Intestinal Surgery for the Gynecologic Surgeon
Mitchel Hoffman
Emmanuel Zervos
DEFINITIONS
Bubble test—Transanal instillation of air into the submersed and proximally compressed rectum for the purpose of looking for a hole or an anastomotic gap.
Closed loop obstruction—Anatomic state wherein a segment of bowel is excluded from the fecal stream due to malignancy, adhesions, or a surgically induced state.
Complicated diverticulitis—Refers to the presence of a perforation, obstruction, abscess, or fistula. Approximately 25% of patients diagnosed with diverticulitis for the first time present with complicated diverticulitis, and nearly all of these cases require surgery.
Cytoreduction—Refers to surgical reduction of the metastatic tumor load in the context of surgery for ovarian cancer.
Diversion—Indicates preclusion of passage of stool to the portion of the intestinal tract distal to the stoma in an ileostomy or colostomy.
Enteric fistula—Epithelialized tract from a portion of the intestine to the skin or mucosa of another organ.
Enterolysis—Division of adhesions involving the intestinal tract.
Enterostomal therapist—Specialist who provides education and assistance to patients who are planned for or have undergone a stoma.
Enterotomy—Hole or laceration in the wall of the intestine.
Hartmann pouch—Healed segment of retained rectosigmoid colon following sigmoid resection with end colostomy.
Inanition—Condition of exhaustion due to starvation.
Laplace law—Explanation for the propensity of the cecum to be the first site of colonic perforation due to dilatation from distal colonic obstruction. The law (T = PR) directly correlates tension (T) to the radius (R) and internal pressure (P) of the bowel.
Lembert sutures—Series of sutures incorporating only the serosa and muscular layers of any portion of the GI tract and designed to reinforce and relieve tension on mucosal suture lines.
Malecot catheter, mushroom catheter—Rubber catheter ranging in size from 6 to 38 French with a mushroom-shaped tip ideally suited to drain large spaces that communicate with the skin through considerably smaller tracts.
Mucous fistula—Portion of defunctionalized bowel exteriorized to a stoma for the purpose of drainage and avoidance of an intestinal mucocele.
Obstipation—Severe constipation, usually due to intestinal obstruction.
Pelvic exenteration—Operation undertaken for pelvic malignancy in which the bladder, vagina, and uterus (anterior); vagina, uterus, and rectum (posterior); or all four organs (complete) are removed.
Percutaneous endoscopic gastrostomy (PEG)—Percutaneous placement of a gastrostomy tube under gastroscopic guidance without laparotomy.
Proctosigmoiditis—Inflammation of the sigmoid colon and/or rectum.
Rectal stump—Segment of rectum remaining after a rectosigmoid resection.
Short bowel syndrome—Any clinical circumstance wherein the inherent small bowel provides insufficient absorptive capacity to maintain a noncatabolic state.
Tenesmus—Urge to defecate, despite empty colon or bladder.
Uncomplicated diverticulitis—Diverticulitis without the complications noted above and accounts for 75% of diverticulitis cases. The majority of cases respond to medical therapy, although up to 30% require surgery.
INTRODUCTION
The female pelvic cavity is a confined space occupied by the female genitalia, the lower urinary tract, and the rectosigmoid colon. Anatomically, these structures are intimately associated. Other portions of the intestinal tract may occupy the pelvis as well, such as the cecum, appendix, and/or small intestine. It is not surprising, therefore, that gynecologic diseases and the complications resulting from their treatment often involve the urinary tract, the intestinal tract, or both. Similarly, diseases of the urinary and intestinal tract may often mimic or influence manifestations of gynecologic disease.
The complete pelvic surgeon must have medical and surgical expertise in the management of specific types of intestinal disorders. With any type of operation, the abdominal surgeon must be prepared for the eventuality of intestinal injury. For the gynecologic oncologist, common indications for intestinal surgery include resection of tumor and bowel obstruction. Oncologists also perform exenterative surgery, urinary diversion, fistula repair, and surgery for severe radiation damage to the bowel. Pelvic reconstructive surgeons are called on to repair rectal prolapse. Bowel resection is occasionally indicated for infiltrating endometriosis. When operating for presumed gynecologic pathology, the pelvic surgeon occasionally discovers a primary bowel disorder that must be managed surgically.
The purpose of this chapter is to provide the pelvic surgeon with basic information necessary for the surgical management of the more common intestinal problems encountered in the management of presumed gynecologic disorders and complications of their treatment.
ANATOMY
Knowledge of the anatomy of the gastrointestinal tract is essential for the performance of intestinal surgery and management of complex pelvic pathology. The relevant anatomy is reviewed here.
Stomach
The stomach is the uppermost organ of the gastrointestinal tract, residing completely in the abdominal cavity. The intraabdominal esophagus ranges from 3 to 6 cm in length under normal anatomic conditions. It is located in the left upper quadrant of the peritoneal cavity. The stomach is composed of the cardia, the portion immediately surrounding the gastroesophageal junction and the largest portion of the stomach; the fundus, the upward extension of the stomach toward the dome of the diaphragm on the left side; the body; and the antrum, the portion of the stomach between the incisura and the pylorus. The incisura is a notched portion of the stomach along the lesser curvature. Being a derivative of the foregut, the stomach receives its arterial blood supply from the celiac trunk, the lower thoracic aorta, and collaterals arising from the superior mesenteric artery (SMA) (Fig. 47.1).
