Intestinal Atresias, Obstructions, Webs

8/13/2019 Intestinal Atresias, Obstructions, Webs

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History case

A child born in term from the Ist pregnancy with nephropathy,

polyhydramnios. The Apgar score 7-8. Birth weight 3000 gr. For

the first time was fed with breast milk on the 2d day, he sucked actively

but had profuse regurgitations immediately after feedings. On the first

day he had poor stool (green color mucus), the next days stools were

absent. Along the feeding volume increasing the milky vomiting

became more prominent, and the body weight loss occurred.

At the age of 4 days the child is in a poor condition, he is flaccid,

adynamic, the skin turgescence is decreased. The teguments are pale

with cutis marmorata. The respiration is hard without rales. Heart

sounds are softened, the pulse rate is 160 b/min. The abdomen is soft

and hollow. At the gastric probing 60 ml of milk without impurities

were obtained. The rectal ampulla is empty. The body weight at the 4th

day is 2460 gr., blood testspH=7,51, pCO2 -34,6 mm Hg, BE - +4,5,

Hb 180 g/l, Ht 75%, plasma Na+ - 132 mEq/l, plasma K+ - 3,8

mEq/l.


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It is not a lupus !!!


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History case

- Esophageal atresia

- Pediatric hypertrophic pyloric stenosis

- Duodenal atresia (above papil la Fater i).- Jejunoileal atresia.


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Intestinal Atresia, Stenosis,

and Webs

Jalba Alexandru,

MD, PhD,

associate professor

Chisinau 2012

N. Testemitanu State University of Medicine and Pharmacy

Department of Pediatric Surgery, Orthopedics and Anesthesiology


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GI development

The GI tract that looks like this, starts up

as a straight tube consisting of the

foregut,

hindgut and the

midgut.

The midgut will further become theduodenum, the jejuno-ileum and the

proximal colon.

In the course of development the midgut

forms a loop that twists counterclockwise

on itself and fixes like this.

In the course of this rotation the blue

loop becomes the proximal colon, the

yellow part forms the duodenum and the

green one the jejuno-ileum. At the end of

embryogenesis the GI tract looks like in

an adult.


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Duodenal Stenosis and Atresia


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The hepatobiliary system

and pancreas form

during the third week of

gestation, as the second

portion of the duodenum

gives rise to biliary and

pancreatic buds at the

junction of the foregut tothe midgut.

Embryology


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The duodenum also undergoes a solid

phase during this time; between 8-10weeks' gestation, the duodenal lumen is

reestablished by the gathering of vacuoles,

and recanalization occurs.

Insults during this crucial period ofdevelopment are believed to result in

failure of recanalization and consequent

atresias, stenoses, and webs. In addition,

duodenal atresias have been associated

with a closely surrounding piece of

pancreatic tissue. Whether this tissue is an

annular pancreas or merely a failure of

duodenal development is debatable.[1, 2]

Embryology
http://emedicine.medscape.com/article/932917-overviewhttp://emedicine.medscape.com/article/932917-overviewhttp://emedicine.medscape.com/article/932917-overviewhttp://emedicine.medscape.com/article/932917-overview


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Classification

Anatomically, duodenal obstructions

are classified as either atresias or

stenoses.

An incomplete obstruction due to a

fenestrated web or diaphragm is

considered a stenosis.

Most stenoses involve the third

and/or fourth part of the duodenum.


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Classification

Atresias, or complete

obstruction, are further

classified into three

morphologic types


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Classification

I II III

A B C

Type Iatresias account for more than 90% of all duodenal obstructions andcontain a luminal diaphragm that includes mucosal and submucosal layers.

A diaphragm that has ballooned distally (windsock) is a type I atresia.The windsockdeformity is of particular concern because a portion of thedilated duodenum may actually be distal to the actual obstruction.

Type II atresias are characterized by a dilated proximal and collapseddistal segment connected by a fibrous cord.

Type IIIatresias have an obvious gap separating the proximal and distalduodenal segments.


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Duodenal web windsock anomaly

a prolapsing membrane in the duodenum


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Classification

Unlike other intestinal atresias, duodenal atresias are associated with othercongenital anomalies.

Approximately 50% of patients with duodenal atresias have some form of

anomaly (eg, cardiac, anorectal, genitourinary), and as many as 40% have

trisomy 21.[3, 4, 5]

Esophageal atresia and the VATER (ie, vertebral defects, anal atresia,

tracheoesophageal fistula with esophageal atresia, and renal and radial

anomalies) syndrome have also been associated with duodenal atresia.[6]

Hence, all neonates with duodenal atresia should be assessed for

concomitant malformations.

