Surgical Disease of the Stomach and Duodenum in Infants and Children

Summary of the Document: Surgical Disease of the Stomach and Duodenum in Infants and Children

This document explores the various surgical diseases affecting the stomach and duodenum in pediatric patients, covering congenital anomalies, acquired conditions, their clinical presentation, diagnosis, and management. Below is a concise summary of each section:

1. Embryology

Stomach development: Occurs during the 4th week of gestation, with rapid growth and rotation forming the greater and lesser curves.
Duodenum development: Arises from the foregut-midgut junction and undergoes obliteration and recanalization by the 11th week. Errors can lead to small bowel obstructions.
Malrotation: Occurs in 1 in 500 births, with a high risk of volvulus, making early diagnosis crucial.

2. Prenatal Diagnosis

Fetal stomach: Visible on ultrasound by 9 weeks, with abnormalities like duodenal atresia often identified between 20 and 25 weeks gestation.
Polyhydramnios: Associated with duodenal atresia, frequently related to trisomy 21 and other congenital abnormalities.

3. Congenital Lesions

Enteric Duplication: Can occur along the GI tract, often asymptomatic or causing obstruction, diagnosed via prenatal imaging or enteric contrast studies. Surgical excision is the main treatment.
Gastric Volvulus: A rare pediatric condition, with acute forms presenting in early childhood. Requires urgent surgical intervention.
Hiatal Hernia: Classified into types I-IV, often associated with anomalies like trisomy 21. Surgical correction via fundoplication is typical.
Agastria and Microgastria: Rare underdevelopment or absence of the stomach, often managed medically or surgically with feeding jejunostomies.
Congenital Gastric Outlet Obstruction: Often due to pyloric atresia, requiring surgical intervention like pyloroplasty or gastroduodenostomy.

4. Duodenal Lesions

Duodenal Atresia: Commonly associated with Down syndrome, presents as nonbilious emesis and is diagnosed with the characteristic “double bubble” sign on ultrasound. Managed surgically via duodenoduodenostomy.
Annular Pancreas: Encircles the duodenum, causing obstruction. Treatment involves bypassing the obstruction with duodenoduodenostomy.
Preduodenal Portal Vein: A rare anomaly that may obstruct the duodenum, managed surgically by bypassing the obstruction.

5. Acquired Lesions

Hypertrophic Pyloric Stenosis (HPS): The most common cause of nonbilious vomiting in infants, treated with pyloromyotomy.
Foreign Bodies and Bezoars: Often requires endoscopic removal or, in severe cases, surgical excision.
Gastric Perforation: Often associated with conditions like necrotizing enterocolitis (NEC) or iatrogenic causes, requiring prompt surgical intervention.

6. Tumors

Gastric Tumors: Extremely rare in children, treatment usually involves surgical resection.
Gastric Lymphoma and Stromal Tumors: Managed based on adult treatment protocols due to the rarity in pediatric populations.

7. Superior Mesenteric Artery (SMA) Syndrome

Etiology: Compression of the duodenum between the SMA and aorta, often following rapid weight loss. Managed conservatively or with surgery in severe cases.

8. Paraduodenal Hernia

Most common congenital internal hernia, due to incomplete midgut rotation. May require surgical repair to prevent bowel strangulation.

9. Inflammatory Bowel Disease (IBD)

Gastroduodenal Crohn’s Disease: Affects 0.5-4% of pediatric patients with Crohn’s, requiring a combination of immunomodulatory therapy and surgery for strictures.

1. Embryology of the Stomach and Duodenum

1.1 Stomach Development

Timeline: The stomach begins forming during the 4th week of gestation.
Process:
- The proximal foregut dilates to become the stomach.
- The posterior wall of the stomach grows faster than the anterior wall, forming the greater and lesser curves of the stomach.
- The stomach undergoes rotation around both longitudinal and anteroposterior (AP) axes:
  - Longitudinal axis rotation: Brings the pylorus (caudal part) to the right and superiorly.
  - AP axis rotation: Moves the fundus (cephalic part) to the left and inferiorly.