Small Intestine
FIGURE 47.1 Blood supply of the stomach. |
The small intestine averages 21 feet in length. From the pylorus of the stomach, the duodenum curves retroperitoneally to the ligament of Treitz, left of the second lumbar vertebrae. In the left upper quadrant of the peritoneal cavity, the intestine then becomes intraperitoneal as the jejunum, which is approximately 8 feet in length. An arbitrary transition to the ileum occurs, which is approximately 12 feet in length and terminates at the ileocecal junction in the right lower quadrant of the peritoneal cavity. Clinically, the jejunum is slightly thicker and greater in diameter, more vascular, and of deeper color.
FIGURE 47.2 Blood supply of the jejunum and ileum. |
The blood supply of the jejunum and ileum is derived from the SMA (Fig. 47.2). There is a progression of arcades from the intestinal branches that are single in the jejunum and increase to four of five in the ileum. The mesentery of the small intestine is fan shaped and is positioned obliquely over the posterior abdominal wall. From its body attachments at the ligament of Treitz, the mesentery travels to the right iliac fossa.
Large Intestine
The large intestine extends from the cecum to the anus and is approximately 5 feet in length. Beginning at the base of the appendix and merging in the rectum, the external muscle layer of the colon is arranged in three longitudinal bands known as taenia. The colon also has small projections of peritonealized fat, known as appendices epiploicae.
The blood supply to the right colon (Fig. 47.3) and the left colon (Fig. 47.4) are derived from the superior and inferior mesenteric arteries, which form a rich collateral network within the mesentery as the arc of Riolan (proximal branches) and the marginal artery of Drummond (distal branches).
The appendix arises near the base of the cecum distal to the ileocecal junction. From the cecum in the right lower quadrant, the partially peritonealized ascending colon extends cephalad to the hepatic flexure. The second portion of the duodenum is intimate with the hepatic flexure, and care must be taken when mobilizing the flexure or resecting this part of the colon. Similarly, the right ureter is also intimately associated with the appendix and ileocecum and should be identified when mobilizing this portion of the colon.
The transverse colon is the longest and most mobile colonic segment, extending from the hepatic to the splenic flexure. It is further attached to the stomach by the gastrocolic ligament (greater omentum), which is intimate with the transverse mesocolon and ventral surface of the colon. Careful separation of the gastrocolic ligament gains access to the lesser sac and is necessary for complete omentectomy. Again, care must be taken when mobilizing this portion of the colon, as excessive traction on the splenic flexure can cause downward tension on the splenocolic ligaments and thus lead to tears in the splenic capsule.
The partially peritonealized descending colon extends from the splenic flexure to the sigmoid colon. The upper descending mesocolon is intimate with the kidney, which is close to the proper plane of dissection as this part of the colon is mobilized. The anastomotic blood supply to the splenic flexure is less robust, is frequently referred to as the watershed area, and may be prone to compromise during dissection.
At the pelvic brim, the descending colon becomes the completely peritonealized and mobile sigmoid colon. The sigmoid mesentery (with its root at the inferior mesenteric artery [IMA]) is generous and extends to the posterior cul-de-sac. This is the rectosigmoid colon, and the blood supply transitions to the lateral sides of the rectum.
FIGURE 47.3 Blood supply of the right and transverse colon. |
FIGURE 47.4 Blood supply of the left colon. |
FIGURE 47.5 Blood supply of the rectum. |
The rectum follows the curve of the sacrum, increasing in size to form the ampulla (i.e., fecal reservoir) just above the levator ani. The anorectal angle is formed here. Ventrally, the rectal wall is invested with a delicate layer of connective tissue known as “Denonvilliers” fascia. This fascial layer extends from the base of the cul-de-sac to the perineal body, separating the rectum from the lower two-thirds of the posterior vaginal wall. During cephalad mobilization of an infiltrating cul-de-sac tumor, division of this fascia is useful for mobilizing the tumor and gaining additional rectal length before transection. The blood supply of the rectum is derived from the terminal branches of the IMA and branches of the internal iliac arteries (Fig. 47.5). There are vast anastomoses between these vessels along the rectal wall.
INDICATIONS
Enterolysis
Adhesions in the peritoneal cavity commonly occur in patients who have undergone prior surgery or have experienced an inflammatory process such as endometriosis or salpingo-oophoritis. Such adhesions frequently involve the intestinal tract and may lead to obstruction, obstipation, or pain. Bowel adhesions may interfere with access to the pelvis during surgery and/or may involve pelvic structures with which the gynecologic surgeon is concerned. Any surgeon who operates in the peritoneal cavity must be competent in intraperitoneal adhesiolysis.
It is important for the surgeon approaching adhesiolysis to have an understanding of the likely cause of the adhesions and to know what operations the patient has previously undergone. The approach to intestinal adhesions is modified by factors such as prior radiotherapy, known inflammatory bowel disease, prior intestinal resection (with potential risk for short gut syndrome), and/or the presence of carcinomatosis.
In a patient with normal intestinal function and intestinal adhesions that will not interfere with the planned operation, lysis of such adhesions may not be indicated. In the setting of small bowel obstruction due to peritoneal carcinomatosis, examination of the entire small bowel is necessary to ensure that downstream adhesion is not overlooked, as a transition point may not be present in the setting of more proximal obstruction.