Growth retardation andpolyhydramniosare often present prenatally.
http://emedicine.medscape.com/article/975821-overviewhttp://emedicine.medscape.com/article/975821-overview


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Pathology

Anatomically, most congenital duodenal obstructions are considered

periampullary, with the biliary outlet occurring proximal or distal to the

site of obstruction.

The degree of obstruction dictates the amount of resulting pathology.

The obstruction causes dilation of the proximal duodenum and stomach as

well as hypertrophy and distension of the pylorus.

A common variation is the windsock anomaly, in which the duodenum is

dilated distal to the point of obstruction because of a prolapsing membrane

or web (see the image below). This may be confused with a more distal

duodenal obstruction.


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Clinical manifestations

Clinically, the presentation of the neonate with duodenal obstruction

varies depending on whether the obstruction is complete or incomplete,

and on the location of the ampulla of Vater in relation to the obstruction

In the newborn, clear or bilious emesis is evident within hours of birth,

with or without abdominal distension.

An output of more than 20 mL of gastric contents is indicative of possible

obstruction as normal aspirate is less than 5 mL

Because of incomplete obstruction, patients with a stenosis or web may

present later with dehydration or failure to thrive.


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Diagnosis

Prenatal ultrasonography

may indicate structural and

associated abnormalities, and

a double bubble sign such as

a dilated stomach and

proximal duodenum.


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Diagnosis

Polyhydramnios is highlysuggestive of a proximal

GI tract obstruction

because the fetus is unable

to swallow the amnioticfluid. Common associated

anomalies and

chromosomal defects may

be assessed by screening

maternal serum and

amniotic fluid.


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Diagnosis

Plain radiography is helpful and

may reveal the classic doublebubble sign, representing air in the

stomach and proximal duodenum,

which is associated with complete

or near complete duodenal

obstruction. Upright and contrast

radiography using air or contrast

may confirm the diagnosis (see the

images below). Malrotation with

volvulus may also result in

duodenal obstruction with a

double-bubble sign and can coexist

with duodenal atresia in as many as

30% of cases.[8]


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Plain abdominal X-ray reveal aduodenal atresia

Contrast GI studyillustrating a duodenalatrezia

Imaging


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Imaging

A contrast study illustratingduodenal stenosis.

Plain radiograph of duodenalstenosis.


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Gastric decompression is essential to prevent aspiration, and

thermoregulation should be monitored at all times.

Unless malrotation with volvulus remains a concern, preoperative

assessment of other associated anomalies should be performed.

When fluid resuscitation and a full assessment have been

accomplished, the neonate may proceed to surgery.

Treatment


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Surgical treatment

Two basic options for repair of duodenal obstruction secondary to a web

or atresia are noted: duodenoduodenostomy and duodenotomy withexcision of the web.

Duodenoduodenostomy Duodenotomy and webexcision


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The most common repair of a duodenal atresia is aduodenoduodenostomy open or laparascopic.

For the open approach, a right upper quadrant supraumbilical transverse

incision is made.

Currently, a proximal transverse to distal longitudinal, or diamond-shapedanastomosis (see figure below) is preferred.

Catheter is inserted through the stomach to help define the site ofobstruction. In addition, the entire small bowel is carefully explored forother sites of obstruction.

Care is taken to examine the gallbladder to ensure that a preduodenalportal vein is not evident and to locate the ampulla of Vater to avoidinadvertent injury.

Surgical treatment


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The technique of duodenoduodenostomy.

A diamond-shaped anastomosis is created via the proximal transverselyoriented and distal vertically oriented duodenotomies

Surgical treatment


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Outcome

An anastomotic leak, injury to the bile duct, and sepsis are earlycomplications. Late complications include peptic ulceration secondary to

alkaline reflux, blind-loop syndrome due to duodenal stasis, and

recurrent obstruction. In one series, as many as 12% of patients had late

complications requiring reoperation for a number of reasons, including

reflux and peptic ulcer disease, associated biliary abnormalities, and

bowel obstruction.