1.2 Duodenum Development

Origin: The duodenum arises at the junction between the foregut and midgut.
Lumen Obliteration:
- By the 5th week of gestation, the lumen of the duodenum is obliterated due to the proliferation of epithelial cells.
- Recanalization occurs by the 8th to 11th week via vacuolization, restoring the lumen.
Errors in Recanalization:
- Failure of recanalization can result in proximal small bowel obstruction, such as duodenal atresia.

1.3 Rotation and Final Positioning

Midline to Retroperitoneum: Between the 5th and 11th week, the duodenum shifts from a freely mobile, midline structure to its final position in the upper retroperitoneum.
Relationship with the Pancreas:
- The pancreas forms from the dorsal and ventral pancreatic buds (originating from the endoderm near the duodenum).
- The ventral pancreas rotates around the duodenum and fuses with the dorsal pancreas, a process that coincides with the rotation and final positioning of the duodenum, forming the typical C-shaped loop.

1.4 Malrotation

Incidence: Malrotation or nonrotation of the intestines occurs in approximately 1 in 500 live births.
Complications:
- Malrotation predisposes the intestines to volvulus (twisting), which can lead to intestinal infarction.
- Diagnosis: Infants presenting with bilious emesis should be suspected of having malrotation, which is confirmed via an upper gastrointestinal (UGI) contrast study. The study will show the abnormal position of the ligament of Treitz (crossing left of midline) and the C-loop of the duodenum.

2. Prenatal Diagnosis

2.1 Visualization of the Fetal Stomach

Timeline: The fetal stomach becomes visible on a prenatal ultrasound by 9 weeks of gestation as a cystic structure in the left upper quadrant.
Bowel Appearance: The fetal bowel appears uniformly echogenic (bright on ultrasound) until the third trimester when meconium-filled large bowel becomes more prominent.

2.2 Identifying Abnormalities

Abnormal Cystic Structures: Proximal obstructions, such as duodenal atresia, can be identified on ultrasound or MRI between 20 and 25 weeks. These abnormalities may appear as cystic structures.
Polyhydramnios:
- Polyhydramnios (excess amniotic fluid) often occurs in conditions like duodenal atresia because the fetus cannot swallow or absorb enough amniotic fluid.
- This is an important marker for prenatal detection of foregut obstructions.

2.3 Associated Anomalies

Rate of Association: Many congenital anomalies of the stomach and duodenum are associated with other abnormalities.
- Example: Duodenal atresia is associated with anomalies in 50% of cases, most notably with trisomy 21 (Down syndrome), malrotation, and skeletal and gastrointestinal abnormalities.
Further Evaluation: Prenatal diagnosis of foregut pathology should trigger evaluation for associated anomalies (e.g., echocardiograms for cardiac defects in suspected Down syndrome cases).

3. Congenital Lesions of the Stomach and Duodenum

3.1 Enteric Duplication Cysts

Incidence and Etiology:

Enteric duplications occur anywhere along the gastrointestinal tract. Gastric and duodenal duplications represent approximately 15% of all cases.
Theories explaining their development include:
- Persistent fetal enteric diverticula.
- Incomplete recanalization of the duodenum during fetal development.
- The split notochord theory, involving abnormal adhesions between ectoderm and endoderm, leading to herniation and local duplication of the gut.
Duplications can be saccular or tubular and are typically located on the mesenteric side of the intestinal segment. They may communicate with the adjacent bowel lumen and contain smooth muscle and mucosal lining.

