Paraduodenal Hernia

Paraduodenal hernias are the most common type of intra-abdominal herniation, and they account for 53% of the reported cases. They are more common in men than in women, with a ratio of about 3 : 1. Approximately 75% occur on the left and involve the paraduodenal fossa of Landzert. This peritoneal pocket is observed at 2% of autopsies. It is located just lateral to the ascending, or fourth, segment of the duodenum, beneath a peritoneal fold elevated by the inferior mesenteric vein and ascending left colic artery. Small bowel loops enter the sac from behind, where the duodenum emerges from its fixed retroperitoneal position. They protrude farther posteriorly and to the left, essentially herniating into the descending mesocolon and distal portion of the transverse mesocolon.

Twenty-five percent of paraduodenal hernias develop on the right side of the abdomen and typically involve the mesentericoparietal fossa of Waldeyer. This abnormal pocket in the jejunal mesentery is found at 1% of autopsies. Its orifice is located immediately behind the superior mesenteric artery and inferior to the transverse segment of the duodenum; however, the peritoneal pocket itself extends to the right and downward, directly in front of the posterior parietal peritoneum. Accordingly, the right paraduodenal hernia can be viewed as small bowel herniation into the ascending mesocolon.

The clinical manifestations of paraduodenal hernias range from intermittent and mild digestive complaints to acute intestinal obstruction. Recurrent periumbilical cramps or postprandial epigastric pain and distention are frequently experienced before the onset of incarceration. Contrast examinations of the gastrointestinal tract are most likely to provide the correct diagnosis during symptomatic periods. After the hernia is reduced spontaneously, however, results of barium studies tend to be negative, and the patient may be mislabeled as psychoneurotic.

The characteristic radiographic features of left paraduodenal hernias have been described by several investigators. A circumscribed, ovoid mass of multiple jejunal loops occupies the left upper quadrant immediately lateral to the ascending duodenum ( Fig. 112-2 ). The hernia indents the posterior gastric wall and depresses the distal transverse colon. Fluoroscopy and serial radiographs reveal a separation of encapsulated loops from the remaining small intestine. Dilation of the involved segments and stasis of barium may also be evident. Because the duodenum is retroperitoneal and the herniated proximal jejunal loops enter the fossa of Landzert posteromedially, only one loop of distal small intestine exits through the hernia orifice. The inferior mesenteric vein and ascending left colic artery lie in the anteromedial border of the left paraduodenal hernia. These findings are best appreciated during laparotomy, but CT scans of the upper abdomen may help demonstrate them before operation.

Left paraduodenal hernia.

A. Graphic illustration of a left paraduodenal hernia depicts loop of small bowel prolapsing ( curved arrow ) through Landzert’s fossa, located behind inferior mesenteric vein and ascending left colic artery ( straight arrow ). Herniated bowel loops are therefore located lateral to the fourth portion of the duodenum. B. Axial CT scan shows a closed loop obstruction of a short segment of proximal jejunum ( arrows ). The mural thickening and mesenteric edema suggest superimposed ischemia.

( A from Martin LC, Merkle EM, Thompson WM: Review of internal hernias: Radiographic and clinical findings. AJR Am J Roentgenol 186:703-717, 2006. Reprinted with permission from the American Journal of Roentgenology.)

Right paraduodenal hernias are manifested as a similar ovoid grouping of several small bowel loops just lateral and inferior to the descending duodenum ( Fig. 112-3 ). They are usually more massive and fixed than those on the left side. Afferent and efferent intestinal loops pass through the hernia orifice, where they are closely apposed and narrowed. Lateral radiographs are particularly useful for demonstrating the retroperitoneal displacement of the hernia contents. Barium enema examination shows that the ascending colon lies lateral to a right paraduodenal hernia, and the cecum retains its normal position.

Right paraduodenal hernia.

A. Graphic illustration of right paraduodenal hernia shows loop of small bowel prolapsing ( arrow ) through Waldeyer’s fossa, behind superior mesenteric artery and inferior to third portion of duodenum ( asterisk ). B. Axial CT scan shows a cluster of jejunal loops ( arrow ) in a closed loop obstruction. Note the poor mural enhancement and edema in the adjacent mesentery, indicating ischemia.

( A from Martin LC, Merkle EM, Thompson WM: Review of internal hernias: Radiographic and clinical findings. AJR Am J Roentgenol 186:703-717, 2006. Reprinted with permission from the American Journal of Roentgenology.)