When adhesiolysis is indicated, some general principles should be followed. Some adhesions are well exposed with clear lines for separation. Dividing these adhesions first will help further restore normal anatomy and improve exposure to remaining adhesions. To the extent possible, define the direction of involved bowel loops before embarking on separation. Use gentle traction-countertraction to define lines of adhesion and to facilitate separation while avoiding traction injury and serosal tears. When segments of the intestine are adhered tightly, use sharp dissection. In general, as adhesions become denser, their separation requires progressively sharper instrumentation. When known or suspected intestinal injury occurs, control any gross contamination with bowel clamps or sutures, and tag these areas for later inspection or repair. When partial enterolysis fails to address adhesions posing a risk for intestinal obstruction, these adhesions must also be divided. It is critical to define a fixed point—either at the ligament of Treitz (moving forward) or at the ileocecal valve (moving backward)—to ensure complete adhesiolysis.
FIGURE 47.6 Repair of a simple enterotomy. |
Incidental Injury
In addition to the intimate anatomic relationship between the female genital tract and the rectosigmoid colon, intestinal adhesions in the pelvis are common. The widespread use of laparoscopy in gynecologic surgery places other portions of the intestinal tract at risk. During gynecologic surgery, occasional injury to the intestinal tract can be expected. Certain disease processes or operations may increase the likelihood of injury, such as obliteration of the posterior cul-de-sac (by endometriosis, salpingo-oophoritis, or malignancy), radical pelvic surgery, and extensive enterolysis. Most injuries will consist of a simple seromuscular tear or full-thickness laceration, which is closed with one or two layers of suture. More significant injuries, such as multiple enterotomies within a short distance of each other, require bowel resection.
Management of thermal bowel injury is highly individualized according to the surgeon’s impression of the extent of damage. Blanched, contracted tissue should be considered nonviable. There may be at least several millimeters of less apparent damage beyond the apparent injury. A limited, superficial cautery burn witnessed by the surgeon generally requires no treatment. If concern exists, the area may be oversewn with inverting seromuscular sutures. More substantial thermal damage requires at least seromuscular resection (including a normal-appearing margin) and repair.
Full-thickness injury of the small bowel should be repaired perpendicular to the lumen to avoid constriction (Fig. 47.6). This is less important when closing a colotomy, since the lumen is larger.
Cytoreduction
Most women who develop ovarian cancer present with intraabdominal metastases. Following a combination of radical surgery and chemotherapy, clinical remission is achieved for a large percentage of these women, who can subsequently enjoy longterm survival. Cytoreductive surgery for ovarian cancer appears to improve survival only when no residual tumor (or a minimal volume residual tumor) is left behind. To achieve optimal clearance of tumor, a large percentage of women require procedures that extend beyond simply the removal of gynecologic organs; the most common of these is colon resection.
In recent published series and as shown in Tables 47.1 and 47.2, more than 33% of women with ovarian cancer underwent colon resection as part of their primary (Table 47.1) or secondary (Table 47.2) cytoreductive operation. Based on proximity alone, the rectosigmoid colon is the segment of bowel most frequently resected during cytoreductive surgery for ovarian cancer (Fig. 47.7; Table 47.3). In such cases, the internal genitalia, rectosigmoid colon, and cul-desac peritoneum become agglutinated as a tumor mass. Original descriptions of radical cytoreductive surgery for ovarian cancer, dating back to the 1960s, were in fact surgical techniques designed to resect such tumors en bloc. In recent series of such operations, nearly all women underwent primary colorectal anastomosis without a protective ostomy, with an average leak/fistula rate of 2.6%, and a mortality rate of 0.8% (Table 47.4).
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TABLE 47.1 Primary Cytoreduction; % Colon Resection | ||||||||||||||||||||||||
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TABLE 47.2 Secondary Cytoreduction: % Colon Resection | ||||||||||||||||||||||||
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FIGURE 47.7 Extensive tumor infiltration of the sigmoid mesentery. |
Colon resection is central to ovarian cancer cytoreduction due to its frequency of involvement (over 50% in some recent series), technical considerations, and complications of resection. It is therefore not surprising that the rectosigmoid colon is the most frequent segment of the bowel resected during cytoreductive surgery. However, as seen in Table 47.3, other portions of the colon may also become involved with disease to the point of requiring resection.
The high incidence of bulky omental metastasis readily explains growth onto the transverse colon and/or its mesentery (Fig. 47.8). Omentectomy en bloc with transverse colectomy is a straightforward operation. Such metastases may extend to involve the splenic hilum, the greater curvature of the stomach, and, less frequently, the tail of the pancreas. Complete cytoreduction of such disease requires extensive left upper quadrant resection (Fig. 47.9).
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TABLE 47.3 Segments of Bowel Resected for Primary Cytoreduction | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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TABLE 47.4 Primary Cytoreduction | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Due to its location in the pelvis, it is not surprising that the ileocecum is the second most frequent portion of the bowel to become extensively involved with ovarian cancer (Table 47.2). Inasmuch as possible, resection of such tumors is carried out en bloc with the pelvic tumor. Reconstruction generally consists of an ileoascending colonic anastomosis (Fig. 47.10A, B). More extensive involvement may require a right hemicolectomy; the same is true of rectosigmoid involvement (left hemicolectomy).
FIGURE 47.8 Tumor encasing the mesentery and growing onto the wall of the transverse colon. |
Because of the haphazard and often widespread intraabdominal distribution of ovarian cancer metastases, multiple bowel segments may become involved in a single patient. In the authors’ experience, the most frequent manifestation has been extensive tumor involving both the rectosigmoid colon and ileocecum. Resection of these two sites leaves the patient with the majority of the colon, although restoration does require two anastomoses.
