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SMALL BOWEL 169
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ABC
FIG. 4 A patient with multiple enterocutaneous (EC) and enteroatmospheric (EA) fistulas along a prior midline incision. (A) Note the skin excoriation
around the fistulas. There is an ileostomy in the right lower quadrant that was distal to the fistulas. (B) The wound care plan included protecting the surrounding skin with stoma paste and barrier rings molded to the shape of the wound, thus also isolating the main fistulas. (C) Stoma appliances were then
placed over the fistulas and the ileostomy to catch the effluent. Note that the main stoma appliance is further secured by adhesive dressings.
on granulation tissue directly over bowel or on a skin graft directly
over bowel, the suction force could promote the development of new
fistulas. Nevertheless, numerous small studies have demonstrated
that, when used appropriately, vacuum dressings can promote wound
healing and may even accelerate spontaneous closure.
Wound care plans often change over time as the wounds ideally
heal and contract. Wound and ostomy nurses work very closely with
patients and their families, teaching them tips and tricks to care for
their wounds during the months- to years-long process.
Define the Fistula Anatomy
Next, it is critical to characterize the anatomy of the EC fistula,
utilizing imaging studies such as CT scans with oral contrast, upper
gastrointestinal swallow studies with small bowel follow through,
contrast enemas, and fistulograms in which the proximal and distal
limbs of the fistula are cannulated and injected with oral contrast
under fluoroscopy (see Fig. 3). The goal of these studies is to delineate the location of the fistula, how much bowel is proximal and
distal to the fistula, and assess if there are multiple fistulas. They can
also determine if fistuloclysis will be possible. Furthermore, these
studies can assess for distal obstructions, which would make spontaneous closure unlikely, and can help with operative planning.
SPONTANEOUS CLOSURE
Approximately 30% to 35% of EC fistulas will close within 2 months
of diagnosis without operative intervention (Box 2). Fistulas with
tracts longer than 2 cm, defect sizes of <1 cm
2
, and decreasing output
are more likely to heal spontaneously. Distal obstructions, ongoing
sepsis or abscess, and malnutrition are all predictors of requiring operative intervention. EC fistulas caused by Crohn’s disease,
malignancy, radiation, or a foreign body are also less likely to close
spontaneously.
OPERATIVE INTERVENTION
EC fistulas that have not spontaneously closed within 2 months will
likely require operative management. Most surgeons recommend
waiting at least 6 months after the diagnosis of the fistula before
BOX 2 Characteristics Predictive of Spontaneous
Closure of Enterocutaneous Fistulas
Increased Likelihood of Spontaneous Closure
Postoperative etiology
Fistula tract longer than 2 cm
Fistula defect <1 cm
Healthy surrounding bowel
Good nutritional status
Low fistula output
Decreased Likelihood of Spontaneous Closure
Non-postoperative etiology (inflammatory bowel disease,
cancer, radiation)
Distal obstruction
Presence of a foreign body
Continued sepsis or abscess present
Epithelialized fistula tract
Steroid use
Malnourished
High fistula output
considering an operation. Over this period of time, intraabdominal
adhesions soften and become more filmy, thus making the operation
easier and less prone to causing enterotomies. The “pinch test” for EA
fistulas, in which tissue or skin graft overlying bowel is pinched to see
if the underlying bowel separates easily, can also be used to determine readiness for surgery. Surgeons should wait until the patient is
nutritionally optimized, sepsis is controlled, and the patient is at or
close to their baseline functional status.
In the operating room, surgeons should prepare for a difficult,
lengthy procedure. Ideally, the case should start in the morning, and,
for complex fistulas, no other operations should be planned for the
same day. Anesthesiologists should be prepared for high insensible
losses and should resuscitate accordingly, using a urinary catheter for
2
170 MANAGEMENT OF ENTEROCUTANEOUS FISTULAS
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FIG. 5 The same patient from Figure 4 was taken to the operating room for an enterocutaneous (EC) fistula takedown. (A) Opening the wound revealed
multiple loops of small bowel densely adhered to the prior incision, which were the sources of the numerous EC and enteroatmospheric (EA) fistulas. (B)
At the conclusion of the case, a unilateral anterior component separation was used to close the fascia primarily. The loop ileostomy was converted to an
end ileostomy.
accurate recording of urine output. Epidural catheters or transversus
abdominis blocks should be considered for postoperative pain management. The incision should be made away from prior incisions,
if possible, usually subxiphoid, and dissection should be started
away from the EC fistula. An extensive lysis of adhesions with sharp
dissection should be performed and the bowel should be fully mobilized, such that the exact location of the fistula, the amount of bowel
involved in the fistula, and the presence of any other enterotomies
can be identified. It is not uncommon for multiple loops of bowel
to be involved in the inflammatory mass surrounding EC fistulas
(Fig. 5A). Any foreign material such as previous mesh should be
removed. The surgeon should look for any distal obstruction so that
it can be fully addressed. At this point, the amount of bowel to resect
can be determined with the goal of preserving as much small bowel
as possible to prevent future short-gut syndrome. Fistula defects
should not be repaired primarily, as it will likely lead to recurrent
leaks. The amount of remaining bowel should be documented.
