INTRODUCTION
The term “short bowel” has been defined by Rickham in 1967 as a small intestinal remnant of 75 cm or less in the newborn, which equals 30% of normal small bowel length in that age group.A more functional de- scription is preferred by most authors defining a
“short bowel syndrome” (SBS) as a state of signifi- cant maldigestion and malabsorption due to an ex- tensive loss of functional absorptive intestinal sur- face area.
The prevalence of SBS has been increasing over the last two decades due to the enormous progress in intensive care of babies with either severe acquired intestinal diseases such as necrotizing enterocolitis and volvulus, or congenital malformations leading to the SBS, such as multiple intestinal atresia. Rarely SBS is caused by a genetically determined disease such as a congenital short bowel or a total intestinal aganglionosis.
Following extensive loss of small bowel, the symp- toms of an individual baby depend on the absorptive capacities of the intestinal remnants. Resection of the jejunum is well tolerated due to an enormous adap- tive capacity of the ileum, the intact enterohepatic circulation of bile salts and the preserved absorption of vitamin B
12. In contrast, if the entire ileum is lack- ing, absorption of nutrients is significantly more dif- ficult due to the limited intestinal adaptation capac- ities of the jejunum. Non-absorbed intestinal con- tents, including bile acids, spill over into the colon and may cause significant diarrhoea. Furthermore, loss of the ileum leads to a reduction of the bile salt pool, malabsorption of fat and fat soluble vitamins, as well as to a vitamin B
12deficiency.
The pathophysiological process that follows an ex- tensive loss of small bowel is called intestinal adapta- tion. It includes, firstly, morphological changes lead- ing to an increase of absorptive surface area, second- ly, functional changes resulting in an augmentation of the absorptive capacity of the remaining enterocy- tes, and thirdly, an increased intestinal diameter with a concomitant reduction of the motility thereby slowing down the intestinal transit time of chyme.
The presence of intraluminal food is the most im- portant driving force for intestinal adaptation. Enter- al nutrients stimulate gastrointestinal secretions and hormones that are known to exert trophic effects on the mucosa. Recent evidence suggests that glucagon- like peptide 2, human growth hormone, epidermal growth factor, and insulin-like growth factor-I may play an important role in the process of intestinal ad- aptation.
Surgery is indicated in selected patients only, first- ly when the absorptive surface area is definitely too small to allow enteral feeding, secondly, when severe dysmotility in grossly dilated loops entails stagnation of chyme, and thirdly, when intestinal transit time is too fast to allow sufficient absorption of nutrients.
Whereas in the first group of patients intestinal trans- plantation is the mainstay of surgical therapy, peris- talsis can be improved in the second group by intesti- nal tapering or tapering and lengthening. In the third group, antiperistaltic segments, colonic interposition, intestinal valves, and/or artificial invagination have been used in selected patients. These surgical tech- niques are described in detail on the following pages.
Michael E. Höllwarth
Figure 25.1
쐽 Tapering. In patients with enough absorptive sur- face area – at least 50 cm with ileocecal valve – the ta- pering can be performed by resection of a long trian- gular (or elliptical) antimesenteric segment. The bowel segment is isolated from surrounding adhe- sions and the chosen length for the tapering is marked by 5/0 stay sutures, which indicate the later-
al margins of the planned triangular resection. One stay suture is located exactly at the antimesenteric line and indicates the end of resection which is at the tip of the triangle. The resection can be performed by means of a GIA stapler in very large dilated loops (see Chap. 22)
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Figure 25.2, 25.3
We prefer to resect in small babies the antimesenter- ic redundant part with sharp scissors, thus allowing some bleeding from the resected margins, and we try to avoid carefully any disturbance of the local circu-
lation, which inevitably would result if we use caut-
ery. The antimesenteric anastomosis can be accom-
plished either by a continuous running 6/0 absorb-
able suture or by 6/0 interrupted sutures.
Figure 25.1
Figure 25.2 Figure 25.3
Figure 25.4–25.7
The important part in performing any kind of intes- tinal anastomosis lies in the technique that the stitch- es should include only the seromuscular layer, there- by leaving out the mucosal layer. If the stitches take equal amounts of tissue on either side, both segments of the bowel are perfectly adapted and the mucosal edges are lying side by side. Another important part of this technique is to avoid too much tension when tying knots, thus not compromising circulation. This technique was originally described by Halsted in 1912 and has the advantage of preventing mucosal necro- sis just under the stitch, thereby supporting a rapid and perfect healing of the anastomosis.
If, additionally, an anastomosis to the distal or proximal part of the intestinal tract has to be per- formed, the same surgical technique is useful. First, the two intestinal ends are brought together with two to four 5/0 stay sutures. Thereafter, the anastomosis with interrupted 6/0 stitches begins at anterior wall.
The needle takes a good part of the seromuscular layer on either side. The suture is tied carefully, avoiding any strangulation. The single interrupted sutures are continued in the same way until the whole anterior wall is anastomosed.