Presentation and Diagnosis:

Two-thirds of cases are diagnosed within the first year of life, while others may remain asymptomatic until adulthood.
Symptoms arise due to mass effect as the duplication enlarges, often causing:
- Abdominal pain or obstruction from compression of adjacent structures.
- Gastric outlet obstruction due to duplications in the stomach or duodenum.
- Approximately half of duplications contain gastric mucosa, which can lead to ulceration and gastrointestinal bleeding.
- Rarely, pancreatitis or perforation can result from peptic ulceration in duodenal duplications.
- In rare cases, malignancy has been reported within enteric duplications.

Diagnostic Tools:

Prenatal diagnosis using ultrasound or MRI can detect duplications, especially if they cause a mass effect.
Postnatal imaging includes enteric contrast studies, which can identify the duplications and assess for associated anomalies like cardiac, pulmonary, or spinal defects【67:0†source】【67:1†source】.

Management:

Surgical excision is the main treatment for enteric duplication cysts.
- Symptomatic patients or those diagnosed prenatally may require surgery within the first 6 months of life.
- Asymptomatic older patients with incidental findings should undergo elective surgery due to the risk of complications.
Surgical approach: Either open or laparoscopic excision is performed, ensuring preservation of the common blood supply with adjacent bowel.
- Duodenal duplications can be particularly challenging due to their proximity to hepatobiliary and pancreatic structures.
- In difficult cases, options include mucosal stripping, cyst excision, or Roux-en-Y cyst-jejunostomy【67:2†source】.
Endoscopy: Rarely used, but it may be employed if the lesion involves the upper GI tract.

3.2 Gastric Volvulus

Incidence and Etiology:

Gastric volvulus is a rare but significant condition in the pediatric population, with only 581 cases described over 78 years.
It typically results from the failure of the stomach's normal anchoring mechanisms, which include the gastrocolic, gastrosplenic, and gastrohepatic ligaments. If these ligaments are absent, lax, or disrupted, the stomach is at risk of rotating.
Volvulus can also occur secondary to neoplasms, intestinal malrotation, or abnormal development of nearby structures such as the diaphragm, spleen, or transverse colon【71:0†source】【71:3†source】.

Types:

Organoaxial Volvulus: This occurs when the stomach rotates along its longitudinal axis between the esophagogastric junction and the pylorus. The greater curvature of the stomach ends up superior to the lesser curvature, resulting in an "upside-down" stomach.
Mesenteroaxial Volvulus: Here, the rotation occurs along the anterior-posterior axis, positioning the pylorus and antrum superior to the esophagogastric junction.
Rare cases involve rotation along both planes【71:0†source】.

Presentation and Diagnosis:

Acute gastric volvulus generally affects children under 5 years old and presents with non-bilious vomiting, epigastric pain, abdominal distension, respiratory distress, and, in severe cases, hematemesis.
In the chronic form, symptoms may be more subtle and intermittent, including feeding intolerance and respiratory distress in infants under 1 year old.
Diagnosis can be suggested by plain radiographs, showing a dilated stomach above the diaphragm. Definitive diagnosis is achieved with an upper GI (UGI) contrast study, which reveals the abnormal positioning of the stomach based on the axis of rotation【71:0†source】【71:0†source】.

Management:

Acute gastric volvulus is considered a life-threatening emergency requiring immediate intervention. Management begins with fluid resuscitation and gastric decompression via a nasogastric or orogastric tube. Surgery aims to reduce the volvulus and fix the stomach in place (gastropexy) while addressing any underlying anatomical abnormalities.
Chronic gastric volvulus can sometimes be managed non-surgically, with techniques such as positioning the child in a prone or right lateral decubitus position after feeding. However, in the United States, surgical management (gastropexy or gastrostomy tube placement) is the preferred treatment【71:0†source】【71:0†source】.

