Short Bowel Syndrome

Introduction

  • Short bowel syndrome (SBS) is characterized by malabsorption of ingested nutrients due to resection of the small intestine.
  • Normal small bowel length in an infant is 250 cm; SBS typically occurs when less than 100 cm remains after surgery.

Figure 1. Three common forms of short bowel syndrome.SBS1.png From Buchman 2015, accessed at http://clinicalgate.com/short-bowel-syndrome-2/

 

Causes

Neonatal

  • Necrotizing enterocolitis (most common etiology) 
  • Intestinal atresia
  • Gastroschisis
  • Volvulus
  • Hirschsprung disease

Older children

  • Trauma
  • Gastrointestinal malignancy
  • Crohn’s disease.

Prognostic Factors

  • The prognosis for children with SBS depends on the length of bowel removed and the segment of bowel removed. 
  • Ileal resection is a poor prognostic factor
    • The ileum has unique functions including Vitamin B12 and bile acid absorption, as well as the secretion of anti-motility peptides that constitute the “ileal brake”.
  • Loss of the ileocecal valve is also a poor prognostic factor
    • Results in reflux of colonic contents into the small bowel and resultant bacterial overgrowth.

Figure 2. Anatomical locations of nutrient absorption in the GI tractSBS2.png From Buchman 2015, accessed at http://clinicalgate.com/short-bowel-syndrome-2/

 

Management

  • Primarily directed toward maintaining adequate nutrition, hydration, and growth, usually through parental nutrition.
  • Secondly directed toward promoting intestinal adaptation
    • Characterized by macroscopic lengthening and dilation of the bowel as well as microscopic villus hyperplasia.
  • This process depends on enteral feeding supplemented with appropriate trophic factors.

Total parenteral nutrition (TPN)

  • Children with SBS require parenteral (intravenous) feeds in order to maintain adequate nutrition and hydration.
  • TPN formulas are determined for each patient based on a weekly panel of labs including electrolytes, albumin, triglycerides, bile acids, and glucose, as well as fat-soluble vitamin and iron panels drawn every three to six months.
    • Intestinal failure-associated liver disease (IFALD) is the most common complication of TPN, occurring due to disrupted enterohepatic circulation and direct lipid-induced toxicity.
    • IFALD may present with elevated transaminases and can be confirmed histologically; progression may be minimized by administering TPN cyclically rather than continuously, and by limiting formula lipids to 1g/kg/day.
    • Recent efforts to reduce IFALD have focused on replacing traditional lipid formulations with fish oil-based emulsions that are rich in omega-3 fatty acids, which stimulate anti-inflammatory cytokines.
    • Because TPN is administered via central venous line, patients are also at risk for catheter-related infections and thrombosis.
    • Infections may present with fevers, lethargy, or ileus.
    • Thrombosis may present with congestion, difficult blood draws, or emboli
      • Alternatively, thromboses are often asymptomatic, prompting some centers to obtain surveillance echocardiograms or ventilation-perfusion scans.
    • TPN may alternatively be administered via PICC line to increase ease of access and preserve central veins.

Enteral feeding

  • Gradual advancement of enteral feeding is critical to promoting intestinal adaption and weaning patients from TPN.
  • Feeds are typically introduced via nasogastric or gastric tube on a continuous schedule.
  • Tolerance of enteral feeding is assessed by monitoring stool volume
    • An output of less than 50 ml/kg/day is considered indicative of adequate absorption and readiness for small advancements in feeding rate.
    • Over time, the patient may also transition from continuous feeding to a bolus regimen.
  • In addition to tube feeds, regular oral feeding is necessary to avoid the development of feeding aversion.
  • Neonates may be started on small tastes of breast milk or formula three to four times per day, with gradual volume advancement and diversification of feeds.

Medications

The following medications are frequently used in the management of SBS:

  1. Anti-secretory agents (H2 blocker, proton pump inhibitor, octreotide)
    • Used to counteract gastric acid hypersecretion (seen in SBS due to loss of gastrin degradation in the small bowel)
  2. Anti-motility agents (loperamide or diphenoxylate/atropine)
  • Used in cases of excessive dumping to slow intestinal transit and promote nutrient absorption
  1. Pro-motility agents (erythromycin, azithromycin)
    • Used in cases of intestinal hypomotility to relieve abdominal distention and vomiting
  2. Antibiotics with anaerobic coverage (metronidazole, augmentin)
    • Used to counteract bacterial overgrowth seen with bowel hypomotility
  3. Intestinal trophic factors (growth hormone, GLP2)
    • Used as a supplement in enteral feeds to promote intestinal cell growth