The superior mesenteric artery and its ileocolic branches are situated in the anterior wall of the right paraduodenal hernia sac. The passage of herniated loops behind these vessels causes arteriographically detectable changes. The jejunal arteries, which normally arise from the left side of the superior mesenteric artery, abruptly reverse direction to the right and course behind the parent vessel to supply the herniated loops in the fossa of Waldeyer.

Operative techniques for the correction of paraduodenal hernias are described elsewhere. Preoperative diagnosis and demonstration of their radiographic anatomy assist the surgeon to better understand the extremely confusing laparotomy findings. Blind division of the hernia sac should be avoided because it carries the risk of injury to the vital mesenteric vessels contained within its wall. It may create a mesenteric defect that could later serve as a potential site for an iatrogenic internal hernia.

Foramen of Winslow Hernia

The lesser sac communicates with the greater peritoneal cavity through the epiploic foramen of Winslow. This small opening can serve as a pathway for protrusion of viscera into the lesser sac, where 8% of all internal hernias occur. The small intestine is the herniated segment in 60% to 70% of cases. The terminal ileum, cecum, and ascending colon are involved in about 25% to 30%. The transverse colon, gallbladder, and omentum account for the remainder. Predisposing factors include an enlarged foramen of Winslow and excessively mobile intestinal loops because of a long mesentery or persistence of the ascending mesocolon. Herniation into the lesser sac may be provoked by a sudden increase in intra-abdominal pressure, like that experienced while lifting heavy weights or during parturition. An elongated right lobe of the liver can also be a contributing factor by directing the mobile intestinal loops toward the foramen of Winslow.

This type of internal hernia usually affects middle-aged patients and is manifested as progressive upper abdominal pain and acute onset of small bowel obstruction. Physical examination usually reveals localized tenderness and distention in the epigastric regions. A helpful sign is the relief of pain with forward bending or in the knee-chest position.

Several radiologic features of hernias through the foramen of Winslow are characteristic:

• 1.
  

  Plain radiographs of the abdomen show bowel loops containing gas within the lesser sac medial and posterior to the stomach, usually in conjunction with markedly dilated proximal small intestine. The right iliac fossa may appear empty if the cecum and ascending colon are the herniated segments.

  
  
• 2.
  

  Upper gastrointestinal examination demonstrates displacement of the stomach to the left and anteriorly because of extrinsic compression by the mass of herniated loops in the lesser sac. The first and second portions of the duodenum may be compressed and deviated to the left side.

  
  
• 3.
  

  Small bowel series show dilation and hyperperistalsis of the intestinal loops that indicate distal mechanical obstruction. Serial radiographs and fluoroscopy can localize the site of obstruction to the right upper abdomen, corresponding to the anatomic location of the foramen of Winslow between the duodenal bulb and the hilum of the liver.

  
  
• 4.
  

  If the herniation involves the cecum and ascending colon, barium enema examination may reveal a tapered narrowing or obstruction near the hepatic flexure.

  
  
• 5.
  

  CT scans of the abdomen show an aberrant position of the bowel loops between the liver, the stomach, and the pancreas ( Fig. 112-4 ). CT is the optimal imaging technique to demonstrate the presence and content of herniations involving the lesser sac.

  
  

  
  

  
  

  

  
  

  
  

  

  
  

  
  

  Foramen of Winslow hernia.

  
  

  A. Graphic illustration of foramen of Winslow hernia shows bowel about to prolapse ( arrow ) into lesser sac, behind hepatoduodenal ligament, the free edge of the lesser omentum. B. CT scan shows small bowel ( arrows ) herniated into the lesser sac, causing a closed loop obstruction. C. Scan obtained several hours later shows that these loops have become ischemic and hemorrhagic.

  
  

  ( A from Martin LC, Merkle EM, Thompson WM: Review of internal hernias: Radiographic and clinical findings. AJR Am J Roentgenol 186:703-717, 2006. Reprinted with permission from the American Journal of Roentgenology.)

  
  
  
  
• 6.
  

  Gallbladder herniation into the lesser sac can be diagnosed when the opacified gallbladder appears elongated and its fundus is malpositioned on the left, indenting the gastric antrum or body of the pancreas. Manual compression of the epigastrium can reduce the hernia if the foramen of Winslow is widely patent. Gallbladder strangulation and perforation in the lesser sac may occur if the condition is not diagnosed and treated promptly.