3.3 Hiatal Hernia

Incidence and Etiology:

Congenital hiatal hernia is a rare condition, accounting for less than 5% of all hiatal hernias.
It can occur as part of syndromes involving intestinal malrotation, microgastria, or trisomy 21.
Hiatal hernias are classified into four types:
- Type I (sliding): Involves the herniation of the gastric cardia into the thoracic cavity.
- Type II (paraesophageal): The gastroesophageal junction remains in the normal position, but the fundus herniates alongside the esophagus.
- Type III: Both the gastroesophageal junction and the gastric fundus herniate into the thoracic cavity.
- Type IV: Herniation of additional abdominal organs (e.g., colon, spleen, or omentum) through the hiatus【75:0†source】.

Presentation and Diagnosis:

Hiatal hernia frequently presents with vomiting and is commonly associated with gastroesophageal reflux disease (GERD).
Respiratory distress may accompany gastrointestinal symptoms in up to 70% of patients with types III and IV hernias.
Diagnosis is often suggested by chest X-rays and confirmed by upper gastrointestinal (UGI) contrast studies or CT scans【75:1†source】【75:0†source】.

Management:

Surgical management is the treatment of choice for congenital hiatal hernias.
Surgery involves the reduction of the herniated stomach and gastroesophageal junction into the abdominal cavity and the repair of the hiatus, often with fundoplication.
Efforts are made to excise the hernia sac to prevent future complications, as the sac may tether intra-abdominal contents and prevent reduction.
The repair may be done laparoscopically or through an open approach, and the defect is typically closed without the use of biologic or mesh material【75:1†source】【75:0†source】.

3.4 Agastria and Microgastria

3.4.1 Agastria

Incidence and Etiology:

Agastria is a rare congenital condition marked by the complete absence of the stomach. It is at the extreme end of the microgastria spectrum.
Associated with multiple congenital anomalies, including asplenia, esophageal atresia, intestinal malrotation, cardiac defects, and renal malformations【79:0†source】.

3.4.2 Microgastria

Incidence and Etiology:

Microgastria is defined by an underdeveloped stomach, with only 63 reported cases.
It is frequently associated with other anomalies, such as asplenia, cardiac defects, and limb irregularities. It can also present alongside esophageal atresia and intestinal malrotation【79:0†source】.

Presentation and Diagnosis:

The small stomach leads to feeding intolerance, frequent emesis, and failure to thrive. Other symptoms include gastroesophageal reflux and recurrent respiratory infections due to aspiration.
Diagnosis is confirmed by an upper gastrointestinal (UGI) study, showing a small tubular stomach and possibly a dilated esophagus【79:0†source】.

Management:

Initial treatment includes small-volume nasogastric feeds and medical control of associated reflux.
Failure of medical management leads to long-term complications, including poor growth and dumping syndrome.
Surgical management may involve the creation of a gastrojejunostomy or a Roux-en-Y feeding jejunostomy. These interventions aim to improve nutrition and growth but have limited success【79:0†source】.

3.5 Congenital Gastric Outlet Obstruction

Incidence and Etiology:

Congenital gastric outlet obstruction is a rare condition, and pyloric atresia is one of the primary causes, occurring in 1 in 100,000 births.
Pyloric atresia is categorized into three types:
- Type I: A luminal web or membrane obstructs the gastric outlet.
- Type II: A complete atresia separated by a fibrous band.
- Type III: A complete separation with a resultant gap.
Approximately 40% of pyloric atresia cases are associated with other congenital conditions such as intestinal atresia or epidermolysis bullosa【83:0†source】【83:1†source】.

Presentation and Diagnosis:

Infants with congenital gastric outlet obstruction typically present with non-bilious vomiting in the neonatal period.
Prenatal diagnosis is possible as early as 24 weeks’ gestation, when ultrasound or MRI may detect a dilated stomach and polyhydramnios.
After birth, a plain radiograph can show a dilated stomach with minimal air distally, and diagnosis is confirmed with an upper gastrointestinal (UGI) study【83:0†source】.