The posterior wall is sutured in a similar way, after turning around.
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Figure 25.4 Figure 25.5
Figure 25.6 Figure 25.7
Figure 25.8–25.11
The abdominal wall is closed using 3/0 or 4/0 inter- rupted single-layer figure-of-eight absorbable su- tures. The knot must be tied rather loosely without strangulating the tissue.
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Figure 25.8 Figure 25.9
Figure 25.10 Figure 25.11
Figure 25.12
쐽 Infolding. This method has the same effect as ta- pering but saves all existing absorptive surface area.
Therefore, it is indicated in cases with a rather short intestinal tract when it seems advisable not to sacri- fice any mucosal surface. The intestinal tract can re- main closed in most of the patients. The intestinal loops that are selected for the infolding method are marked with 5/0 stay sutures on the lateral side and
on both ends. The lateral margins are approximated with 5/0 or 4/0 nonabsorbable seromuscular stitches, thereby enfolding the tissue in-between. It is report- ed that the plicated segments are prone to break- down with time and some authors suggest resecting on each side a serosal strip or a triangular segment in order to support the development of dense adhe- sions (see Chap. 22)
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Figure 25.13, 25.14
쐽 Tapering and Lengthening. Bianchi first reported an experimental procedure combining the method of tapering with the use of the redundant tissue for lengthening the bowel. Indications for this method are patients with very short bowel segments but largely dilated loops characterised by inefficient to- and-fro peristalsis, stasis of chyme and bacterial overgrowth. The technique is based on the fact that the vessels coming from the mesentery are divided extramurally in branches supplying either side of the bowel separately. Therefore, careful longitudinal di- vision of a dilated intestinal segment between the branching vessels results in two intestinal halves
with an intact blood supply for each side. The first step of the procedure consists of careful separation of the vessel branching in the right and left group and supplying either part of the selected intestinal tract. The space between the vessel layers can be opened by introducing a haemostat and spreading the two layers. The small vessel groups on each side are secured by fine vessel loops of different colours for the right and left parts.
If the space between the branches is large enough
that a GIA stapler can be introduced, the intestinal
loop can be divided in the midline and anastomosed
longitudinally, step by step.
Figure 25.12
Figure 25.13 Figure 25.14
Figure 25.15, 25.16
However, if the space is too small to insert a stapler – which is the case when the bowel is not extremely di- lated – then a sharp longitudinal division is our pre- ferred method.As already mentioned above, we try to
avoid any cautery or to use it very cautiously. Sero- muscular 6/0 absorbable sutures are used for the lon- gitudinal anastomosis of the divided segments of the bowel.
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Figure 25.17, 25.18
Since both sections of the bowel hang on the same mesenteric segment, a helix-like isoperistaltic anas- tomosis is easier to perform than an anastomosis with the two segments sliding one on the other. The
helix technique avoids traction on the nutrient ves-
sels, which is critical because necrosis of the divided
segments has been reported.
Figure 25.15 Figure 25.16
B’
A’
A B
Figure 25.17
A
B
B’
A’
Figure 25.18
Figure 25.19–25.21
Antiperistaltic segments are only indicated in cases with good propulsion of the luminal chyme, while it would be contraindicated in cases with a disturbed motility. A number of different intestinal interposi- tions have been used in the past, both experimental- ly and in some selected cases clinically. In the follow- ing paragraph the method of antiperistaltic small or large bowel segment, as well as the interposition of a isoperistaltic colonic segment will be briefly demon- strated.
Reversal of distal small bowel loops has been stud- ied experimentally for years. The ideal length of the reversed segment appears to be 10 cm in adults and 3 cm in infants. The antiperistaltic segment acts as a physiological valve by causing either a retrograde peristalsis or by functioning as an effective brake for the passage of chyme. Since the ideal length is diffi- cult to estimate for a given patient, this method has not consistently resulted in clinical improvement.
The distal ileum – if available – is best used as anti- peristaltic segment shortly before the ileocecal valve.
In an infant, a 3-cm segment of small bowel is first identified in regard to its blood supply, which should come from one major branch of the mesenteric ves- sels. Care must be taken that neither the blood supply to the remainder small intestine nor to the colon, if present, is disturbed. The segment is isolated and the appropriate mesenteric base is isolated in a way that the segment can be reversed by 180º without impair- ing the blood flow. Finally the proximal and distal in- testinal anastomoses are performed as described above.
In the same way as described above a 3 cm to 5 cm antiperistaltic segment of the colon can be used. If no ileocecal valve is present, the best way is to reverse the first part of the colon immediately after the small intestine. However, if the ileocecal valve has been pre- served the antiperistaltic colonic segment can be interposed between the distal small bowel and the valve. The method has rarely been used in humans and long term results are not available.
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Figure 25.19
A
B
Figure 25.20
B A