Besides the foramen of Winslow, there may be other openings for herniation into the lesser sac. For instance, a defect in the gastrohepatic ligament forming the anterior wall of the lesser sac may follow partial gastrectomy. A congenital or acquired defect may also be present in the transverse mesocolon or gastrocolic ligament, which constitutes the floor of the lesser sac. The intestinal loops can prolapse through these openings to occupy the lesser sac or reenter the greater peritoneal cavity by the foramen of Winslow.

Pericecal Hernia

Four peritoneal fossae located in the ileocecal region as well as congenital and acquired defects in the mesentery of the cecum or appendix may lead to development of a pericecal hernia. The various other terms used to classify these hernias (e.g., ileocolic, retrocecal, ileocecal, paracecal) appear to have limited practical value for radiologic differential diagnosis and surgical management.

In a collective review of 467 cases of internal hernia, 13% involved the ileocecal region. The clinical manifestations are usually intermittent episodes of colicky right lower abdominal pain associated with small bowel distention, nausea, and vomiting. Chronic incarceration may produce symptoms compatible with periappendiceal abscess, regional enteritis, or intestinal obstruction caused by adhesions.

In most cases, an ileal segment herniates through a defect in the mesentery of the cecum and occupies the right paracolic gutter. The correct diagnosis may be suggested on plain radiographs of the abdomen ( Fig. 112-5 ), provided the unusual relationship of the ileum to the cecum is recognized in association with small bowel obstruction. More useful are delayed radiographs of a small bowel series or a barium enema examination with retrograde opacification of the terminal ileum. Careful fluoroscopic evaluation and filming in lateral and oblique projections are particularly valuable for the demonstration of the fixed position of the herniated ileal loop posterolateral to the cecum.

Pericecal hernia.

A. Diagram of a pericecal hernia shows a loop of ileum prolapsing ( arrow ) through cecal mesenteric defect, behind and lateral to the cecum, into right paracolic gutter. B. CT scan shows small bowel loops ( arrows ) lateral to the proximal ascending colon.

( A from Martin LC, Merkle EM, Thompson WM: Review of internal hernias: Radiographic and clinical findings. AJR Am J Roentgenol 186:703-717, 2006. Reprinted with permission from the American Journal of Roentgenology.)

Intersigmoid Hernia

Intersigmoid hernias involve the intersigmoid fossa, a peritoneal pouch located between the two loops of the sigmoid colon and its mesentery. This pocket is found at 65% of autopsies.

Intersigmoid hernias are usually reducible and are an incidental finding during laparotomy. Radiologic diagnosis is best made on barium enema studies in which retrograde filling of the small bowel has been achieved. The examination typically shows a portion of jejunum or ileum to be encapsulated between the sigmoid loops ( Fig. 112-6 ).

Intersigmoid hernia.

A. Illustration of an intersigmoid hernia shows bowel protruding ( arrow ) through defect in sigmoid mesocolon to lie posterolateral to sigmoid colon itself. B . A small knuckle of ileum has herniated into the intersigmoid fossa, leading to small bowel obstruction. Notice the small bowel feces sign of the obstructed loop ( arrows ).

( A from Martin LC, Merkle EM, Thompson WM: Review of internal hernias: Radiographic and clinical findings. AJR Am J Roentgenol 186:703-717, 2006. Reprinted with permission from the American Journal of Roentgenology.)

In this context, two similar entities deserve a brief mention:

• 1.
  

  In transmesosigmoid hernias , a defect involving both layers of the sigmoid mesentery allows herniation of the small bowel loops toward the left lower abdomen, posterolateral to the sigmoid colon. The hernia ring is usually a long slit whose fibrous edge is bound by branches of the inferior mesenteric vessels.

  
  
• 2.
  

  In intramesosigmoid hernia , a congenital defect may be present in only one of the constituent leaves of the sigmoid mesentery. The small bowel loops passing through this orifice are incarcerated in a hernia sac, which is formed by separation of medial and lateral leaves of the mesosigmoid.

Radiologic differentiation of these three types of hernias involving the mesosigmoid is often difficult, and in terms of their ultimate surgical management, it is irrelevant.

Transmesenteric Hernia

Approximately 5% to 10% of all internal hernias occur through defects in the mesentery of the small bowel. They have no limiting sac, but their functional significance is similar to that of true internal hernias.

