left paraduodenal hernia image with a sac of bowel behind the stomach and inward-directed, engorged mesenteric vessels.
image
Axial CECT shows a sac of dilated bowel image with dilated, distorted mesenteric vessels.
image
Axial CECT shows a right paraduodenal hernia image with the dilated jejunum and its mesenteric vessels twisted and displaced. (Courtesy D. Meyers, MD.)
image
Axial CECT shows dilation of SB loops limited to L hypogastric region. Note ovoid cluster of mildly dilated jejunal segments image with distorted, inward-directed mesenteric vessels interposed between pancreatic body and stomach, in keeping with a paraduodenal hernia.

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