Jejuno-ileal Atresia Heinz Rode, Alastair J.W. Millar

and represent one of the most common causes of neonatal intestinal obstruction. Jejuno-ileal atresia has a prevalence rate of approximately 1:1000 live births, with a third of the infants being either born prematurely or small-for-date. The anomaly is rarely genetically determined and <1% of babies will have chromosomal or other associated anomalies.

Most jejuno-ileal atresias or stenoses result from a localized intra-uterine vascular insult to the develop- ing bowel with ischaemic necrosis and subsequent reabsorption of the affected segment(s). Additional pathology in the form of intra-uterine fetal intussus- ception, malrotation and midgut volvulus, throm- boembolic occlusions, transmesenteric internal her- nias and incarceration or snaring of fetal bowel in a gastroschisis or exomphalos further supports the ischaemic hypothesis. The ischaemic insult also ad- versely influences the structure and subsequent function of the remaining bowel. Histological and histochemical abnormalities can be observed up to 20 cm cephalad from the end of the atretic proximal segment. The distal bowel is unused and potentially normal in function.

Prompt recognition of intestinal atresia is essen- tial for the early institution of management. A prena- tal history of polyhydramnios and ultrasonography showing dilated and obstructed fetal intestine are strong indicators of congenital intestinal atresia. A positive family history will help to identify heredi- tary forms. Postnatally, intestinal atresia or stenosis may present initially with large intragastric volumes at birth (>20 ml gastric aspirate) followed by persis- tent bile-stained vomiting. In 20% of children symp- toms may be delayed for more than 24 h. Abdominal distension is frequently present from birth and the

presents with gastric distension and one or two loops of visible bowel in the upper abdomen relieved by nasogastric tube aspiration. With delay in presenta- tion increasing intraluminal pressure and/or secon- dary torsion of the proximal atretic distended bowel may lead to ischaemia, perforation and peritonitis.

The differential diagnosis includes midgut volvu- lus, intestinal stenosis, meconium ileus, duplication cyst, internal hernia, strangulated inguinal hernia, Hirschsprung’s disease and ileus due to sepsis, birth trauma, maternal medications, prematurity or hypo- thyroidism.

The diagnosis of jejuno-ileal atresia can be estab- lished in most cases by an abdominal roentgenogram with air as contrast medium. Erect and supine ab- dominal radiographs show distended air and fluid filled loops of bowel.

The lower the obstruction the greater the number of distended loops of bowel and fluid levels that will be observed. Occasionally intraperitoneal calcifica- tion may be seen on the plain radiographs signifying intrauterine bowel perforation, meconium spill and dystrophic calcification. In the presence of complete obstruction a contrast enema is usually performed to confirm the level of obstruction and document the calibre of the colon, exclude colonic atresia, and to lo- cate the position of the caecum as an indication of malrotation. With incomplete upper small bowel ob- struction an upper gastrointestinal contrast study is indicated to demonstrate the site and nature of the obstruction and to exclude midgut volvulus.

The clinical and radiological presentation of jeju-

no-ileal stenosis will be determined by the level and

degree of stenosis. The diagnosis is often delayed for

years because of subclinical symptoms and findings.

The morphological classification of jejuno-ileal atre- sia into types I–IV has significant prognostic and therapeutic implications. The most proximal atresia determines whether it is classified as jejunal or ileal.

Although single atresias are most commonly en- countered, 6–12% of infants will have multiple atretic segments and up to 5% may have a second colonic atresia. The appearance of the atretic segment is de- termined by the type of occlusion, but in all cases the maximum dilatation of the proximal bowel occurs at the site of the obstruction and is often hypoperistal- tic and of questionable viability when presentation is delayed.

쐽 Stenosis (12%) is characterised by a short local- ized narrowing of the bowel without discontinuity or a mesenteric defect. The bowel is of normal length.

쐽 Atresia type I (23%) is represented by a translumi- nal membrane or short atretic segment causing complete intestinal obstruction. The bowel re- mains in continuity, has no mesenteric defect, and is of normal length.

쐽 Atresia type II (10%) has the blind-ending proxi- mal bowel attached to the collapsed and underde-

veloped distal bowel by a fibrous cord along the edge of the mesentery. The proximal bowel is dis- tended and hypertrophied for several centimetres.

There is no mesenteric defect and the bowel length is not foreshortened.

