Surgery of the Small Intestine

DEFINITIONS
Enterotomy is an incision into the intestine, and enterostomy is removal of a segment
of intestine. Intestinal resection and anastomosis is an enterostomy with
reestablishment of continuity between the divided ends. Entero Enteropexy, or intestinal
plication, is surgical fixation of one intestinal segment to another; enteropexy is fixation of an
intestinal segment to the body wall or another loop of intestine.
Indications
Surgery of the small intestine is most often indicated for gastrointestinal obstruction (i.e.,
foreign bodies, masses). Other indications include trauma (i.e., perforation, ischemia),
malpositioning, infection, and diagnostic or supportive procedures.
SURGICAL ANATOMY
The intestines in dogs are approximately five times the body (crown to rump) length, with
80% being small intestine. Duodenum, jejunum, and ileum make up the small intestine. The
duodenum is the most fixed, portion beginning at the pylorus to the right of midline and
extending approximately 25 cm. It courses dorsocranially for a short distance, turns caudally at
the cranial duodenal flexure, and continues on the right as the descending duodenum. The
duodenum turns cranially at the caudal duodenal flexure where the duodenocolic ligament
attaches. The ascending duodenum lies to the left of the mesenteric root. The common bile duct
and pancreatic duct open in the first few centimeters of the duodenum at the major duodenal
papilla in dogs. The accessory pancreatic duct enters caudal to this at the minor duodenal
papilla.
The jejunum forms most of the small intestinal coils lying in the ventrocaudal abdomen. It is the
longest and most mobile segment of the small intestine. It begins to the left of the mesenteric
root where the ascending duodenum turns to the right at the duodenojejunal flexure. The ileum
has an antimesenteric vessel and is approximately 15 cm long. It passes from the left to the
right side in a transverse plane through the midlumbar region caudal to the root of the
mesentery and joins the ascending colon on the right of the midline at the ileocolic orifice. The
root of the mesentery attaches the jejunum and ileum to the dorsal body wall. Branches of the
celiac and cranial mesenteric arteries supply the small intestine. Mesenteric lymph nodes lie
along vessels in the mesentery.
The layers of the intestinal wall are the mucosa, submucosa, muscularis, and serosa. Mucosa is
an important barrier that separates the luminal environment from that of the abdominal cavity.
Mucosal health and the intestinal blood supply are important for normal intestinal secretion and
absorption. The submucosal layer provides blood vessels, lymphatics, and nerves. It is the layer
of greatest tensile strength. The muscularis is needed for normal motility. The serosa is
important for forming a quick seal at a site of injury or incision.
Enterotomy
Exteriorize and isolate the diseased or desired intestine from the abdomen by packing with
towels or laparotomy sponges. Gently milk chyme (intestinal contents) from the lumen of the
identified intestinal segment. To minimize spillage of chyme, occlude the lumen at both ends of
the isolated segment by having an assistant use a scissor-like grip with the index and middle
fingers 4 to 6 cm on each side of the proposed enterotomy site . If an assistant is not available,
use noncrushing intestinal forceps (Doyen) or a Penrose drain tourniquet to occlude the
intestinal lumen. Make a full-thickness stab incision into the intestinal lumen on the
antimesenteric border with a No. 11 scalpel blade.If a foreign body is present make the incision
in healthy-appearing tissue distal to the foreign body . Lengthen the incision along the intestine’s
long axis with Metzenbaum scissors or scalpel as necessary to allow you to remove the foreign
body without tearing the intestineAfter biopsy or removal of the foreign body, prepare the
incision for closure by trimming everted mucosa so that its edge is even with the serosal edge (if
necessary) or use a modified Gambee suture . Suction the isolated lumen. Close the incision
with gentle appositional force in a longitudinal or transverse direction using simple interrupted
suture.Use a monofilament, absorbable suture material (4-0 or 3-0 polydioxanone,
polyglyconate, or poliglecaprone 25) with a swaged-on taper or tapercut point needle.
Consider a slowly absorbable monofilament suture (see p. 67) or even a monofilament,
nonabsorbable suture (4-0 or 3-0 polypropylene, nylon, or polybutester) if the patient has
an albumin level of 2 g/dl or lower.
Intestinal Resection and Anastomosis
Intestinal resection and anastomosis are recommended for removing ischemic, necrotic,
neoplastic, or fungal-infected segments of intestine. Irreducible intussusceptions are also
managed by resection and anastomosis. End-to-end anastomoses are recommended
Surgical Technique
Sutured anastomoses. Make an abdominal incision long enough to allow exploration of the
abdomen. Thoroughly explore the abdomen, and collect any nonintestinal specimens; then
exteriorize and isolate the diseased intestine from the abdomen by packing with towels or
laparotomy sponges. Assess intestinal viability and determine the amount of intestine needing
resection. Occlude (double ligate, staple or heat seal) and transect the arcadial mesenteric
vessels from the cranial mesenteric artery that supplies this segment of intestine .
Occlude (double ligate, staple or heat seal) the terminal arcade vessels and vasa recta
vessels within the mesenteric fat at the points of proposed intestinal transection. Gently
milk chyme (intestinal contents) from the lumen of the identified intestinal segment. Use fingers
or intestinal forceps to occlude the lumen at both ends of the segment to minimize spillage of
chyme (discussed earlier). Place forceps across each end of the diseased bowel segment
(these forceps may be either crushing or noncrushing because this segment of the intestine will
be excised). Transect the intestine with either a scalpel blade or Metzenbaum scissors along the
outside of the forceps. Make the incision either perpendicular or oblique to the long axis. Use a
perpendicular incision (75- to 90-degree angle) at each end if the luminal diameters are the
same. When the luminal sizes of the intestinal ends are expected to be unequal, use a
perpendicular incision across the intestine with the larger luminal diameter and an oblique
incision (45- to 60-degree angle) across the intestine with the smaller luminal diameter to help
correct size disparity . Make the oblique incision such that the antimesenteric border is shorter
than the mesenteric border. If further correction for size disparity is needed, space sutures
around the larger lumen slightly farther apart than around the smaller lumen or remove a wedge
from the antimesenteric border of the smaller segment . Suction the intestinal ends and remove
any debris clinging to the cut edges with a moistened gauze sponge. Trim everting mucosa with
Metzenbaum scissors just before beginning the end-to-end anastomosis.
Use 3-0 or 4-0 monofilament, absorbable suture (polydioxanone, polyglyconate, or
poliglecaprone 25) with a swaged-on taper or tapercut point needle. In animals with
peritonitis, consider using a more slowly absorbable monofilament suture (see p. 513).
Place simple interrupted sutures through all layers of the intestinal wall. Angle the needle
so that the serosa is engaged slightly farther from the edge than the mucosa (see Fig.
20-97, A). This helps reposition everting mucosa within the lumen. Tie each suture
carefully to gently appose the edges of the intestine with the knots positioned
extraluminally.
Appose the intestinal ends by first placing a simple interrupted suture at the mesenteric
border (see Fig. 20-99) and then placing a second suture at the antimesenteric border
approximately 180 degrees from the first (this divides the suture line into equal halves and
allows determination of whether the ends are of approximately equal diameter)