When metastatic ovarian cancer involves the transverse colon and separately involves either the rectosigmoid colon or ileocecum, surgical management is less straightforward. The segments may be excised separately, followed by two bowel anastomoses; alternatively, an en bloc resection can be performed, which then requires only a single ileocolic or colorectal anastomosis. Factors to be taken into account when considering these two options include length of normal colon that can be saved, integrity of blood supply to the two anastomoses, technical ability to restore bowel continuity with each option, tension on the anastomosis, quality of bowel preparation, condition of the colon (particularly of the left side), length of the small bowel remaining, and overall condition of the patient.
The authors prefer to perform en bloc resection with a single restorative anastomosis. Less frequently, there is extensive multifocal involvement of the colon. Intervening segments of colon might be saved in some women, but this may require three colon anastomoses. Subtotal colectomy with an ileostomy, ileoproctostomy, or cecoproctostomy are all reasonable alternatives. Defecatory function is acceptable as long as at least 12 cm of rectosigmoid colon and the full length of the small bowel remain. With a shorter rectal segment, many authors advocate creation of an ileal pouch for anastomosis to the rectum, in an attempt to augment the reservoir capacity and minimize bowel frequency.
FIGURE 47.9 Metastatic omental tumor mass extending in the left upper quadrant to involve the splenic hilum and stomach. |
Endometriosis
Endometriosis occasionally involves the bowel, especially when severe. The most common sites of involvement are located in the pelvis, including the appendix, rectosigmoid colon, cecum, and terminal ileum. Appendiceal endometriosis is generally an incidental finding not clinically significant. The most important potential consequence of bowel involvement is obstruction, which is more likely to occur in the small intestine. Other clinically significant consequences include pain (from dyschezia, tenesmus, dyspareunia, or nonspecific pelvic, or rectal), cyclic rectal bleeding, and nonspecific bowel symptoms. Further, the fibrotic mass effect and symptoms of bowel endometriosis may create the suspicion of malignancy.
FIGURE 47.10 A: Ovarian cancer involving cecum. B: Right hemicolectomy with ileo-ascending enterocolostomy. |
Asymptomatic endometriosis of the bowel does not require surgical treatment. A trial of medical management is warranted for symptomatic disease but is not effective against large, fibrotic lesions. A small percentage of patients require bowel resection for endometriosis. Indications for bowel resection include obstruction, suspicion of malignancy, or other severe symptoms. A common scenario requiring bowel resection involves extensive endometriosis in the posterior cul-de-sac, including the anterior wall of the rectosigmoid colon. When focal, resection can be limited to a portion of the anterior rectal wall. With larger and more extensive involvement, segmental resection is necessary.
In patients with a known history of endometriosis and prior abdominal surgery, deposits of endometriosis may manifest in the abdominal wall in and around the prior incision. These implants are often confused with soft tissue tumors, especially when the interpreting radiologist is unaware of the patient’s past medical or surgical history.
Bowel Obstruction
The gynecologic surgeon must be familiar with the management of bowel obstruction. In women who have undergone prior surgery or have experienced an extensive inflammatory process (e.g., infection, endometriosis), small bowel obstruction may develop secondary to surgically induced adhesions or internal hernia formation. When persistent obstruction is secondary to adhesions, simple adhesiolysis may resolve the problem. Occasionally, however, resection of a nonviable portion of the bowel is required.
The gynecologic oncologist must manage bowel obstruction in a variety of settings. As previously described, epithelial ovarian cancer has a propensity toward intra-abdominal spread and may present with bowel obstruction. When the disease recurs and progresses, it is especially common for the patient to develop intestinal obstruction. Although other gynecologic malignancies may also cause bowel obstruction secondary to intra-abdominal carcinomatosis, ovarian cancer is by far the most common risk factor. Small intestinal obstruction is most common, but colonic obstruction or both can also occur (Fig. 47.11).
The prognosis for patients with small intestinal and colonic obstruction is extremely poor, and decisions regarding surgical intervention must be carefully considered. A recent analysis of patients with malignant bowel obstruction due to ovarian cancer undergoing surgical intervention found symptomatic improvement in 88% of patients at 30 days and 61% at 60 days with median survival just over 6 months. Endoscopic intervention (with palliative, decompressive procedures) yielded much less durable relief of symptoms at just over 2 months. The same authors reviewed 141 patients undergoing surgical or endoscopic procedures for symptoms of malignant bowel obstruction of all types; this review showed that the presence of carcinomatosis, ascites, or multifocal obstruction predicted the application of decision to pursue palliative decompression (percutaneous endoscopic gastrostomy [PEG], G-tube, or stoma) rather than resection.
Regardless of the origin of malignant bowel obstruction, a thorough discussion must be embarked on with patients and their families regarding goals and objectives of the proposed intervention, ensuring to ensure that each party understands the implications of aggressive surgical management—and the potential for extended recovery—in the setting of limited life expectancy.
FIGURE 47.11 Abdominal plain film showing small and large bowel obstruction. |
Where there is an occurrence of extensive ascites, bulky intraabdominal tumor, or an ileus-type pattern, or when the patient is malnourished (albumin <3 g/dL) or in generally in poor condition, surgical management of the obstruction is unlikely to be beneficial. A gastrostomy tube may provide substantial relief and free the patient from the discomfort of a nasogastric tube. In most instances, a gastrostomy tube may be placed percutaneously. Some women with left colon obstruction may be palliated with an endoscopically placed, expandable metallic stent. Select patients with advanced ovarian cancer and persistent obstruction do appear to benefit from surgical intervention. Due to extensive carcinomatosis, the intra-abdominal anatomy in these patients may be difficult to establish. The unobstructed proximal small bowel is freed to the extent possible, and a simple bypass to the proximal colon is carried out. In the presence of large bowel obstruction, a proximal diverting ostomy will generally be necessary. Even in the presence of obvious small bowel obstruction, whenever possible, the large bowel should be evaluated preoperatively for concomitant obstruction. Gastrografin enema performed prior to exploration for malignant small bowel obstruction provides assurance that resected or bypassed small bowel obstruction will not be undermined by existing or impending downstream colonic obstruction.
