| Intestinal atresia | |
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| Radiograph with double bubble sign indicating duodenal atresia | |
| Specialty | Gastroenterology, surgery  |
Intestinal atresia is any congenital malformation of the structure of the intestine that causes bowel obstruction. The malformation can be a narrowing (stenosis), absence or malrotation of a portion of the intestine. These defects can either occur in the small or large intestine.
The most prominent symptom of intestinal atresia is bilious vomiting soon after birth. [1] This is most common in jejunal atresia. [2] Other features include abdominal distension and failure to pass meconium. The distension is more generalised the further down the bowel the atresia is located and is thus most prominent with ileal atresia. [1] [2] Inability to pass stool is most common with duodenal or jejunal atresia; [2] if stool is passed, it may be small, mucus-like and grey. [1] Occasionally, there may be jaundice, which is most common in jejunal atresia. [2] Abdominal tenderness or an abdominal mass are not generally seen as symptoms of intestinal atresia. Rather, abdominal tenderness is a symptom of the late complication meconium peritonitis. [1]
Before birth, excess amniotic fluid (polyhydramnios) is a possible symptom. This is more common in duodenal and oesophageal atresia. [1]
The most common cause of non-duodenal intestinal atresia is a vascular accident in utero that leads to decreased intestinal perfusion and ischemia of the respective segment of bowel. [3] This leads to narrowing, or in the most severe cases, complete obliteration of the intestinal lumen.[ citation needed ]
In the case that the superior mesenteric artery, or another major intestinal artery, is occluded, large segments of bowel can be entirely underdeveloped (Type III). Classically, the affected area of bowel assumes a spiral configuration and is described to have an "apple peel" like appearance; this is accompanied by lack of a dorsal mesentery (Type IIIb). [ citation needed ]
An inherited form – familial multiple intestinal atresia – has also been described. This disorder was first reported in 1971. [4] It is due to a mutation in the gene TTC7A on short arm of chromosome 2 (2p16). It is inherited as an autosomal recessive gene and is usually fatal in infancy. Ileal atresia can also result as a complication of meconium ileus.[ citation needed ]
A third of infants with intestinal atresia are born prematurely [1] or with low birth weight. [2]
Intestinal atresias are often discovered before birth; either during a routine sonogram which shows a dilated intestinal segment due to the blockage, or by the development of polyhydramnios (the buildup of too much amniotic fluid in the uterus). These abnormalities are indications that the fetus may have a bowel obstruction which a more detailed ultrasound study can confirm. [5] Infants with stenosis instead of atresia are often not discovered until several days after birth. [1]
Some fetuses with bowel obstruction have abnormal chromosomes. An amniocentesis is recommended because it can determine not only the sex of the baby, but whether or not there is a problem with the chromosomes.[ citation needed ]
If not diagnosed in utero, infants with intestinal atresia are typically diagnosed at day 1 or day 2 after presenting with eating problems, vomiting, and/or failure to have a bowel movement. [3] Diagnosis can be confirmed with an X-ray, and typically followed with an upper gastrointestinal series, lower gastrointestinal series, and ultrasound. [5] [3]
Intestinal atresia may be classified by its location. Patients may have intestinal atresia in multiple locations. [6]
Malformations may also occur along multiple portions of the intestinal tract; for instance a malformation that occurs along or spans the length of the jejunum and the ileum is termed jejunoileal atresia. [5] [3]
Intestinal atresia can also by classified by the type of malformation. [8] The classification system by Bland-Sutton and Louw and Barnard (1955) [9] initially divided them into three types. [8] [5] This was later expanded to five by Zerella and Grosfeld et al. [2]
In type I, there is a wall (septum) or membrane at some point in the bowel, leading to dilation of the bowel on the nearer side and a collapse of the bowel on the latter side. Bowel length is not usually affected in this type. [1]
In type II, there is a gap in the bowel, and either end of the remaining intestine is closed off and connected to the other by a fibrous cord that runs along the edge of the mesentery. The mesentery remains intact. [1]
Type IIIa is similar to type II, but the mesentery is defective (there is a V-shaped gap), [2] and the bowel length may be shortened. [1]
In type IIIb, also known as the "apple peel" or "Christmas tree" deformity, the atresia affects the jejunum, and the intestine is often malrotated with most of the mesenteric arteries absent. The remaining ileum, which is of varying length, survives on a single mesenteric artery, which it is twisted around in a spiral form. [1] The term apple-peel intestinal atresia is generally reserved for when it affects the jejunum, [10] [11] while Christmas tree intestinal atresia is used if it affects the duodenum. It may affect both, however. [6]
