Bowel surgery

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Eileen M Segreti Charles Levenback

Introduction

The intestine is vulnerable to injury and obstruction as a result of involvement by gynecologic malignancies. Intestinal injury may also complicate the successful surgical or radiotherapeutic treatment of these diseases. This chapter focuses on common surgical procedures performed by gynecologic oncologists on the gastrointestinal tract during the management of gynecologic malignancies.

Small bowel surgery

Indications

Small bowel resection is often necessary to remove obstructed, perforated or tumor-infiltrated intestine. Resection of the involved small bowel is preferred; however if this is not feasible, a small bowel bypass may be necessary. For instance, bowel bypass may be necessary when the involved small bowel is densely adherent to a fibrotic area in an irradiated pelvis. In addition, a bypass procedure may be considered to palliate an intestinal obstruction in a woman with refractory ovarian cancer and a short life expectancy.

Anatomic considerations

The small bowel begins at the pylorus and ends at the cecum. The overall length averages 620 cm, and the normal range is 365-720 cm. The duodenum and jejunum are separated by the ligament of Trietz. The distinction between the jejunum and the ileum is more gradual. The small bowel is perfused by straight vessels that disperse into the anterior and posterior surfaces of the bowel. The straight vessels (vasa recta) emerge from the arcades of the superior mesenteric artery. In the ileum the straight vessels are surrounded by fat, which encroaches upon the bowel wall. In the jejunum, the vasa recta are more easily seen, as the mesenteric fat ends before it reaches the jejunal serosa. The venous drainage of the small bowel is to the superior mesenteric vein which is a tributary of the portal vein.

The autonomic nervous system, in conjunction with the gastrointestinal hormonal system, regulates peristalsis and bowel secretory action. The parasympathetic ganglia lie within the bowel wall, whereas the sympathetic ganglia lie close to the origin of the superior mesenteric artery

The small intestine has four layers. They are the mucosa, the submucosa, the muscularis and the serosa. The mucosa contains villi and crypts which greatly increase the absorptive surface area. The submucosa is a

Figure 1

Layers of the small intestine

1 Mucosa

2 Submucosa

3 Inner circular muscle

4 Outer longitudinal muscle

5 Serosa strong connective tissue layer important for structural integrity. It is especially vital to include this layer during bowel reanastomosis. The muscularis consists of an inner circular layer and an outer longitudinal layer. The serosa is the outermost layer and is a continuation of the mesothelium that lines the peritoneal cavity (Figure 1).

The terminal ileum is the site of absorption of the fat-soluble vitamins A, D, E and K, as well as vitamin B12. Extensive resection of the terminal ileum will necessitate vitamin supplementation. Every effort should be made to preserve as much bowel as possible. Severe malabsorption problems will occur if less than 200 cm is conserved.

Operative procedure

Resection

Small bowel resection, to be successful, must completely remove the damaged or involved intestinal segment. Intestinal continuity must then be re-established using healthy ends of bowel which are approximated without tension while maintaining a good blood supply. Tissues should be handled gently, and a watertight anastomosis should be achieved. If not precluded by complete or advanced small bowel obstruction, a mechanical and antibiotic bowel preparation should be administered to decrease the chance of infection or anastomotic breakdown.

Bowel SurgeryHand Sewn Anastomosis

Figure 2

Positioning of clamps

There are several different methods of performing small bowel reanastomosis. Automatic gastrointestinal staplers can be used, or the anastomosis can be entirely hand-sewn. The damaged or obstructed portion of the small bowel is identified. The vascular arcades are visualized by transillumination. Rubber- or linen-shod, noncrushing intestinal clamps or Penrose drains can be used to occlude the bowel lumen on either side of the site of resection. A small defect is created in the mesentery proximal and distal to the affected bowel. Either staplers or bowel clamps are used to isolate the abnormal section of small intestine. The stapler or clamps are oriented obliquely to maximize the mesenteric side of the bowel and minimize the antimesenteric side (Figure 2). This maneuver will also create a larger lumen, thereby decreasing the chance of a subsequent stricture. The mesentery is scored with scissors or an electrocautery device, and the vessels are isolated between small clamps. The vessels are cut and secured with 2-0 sutures or a stapler such as the ligate-divide-staple (LDS) device.