Small bowel obstruction following radiotherapy for a gynecologic malignancy requires a more calculated approach. These obstructions typically occur in the terminal ileum, although coexistent rectosigmoid colon injury is not uncommon. As such, both areas should be evaluated prior to surgical intervention. Surgical management of radiation-related small bowel obstruction remains controversial. Some experts recommend bypass of the obstruction while others believe the damaged bowel should be resected with primary reanastomosis. Simple bypass involves a side-to-side anastomosis of the proximal uninvolved small bowel to a relatively nonirradiated portion of the colon (Fig. 47.12). This is the fastest and least complicated surgical intervention. Advantages include the avoidance of extensive dissection of matted loops of the bowel—which dissection presents a potential for injury—in the resultant raw, previously irradiated pelvis. The side-to-side anastomosis ensures a good blood supply, avoids the need for a mucous fistula, and may allow the remainder of the bowel to provide some absorptive capacity in cases of partial obstruction; this is especially important when there is a short afferent limb. It also minimizes the risk of injury to other organs or structures, such as the ureter or vascular system. Overall, the results of simple bypass for these patients are reasonably good.
FIGURE 47.12 Simple side-to-side anastomosis of proximal small bowel to transverse colon in order to bypass radiation-related obstruction of the terminal ileum. |
If the fecal stream is incompletely diverted, there is the potential for development of blind loops and/or fistulization of the remaining damaged and potentially necrotic bowel. Certain individuals may be at increased risk for subsequent fistulization, including those who have received greater than 50 Gray to the pelvis, are thin or elderly, or have arteriosclerosis, hypertension, or diabetes and those who have had prior pelvic surgery, chemotherapy (i.e., doxorubicin or actinomycin D), or pelvic inflammatory disease. An end-to-side or end-toend enterocolostomy without resection and with one or two mucous fistulae is an alternative to simple bypass (Fig. 47.13). The main advantage is complete diversion of the fecal stream from the damaged segment and thus avoidance of subsequent fistulization from this area. This type of procedure is often used to manage a postirradiation enterovaginal fistula. Bypass with isolation for management of radiation-related obstruction has not been carefully evaluated separately from simple bypass.
Resection with anastomosis involves removal of all diseased intestine and anastomosis of minimally radiated bowel (Fig. 47.14) and prevents the development of a mucous fistula. This is an often extensive and time-consuming surgery that frequently leaves the remaining bowel exposed to a raw, irradiated pelvis. Other potential disadvantages of resection include a less optimal blood supply at the anastomosis; the functional maintenance of portions of the bowel that have been dissected out (many experts resect all of this bowel) and, though not obstructed, are still radiated and potentially damaged subclinically (e.g., blood supply, enterotomies, aperistaltic); and the injury of other structures during dissection, such as bladder, colon, ureter, and major blood vessels.
FIGURE 47.13 Enterocolostomy that both bypasses and diverts the fecal stream from the obstructed ileum. |
FIGURE 47.14 Resection of obstructed, damaged bowel with anastomosis of small bowel to unirradiated transverse colon. |
The surgical approach to a patient with radiation-related small bowel obstruction must be individualized. If the overall condition of the patient is poor or there is recurrent disease, the most expeditious and least complicated procedure (i.e., simple bypass) should be carried out. If there is potential impending necrosis of the involved bowel, there are multiple injuries to the bowel as a result of dissection, or the involved bowel is a simple loop that is not densely adherent, resection with end-toend enterocolostomy is preferred. Isolation bypass may still be applicable in some of these cases. Matted loops of bowel in the irradiated pelvis should be left in place as long as a reasonable length of proximal small bowel can be bypassed to nonirradiated proximal colon. It is preferable to avoid resection, but the bypassed bowel should be diverted from the fecal stream in the event that further necrosis with potential fistulization should develop.
Colon resection secondary to benign gynecologic disease is infrequent. Gynecologic malignancy, especially ovarian cancer, may encase and partially obstruct the sigmoid or transverse colon. When such disease is surgically resected, the decision for left colon anastomosis is individualized. Radiation-related stricture of the rectosigmoid colon is discussed below. Rarely does endometriosis cause partial obstruction of the rectosigmoid colon.
Fistulae
The common sources of an intestinal fistula include anastomotic failure, occult operative injury, incorporation into wound closure, inflammatory bowel disease, tumor erosion into adjacent bowel (e.g., enterovaginal), radiation necrosis of the bowel wall, an exposed and/or compromised bowel following fascial dehiscence, or any combination of these factors. In the general surgery literature, the majority of fistulae communicate with the skin and can arise from any portion of the gastrointestinal tract. The reported overall mortality rate is between 5% and 20%, with most deaths resulting from uncontrolled sepsis. The mortality rate is significantly enhanced in the setting of small bowel fistulae, inflammatory bowel disease, cancer, or previous abdominal radiation.
Enteric fistulae occurring in gynecologic cancer patients encompass a much different population. The majority of patients have active intra-abdominal cancer, prior extensive radiotherapy, or both. Most fistulae develop, at least in part, as a consequence of these factors. A large percentage of the fistulae in these patients communicate with the vagina (Fig. 47.15), and the majority arise from the terminal ileum or rectosigmoid colon.