The prognosis is good for patients with a repaired duodenal stenosis or

atresia; however, coexisting diagnoses, such as Down syndrome and

cardiac anomalies, affect the outcome. Recent long-term data

demonstrated that a 9% combined early and late mortality rate over an

average 6-year follow-up period was due almost exclusively to

associated congenital anomalies. In addition, birth weight has been

shown to be a predictor of mortality. Infants with duodenal atresia who

weigh less than 2 kg at birth have poorer survival, regardless of the

presence of other congenital abnormalities.
http://emedicine.medscape.com/article/943216-overviewhttp://emedicine.medscape.com/article/943216-overviewhttp://emedicine.medscape.com/article/943216-overviewhttp://emedicine.medscape.com/article/943216-overview


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Jejunoileal Stenosis and Atresia


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Jejunoileal atresia occurs in approximately 1 in 5000 live births.

It occurs equally in males and females, and about one in three infants is

premature.

Although the majority of cases are thought to occur sporadically, familial

cases of intestinal atresias have been reported.

Etiology


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It is generally accepted that

jejunoileal atresia occurs as aresult of an intrauterine ischemic

insult to the midgut affecting

single or multiple segments of the

already developed intestine.

Intrauterine vascular disruption

can lead to ischemic necrosis of

the bowel with subsequent

resorption of the affected segmentor segments.

Etiology

Vesselstrombosed

Endarteries

No blood supplyPrecarious

blood supply Precarious

blood supply

Relativeischemia

Critical ischemia

Impaired function

Irreversible changes

Disintegration

Atretic segmentDefectivepropulsion

Early necrosis


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Although jejunoileal atresias are usually not hereditary, there is a well-documented autosomal recessive pattern of inheritance of multiple atresias

first documented in Montreal and later identified elsewhere.

In these cases of inherited jejunoileal atresia, rotation was normal,

mesenteric defects were never observed, and lanugo hairs and squamous

cells were not identified distal to the most proximal atresia, suggesting an

early intrauterine event.

This disorder is uniformly lethal even with successful bowel resection. No

correlations have been found between jejunoileal atresia and parental or

maternal disease. However, the use of maternal vasoconstrictive medications as well as

maternal cigarette smoking in the first trimester of pregnancy has been

shown to increase the risk of small bowel atresia. Chromosomal

abnormalities are seen in less than 1% of the patients.

Etiology (hereditary implications)


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Pathology

Following the Grosfeld classification, the defects of

jejunoileal atresia are separated into four groups based on

the type of atresia, with an additional consideration for

type III(b) (applepeel or Christmas treeappearance)

(See figure below).


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Classification


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Classification

This classification has significant prognostic and

therapeutic value because it emphasizes the importance of

associated loss of intestinal length, abnormal collateral

intestinal blood supply, and concomitant atresia orstenosis.

Regarding classification, the most proximal atresia

determines whether the atresia is classified as jejunal orileal atresia. Multiple atresias are found in up to 30% of

patients.


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Stenosis

Stenosis is defined as a localizednarrowing of the intestinal lumen

without disruption in the intestinal wall

or a defect in the mesentery.

At the stenotic site, a short, narrow,

somewhat rigid segment of intestinewith a small lumen is found.

Often the muscularis is irregular and

the submucosa is thickened.

Stenosis may also take the form of a

type I atresia with a fenestrated web.

Patients with jejunoileal stenosis

usually have a normal length of small

intestine.


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Type I jejunal atresia

In type I atresia, the intestinal

obstruction occurs secondary to amembrane or web formed by both

mucosa and submucosa while the

muscularis and serosa remain intact.

On gross inspection, the bowel and its

mesentery appear to be in continuity.

However, the proximal bowel is dilated

while the distal bowel is collapsed.

With the increased intraluminal pressure

in the proximal bowel, bulging of theweb into the distal intestine can create a

windsock effect. As with stenosis, there

is no foreshortening of the bowel in

type I atresias.


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Type II atresia

The clinical findings of a type II

atresia are a largely dilated, blind-ending proximal bowel loop connected

by a fibrous cord to the collapsed distal

bowel with an intact mesentery.

Increased intraluminal pressure in the

dilated and hypertrophied proximal

bowel may lead to focal proximal small

bowel ischemia.

The distal collapsed bowel commences

as a blind end, which sometimesassumes a bulbous appearance owing to

the remains of an intussusception.

Again, the total small bowel length is

usually normal.


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Type III(a) atresia

In type III(a) atresia, the atresia ends

blindly with no fibrous connecting cordto the distal intestine.

A V-shaped mesenteric defect of

varying size is present between the two

ends of intestine.