Commonly, staplers are used to create a side-to-side, functional end-to-end, anastomosis. The ends of the small bowel are juxtaposed and inspected for viability. If there is any doubt as to bowel viability, the bowel is excised further until quality is acceptable. The anastomosis must be tension-free. The loops are mobilized as necessary to relieve any tension. The antimesenteric borders are lined up in parallel. Stay sutures are placed 5-8 cm from the closed bowel ends along the antimesenteric border. The corners of the antimesenteric staple line are then excised (Figure 3). This allows one arm of the stapler to be placed along the antimesenteric border of each limb of bowel (Figure 4). The stapler is closed and fired to place two double rows of titanium staples and incise an opening between the limbs (Figure 5). The staple line is then inspected for bleeding. Any bleeding area should be reinforced with an interrupted suture. Next, the remaining defect is grasped with Allis clamps and a thoracoabdominal (TA) stapler is set and fired to close

Right Colectomy Stapled Anastomosis

Figure 3

Preparation for anastomosis

1 Incision

2 Staple line

3 Bowel lumen

4 Mucosa

5 Serosa the remaining enterotomy. The staple lines should overlap to prevent leakage at the anastomosis (Figure 6). Excess tissue above the TA stapler can be excised.

The small bowel can also be anastomosed end-to-end with a single or double layer of sutures. If the bowel lumens are of disparate sizes, an antimesenteric incision parallel to the length of the bowel can be made in the smaller lumen (Cheatle slit) to equalize the lumen sizes (Figure 7). If two layers are used, the inner layer is a continuous inverted layer of absorbable suture, and the outer layer is a series of interrupted, inverting silk seromuscular sutures. In a single-layer closure, either a continuous inverted or an interrupted inverted single-layer technique may be used (Gambee et al 1956). In the Gambee technique, 3-0 sutures are placed from the mucosa through the bowel wall to the serosa and back through serosa to mucosa. The knots are tied on the mucosal side, and the sutures are placed 3 mm apart. The last sutures should be held until all the sutures are placed. The last few knots must be tied on the serosal surface (Figure 8). Closure should be secure enough to prevent seepage of liquid. The mesenteric defect is then closed to prevent an internal hernia and subsequent bowel strangulation, without mesenteric vessel ligation.

A diseased terminal ileum may require extensive resection with ileoascending or ileotransverse enterocolostomy in an effort to avoid an anastomosis with irradiated tissues (Hoskins et al, 1987). An ileoileoenterostomy should probably be avoided within 10 cm of the cecum. The blood supply in this area may be marginal.

Cancer The Cecum Pictures

Figure 4

Positioning of stapler

Bypass

An alternative to small bowel resection is small bowel bypass, whereby an abnormal segment of bowel is bypassed by creating an anastomosis proximal to the abnormal area. This allows intestinal contents to progress beyond an area of obstruction. A side-to-side enteroenterostomy is created, using either staplers or a double- or single-layer suture technique (Figure 9). This procedure would leave the damaged loop adherent to the underlying viscera, yet still open to drain into the fecal stream. Alternatively, the bowel is divided proximally and distally to the damaged segment, and the damaged bowel is completely excluded from the intestinal stream. The proximal end of the bypassed limb is brought up to the skin as a mucous fistula. The distal limb should be transected immediately after the obstructed, adherent end to prevent a closed loop. The mucous fistula may be incorporated into the inferior aspect of the incision. A disadvantage of bowel bypass is that it may subsequently foster a blind loop syndrome as the disease process worsens. This syndrome is characterized by bacterial overgrowth with subsequent cramps, diarrhea, anemia and weight loss (Schlegel and Maglinte 1982). If a small bowel fistula is bypassed, it is important to isolate this bowel segment completely from the intestinal stream. A third option is to divide the bowel proximally to the damaged area and create an anastomosis distally.