Management:

Initial management includes gastric decompression using a nasogastric or orogastric tube and fluid resuscitation to correct electrolyte imbalances.
Surgical options depend on the type of obstruction:
- Type I (web or membrane): Treated with excision of the membrane and Heineke-Mikulicz pyloroplasty if the obstruction is near the pylorus.
- Type II: Requires resection of the obstructed segment and the creation of a gastroduodenostomy.
- Type III: Managed with gastrogastrostomy or gastroduodenostomy to bypass the obstruction【83:0†source】.

4. Duodenal Lesions

4.1 Duodenal Atresia

Incidence and Etiology:

Duodenal atresia occurs in about 1 in 10,000 live births. It was first described by Ladd in 1931.
The condition is caused by a failure of recanalization during the solid cord stage of the duodenum, which results in duodenal obstruction.
It is often associated with other congenital anomalies, particularly Down syndrome (30% of cases). Other associated anomalies include cardiac and renal defects.

Types:

Type I: The most common type (~ two-thirds of cases). Involves an obstructing web within an otherwise intact duodenal wall. A variant called the "windsock" deformity can occur when the web balloons intraluminally.
Type II: The proximal and distal ends of the duodenum are separated by a fibrous cord.
Type III: The most severe form, with a complete separation of the proximal and distal ends of the duodenum, often accompanied by a mesenteric defect【55:9†source】.

Presentation and Diagnosis:

Double bubble sign: Characteristic feature seen on prenatal ultrasound or postnatal abdominal X-ray, showing dilation of the stomach and first part of the duodenum.
Prenatal ultrasound often shows polyhydramnios in over 50% of cases, as the fetus cannot absorb sufficient amniotic fluid.
The majority of infants present with bilious vomiting and feeding intolerance shortly after birth【55:9†source】【55:2†source】.

Management:

Initial management includes nasogastric decompression and fluid resuscitation to correct electrolyte imbalances.
Surgical intervention typically involves a duodenoduodenostomy, where the duodenum is reconnected. Care must be taken to avoid injury to the common bile duct or pancreatic duct.
Post-operative care focuses on restoring normal feeding and monitoring for complications【55:9†source】.

4.2 Annular Pancreas

Incidence and Etiology:

Annular pancreas is a rare congenital anomaly where pancreatic tissue encircles the second part of the duodenum, leading to duodenal obstruction.
It results from the failure of the ventral pancreatic bud to rotate normally during embryonic development.
The condition is often associated with other anomalies like Down syndrome, duodenal atresia, and imperforate anus【55:4†source】【55:5†source】.

Presentation and Diagnosis:

Asymptomatic cases are possible, but when symptoms occur, they include vomiting, feeding intolerance, and sometimes bilious emesis depending on the site of obstruction.
Double bubble sign may be visible on imaging, though annular pancreas is often diagnosed intraoperatively due to its similar presentation to duodenal atresia【55:4†source】.

Management:

Surgical intervention is required to bypass the obstruction, often via duodenoduodenostomy. The pancreatic tissue is left intact to prevent damage to the biliary drainage system【55:5†source】.

4.3 Preduodenal Portal Vein

Incidence and Etiology:

Preduodenal portal vein is a rare anomaly where the portal vein crosses anteriorly to the duodenum instead of posteriorly, potentially leading to duodenal obstruction.
It was first described in 1921 and is thought to occur due to the abnormal development of the vitelline veins.
During 6 weeks of gestation, two parallel vitelline veins are connected by two extrahepatic branches: a cephalad branch (posterior) and a caudal branch (anterior) to the duodenum. Aberrant regression of these veins can result in an anteriorly located portal vein.

Presentation and Diagnosis:

Patients may remain asymptomatic, or they may present with symptoms of duodenal obstruction.
A “double bubble” sign can appear on imaging, indicative of duodenal obstruction. The differential diagnosis includes duodenal web, annular pancreas, and other conditions that may present similarly.

Management:

The management is similar to other pediatric duodenal obstructions. This includes fluid resuscitation and nasogastric or orogastric decompression.
Surgical correction involves bypassing the obstruction with a duodenoduodenostomy while leaving the portal vein intact to avoid damage to the biliopancreatic drainage system【59:0†source】【59:2†source】.