쐽 Atresia type III(a) (16%) is similar to type II ex- cept that the fibrous connecting cord is absent and there is a V-shaped mesenteric defect. The bowel length may be foreshortened.

쐽 Atresia type III(b) (apple peel) (19%) consists of a proximal jejunal atresia often with associated malrotation, absence of most of the superior mes- enteric artery and a large mesenteric defect. The distal bowel is coiled in a helical configuration around a single perfusing artery arising from the right colic arcades. There is always a significant reduction in intestinal length. The infants are usu- ally of low birth weight and may have associated anomalies.

쐽 Atresia type IV (20%) represents multiple seg-

ment atresias like a string of sausages or a combi-

nation of types I–III. Bowel length is always re-

duced.

Type II Type III(a)

Type III(b)

Type IV

Figure 22.2

Figure 22.3

The infant is placed supine on a warming blanket and the exposed abdomen cleaned and sealed with plas- tic adherent drapes. Access to the abdominal cavity is obtained through an adequate transverse supra-um- bilical incision transecting the rectus abdominis muscles. The ligamentum teres is divided between ligatures.

Exploration and basic surgical considerations: the small intestine can easily be exteriorised from the ab- dominal cavity by gentle pressure on the wound edg- es and manual delivery of the intestine. Anatomic- pathological findings will determine the operative procedure.

Steps in the operative procedures are:

쐽 Identification of pathological type and possible aetiology.

쐽 Confirmation of patency of distal small and large bowel with saline injection (patency of the colon could have been demonstrated by contrast enema prior to surgery).

쐽 Resection of the proximal bulbous atretic segment.

쐽 Volvulated bowel must be untwisted carefully, es- pecially in type III(b) atresia.

쐽 Limited distal bowel resection.

쐽 Accurate measurement of residual bowel length proximal and distal to the anastomosis.

쐽 Single-layer end-to-end or end-to-back anastom- osis.

쐽 Bowel lengthening procedures have no place dur- ing the initial surgery.

쐽 Gastric decompression post-operatively is best achieved with a Replogle tube on low continuous suctioning. Neither decompression Stamm gas- trostomy nor transanastomotic feeding tubes are recommended.

쐽 The fashioning of proximal or distal stomas are only indicated in the presence of established peri- tonitis, or with compromised vascularity of the re- maining intestine.

쐽 Additional steps may include derotation of a prox- imal jejunal atresia, back resection to the distal second part of the duodenum and excision or in- version tapering of the duodenum if very dilated.

Where total bowel length is significantly reduced (type III and type IV), the bulbous dilated seg- ment proximal to the atresia is conserved. As pro- grade peristalsis of this bowel is deficient the lu- men calibre should be reduced. Maximum muco- sal conservation is achieved by inversion plication prior to anastomosis to the distal bowel.

Figure 22.5

쐽 Detection of Distal Atretic Areas. It is imperative to exclude distal atresia, which have a prevalence rate of 6–21%. This is best achieved with a preoperative barium enema to exclude an associated colonic atre- sia and by injecting saline into the distal collapsed small bowel and following the fluid column distally until it reaches the caecum.

쐽 Bowel Length Measurement. The total length of

the small bowel is measured along the antimesenter-

ic border. Once bowel resection has been completed,

residual bowel length is of prognostic significance

and may determine the method of reconstruction es-

pecially in types III and IV atresia. The normal bow-

el length at full term is approximately 250 cm and in

the premature infant it is 115–170 cm.

Ligament of Treitz

Figure 22.5

The atretic region and the adjacent distended proxi- mal and collapsed distal bowel are isolated with ster- ile moist swabs. The intestinal content is milked backwards into the stomach from where it is aspirat- ed and a bacteriology swab is sent for culture and sensitivity. Alternatively, proximal bowel contents are milked into the bulbous blind end if it is to be resect- ed. An atraumatic bowel clamp is then placed across the bowel a few centimetres proximal to the elected site for transection.

If total bowel length is deemed of adequate length (>80 cm + ileocaecal valve) the bulbous hypertro- phied proximal bowel is resected (5–15 cm) alongside the mesenteric bowel border in order to preserve maximal mesentery for later use, until normal diam- eter bowel has been reached. The bowel should then be divided at right angles leaving an opening of ap- proximately 0.5–1.5 cm in width. The blood supply should be adequate to ensure a safe anastomosis.