Type IV involves a combination of all the other types and takes the appearance of a string of sausages. The length of the bowel is always shortened, but the last part of the ileum is usually not affected, as in type III. [1] This type usually affects the nearest end of the jejunum, but the far end of the ileum may instead be affected. [2]
Fetal and neonatal intestinal atresia are treated using laparotomy after birth. If the area affected is small, the surgeon may be able to remove the damaged portion and join the intestine back together. In instances where the narrowing is longer, or the area is damaged and cannot be used for period of time, a temporary stoma may be placed.[ citation needed ]
The infant is usually given intravenous fluid hydration, and a nasogastric or orogastric tube may be used to aspirate the contents of the stomach. The nutritional administration is maintained after surgery until the bowel can resume normal function. [1]
Prognosis is usually good if treated with surgery in infancy. The main factor in mortality is the availability of care and appropriate parenteral nutrition after surgery until the bowel can resume normal function. [1]
The most common complication is pseudo-obstruction at the site of surgery due to pre-existing intestinal dysmotility. This can usually only be treated by non-surgical methods. [1]
If the atresia is not treated, the bowel may become perforated or ischemic. This can lead to abdominal tenderness and meconium peritonitis, which can be fatal. [1]
Intestinal atresia occurs in around 1 in 3,000 births in the United States. [1] The most common form of intestinal atresia is duodenal atresia. It has a strong association with Down syndrome. [12] The second-most common type is ileal atresia. 95% of congenital jejunoileal obstructions are atresias; only 5% are stenoses. [2]
Prevalence of jejunoileal atresia is 1 to 3 in 10,000 live births. It is weakly associated with cystic fibrosis, intestinal malrotation, and gastroschisis. [3]
The frequencies of each type from Louw and Barnard's classification are as follows: [1] [13] [2]
Ileal atresia was first described in 1684 by Goeller. In 1812, Johann Friedrich Meckel reviewed the topic and speculated on an explanation. In 1889, English surgeon John Bland-Sutton proposed a classification system for intestinal atresia and suggested that it occurs at areas that are obliterated as part of normal development. In 1900, Austrian physician Julius Tandler first put forward the theory that it may be caused by lack of recanalisation during development. [2]
The vascular ischemic cause of non-duodenal atresia was confirmed by Louw and Barnard in 1955 and was repeated in later studies. It had first been proposed by N. I. Spriggs in 1912. [2]
The gastrointestinal tract is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines. Food taken in through the mouth is digested to extract nutrients and absorb energy, and the waste expelled at the anus as feces. Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines.
The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum. Its main function is to absorb vitamin B12, bile salts, and whatever products of digestion that were not absorbed by the jejunum.
The jejunum is the second part of the small intestine in humans and most higher vertebrates, including mammals, reptiles, and birds. Its lining is specialised for the absorption by enterocytes of small nutrient molecules which have been previously digested by enzymes in the duodenum.
The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion. The small intestine is about 18 feet long and folds many times to fit in the abdomen. Although it is longer than the large intestine, it is called the small intestine because it is narrower in diameter.
The mesentery is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines, among other functions.
A Meckel's diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the omphalomesenteric duct. It is the most common malformation of the gastrointestinal tract and is present in approximately 2% of the population, with males more frequently experiencing symptoms.
Enteric duplication cysts, sometimes simply called duplication cysts, are rare congenital malformations of the gastrointestinal tract. They most frequently occur in the small intestine, particularly the ileum, but can occur anywhere along the gastrointestinal tract. They may be cystic or tubular in conformation.
Colic in horses is defined as abdominal pain, but it is a clinical symptom rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract. The most common forms of colic are gastrointestinal in nature and are most often related to colonic disturbance. There are a variety of different causes of colic, some of which can prove fatal without surgical intervention. Colic surgery is usually an expensive procedure as it is major abdominal surgery, often with intensive aftercare. Among domesticated horses, colic is the leading cause of premature death. The incidence of colic in the general horse population has been estimated between 4 and 10 percent over the course of the average lifespan. Clinical signs of colic generally require treatment by a veterinarian. The conditions that cause colic can become life-threatening in a short period of time.