Almost 35% of transmesenteric hernias affect the pediatric age group, in which they constitute the most common type of internal herniation. The underlying mesenteric defects are usually 2 to 5 cm in diameter and located close to the ligament of Treitz or the ileocecal valve. A causal relationship to prenatal intestinal ischemic accidents seems likely because such mesenteric apertures and associated hernias are frequently found in infants with atretic bowel segments. In adults, however, most mesenteric defects are probably the result of previous gastrointestinal operations, abdominal trauma, or intraperitoneal inflammation.

In the absence of a limiting hernia sac, a considerable length of small intestine may protrude through the mesenteric aperture. Volvulus may further complicate the process and cause rapid strangulation and intestinal gangrene. Patients present with severe periumbilical cramps accompanied by hyperactive bowel sounds and progressive distention. A tender abdominal mass, representing the Gordian knot of herniated intestine, may be palpable. Plain radiographs of the abdomen demonstrate a mechanical small bowel obstruction and occasionally show a single, distended closed loop ( Fig. 112-7 ). Small bowel examination may disclose a constriction around the closely approximated afferent and efferent limbs of the herniated intestine. The superior mesenteric arteriogram shows abrupt angulation and displacement of the visceral branches as they pass through the mesenteric defect to supply the herniated loops. These findings signal a surgical emergency, although clinical and radiologic differentiation of the mesenteric hernia from other closed loop obstructions (e.g., small bowel volvulus or entrapment beneath peritoneal adhesions) may be impossible.

Transmesenteric hernia.

A. Coronal, reformatted CT scan shows a closed loop obstruction ( circle ) with clustering of small bowel loops and the small bowel feces sign. B. In a different patient, the obstructed loops converge at the mesenteric defect ( arrow ).

Defects in the mesenteric attachments of the colon are also the potential sites of internal herniation. For example, a congenital or postsurgical opening in the transverse mesocolon permits small bowel loops to herniate into the lesser sac. A somewhat similar situation can be present in cases of congenital persistence of descending mesocolon. A defect in this structure may allow small bowel herniation into the left paracolic gutter, causing medial displacement of the descending colon.

Transomental Hernia

Approximately 1% to 4% of internal hernias occur through defects in the greater omentum. Fewer than 100 cases have been reported from observations made at surgery or autopsy. The hernia orifice is usually a slitlike opening up to 10 cm long, located in the periphery of the greater omentum. Most have a congenital origin, but trauma and inflammation may also produce omental perforations or weak areas. These defects can subsequently serve as potential sites for transomental herniation of the small intestine ( Fig. 112-8 ) and other mobile segments, such as the cecum or sigmoid colon. The clinical and radiologic findings are almost identical to those of transmesenteric hernias.

Transomental hernia.

A. A group of ischemic small bowel loops ( arrows ) shows poor enhancement and mesenteric edema due to a strangulating transomental hernia. B. Note the clustering of small bowel loops ( circle ) at the origin of the hernia.

Retroanastomotic Hernia

Retroanastomotic hernias are a well-recognized and preventable complication of gastrointestinal surgery. They usually develop after partial gastrectomy and gastrojejunostomy. About 75% of cases involve incarceration of the efferent jejunal segment in the retroanastomotic space, which is created during antecolic or retrocolic anastomosis. The herniation is usually from right to left, so that the efferent jejunal loop or an excessively long afferent segment occupies the left upper quadrant of the abdomen. Less commonly, the ileum, the cecum, or the omentum is also involved.

Approximately half of these hernias occur in the first postoperative month, and the others occur within 1 year or several years after surgery. The presenting symptom is cramping abdominal pain, and the signs are those of high small bowel obstruction. The herniated loops are occasionally palpable as a tender mass in the left upper abdomen. These nonspecific findings may be mistaken for gastric outlet obstruction caused by stomal edema, dumping syndrome, or postoperative pancreatitis. Delay in establishing the correct diagnosis may lead to strangulation of the herniated loops; the associated mortality rate is up to 30% for surgically treated cases and almost 100% if the problem is not corrected.

