Autologous intestinal reconstruction surgery in short bowel syndrome

Small bowel diameter as a continuous variable was a significant predictor of duration of parenteral nutrition in studies from both Ann Arbor (Teitelbaum group) and Helsinki, published in 2017.

Patients with small bowel diameter ratio greater than 3 had significantly worse outcomes than those with ratio less than 2, with patients having ratio <2 being approximately 14 times more likely to wean off parenteral nutrition than those with ratio >3.

In multivariate analysis, small bowel diameter ratio remained a significant predictor of weaning from parenteral nutrition independent of remaining small bowel length.

Small bowel diameter ratio of 2.17 was identified as the optimal cutoff for pathological dilatation, providing the best combination of sensitivity and specificity for predicting PN dependence.

Patients with pathological small bowel dilatation (ratio ≥2.17) had higher fecal calprotectin levels indicating mucosal inflammation, lower citrulline levels suggesting worse mucosal state, and higher GGT levels indicating liver irritation or pre-cholestatic state.

Patients with pathological dilatation had significantly more bloodstream infections caused by intestinal bacteria compared to those without pathological dilatation.

Patients with pathological dilatation more often presented with histological cholestasis on liver biopsy.

The proposed pathophysiological sequence is: dilatation leads to dysmotility, which causes dysbiosis (mainly increased proteobacteria), leading to mucosal injury and defective barrier function, resulting in malabsorption, bacterial translocation to portal circulation, and finally liver injury.

After tapering surgery (STEP/LILT/simple tapering), the duration of parenteral nutrition post-procedure was comparable to patients who did not undergo surgery, suggesting surgery can restore clinical trajectory to baseline.

Following tapering procedures, small bowel diameter ratio significantly decreased, bloodstream infections decreased, intestinal bloodstream infections decreased to zero in the series, liver values improved, and albumin improved.

No increase in citrulline was found after tapering procedures, which is unsurprising because tapering does not create more bowel, only reduces diameter.

Redilatation after lengthening procedures occurs in approximately 40% of patients in most series.

In a study of 27 STEP patients from multiple Swedish centers, the only predictive factor for requiring repeat STEP was absence of ileocecal valve.

Patients without ileocecal valve presented with less crypt cell proliferation but more severe mucosal inflammation than those with retained ileocecal valve, possibly mediated by GLP-2 or similar endocrine hormones secreted from that bowel region.

Intestinal failure is defined as inability of intestinal mucosa to sufficiently absorb proteins, energy, fluids, and electrolytes, requiring parenteral nutrition for more than 4 months, with residual small bowel length being irrelevant to the definition.

To avoid short bowel syndrome, it is important to prevent ample resections, use second-look procedures and laparostomy when appropriate, avoid long-term enterostomy, and restore continuity as soon as possible after resolving septic complications.

Fasting has a negative trophic effect on the bowel; breast milk is best for intestinal adaptation, along with complex nutrients.

Enterostomy results in not utilizing all resortive surface (especially in deactivated bowel), high output stoma in jejunum hampering fluid and electrolyte resorption, and increased risk of liver disease from endotoxins reaching liver via portal route.

The bowel grows remarkably in the first year of life; lengthening procedures should not be planned too early, preferably not in the first year of life.

In Wessel's cohort, approximately 10 children showed remarkable bowel length growth depending on which part of small bowel was preserved.

Historical procedures to improve resorption and transport (antiperistaltic segment, valves, colonic interposition, blind loops) showed no positive long-term effects.

Bianchi introduced LILT in 1981; Kim introduced STEP in 2003.

Indications for lengthening procedures include dependence on parenteral nutrition and massive dilatation with bacterial overgrowth; bowel must have double normal diameter but not less than 5 cm for technical feasibility.

Contraindications for lengthening include motility disorders (especially chronic intestinal pseudo-obstruction), absence of bowel dilatation, severe liver disease with portal hypertension or impaired coagulation, inability to insert central line (consider transplant referral), and active cachexia or sepsis.

The Bianchi (LILT) procedure involves separating mesenteric vessels that run to right and left of bowel, creating two intestinal plates from one, then tubularizing each plate; historically done with hand sutures but now facilitated by endoscopic staplers.

Staples used in lengthening procedures may cause inflammation and ulcers resembling Crohn's disease.

In intestinal lengthening (LILT), it is never possible to achieve more than half lengthening because the intestine is divided in two; STEP should theoretically allow more lengthening.

Weaning off parenteral nutrition is possible after both LILT and STEP procedures.

Mortality after lengthening procedures was approximately 23% but not related to surgery itself; mortality mostly depends on underlying complications like liver failure, sepsis, and pneumonia.

Complications after lengthening include intestinal necrosis (not seen in Mannheim series for LILT), perforation, and inter-enteric fistula.

Primary dilatation predisposes to relapsing dilatation after lengthening and is associated with worse outcomes.

After STEP, redilatation is seen earlier and more markedly than after LILT.

Redilatation is due to bacterial small bowel overgrowth that can lead to stenosis, ulceration, and fistula in the operated bowel.

Cyclic antibiotics for bacterial overgrowth are very controversial; Mannheim now tries to have periods without antibiotic therapy rather than continuous use.

Post-operative complications can include Crohn-like disease with marked diarrhea, vomiting, failure to thrive, stenosis, and inter-enteric fistula.

When remaining bowel is less than 20 cm, it is generally not possible to wean off parenteral nutrition, but outcomes are better after LILT than STEP in this scenario.

Outcomes are much better when substantial colon is preserved (versus only 20 cm or less of colon).

GLP-2 therapy (teduglutide) should not be used in the first year of life, is appropriate for congenital or postoperative short bowel syndrome with intestinal failure regardless of remaining length, requires PN dependence, and should only be used after optimizing home parenteral nutrition with patient in stable condition, waiting at least 6-12 months after restorative surgical procedures.

GLP-2 therapy may be worthwhile when patients are on oral/enteral nutrition plus some parenteral nutrition; in one case with 40 cm jejunum and 20 cm rectum/sigmoid, good improvement was achieved and patient is currently off parenteral nutrition.

Before GLP-2 therapy, stenosis and motility disorders should be ruled out; it is unclear whether bacterial overgrowth is a contraindication.

In Mannheim's experience, less than 20% of children born in their center with short bowel syndrome undergo lengthening procedures; they perform approximately 2-4 lengthening procedures per year, with about 100 procedures total over 40 years.

In Helsinki's experience, approximately 120 short bowel patients have been treated with 20-25 undergoing tapering procedures, representing less than 20% of their own patients; the percentage has decreased in recent years with more restrictive selection.

Helsinki has treated more than 10 patients with teduglutide, some after lengthening procedures; prior lengthening does not make much difference for teduglutide candidacy as long as severe dysmotility is absent.

When colon is preserved, approximately 30% of nutrient needs can be met by the colon through bacterial fermentation of complex fibers.