Intestinal malrotation is a congenital anomaly of rotation of the midgut. It occurs during the first trimester as the fetal gut undergoes a complex series of growth and development. Malrotation can lead to a dangerous complication called volvulus. Malrotation can refer to a spectrum of abnormal intestinal positioning, often including:
In human anatomy, the superior mesenteric artery (SMA) arises from the anterior surface of the abdominal aorta, just inferior to the origin of the celiac trunk, and supplies blood to the intestine from the lower part of the duodenum through two-thirds of the transverse colon, as well as the pancreas.
The intestinal arteries arise from the convex side of the superior mesenteric artery. They are usually from twelve to fifteen in number, and are distributed to the jejunum and ileum.
Bowel infarction or gangrenous bowel represents an irreversible injury to the intestine resulting from insufficient blood flow. It is considered a medical emergency because it can quickly result in life-threatening infection and death. Any cause of bowel ischemia, the earlier reversible form of injury, may ultimately lead to infarction if uncorrected. The causes of bowel ischemia or infarction include primary vascular causes and other causes of bowel obstruction.
Vasa recta are straight capillaries coming off from arcades in the mesentery of the jejunum and ileum, and heading toward the intestines.
Duodenal atresia is the congenital absence or complete closure of a portion of the lumen of the duodenum. It causes increased levels of amniotic fluid during pregnancy (polyhydramnios) and intestinal obstruction in newborn babies. Newborns present with bilious or non-bilous vomiting within the first 24 to 48 hours after birth, typically after their first oral feeding. Radiography shows a distended stomach and distended duodenum, which are separated by the pyloric valve, a finding described as the double-bubble sign.
Jejunoileal bypass (JIB) was a surgical weight-loss procedure performed for the relief of morbid obesity from the 1950s through the 1970s in which all but 30 cm (12 in) to 45 cm (18 in) of the small bowel were detached and set to the side.
Megaduodenum is a congenital or acquired dilation and elongation of the duodenum with hypertrophy of all layers that presents as a feeling of gastric fullness, abdominal pain, belching, heartburn, and nausea with vomiting sometimes of food eaten 24 hours prior.
The development of the digestive system in the human embryo concerns the epithelium of the digestive system and the parenchyma of its derivatives, which originate from the endoderm. Connective tissue, muscular components, and peritoneal components originate in the mesoderm. Different regions of the gut tube such as the esophagus, stomach, duodenum, etc. are specified by a retinoic acid gradient that causes transcription factors unique to each region to be expressed. Differentiation of the gut and its derivatives depends upon reciprocal interactions between the gut endoderm and its surrounding mesoderm. Hox genes in the mesoderm are induced by a Hedgehog signaling pathway secreted by gut endoderm and regulate the craniocaudal organization of the gut and its derivatives. The gut system extends from the oropharyngeal membrane to the cloacal membrane and is divided into the foregut, midgut, and hindgut.
Neonatal bowel obstruction (NBO) or neonatal intestinal obstruction is the most common surgical emergency in the neonatal period. It may occur due to a variety of conditions and has an excellent outcome based on timely diagnosis and appropriate intervention.
Intestine transplantation is the surgical replacement of the small intestine for chronic and acute cases of intestinal failure. While intestinal failure can oftentimes be treated with alternative therapies such as parenteral nutrition (PN), complications such as PN-associated liver disease and short bowel syndrome may make transplantation the only viable option. One of the rarest type of organ transplantation performed, intestine transplantation is becoming increasingly prevalent as a therapeutic option due to improvements in immunosuppressive regimens, surgical technique, PN, and the clinical management of pre and post-transplant patients.
Intestinal bypass is a bariatric surgery performed on patients with morbid obesity to create an irreversible weight loss, when implementing harsh restrictions on the diets have failed. Jejunocolic anastomosis was firstly employed. Nonetheless, it led to some unexpected complications such as severe electrolyte imbalance and liver failure. It was then modified to jejunoileal techniques. Viewed as a novel form of treatment for obesity, many intestinal bypass operations were carried out in the 1960s and 1980s. Significant weight loss was observed in patients, but this surgery also resulted in several complications, for instance, nutritional deficiencies and metabolic problems. Due to the presence of surgical alternatives and anti-obesity medications, intestinal bypass is now rarely used.
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