Management of Small Bowel, Colon, and Rectal Injuries

Divisions of the small bowel

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  The small bowel is 4–6 meters long and divided into the duodenum, jejunum, and ileum.

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  Duodenum (see Chapter 28 for details)

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  Jejunum

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    Continuation of the fourth part of the duodenum at duodenojejunal flexure situated on the left side of L2 vertebra

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    It is fixed to the retroperitoneum by the ligament of Treitz.

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    The aorta and the superior mesenteric vessels are located on the right, and the inferior mesenteric vein is located on the left side of the ligament of Treitz.

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    It constitutes about two-fifths of the proximal small intestine.

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    Features to identify jejunum

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      Situated in the left upper and central abdomen

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      Thicker wall and a wider lumen than the ileum

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      Less mesenteric fat compared to mesentery of the ileum, mesenteric vessels more visible

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  Ileum

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    Continuation of jejunum; terminates at the ileocecal junction

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    Constitutes the distal three-fifths of the small bowel

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    Features to identify ileum

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      Thinner wall and a smaller lumen

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      Situated in the central and right lower abdomen and pelvis

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      Abundant mesenteric fat; mesenteric vessels are not well visualized

Mesentery of the small bowel

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  Double-folded peritoneum attached to the posterior abdominal wall

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  The root of the mesentery extends obliquely from the left L2 vertebra level to the right sacroiliac joint.

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  The mesentery crosses the third part of the duodenum, aorta, inferior vena cava (IVC), and right ureter.

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  The mesenteric vessels and lymph nodes are situated between the two leaves of the mesentery.

Blood supply of small bowel

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  Arterial supply

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    Jejunal and ileal branches of the superior mesenteric artery (SMA) arise from the left side of the SMA

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    Jejunal and ileal arterial branches form 2–3 arterial arcades in the jejunum, and 4-5 in the ileum to supply the small bowel.

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    Right colic artery, middle colic artery, and ileocolic artery arises form the right side of the SMA.

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  Venous drainage

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    Veins from the jejunum and ileum drain into the superior mesenteric vein (SMV).

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    Veins run parallel to the arteries.

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    The SMV lies slightly anterior and to the right of the SMA anterior to the uncinate process and third part of the duodenum.

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    The SMV and splenic vein join to form the portal vein posterior to the neck of the pancreas.

Blunt injury

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  Shearing force: Perforation of the small bowel, usually at the antimesenteric border

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  Traction injury: Injury at the point of fixation, such as at the ligament of Treitz or ileocecal junction

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  Deceleration injury: Bucket handle tear of the mesentery causing small bowel ischemia

Grade I injury

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  Minor hematoma

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  Partial-thickness laceration

Grade II injury

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  Full-thickness laceration involving <50% of the circumference

Grade III injury

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  Full-thickness laceration involving >50% of the circumference without complete transection

Grade IV injury

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  Complete transection without devascularization

Grade V injury

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  Mesenteric disruption causing devascularized bowel

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  Transection with segmental tissue loss

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  Advance one grade for multiple injuries up to Grade III .

Indications

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  Hemodynamically unstable patients

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  Bowel injury with:

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    significant edema.

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    significant bowel distention (ileus).

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    gross intraperitoneal contamination.

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  Mesenteric injury with concern of bowel ischemia

Damage-control options in small bowel injury

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  Grade I injury

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    Minor hematoma: Nonoperative treatment

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    Partial thickness laceration: Repair with interrupted seromuscular sutures using nonabsorbable 3-0 Silk or absorbable 3-0 Polydioxanone/Polyglactin sutures

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  Grade II injury

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    Laceration: Repair (enterorrhaphy) transversely in two layers, inner layer with full thickness running absorbable 3-0 Polydioxanone/Polyglactin sutures, and outer layer with interrupted seromuscular absorbable 3-0 Polydioxanone/Polyglactin or nonabsorbable 3-0 Silk sutures.

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  Grade III/IV/V injuries

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    Bowel resection using stapler or ligation of injured bowel without anastomosis

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    Temporary abdominal closure

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    Reexploration after hemodynamic stability, and resolution of coagulopathy, acidosis, and hypothermia

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      Bowel resection/anastomosis

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      Definitive abdominal closure if possible

Grade I injury

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  Minor hematoma

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    Blunt injury: Nonoperative treatment

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    Penetrating injury

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      Hematoma should be explored to examine for perforation.

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      Missed bowel perforation is common at the mesenteric border hematoma.

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  Partial-thickness laceration: Repair with interrupted seromuscular sutures using 3-0 nonabsorbable or absorbable sutures.

Grade II injury

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  Laceration: Repair (enterorrhaphy) transversely in two layers: inner layer with full thickness running absorbable 3-0 Polydioxanone/Polyglactin sutures, and outer layer with interrupted seromuscular absorbable 3-0 Polydioxanone/Polyglactin or nonabsorbable 3-0 Silk sutures.

Grades III/IV/V

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  Bowel resection with stapled anastomosis or hand-sewn anastomosis in two layers: inner full thickness with running absorbable 3-0 Polydioxanone/Polyglactin sutures, and outer interrupted seromuscular layer using absorbable 3-0 Polydioxanone/Polyglactin or nonabsorbable 3-0 Silk sutures.

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  Hand-sewn anastomosis should be considered in patients with significant bowel edema.

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  In multiple lacerations, multiple anastomosis should be avoided.

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  Bowel resection may result in short bowel syndrome.

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    Approximately 100 cm of small bowel without ileocecal valve or 60 cm of small bowel with ileocecal valve is essential to prevent short bowel syndrome.

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    Resection of up to 70% of the small bowel is usually tolerated well if the terminal ileum and ileocecal valve are preserved.

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    Proximal bowel resection is tolerated better than distal resection because the ileum can adapt and increase its absorptive capacity more efficiently than the jejunum.