Large bowel surgery Indications

Partial colectomy, rectosigmoid resection and abdominal perineal resection are all used to treat gynecologic malignancies. These procedures may be integral to ovarian cancer debulking or treatment of radiation complications, or from a component of pelvic exenteration for cervical, endometrial, vaginal or vulvar cancer. If the sphincter or distal rectum is damaged or involved with tumor, a colostomy may be required to provide fecal continence. Stoma formation is required for either permanent or temporary fecal diversion. End colostomies are typically preferred for permanent stomas, as they are smaller and prone to fewer complications (Segreti et al 1996). Loop colostomies are preferred when stomal closure is anticipated or

Surgery For Ovarian Cancer

Figure 5

Stapling large bowel obstruction occurs secondary to advanced, refractory ovarian cancer, and life expectancy is short. After a colostomy has served its purpose, allowing a distal anastomosis to heal or a fistula to be repaired, intestinal continuity is restored by closing the colostomy. Lastly, removal of the appendix may be useful in ovarian cancer debulking or urinary conduit construction, or to serve as prophylaxis against future infectious or neoplastic complications.

Anatomic considerations

The blood supply to the colon and rectum is derived from branches of the superior mesenteric, inferior mesenteric and internal iliac arteries. The right colon is supplied by the ileocolic artery, the right colic artery and a branch of the middle colic artery. The transverse colon is chiefly supplied by the middle colic artery, but there is a communication with the inferior mesenteric arterial system via the marginal artery of Drummond. The inferior mesenteric artery supplies the colon from the splenic flexure to the proximal rectum. The inferior mesenteric artery branches into the superior rectal artery, the sigmoidal arteries and the left colic artery. The distal rectum receives its blood supply from the paired middle and inferior rectal arteries which originate from the internal iliac artery system (Figure 10).

The appendix is the embryologic continuation of the cecum. Its location is identified by the confluence of the three taenia of the cecum. The position of the appendiceal tip relative to the cecum may vary. The tip

Thoracoabdominal Stapler

Figure 6

Positioning of thoracoabdominal stapler may be found lateral to, medial to or behind the cecum. The mesentery of the appendix passes behind the terminal ileum. The blood supply to the appendix is derived from the appendiceal artery, which is a branch of the ileocolic artery.

The nerves to the colon parallel the blood supply, and consist of sensory afferent nerves and motor nerves from the autonomic system. The anal sphincter is under voluntary motor control. The colonic wall is more muscular than that of the small bowel. In addition, the longitudinal muscles are gathered in three places to form the taenia coli. The colon also has numerous fatty appendices epiploicae that hang from the taenia.

Operative procedures

The colon contains much more infectious material than the small bowel, and a thorough mechanical and antibiotic bowel preparation is very important prior to large bowel surgery. The principles of large bowel resection and reanastomosis are similar to those for small intestinal anastomosis and are based on the blood supply and the location of the diseased segment. Resection and reanastomosis of the colon and proximal rectum are performed equally well with either a hand-sewn or a stapled technique. For the distal rectum, the automatic end-to-end anastomosis circular stapling device has provided the ability to perform successful low and very low rectal anastomoses. Adequate mobility of the rectosigmoid must be achieved by incision along the lateral peritoneal reflection. The two ends of the bowel to be anastomosed must be mobile enough to lie adjacent to each other without tension. The largest stapling device that fits comfortably should be used. Sizers are available to measure the lumen. After resection of the diseased large bowel, a purse-string suture

End Side Bowel Anastomosis

Figure 7

End-to-end anastomosis is placed around the proximal lumen. This is easily performed with the purse-string instrument and a straight needle. The purse-string suture is then secured around the anvil of the stapler (Figure 11). The rectal stump can similarly be circumscribed with a purse-string suture. Alternatively, a stapler can be used to close the rectal pouch. A trocar attached to the stapler is used to puncture the closed rectal pouch at the site of the future anastomosis. The trocar is then removed, and the anvil shaft can be inserted into the stapler instrument. By turning the wing nut on the stapler handle, the two lumens are approximated. After releasing the safety catch, the handle is squeezed and two circular rows of staples are placed. A circular knife cuts the excess inverted tissue, and two 'donut' shapes are created. The wing nut is then turned in the opposite direction to open the instrument which is then withdrawn gently through the rectum. The two 'donuts' of tissue should be inspected and be complete (Figure 12). A defect in one of them is reason to redo or repair the anastomosis. The seal of the anastomosis can be tested by filling the pelvis with saline and injecting air into the rectum. Bubbles indicate an air leak that should be oversewn. The anastomosis can also be visually inspected with a sigmoidoscope.