Radiologic diagnosis of a retroanastomotic hernia requires careful fluoroscopic evaluation of the gastrointestinal tract after administration of barium or water-soluble contrast medium. The examination reveals that the site of obstruction is not the gastric stoma but is more distal in either of the anastomotic limbs. Gradual opacification of the partially obstructed efferent loop discloses its abnormal position lateral and posterior to the gastrojejunostomy ( Fig. 112-9 ). The herniated segments of jejunum appear clumped or fixed in the left upper abdomen, usually associated with some degree of dilation and stasis.

Retroanastomotic hernia.

The diagram shows a retrocolic Roux-en-Y gastric bypass procedure. The arrow indicates a loop of small bowel protruding posterior to the enteroenterostomy, in keeping with a retroanastomotic internal hernia.

(From Martin LC, Merkle EM, Thompson WM: Review of internal hernias: Radiographic and clinical findings. AJR Am J Roentgenol 186:703-717, 2006. Reprinted with permission from the American Journal of Roentgenology.)

The diagnosis of afferent loop hernia, which occurs primarily after an antecolic anastomosis, is more difficult. The clinical findings include persistent epigastric pain and tenderness, nonbilious vomiting, and elevated serum amylase level. Contrast studies of the upper gastrointestinal tract show patency of the anastomosis and the efferent loop; however, opacification of the herniated afferent limb may not occur or may be delayed. CT scans or sonograms of the upper abdomen usually disclose the obstructed afferent loop as a fluid-filled and markedly distended tubular structure. Scintigraphy is another diagnostic method for this entity. Radionuclide agents excreted by the biliary tract into the duodenum permit visualization of the dilated afferent loop and the site of obstruction.

Like any other symptomatic internal hernia, hernias involving the retroanastomotic space also require surgical correction. However, this iatrogenic hernia should be prevented during initial gastric operation by the use of a short afferent loop and the closure of the retroanastomotic space with sutures placed between the jejunal mesentery and the transverse mesocolon.

Umbilical Hernia

In infants and children, a patent umbilical ring is a common site of herniation. It often is manifested as a soft, asymptomatic bulge that tends to disappear spontaneously. In some instances, however, the development of umbilical tenderness and obstructive symptoms caused by incarceration necessitate surgical repair. The congenital entity known as an omphalocele is not a true umbilical hernia because the bowel loops never return to the peritoneal cavity during gestation in this disorder.

In adults, umbilical hernias occur predominantly in women with a history of multiple pregnancies and in patients with obesity or with increased abdominal pressure resulting from ascites and chronic bowel distention ( Fig. 112-10 ). The hernia contents are usually the greater omentum and various segments of the small or large intestine. Adhesions often develop between the protruding viscera and the peritoneal sac and cause digestive symptoms and other complications.

Types and locations of hernias.

Herniations through the walls of the abdominal cavity usually involve specific sites of congenital weakness or previous surgical incision.

The clinical diagnosis of an incarcerated umbilical hernia should be suspected when a patient presents with intestinal obstruction and umbilical tenderness, even if there is no obvious bulge on the surface. Radiographs of the abdomen usually show the distended bowel loops and a tumor-like density, the umbilical hernia. A coned-down lateral or cross-table view of the anterior abdominal wall using low peak kilovoltage can be helpful in detecting the presence of omental fat or bowel loops in the umbilical hernia. Barium studies of the small or large intestine can show obstruction or protrusion of gut in the umbilical region. Ultrasound and CT studies of the abdomen establish the diagnosis when they demonstrate a “knuckle” of bowel protruding through an umbilical defect.

Ventral Hernia

The term ventral hernia encompasses several types of herniations through the anterior and lateral aspects of the abdominal wall ( Fig. 112-11 ). Most occur in the midline and emerge through the aponeurosis forming the linea alba. They are referred to as epigastric or hypogastric hernias, depending on their location above or below the umbilicus, respectively. The hernia aperture is often a small, firm defect that allows portions of the greater omentum, properitoneal fat, or a bowel loop to protrude anteriorly. Incarceration and strangulation of the contents may occur frequently and produce symptoms out of proportion to the objective findings. The severity of abdominal pain may simulate a perforating peptic ulcer. The pain of a ventral hernia, however, is aggravated by exertion and associated with focal tenderness of the abdominal wall.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related posts:

Abdominal Calcifications Stomach and Duodenum: Differential Diagnosis Benign Tumors of the Small Bowel Magnetic Resonance Imaging of the Solid Parenchymal Organs Abdominal Trauma Vascular Disorders of the Liver and Splanchnic Circulation

Stay updated, free articles. Join our Telegram channel

Join