A leaking small bowel anastomosis may form a communication with the abdominal wall or vagina, resulting in an enterocutaneous or enterovaginal fistula. During the process of fistulization, intra-abdominal leakage of bowel contents may result in peritonitis or abscess formation, and in some cases there may be continued intraperitoneal leakage. Uncontrolled sepsis in these patients is the major factor associated with mortality. In the presence of active malignancy or prior radiation, these complications are more likely to occur and more difficult to detect.
More proximal small bowel fistulae cause other types of difficulties and, fortunately, are less commonly seen in the gynecologic cancer patient. Jejunal fistulae have a high output of caustic succus that is corrosive to the skin and results in substantial loss of fluids and electrolytes. As fistulae become more proximal, total parenteral nutrition (TPN)—and its associated complications and expense—becomes less a matter of preference and more a matter of necessity. In some cases, however, the distal small bowel may be intubated with a catheter or feeding tube to allow for nutritional support/supplementation as the fistula contracts and heals.
FIGURE 47.15 Contrast study demonstrating enterovaginal fistula. Note that the contrast passes from the distal small bowel into the vagina in the center lower area of this radiograph. |
Initial management of the patient with a small bowel fistula consists of bowel rest with nasogastric suction, fluid resuscitation, electrolyte replacement, local management of the fistula output to prevent skin erosion, and control of sepsis. The extent of intra-abdominal contamination requiring laparotomy, washout, and drainage must be assessed either radiographically or by physical exam, specifically eliciting signs of peritonitis, such as rigidity, guarding, or rebound tenderness. In the setting of a contained leak, sepsis may resolve with bowel rest and antibiotics but in some cases will require drainage of an abscess and/or prompt proximal diversion.
TPN is often used to enable complete bowel rest in patients whose fistulae have a high probability of spontaneous closure (i.e., long tract, incompletely diverting, absence of radiation injury, or distal obstruction). With TPN, the overall condition of the patient improves, and time can be allowed for the inflammatory reaction of the bowel and peritoneal cavity to subside. After sepsis and local wound issues are addressed, oral or enteral feeding can be reinstituted.
Once sepsis is controlled, spontaneous closure of the fistula is reported to occur in 30% to 60% of cases, and nearly all spontaneous closures occur within 4 weeks. During that time, placement of a gastrostomy tube may be considered as a replacement for the nasogastric tube if necessary. After the patient has been initially stabilized, a thorough radiologic evaluation of the fistula and the remaining small and large bowel is undertaken. An early attempt at closure of a postoperative fistula is associated with a low likelihood of success and a high rate of morbidity. The use of somatostatin (or octreotide) has been shown in some series to shorten the interval to spontaneous closure, improve the spontaneous closure rate, and reduce gastrointestinal secretions through the fistula. A recent metaanalysis comprising 14 randomized controlled trials supported early use of somatostatin or its analogues in increasing both the likelihood and rate of fistulae closure.
In certain clinical situations, spontaneous closure is unlikely to occur, and indeed, the majority of fistulae in gynecologic cancer patients will not close spontaneously. These situations include intestinal obstruction distal to the fistula, malignancy at the fistula site, fistula location in a previously irradiated field, the presence of a foreign body, epithelialization of the fistula tract, and a fistula related to inflammatory bowel disease. The mnemonic F.R.I.E.N.D.S. is often used to remember factors that prevent fistulae from closing spontaneously: foreign body, radiation, inflammation, epithelialization, neoplasm, distal obstruction, and short (≤2 cm) tract fistulae.
In patients with fistulae that have not closed spontaneously, operative intervention should be postponed as long as the patient is doing well. If spontaneous closure has not occurred after 4 to 5 weeks of stabilization, then surgery will be eventually required to restore continuity. The actual point at which decision regarding when closure should be attempted surgically is dependent on a number of factors, including the patient’s remaining life expectancy, nutritional state, overall medical condition, and his or her ability to manage the fistula as is.
Surgical management of a small bowel fistula must be highly individualized. Occasionally, it is possible to excise the fistula opening from the bowel and close the defect in layers or to resect the involved segment and perform an end-toend anastomosis (EEA). However, small bowel fistulae to the vagina encountered in gynecologic cancer patients must often be bypassed, leaving the irradiated or tumor-involved adherent loops of bowel in the pelvis. As with the case of obstruction, the proximal uninvolved small bowel is followed as far as possible, avoiding dissection of densely adherent loops from the pelvis. At this point, the small bowel is divided and anastomosed to a relatively nonirradiated portion of the large intestine. This should be a functional EEA so as to completely exclude the fistula from the fecal stream. Mucus fistulae should be utilized whenever the risk of closed loop obstruction exists.
As a consequence of advancing pelvic malignancy, prior extensive pelvic radiotherapy (possibly combined with the effects of prior extensive pelvic surgery), or a combination of these factors, occasionally develops between the bowel and the bladder. The first concern is to stabilize the patient and control sepsis, which may be more difficult due to involvement of the urinary tract. After short-term stabilization, surgical intervention will be required.
For relatively simple cases of small bowel involvement, the fistulized loop is resected. Repair of the bladder is individualized. It is less preferable to bypass the fecal stream due to the persistent ill-effects of mucus or partially contaminated drainage into the bladder. Usually, management of a sigmoidovesical fistula will require a diverting colostomy, at least temporarily. In more complicated cases of fistula development between the bowel and bladder—and especially when there is evident involvement of the bladder by radiation necrosis or tumor, or when there is persistent sepsis, bypass, or diversion of both the intestinal and urinary tracts will be necessary. The mortality rate for such cases is high.