5. Acquired Lesions

5.1 Hypertrophic Pyloric Stenosis (HPS)

Incidence and Etiology:

Hypertrophic pyloric stenosis (HPS) is the most common cause of non-bilious vomiting in infants and accounts for an acquired gastric outlet obstruction.
It has an incidence of approximately 2 per 1,000 live births, with a male predominance of 4:1. HPS is more common in Caucasian and Hispanic populations compared to African Americans and Asians.
The exact cause is unknown, but there is a familial predisposition. Environmental factors such as erythromycin exposure have been associated with an increased risk of HPS.

Pathophysiology:

HPS is characterized by progressive hypertrophy of the pyloric muscle, causing narrowing of the pyloric canal.
Dysregulation of the nitric oxide (NO) pathway and loss of smooth muscle relaxation has been implicated in the pathogenesis of HPS. Additionally, abnormalities in hormonal regulation, including gastrin, cholecystokinin, and somatostatin, have been suggested as contributing factors【91:0†source】【91:1†source】.

Presentation and Diagnosis:

Projectile non-bilious vomiting typically begins around 3 to 6 weeks of age. The infant may exhibit signs of dehydration, weight loss, and poor feeding.
A characteristic finding is a palpable "olive-shaped" mass in the right upper quadrant of the abdomen.
Diagnosis is confirmed by abdominal ultrasound, showing a pyloric muscle thickness greater than 3.5 mm and a pyloric canal length greater than 14 mm【91:2†source】.

Management:

Initial treatment includes fluid resuscitation and correction of electrolyte imbalances, particularly hypochloremic metabolic alkalosis.
The definitive treatment is pyloromyotomy, which can be performed through open surgery or laparoscopic surgery. This involves making an incision in the hypertrophic pyloric muscle to relieve the obstruction.
Postoperatively, most infants can resume feeding within 24 hours, and the prognosis is excellent【91:0†source】【91:4†source】【91:3†source】.

5.2 Foreign Bodies and Bezoars

Incidence and Etiology:

Children frequently present with concerns about ingestion of foreign material. In the majority of cases, foreign body ingestion occurs in the context of upper airway compromise, which may require rapid identification and removal of the object.
Foreign bodies are responsible for significant morbidity in less than 1% of cases, but have been attributed to 1,500 deaths annually in the United States.
Bezoars, which are concretions of ingested foreign and intrinsic materials in the stomach or bowel, are named based on their material:
- Trichobezoar: Composed of hair, often associated with trichotillomania (hair-pulling disorder), particularly in girls.
- Phytobezoar: Made up of fibers, seeds, and vegetable skins.
- Lithobezoar: Composed of rocks and dirt【95:0†source】【95:1†source】.

Presentation and Diagnosis:

Most patients present after a witnessed ingestion event, although symptoms may be minimal. Some foreign bodies, such as button batteries and magnets, require immediate removal due to the risk of severe complications:
- Button batteries can cause electrochemical burns.
- Magnets can lead to pressure necrosis and fistula formation when swallowed in multiples.
Plain radiographs and ultrasonography are useful in identifying the location of the foreign object. In cases involving radiolucent objects or ongoing symptoms, endoscopy may be both diagnostic and therapeutic【95:2†source】【95:2†source】.

Management:

Foreign bodies that are expected to pass through the gastrointestinal tract without obstruction can be safely observed in an outpatient setting. The use of laxatives or cathartics to speed up expulsion is not supported by current evidence.
Foreign bodies located in the proximal gastrointestinal tract can often be removed via flexible or rigid esophagoscopy.
In cases where the object has reached the third portion of the duodenum, a decision between ongoing surveillance and operative removal must be made based on clinical presentation.
Children should be monitored for the development of obstructive or peritoneal symptoms, especially in cases involving bezoars, which may require surgical removal【95:0†source】【95:1†source】.