The dilated, blind-ending proximal

bowel is often aperistaltic and

frequently undergoes torsion or

becomes overdistended, with

subsequent necrosis and perforationoccurring as a secondary event. In this

scenario, the total length of the small

bowel is variable (but usually less than

normal), owing to intrauterine

resorption of the affected bowel.


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Type III(b) atresia

Type III(b) atresia (apple peel,Christmas tree, or maypole

deformity) consists of a proximal

jejunal atresia, absence of the superior

mesenteric artery beyond the origin of

the middle colic branch, agenesis of thedorsal mesentery, a significant loss of

intestinal length, and a large mesenteric

defect.

The decompressed distal small bowel

lies free in the abdomen and assumes a

helical configuration around a single

perfusing vessel arising from the

ileocolic or right colic arcades.


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Type IV atresia

Multiple-segment atresias or acombination of types I to III are

classified as type IV.

Twenty to 35 percent of infants

affected with jejunoileal atresia present

with multiple atresias.

A familial form of multiple intestinal

atresia involving the stomach,

duodenum, and both the small and large

bowel has been described. It is

associated with prematurity and

shortened bowel length. To date, it has

been uniformly fatal. It is associated

with type I and II atresias, with type II

predominating.


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Pathophysiology

The vascular and subsequent ischemic insult not only causesmorphologic abnormalities but also adversely influences the structure

and subsequent function of the remaining proximal and distal bowel.

The blind-ended proximal bowel is dilated and hypertrophied with

histologically normal villi, but without effective peristaltic activity.

A deficiency of mucosal enzymes and muscular adenosine

triphosphatase has also been found. At the level of the atresia, the

ganglia of the enteric nervous system are atrophic with minimal

acetylcholinesterase activity.

These changes are most likely secondary to local ischemia.

Obstruction alone can elicit similar, but less severe, morphologic and

functional abnormalities.


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Clinical manifestations

In neonates with atresia or stenosis, the presenting symptoms areconsistent with bowel obstruction, including bilious emesis and

abdominal distention.

Although the meconium may appear normal, it is more common to see

gray plugs of mucus passed via the rectum.

Occasionally, if the distal bowel in type III(b) atresia is ischemic, blood

may be passed through the rectum.

Intestinal stenosis is more likely to create diagnostic difficulty when

compared with intestinal atresia. Intermittent partial obstruction or

malabsorption may improve without treatment. Clinical investigations may initially be normal.

However, these infants usually develop failure to thrive and ultimately

progress to complete intestinal obstruction and require exploration.


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Diagnosis

The diagnosis of jejunoileal atresia can usually be made byradiographic examination of the abdomen with only swallowed air as

contrast.

Swallowed air reaches the proximal bowel by 1 hour and the distal

small bowel by 3 hoursin a normal vigorous infant in whom its passage

is blocked, but this pattern may be delayed in premature or sick infants

with poor sucking.

Jejunal atresia patients have a few gas-filled and fluidfilled loops of

small bowel, but the remainder of the abdomen is gasless (See figure

below). When the atresia is associated with cystic fibrosis, fewer air-fluid levels

are evident, and the typical ground-glass appearance of inspissated

meconium is present. A limited-contrast meal may be useful if intestinal

stenosis is suspected.


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Diagnosis

Figure. A, The abdominal radiograph in this neonate shows several

proximally dilated intestinal loops consistent with jejunal atresia. B, A type

III(a) distal atresia was found at operation.

A B


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Differential diagnosis

Diseases that mimic jejunoileal atresia include:

colonic atresia,

midgut volvulus,

meconium ileus, duplication cysts,

internal hernias,

ileus due to sepsis,

birth trauma,

maternal medications,

prematurity,

hypothyroidism.

Special investigations, including an upper gastrointestinal contrast study,

contrast enema, rectal biopsy, and a F508 gene deletion assay or sweat

test to exclude associated cystic fibrosis, may be needed.


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Management

Delay in diagnosis may lead to impairment of intestinal viability (50%),

frank necrosis and perforation (10% to 20%), fluid and electrolyte

abnormalities, and sepsis.

Preoperative management involves insertion of a nasogastric or

orogastric tube to decompress the stomach and fluid resuscitation tocorrect electrolyte abnormalities and hypovolemia.

Antibiotics should be initiated if there is any concern for perforation or

infection.


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Surgical considerations

The surgical management of intestinal atresias is based on

the location of the lesion, anatomic findings, associated

conditions noted at operation, and the length of the

remaining intestine. Resection of the dilated and hypertrophied proximal bowel,

with primary end-to-end anastomosis with or without

tapering of the proximal bowel, is the most common surgical

technique.