This is followed by very limited distal small bowel re- section over a length of 2–3 cm. The resection line should be slightly oblique towards the antimesenter- ic border to ensure that the openings of the proximal

and distal bowels are of approximately equal size to facilitate easy axial or end-to-back (Denis-Browne) single-layer anastomosis. However, the discrepancy in luminal width of the proximal and distal bowel may vary from 2–5 cm depending on the distance from the stomach.

With type III(b) or high jejunal atresia the proxi- mal bowel should be derotated and resection of the bulbous portion may be extended into the third or second part of the duodenum without jeopardizing the ampulla of Vater. The distal “apple peel” compo- nent of Type III(b) atresia may require release of re- stricting bands along the free edge of the distally coiled and narrow mesentery to avoid kinking and interference with the blood supply. The large mesen- teric defect is usually left open but with proximal bowel resection the residual mesentery can be used to obliterate the defect. Furthermore, to prevent kinking of the marginal artery after completion of the anastomosis, the bowel needs to be replaced very carefully into the peritoneal cavity in a position of non-rotation.

Figure 22.7, 22.8

The anastomosis is either end-to-end or end-to-back (Denis-Browne method); 5/0 or 6/0 absorbable sutu- res stitches are used. The mesenteric border of the di- vided ends is united with a stay suture and a match- ing stitch is placed at corresponding points of the

anti-mesenteric borders of the divided ends. The “an-

terior” edges of the bowel are then united with inter-

rupted through-and-through extramucosal stitches,

which are tied on the serosal surface.

Figure 22.7 Figure 22.8

After completion of one-half of the anastomosis the bowel is rotated through 180 ° and the “posterior”

anastomosis completed. Alternatively the posterior edge of the bowel is anastomosed with the stitches tied on the mucosal surface followed by anastomosis of the “anterior” edges with interrupted stitches tied on the serosal surface. The suture lines are inspected for anastomotic integrity or tested with saline injec- tion on completion.

Although isolated type I atresia is best dealt with by primary resection and anastomosis, multiple dia- phragms have been successfully perforated with transluminal bougies being passed along the entire length of the affected small bowel.

Multiple type IV atresias, present in 18% of in- fants, are often localized necessitating en-bloc resec- tion and a single anastomosis, rather than multiple anastomosis. It is important, however, to maintain maximum bowel length to avoid the short bowel syn- drome.

Similar techniques are used for intestinal stenosis and type I atresias. Procedures such as simple trans- verse enteroplasties, excision of membranes, bypass- ing techniques or side-to-side anastomosis are no longer utilized. They fail to remove the abnormal dysfunctional segments of intestine, thus increasing the risk of the blind loop syndrome.

Figure 22.10

The defect in the mesentery is repaired by approxi- mating or overlapping the divided edges with inter- rupted sutures taking great care not to incorporate blood vessels or kinking the anastomosis. Closure of the large mesenteric defect can be facilitated by using the preserved mesentery of the resected proximal bowel.

쐽 Wound Closure. The peritoneal cavity is thorough-

ly irrigated with warm saline to remove all macro-

scopic debris and the bowel then returned to the ab-

dominal cavity. Care is taken not to kink the anas-

tomosis. The abdomen is closed by approximating en

mass all the layers of the abdominal wall, excluding

Scarpa’s fascia, with a single continuous 4/0 monofil-

ament absorbable suture, followed by subcutaneous

and subcuticular absorbable stitches. No drains or

trans-anastomotic tubes are used.

Figure 22.10

Alterative surgical techniques may be required if the ischaemic insult has resulted in an atresia with mark- edly reduced intestinal length, where large resections of abnormal or multiple atretic segments are re- quired or if the measured residual small intestinal length is <80 cm.