5.3 Gastric Perforation

Incidence and Etiology:

Gastric perforation in neonates can be either spontaneous or due to underlying conditions such as necrotizing enterocolitis (NEC). It occurs more frequently in preterm infants and can be associated with gastric pneumatosis.
Iatrogenic causes include perforation during endotracheal intubation or nasogastric tube placement. Other contributing factors include the use of steroids or NSAIDs and conditions like atresia, internal hernia, or volvulus, which can lead to gastric overdistension and perforation, especially in gavage-fed infants【99:0†source】.

Presentation and Diagnosis:

Neonates with gastric perforation often present in shock with symptoms such as thrombocytopenia, abdominal distension, feeding intolerance, lethargy, and respiratory distress.
Diagnosis is usually made using plain abdominal radiographs. A lateral decubitus view can show free air and extraluminal air-fluid levels, aiding in diagnosis【99:0†source】.

Management:

The treatment approach depends on the neonate’s overall condition, weight, and associated comorbidities.
- For neonates who cannot tolerate a laparotomy, a bedside drainage procedure (e.g., placing a Penrose drain) can be performed.
- If laparotomy is performed, the surgeon must thoroughly evaluate the stomach and intestines to identify the perforation and ensure the surrounding tissue is viable for repair.
- Repair usually involves debridement of the perforation edges, followed by primary repair and washout.
- In cases of ongoing concerns, the abdomen may be left open with a temporary closure or silo for a second-look laparotomy【99:2†source】.

5.4 Gastric Tumors in Children

Incidence and Etiology:

Gastric tumors are extremely rare in the pediatric population, accounting for less than 0.5% of all gastric cancers.
Tumors that can occur include:
- Gastric lymphoma, often secondary to Helicobacter pylori infection.
- Gastrointestinal stromal tumors (GIST).
- Teratomas, schwannomas, and rhabdomyosarcomas【103:0†source】【103:1†source】.

Presentation and Diagnosis:

Most children with gastric tumors present with nonspecific symptoms, including vague epigastric discomfort, weight loss, poor appetite, and changes in bowel habits, such as nausea and vomiting.
Diagnosis often involves:
- Laboratory evaluation: Can show anemia or other signs of malnutrition.
- Endoscopy: Is the definitive tool for direct visualization, biopsy, and assessment of any potential hemorrhage【103:1†source】.

Management:

The main treatment approach is surgical excision with wide margins.
Prognosis depends on the initial pathology, stage of disease, and response to treatment. As pediatric cases are rare, treatment protocols are often adapted from adult cases【103:1†source】【103:1†source】.

5.5 Superior Mesenteric Artery Syndrome (SMAS)

Incidence and Etiology:

Superior Mesenteric Artery Syndrome (SMAS), also known as Wilkie syndrome, was first described by Carl von Rokitansky in 1842.
It is caused by the compression of the third portion of the duodenum between the aorta and the superior mesenteric artery (SMA), leading to upper gastrointestinal (UGI) obstruction.
The prevalence is estimated at 0.3%, with a higher occurrence in females, typically peaking between the ages of 10 and 18 years.
Factors contributing to SMAS include rapid weight loss seen in patients with eating disorders, hyperthyroidism, or during chemotherapy. It is also associated with orthopedic surgeries, such as scoliosis correction and hip-spica cast application【107:0†source】.

Presentation and Diagnosis:

Symptoms are often nonspecific but may include bilious vomiting, epigastric pain, nausea, and postprandial discomfort. Some patients report symptomatic relief when lying on their stomach or bringing their knees up to their chest, which alters the angle between the aorta and SMA.
Diagnostic tools include:
- Upper GI fluoroscopy, which can reveal duodenal obstruction.
- CT angiography, which is the definitive imaging technique. It measures the aortomesenteric angle, with SMAS defined by an angle less than 22 degrees (normal: 38-65 degrees) and an aortomesenteric distance of less than 8 mm (normal: 10-28 mm)【107:2†source】.