S i i i


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Figure. The operative approach through the umbilical ring allows for complete

evaluation of the intestine and repair of an atresia. Shown here is the technique using the

Lonestar retractor to maintain exposure during repair of a type IIIa jejunal atresia.


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Figure. The intestinal

anastomosis in the infant seen

in previous figures is shown. At

the time of repair, there can be

a significant size discrepancy

between the proximal and distal

bowel. The proximal bowel has

been resected to a point that

will allow for a more

appropriately sized intestinalanastomosis



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Functional outcome ultimately depends on the following factors:

(1) the location of the atresia (the ileum adapts to a greater degree

than the jejunum),

(2) the maturity of the intestine (the small intestine in a premature

infant still has time for maturation and growth), and

(3) the length of the small intestine, which can be difficult to

determine accurately after birth. The ileocecal valve is critically

important because it allows for more rapid intestinal adaptation

when the residual small bowel length is short.

Outcome


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Colonic atresia


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Colonic atresia is a rare cause of intestinal obstruction and

comprises 1.8% to 15% of all gastrointestinal atresias.

The reported incidence of colonic atresia varies greatly

from 1:5000 to 1:60,000 live births.

The accepted incidence is approximately 1 in 20,000 live

births.

Although it is most commonly reported as an isolated

anomaly, approximately one third of infants have associated

congenital lesions.

Epidemiology

C ifi i


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Type I consists of mucosal atresiawith an intact bowel wall and

mesentery.

In type II the atretic ends areseparated by a fibrous cord.

In type III the atretic ends areseparated by a V-shaped mesenteric

gap (See figure). In the ascending and transverse

colon, type III colonic atresiaspredominate.

Types I and II are seen more

commonly distal to the splenicflexure.

Type III lesions are the mostcommonly occurring lesionsoverall

Classification

A i d li


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The rate of associated anomalies with colonic atresias is much

smaller when compared with other atresias.

Colonic atresias have been found in approximately 2.5% of

neonates with gastroschisis.

There are fewer than 25 published cases of colonic atresia andHirschsprungsdisease.

Complex urologic abnormalities, multiple small intestinal

atresias, an unfixed mesentery, and skeletal anomalies have also

been reported to occur with colonic atresia.

Similar to small bowel atresias, a vascular insult to the fetal

intestine continues to be the accepted cause for all types of

colonic atresia.

Associated anomalies

P l di i


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Prenatal diagnosis is of great importance in the

management of colonic atresia.

On prenatal ultrasonography, the colon has a relatively

characteristic appearance.

The presence of an obstruction can usually be determined

when the diameter of the colon is larger than expected for

gestational age.

Prenatal diagnosis

Cli i l f t


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The characteristic clinical features of colonic atresia areabdominal distention, bilious emesis, and failure to pass

meconium.

On plain radiographs, air-fluid levels are usually

appreciated as well as dilated intestinal loops of large

bowel often associated with a groundglassappearance of

meconium mixed with air.

Occasionally, the dilation can be so massive that it mimics

pneumoperitoneum.

The diagnosis is made with a contrast enema showing a

small diameter distal colon that comes to an abrupt halt at

the level of the obstruction (See figures below).

Clinical features

X


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A, Abdominalradiograph of colonic

atresia showing huge

air-filled proximal

colon mimicking a

pneumoperitoneum. B, Colonic atresia

with rectal stenosis

(arrow) is seen on

this retrograde

contrast study.

X-ray

A B

X


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The contrast enema in a patient with a distalintestinal obstruction shows a small colon andfailure of the contrast agent to move

proximally past the mid-transverse colon.

X-ray

S i l id ti


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A staged surgical approach consisting of colostomy with

mucous fistula is generally preferred.

Because the proximal and distal ends adjacent to the atresia

are abnormal in both innervation and vascularity, resection

of the bulbous proximal colon as well as a portion of the

distal microcolon is suggested.

Primary resection with anastomosis has a higher incidence of

complications, usually due to undiagnosed distal pathology.


P i


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In the absence of other serious co-morbidities, the prognosisin colonic atresia is excellent.

If diagnosed early, the overall mortality is less than 10%.

A delay in diagnosis beyond 72 hours, however, may result

in a mortality of greater than 60%.

This high mortality is due, in part, to the formation of a

closed loop obstruction between an intact ileocecal valve and

the atresia, leading to massive colonic distention andperforation.

Prognosis


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Intestinal Atresias, Obstructions, Webs

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