Hand-sutured colonic anastomoses have classically been formed of two layers in the tradition of Lembert and Halsted. The two-layer closure consists of a running inverted layer of 3-0 chromic or polyglactic acid suture, followed by an outer layer of interrupted 3-0 silk Lembert sutures. Recently several investigators have reported using a one-layer inverting colonic closure with satisfactory results (Curley et al 1988, Max et al 1991, Ceraldi et al 1993). One-layer closures are faster than the two-layer technique and less expensive than the stapled closure. The single-layer closure is performed with 3-0 or 4-0 polypropylene or polyglyconate suture using a double-armed needle. The suture is begun at the mesenteric border of the bowel (Figure 13). The sutures are placed from outside in, including a larger amount of the serosa, muscularis and submucosa (approximately 5 mm) than the mucosa (minimal) to effect mucosal inversion.

Gambee Lambert Suture

Figure 8

The Gambee technique

1 Serosa

2 Mucosa

3 Last suture

4 Lumen

5 Inverting suture held until all sutures in place

6 Defect to be dosed without vessel compromise

The knot is secured outside the bowel lumen. Each end of the suture is then continued around to the antimesenteric border, spacing the stitches 3-4 mm apart. The sutures are then tied together.

The thoracoabdominal stapler can also be used to create an end-to-end anastomosis by triangulation (Figures 14-19). Three stay sutures are placed equidistantly on each limb of the bowel. One stay suture should be located at the level of the mesentery, and the other two stay sutures should be placed to form an

Enterocolostomy

Figure 9

Side-to-side enterocolostomy equilateral triangle. The back wall is stapled first, and the mucosa is inverted. The second row of staples is placed to overlap the first row. The last row of staples is placed, and the mucosa is everted. The diameter of the lumen is palpated to ensure adequate size.

The patient should meet with an enterostomal therapist for preoperative teaching and evaluation of the abdominal wall for stomal placement. Stomas should ideally pass through the rectus muscles and avoid abdominal wall folds or creases (Figure 20). The patient should be examined in both the sitting and standing position. Stoma placement in the waistline should be avoided. Obese patients have a significant amount of skin movement with position changes from supine to erect. This skin travel and the degree of tension it may place on the stoma in different positions must be considered when planning the stoma site.

A vertical laparotomy incision helps to provide adequate exposure. Prior to dividing the colon, the bowel is mobilized by dividing the lateral peritoneal attachments; adequate mobility must be achieved to provide a tension-free stoma. The distal bowel is resected or oversewn as a pouch. A 3 cm circular skin button is removed at the previously marked site. The subcutaneous tissues are bluntly separated. The anterior rectus sheath is incised in a cruciate fashion. The rectus muscles are split longitudinally with care taken to avoid the inferior epigastric vessels. The peritoneum is then incised and two fingers are passed through the abdominal wall. The stapled bowel end is grasped with a Babcock clamp and brought through the stomal aperture. Care is taken not to twist the mesentery. Excess fat and mesentery are trimmed from the stoma. The mesentery can be fixed to the parietal peritoneum to prevent internal herniation. The abdominal incision is then closed. The staple line on the bowel is excised, and the stoma is matured in a 'rosebud' fashion by inserting the needle into the skin 1 cm from the stomal edge, then running it up the bowel serosa and

Partial Colectomy Blood Supply

Blood supply to the colon and rectum

1 Superior rectal artery

2 Sigmoid artery

3 Inferior mesenteric artery

4 Left colic artery

5 Ovarian artery

6 Superior mesenteric artery

7 Renal artery

8 Coeliac trunk

9 Marginal artery

10 Middle colic artery

11 Right colic artery

12 Ileojejunal artery

13 Ileocolic artery

14 Middle rectal artery

15 Inferior rectal artery

Colostomy RosebudRight Proximal Transverse Colostomy

Figure 11

Positioning of purse-string suture muscularis for one or two stitches, exiting on the mucosal side and securing the knot over the mucocutaneous junction (Figure 21).