Management:

Conservative management is preferred when there is no need for surgical intervention due to complications like vascular aneurysms or tumors.
- Initial management includes nasogastric decompression and fluid resuscitation.
- Nutritional support is essential, with nasojejunal feeding initiated if possible. In some cases, total parenteral nutrition (TPN) may be required.
If conservative measures fail, surgical procedures like Strong’s procedure (mobilization of the duodenum by dividing the ligament of Treitz) or duodenojejunostomy can relieve the compression【107:2†source】【107:0†source】.

5.6 Paraduodenal Hernia

Incidence and Etiology:

Paraduodenal hernias are the most common type of congenital internal hernia, accounting for approximately 50% of such cases. Internal hernias, unlike external hernias, remain within the thoracoabdominal cavities.
These hernias result from congenital abnormalities in the rotation of the midgut and attachment of the peritoneum.
Incomplete midgut rotation leads to the entrapment of the duodenum in the mesocolon, passing through the Waldeyer fossa at the root of the small bowel mesentery.
Around 75% of paraduodenal hernias occur on the left side, while 25% are found on the right side【111:0†source】【111:5†source】.

Presentation and Diagnosis:

Most patients are asymptomatic, with the hernia often being discovered incidentally during evaluation for other conditions. However, in some cases, intermittent abdominal discomfort, intestinal obstruction, or even strangulation may occur.
Chronic abdominal symptoms with a history of intermittent episodes can suggest the possibility of intermittent obstruction of the herniated intestine.
Cross-sectional imaging, such as CT, is the most sensitive diagnostic tool, especially when performed during a symptomatic episode. Imaging may reveal a closed-loop obstruction and abnormal positioning of small bowel loops within the mesentery【111:0†source】【111:3†source】.

Management:

The treatment of choice is surgical reduction of the herniated bowel and closure of the defect. During surgery, careful examination is needed to assess bowel viability.
Left-sided paraduodenal hernias are usually easier to manage, with simple reduction and closure of the peritoneal defect.
Right-sided paraduodenal hernias can be more challenging, as the herniated contents may be fixed into the retroperitoneum. A lateral-to-medial approach is recommended to avoid injury to the superior mesenteric artery, ileocolic artery, or right colic vein【111:5†source】【111:0†source】.

5.7 Gastroduodenal Crohn's Disease

Incidence and Etiology:

Gastroduodenal Crohn's disease is a less common manifestation of Crohn’s disease, with an incidence of about 0.5% to 4% in pediatric patients.
It typically involves the distal stomach, pylorus, and duodenum. The exact cause of Crohn’s disease remains unclear, but it is thought to involve a combination of genetic and environmental factors, leading to an abnormal immune response that causes chronic inflammation in the gastrointestinal tract【115:1†source】【115:0†source】.

Presentation and Diagnosis:

Patients often present with epigastric pain, nausea, and vomiting, and may have blood-tinged emesis.
Laboratory tests may reveal protein-losing enteropathy and nutritional deficiencies.
Endoscopy remains the primary diagnostic tool, with findings of cobblestoning and non-caseating granulomas upon biopsy, which are characteristic of Crohn's disease【115:0†source】.

Management:

The mainstay of treatment includes immunomodulatory therapy and acid suppression. Helicobacter pylori eradication may be beneficial in some cases.
Initial treatment involves corticosteroids for induction, followed by maintenance with aminosalicylates, immunosuppressants like 6-MP, methotrexate, or TNF inhibitors (such as monoclonal antibodies).
Surgical intervention is reserved for patients with strictures, obstruction, or hemorrhage. Endoscopic balloon dilation may be an option for strictures, while more advanced cases may require duodenal strictureplasty or gastrojejunostomy【115:0†source】【115:0†source】.