Autologous intestinal reconstruction surgery (AIRS)

  • The following surgical procedures make use of the SBS patient’s native bowel to increase absorptive surface area:
  1. Longitudinal intestinal lengthening and tailoring (LILT) or “Bianchi procedure”
    • A dilated segment of bowel is divided horizontally into two segments, which are then re-anastomosed end-to-end to produce a narrowed, lengthened segment of bowel

Figure 3. Longitudinal intestinal lengthening and tailoring procedure SBS3.png From Konig 2015, accessed at www.paediatricstoday.com/index.php/pt/article/download/234/pdf

 

  1. Serial transverse enteroplasty (STEP) or “Kim procedure”
    • A dilated segment of bowel is reshaped through a series of angled incisions to produce a narrowed, zigzag-shaped bowel segment. This technique avoids the risk of anastomotic leak incurred with the Bianchi procedure.

Figure 4. Serial transverse enteroplasty procedure SBS4.pngFrom Konig 2015, accessed at www.paediatricstoday.com/index.php/pt/article/download/234/pdf

 

  1. Spiral intestinal lengthening and tailoring (SILT) or “Cherni procedure”
    • A dilated segment of bowel is incised along a 45-degree spiral, stretched longitudinally, and re-sutured along the spiral incision line. This is a relatively new method, thought to minimize damage to the mesenteric vessels and to the circular and longitudinal muscle fibers, thereby minimizing disordered motility.

Figure 5. Spiral intestinal lengthening and tailoring procedure SBS5.png From Konig 2015, accessed at www.paediatricstoday.com/index.php/pt/article/download/234/pdf

 

Small bowel transplant

  • Small bowel transplant is the most definitive treatment for SBS.
    • It is used in patients who have undergone “TPN failure” characterized by who have:
      • Loss of venous access sites
      • Multiple catheter-associated infections
      • Frequent episodes of electrolyte abnormality or dehydration
      • Progressive liver failure.
  • Small bowel transplant for SBS patients may take any of three forms:
  1. Isolated small bowel transplant
    • Transplantation of jejunum and ileum from a cadaveric donor or of 150-200 cm distal ileum (sparing terminus) from a live donor
    • This procedure is used when a patient has isolated intestinal failure without liver disease
  2. Liver-intestinal transplant – en bloc transplantation of jejunum, ileum, and liver
    • This procedure is more common than isolated bowel transplant in children due to the high frequency of TPN-associated liver damage
  3. Multivisceral transplant – en bloc transplantation of stomach, duodenum, pancreas, jejunum, ileum, and liver
    • This procedure is used in patients with multi-organ involvement (for example, related to trauma or malignancy)
  • Transplants may be complicated by acute cellular rejection, graft-versus-host disease, and post-transplant lymphoproliferative disorder.
  • The one-year survival rate for these procedures is approximately 80%.

 

References

1. Buchman, Alan L. "The medical and surgical management of short bowel syndrome." Medscape General Medicine 6.2 (2004).

2. Coletta, Riccardo, Basem A. Khalil, and Antonino Morabito. "Short bowel syndrome in children: Surgical and medical perspectives." Seminars in pediatric surgery. Vol. 23. No. 5. WB Saunders, 2014.

3. Cserni, Tamas, et al. "Spiral intestinal lengthening and tailoring—first in vivo study." Journal of pediatric surgery 48.9 (2013): 1907-1913.

4. Konig, Robert. "Overview of non-transplant surgical management of short bowel syndrome in children.” Paediatrics Today 11.2 (2015): 85-92.

5. Minneci, Peter C. "Intestinal transplantation: An overview." Pathophysiology 21.1 (2014): 119-122.

6. Nightingale, J., and Jeremy M. Woodward. "Guidelines for management of patients with a short bowel." Gut 55.suppl 4 (2006): iv1-iv12.

7. Sulkowski, Jason P., and Peter C. Minneci. "Management of short bowel syndrome." Pathophysiology 21.1 (2014): 111-118.

8. Thompson, Jon S. "Short Bowel Syndrome and Malabsorption-Causes and Prevention." Viszeralmedizin 30.3 (2014): 3-3.

9. Zavras, Nick, et al. "Short-Bowel Syndrome in Children—An Update in Management Strategies." (2015).

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