The other type of fistula commonly encountered in gynecologic patients arises from the sigmoid colon to the vagina or from the rectum to the vagina. Such a fistula may develop as a complication of surgery (delayed leak from a partial or segmental resection or from an inadvertent injury) or radiation therapy. A postmenopausal woman presenting with a sigmoidovaginal fistula most likely has ruptured diverticulitis. Women may develop an intestinal fistula to the vagina as a result of inflammatory bowel disease, or as a consequence of advanced colorectal cancer, although the latter is uncommon. In gynecologic cancer patients, a sigmoidovaginal fistula may be related to the malignancy, occurring often as a result of or associated with distal obstruction. A large percentage of these cases is due to radiation injury or perhaps to a combination of factors. After short-term stabilization, a diverting or end (if permanent) colostomy is performed.
Severe Radiation Injury of the Rectosigmoid Colon
Severe proctosigmoiditis develops in a small percentage of patients following pelvic radiotherapy for gynecologic cancer. Abdominal cramping, diarrhea, and/or bleeding may result. With medical management, some of these symptoms improve over time. However, if progressive or left unattended to, the injury may progress to perforation or a fistula. As previously discussed, the area of injury may be mapped out with the use of contrast studies through the normal GI tract and fistula and with endoscopy. Resection is performed accordingly, and in some cases, colorectal continuity can be reestablished. A diverting colostomy is advisable until it is certain that the anastomosis has healed (i.e., at least 6 months).
Radiation stricture of the rectosigmoid colon may also develop, causing obstruction (Fig. 47.16) and necessitating surgical intervention. The area of involvement should be mapped out preoperatively with radiologic and endoscopic studies. When feasible, this portion of the large bowel may be resected and anastomosed. The anastomosis should be wrapped with transposed omentum when available. Proximal diversion is strongly considered. The colon anastomosis is reevaluated 6 months postoperatively, and if healing is satisfactory, the ostomy is taken down.
As in the case of severe radiation sigmoiditis, the patient with a radiation-induced sigmoidovaginal fistula can sometimes undergo resection and colorectal anastomosis in hopes of eventually restoring bowel continuity. Some radiationinduced rectovaginal fistulae can eventually be surgically closed. Boronow et al. described local repair of such fistulae after a period of diversion. Park described resection of the rectum beyond the fistula (and the region of severe radiation damage) with transanal anastomosis of the colon to the anus. Bricker described the technique of folding the rectosigmoid colon over itself to cover the fistula with anastomosis of the colon to the top of the loop.
FIGURE 47.16 Contrast study of a symptomatic radiated patient, demonstrating stricture of the rectosigmoid colon. |
Perforated Bowel
Perforated bowel with intraperitoneal leakage is infrequently encountered in gynecologic and nongynecologic cancer patients. The complication may develop as a result of radiation-induced necrosis (usually of the terminal ileum or sigmoid colon), leakage from an intestinal anastomosis or occult operative injury, or bowel ischemia related to obstruction. When perforated bowel with intraperitoneal leakage is due to radiation injury, diagnosis is often delayed, and the mortality rate is high.
Surgery is performed on an emergent basis. If the perforation is highly localized and walled off, resection or exclusionary bypass of the small bowel may be considered. In general, however, proximal exteriorization should be carried out. The peritoneal cavity should be thoroughly lavaged with an antibiotic solution. Several months of stabilization should elapse to allow the inflammatory reaction of the bowel and peritoneal cavity to resolve before considering an attempt at reestablishment of bowel continuity.
Exenteration
Pelvic exenteration is occasionally performed for recurrent or persistent gynecologic cancer in the central pelvis and is covered in Chapter 54. Diversion or reconstruction of the urinary and/or intestinal tract is necessary in these patients, requiring one or more surgical procedures involving the bowel. The majority of these patients have received prior radiotherapy, which further complicates treatment. For purposes of urinary tract reconstruction, a portion of the bowel is isolated from the fecal stream and intestinal continuity is reestablished. In the case of an ileal conduit performed in a previously radiated patient, it is recommended that the anastomosis occur between the ileum and the nonirradiated transverse colon to ensure better healing.
When the rectum or anus must be removed, a permanent colostomy is performed. When a portion of the rectum can be preserved, it may be possible to perform a colorectal (i.e., coloanal) anastomosis. Strong consideration is given to proximal diversion. Even when continuity cannot be restored, it may be preferable in some cases to leave a very short rectal stump to avoid potential morbidity of a perineal wound.
Urinary Tract Reconstruction
Urinary diversion and bladder reconstruction utilize intestine that has been isolated from the fecal stream. These procedures are covered in detail in Chapter 24. Another infrequent use for intestine in urinary tract reconstruction is ureteral substitution, generally done with a portion of ileum.
Vaginal Reconstruction
One of the myriad types of vaginal reconstruction in gynecologic patients is intestinal substitution. There are few reports on this type of neovagina in the gynecologic cancer patient, and the results obtained are unclear. After pelvic resection, a portion of the sigmoid colon or ileum is diverted from the fecal stream. In exenterative surgery, this should be coordinated with other necessary intestinal components to minimize the number of anastomoses. The intestinal segment with its blood supply is mobilized so that one end may be anastomosed to the introitus or vaginal stump. The other end is closed to form a pouch.