A loop colostomy may be situated at either the proximal or distal transverse colon. If a loop colostomy is performed for palliation of large bowel obstruction secondary to advanced, refractory ovarian cancer, the distal transverse colon may be selected to maximize colonic length. However, if the purpose is to create a temporary diverting colostomy while an anastomosis heals, the proximal transverse colon is usually preferred. A 10-12 cm transverse skin incision is made in the right or left upper quadrant. The fascia is incised transversely, and the rectus muscles are separated longitudinally. The peritoneal cavity is entered sharply. When a large bowel obstruction is present, the transverse colon is easily identified owing to its dilatation. The adjacent omentum is dissected off the loop of colon. A defect is created in the mesentery to allow passage of a thin rubber drain, such as a Penrose, with which to lift and manipulate the colon. The fascial incision is then partially closed. A flat plastic bridge is passed through the mesenteric defect and

Partially Closed Incision

Figure 12

Two intact 'donuts' of tissue secured to the skin with a nylon suture. The skin incision, if larger than needed for the stoma, may be partially closed with skin staples or non-absorbable sutures. The colon is then opened either longitudinally along the taenia, or at a transversely oriented angle. The bridge may be removed in 7-10 days (Figure 22).

A loop stoma is closed by incising the skin adjacent to the mucocutaneous junction, elevating the stoma with Allis clamps, and dividing the filmy attachments to the subcutaneous tissues. The fascial edge is then identified, and the plane sharply developed between the stoma and the fascial opening. The peritoneal adhesions are then lysed. The stomal edge can then be excised, and an extraperitoneal one- or two-layer closure can be performed. The loop is then dropped back into the peritoneal cavity and the fascia closed with delayed absorbable suture. The skin defect can be packed open and left to close secondarily, or alternatively staples can be used for immediate skin closure (Hoffman et al 1993).

Another option to close a loop colostomy is to use the thoracoabdominal stapler. After incision of the mucocutaneous junction, the edges of the stoma are grasped with Allis clamps. The colostomy edges are held together to form a line perpendicular to the long axis of the bowel: this will maximize the lumen diameter. The stapler is fired, and the excess tissue is excised as described above.

To close an end stoma, an exploratory laparotomy is usually needed to identify the distal limb and create a large bowel anastomosis. Laparoscopy may alternatively be used and an extraperitoneal closure effected, if the distal limb is nearby and can be mobilized adequately. The end stoma is excised in a similar

Halsted Suture Anastomosis

Figure 13

Single-layer anastomosis, with (inset left) continuous sutures and (inset right) interrupted sutures manner to that described for a loop stoma. The mucocutaneous junction of the distal end is excised. A large bowel anastomosis is performed as previously described. Mesenteric defects are closed to prevent internal hernias.

Appendectomy is accomplished by isolating and ligating the blood supply to the appendix and closing or burying the stump of the appendix to prevent fecal spillage. If present, filmy adhesions from the appendix to the peritoneal surfaces are lysed. If the appendix is retrocecal, the cecum is mobilized by incising the peritoneal reflection. The appendiceal artery is isolated, doubly clamped, ligated and secured with 2-0 suture. The base of the appendix is then crushed between two straight hemostats. The specimen is excised between the hemostats, and the stump tied off with 2-0 suture (Figure 23). Alternatively, the ligated stump can be buried into the cecum with a Z stitch or purse-string suture. However, burial into the cecum may promote a mucocele or an abscess. Another approach after dividing and securing the appendiceal artery is to remove the appendix using the stapling device.

Appendiceal Artery

Figure 14

End-to-end anastomosis by triangulation

Triangulating End End Anastomoses

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