Indications for tapering are:

쐽 As part of bowel length preservation where the proximal atretric segment is grossly dilated and hypertrophied over an extended distance – typical in type III(b) atresia and high jejunal atresia

쐽 To equalize disparity in anastomotic lumen size

쐽 For the correction of a failed inversion plication procedure

쐽 To improve function in a persistently dilated non- functioning mega-duodenum following surgery for upper jejunal atresia

쐽 Tapering duodeno-jejunoplasty. This method is

primarily indicated to conserve bowel length (high

jejunal atresia, type III(b) atresia) and to reduce dis-

parity in anastomotic diameter size. The atretic jeju-

noduodenum is derotated and the antimesenteric

segment of the dilated proximal segment is resected

over a 22–24F catheter. The resection may extend

cephalad to the second part of the duodenum. An in-

testinal auto-stapling device may be used to facilitate

the resection and anastomosis. The longitudinal

anastomotic line is reinforced with an absorbable 5/0

or 6/0 Lambert suture. Tapering can safely be done

over a length of 20–35 cm. The tapered bowel is then

primarily anastomosed to the distal bowel (with or

without equal bowel diameters) and left in a depen-

dant position as for corrected malrotation with the

caecum in the left hypochondrium.

Figure 22.12

쐽 Plication and Folding. The basic derotation and back resection methods are used as previously de- scribed for tapering procedures. The plication meth- od has the advantage of reducing the risk of leaking from the antimesenteric suture line, conserves mu- cosal surface area and may even facilitate return of bowel peristalsis. More than half of the antimesen- teric bowel circumference may be infolded into the lumen over an extended length without causing an

obstruction with care being taken not to narrow the

lumen excessively. The “keel” must be trimmed and

closed with interrupted sutures. The main drawback

of this method is unravelling of the suture line with-

in a few months, necessitating revision. The bowel is

left in a position of derotation with the duodenojej-

unum dependant, the mesentery broad based and the

caecum in the left hypochondrium.

Figure 22.14

쐽 Antimesenteric Seromuscular Stripping and In- version Plication. This technique prevents unravell- ing of the plication method and preserves maximal mucosal surface for absorption. A single or two anti- mesenteric converging seromuscular strips ±2 mm in width are resected. This is easily performed by sta- bilizing the proposed line of resection with straight non-toothed forceps. A seromuscular strip is then

excised taking care not to damage the mucosa. The

two denuded mucosal strips are then approximated

with a running monofilament suture. The keel of the

inverted bowel should be trimmed and bowel edges

approximated with interrupted sutures prior to

anastomosis to the distal bowel. Proximal and distal

luminal size can be approximated to facilitate the

anastomosis.

Figure 22.16 Figure 22.17

The overall survival amongst newborn babies with intestinal atresia has increased from a dismal 10% in 1952 to 90% at present. This came about primarily from a change in the surgical procedure from pri- mary anastomosis without resection to liberal resec- tion of the blind proximal and distal ends followed by end-to-end anastomosis.

Understanding the pathogenesis of atresia and adapting surgical procedures to minimize loss and conserve bowel length ensured that most infants will have sufficient bowel length for normal alimentary tract function and overall growth and development.

Despite improvement in surgery, anaesthesia and peri-intra- and post-operative care, type III(b) atre- sia still carries a mortality of 19% predominantly due to gangrene of the proximal end of the distal segment (7%), anastomotic leak (15%) and stricture formation (15%). The prognosis of intestinal atresia is further determined by genetic factors, prematurity (30%), delay in presentation, associated diseases, i.e., cystic fibrosis, malrotation (45%), exomphalos, gastroschi- sis and Hirschsprung’s disease, together with other gastro-intestinal atresias, infarction of the proximal atresia with peritonitis, sepsis, pneumonia and the complications of prolonged parenteral nutrition.

The incidence of post-surgical complications such as anastomotic leaks, stricture formation, transient

intestinal dysfunction, blind loop syndrome and the short bowel syndrome can be minimized by careful attention to the presenting anatomical detail, meticu- lous surgical technique and maximal bowel length conservation methods. Because of the high incidence of unravelling, the plication technique is rarely used.

The short bowel syndrome is a major factor influ- encing outcome. It may be due to predisposing fac- tors such as extensive intra-uterine bowel loss, oper- ative factors, i.e., over-zealous bowel resection and is- chaemic injury to the bowel or post-operative com- plications. Under ideal circumstances a survival rate of 46–70% can be expected in most infants with less than 25 cm jejuno-ielum.

Several surgical procedures have been identified to improve the outcome of the short bowel syndrome including reversal of segments of bowel, interposi- tion of colonic segments and methods to increase mucosal surface area for absorption purposes. Most are of experimental value only except for bowel- lengthening procedures. The latter should not be performed initially until conservative methods to stimulate and allow maximum bowel adaptation to occur, have failed. Full bowel adaptation may require 6–18 months to become achieved.

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