PRIMARY INTESTINAL DISEASE
Diverticulitis
Acute diverticulitis can mimic benign adnexal pathology, such as torsion, ovarian cysts, abscesses, or malignant pathology of either gynecologic or colorectal origin. Perhaps the most useful means of distinguishing diverticulitis from these diagnoses is a history of radiographically or endoscopically diagnosed diverticular disease or a prior acute episode resulting in emergency department presentation or inpatient hospitalization. In patients without a diagnosis of diverticular disease, arriving at the correct diagnosis may be difficult, especially in the absence of absolute indications for exploration (e.g., free intra-abdominal perforation, uncontrollable hemorrhage, or obstruction). In these cases, the diagnosis relies on the combined efforts of an astute radiologist and clinician, with an abdominopelvic computed tomography (CT) scan being the most useful diagnostic maneuver.
In most cases, pericolonic inflammation, abscess, or colonic wall thickening in association with left lower quadrant pain and normal-appearing ovaries and uterus is sufficient to establish a diagnosis of diverticulitis. Based on CT findings, diverticulitis can then be subcategorized into complicated or uncomplicated diverticulitis. Nonoperative therapy through bowel rest and antibiotics is successful in 70% to 100% of patients with uncomplicated diverticulitis. A CT scan demonstrating uncomplicated diverticulitis is shown in Figure 47.17. More recently, prospective randomized data have brought the routine use of antibiotics in uncomplicated diverticulitis into question. Complicated diverticulitis—as manifested by obstruction, abscess, perforation, or fistula—may be managed with percutaneous drainage with a low threshold for surgical exploration in the setting of progressive peritonitis or in high-risk patients (i.e., older, deconditioned, or immunocompromised patients).
Distinguishing diverticulitis from colorectal malignancy in both complicated and uncomplicated diverticulitis is critical and can be challenging. Missing or delaying the latter diagnosis may have devastating consequences for the patient and, as soon as clinically feasible, a limited endoscopic evaluation should be undertaken to rule out a mucosal-based lesion. This can be safely undertaken as early as 2 to 6 weeks after the acute inflammatory phase has resolved (normal white blood cell count, afebrile, resolved left lower quadrant pain, and resumption of normal bowel activity). At initial presentation, if the suspicion for cancer is high, then surgical exploration with Hartmann procedure (i.e., resection, end colostomy, rectal pouch) is the safest and most effective diagnostic and therapeutic intervention (Fig. 47.18).
FIGURE 47.17 CT scan showing acute, uncomplicated diverticulitis. |
FIGURE 47.18 Hartmann procedure indicating resection, end colostomy, and rectal pouch (A, B). |
Acute Appendicitis
Due to the profound overlap in presenting symptoms, age, and prodrome illness in a patient, acute appendicitis is the gastrointestinal diagnosis most difficult to distinguish from gynecologic pathology. Pregnancy, especially in the second and third trimesters, may further confound the diagnosis as the gravid uterus displaces not only the appendix but also the focal point of pain. Delayed diagnosis of appendicitis due to pregnancy is a source of significant added morbidity. Although female patients are slightly less likely to develop acute appendicitis than are males, the high prevalence of this disease in the third decade of life continues to make this a diagnostic challenge.
The classic presentation consists of three fundamental components: periumbilical pain migrating to the right lower quadrant, anorexia, and nausea/vomiting. Most surgeons trained prior to the CT-scan era relied heavily on the presence of fever and/or leukocytosis to establish the diagnosis of appendicitis. More recently, several scoring systems have been established that assign a relative numeric value to those presenting signs and symptoms most predictive of appendicitis. These scoring systems are designed to avoid axial imaging in patients with a high probability of acute appendicitis based on clinical presentation alone.
The Alvarado score is the most popular of these scoring systems and takes into account leukocytosis (2 points), iliac fossa tenderness (2 points), migratory pain, anorexia, nausea/vomiting, rebound pain, and fever (all 1 point). A high Alvarado score (≥7) generally supports exploration without further diagnostic studies, while lower scores, especially in diagnostically challenging subgroups (e.g., children younger than 3 years, adults older than 60 years, and pregnant women in the second and third trimesters) supports further diagnostic imaging such as CT scan. In one recent review in 71 patients with appendicitis and 167 patients with alternative diagnoses, CT findings consistent with appendicitis identified enlarged appendix (93% sensitive/92% specific), appendiceal wall thickening (66% sensitive/96% specific), periappendiceal fat stranding (87% sensitive/74% specific), and appendiceal wall enhancement (75% sensitive/85% specific).
Ultrasound is similarly useful in establishing the diagnosis with sensitivity, specificity, and positive and negative predictive value all as high as 99% in some series. Sonographic findings consistent with appendicitis include diameter greater than 6 mm, noncompressibility, presence of appendicolith, periappendiceal fat changes, or nonvisualization of the appendix (i.e., negative finding). In patients whose diagnosis remains uncertain despite all imaging modalities, early engagement of the general surgery team for serial abdominal exam is essential.
Meckel Diverticulum
Meckel diverticulum is a relatively common diagnosis occurring in 1 % to 2% of adult patients in autopsy studies. Since the majority of patients with Meckel diverticulum are asymptomatic, the disorder is most commonly diagnosed as an incidental finding during celiotomy for other intra-abdominal pathology. Meckel diverticulum represents a remnant of the vitelline yolk duct and usually occurs within 2 feet of the ileocecal valve along the antimesenteric border of the ileum (Fig. 47.19). Most Meckel diverticula are lined by small bowel mucosa, but as many as 20% of patients have ectopic gastric or pancreatic tissue in the lining that causes symptoms of bleeding or pain. In addition to bleeding,
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