Most of these operations require closure of a large abdominal
wall defect. Due to the contamination of the wound, many surgeons
would not recommend placing synthetic mesh to aid in abdominal
closure. Instead, component separations should be used to close the
fascia if simple primary closure is not possible (Fig. 5B). Biologic
mesh can be placed in an underlay fashion if needed. Involving general surgeons or plastic surgeons who specialize in abdominal wall
reconstruction can be beneficial, particularly for large and complex
abdominal wall defects.
Surgeons and patients must be prepared for the possibility of a
frozen abdomen. If it becomes clear that the EC fistula itself cannot
be resected safely, other options include creating a diverting stoma, if
one is not already present, or placing a venting gastrostomy tube and/
or a distal feeding jejunostomy tube.
Though the morbidity and mortality rates of EC fistula takedowns have been improving over time, patients must still be counseled preoperatively on the risks of the procedure and the long
postoperative recovery. Approximately 16% to 36% of EC fistulas
will recur after surgery, though some recent studies quote operative success rates as high as 92%. Mortality has decreased from
approximately 40% in the 1970s to approximately 20% currently,
with some studies citing mortality rates as low as 2%. Nevertheless,
30-day morbidity rates have been reported to be nearly 50% based
on analysis of the American College of Surgeons National Surgical
Quality Improvement dataset. Although significant improvements
have been made over the years, EC fistula takedowns remain complex, morbid operations, and patient expectations should be set
preoperatively.
The postoperative recovery period typically lasts for several
months. Parenteral nutrition can be weaned off as enteral nutrition
improves. Many patients benefit from postoperative physical therapy,
and some require stays in rehabilitation facilities.
SUMMARY
EC fistulas are complex, debilitating conditions that require multidisciplinary, long-term management. By using the algorithm of sepsis
control followed by simultaneous fluid and electrolyte management,
nutritional optimization, decreasing the volume of effluent, and
wound care, approximately one-third of EC fistulas will close on
their own. For patients who require operative intervention, waiting
at least 6 months to allow for preoperative optimization and softening of adhesions has led to decreasing mortality rates and increasing
rates of operative success.
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S u g g e S t e d R e a d i n g S
Bhama AR. Evaluation and management of enterocutaneous fistula. Dis
Colon Rectum. 2019;62(8):906–910.
Christensen MA, Gaitanidis A, Parks J, et al. Thirty-day outcomes in the
operative management of intestinal-cutaneous fistulas: A NSQIP analysis.
Am J Surg. 2021;221(5):1050–1055.
Evenson AR, Fischer JE. Current management of enterocutaneous fistula.
J Gastrointest Surg. 2006;10(3):455–464.
Management of
Radiation-Induced
Injury to the Small and
Large Bowel
Sophia Y. Chen, MD, MPH, and Chady Atallah, MD
INTRODUCTION
Radiation therapy plays an important role in the multimodal management of anorectal, gynecologic, and urogenital pelvic malignancies. Approximately 70% of cancer patients undergo radiation
therapy for the treatment of these malignancies to prolong their
disease-free survival and reduce local recurrence. Although radiation delivery is directed at the target tissue for maximum benefit,
radiation fields required to treat these malignancies may nevertheless include normal small intestine, colon, and/or rectum, leading
to potential injury of otherwise healthy tissue. Radiation-induced
injury to the bowel therefore remains a critical issue requiring careful
management considerations and preventative strategies.
PATHOPHYSIOLOGY AND
HISTOPATHOLOGY
Radiation therapy is most commonly delivered via external beam
radiation therapy (EBRT), which uses a linear accelerator to produce
ionizing radiation. EBRT can directly or indirectly damage DNA within
malignant and normal cells through its interaction with water and the
release of free radicals. Depending on the extent of DNA damage, EBRT
can result in mitotic inhibition or cellular apoptosis. Brachytherapy is
another method of radiation delivery and involves the placement of a
radiation source within the body, often in the form of pellets or beads.
The pathophysiology of radiation damage to the bowel has been
described in the literature via the “target cell” theory, in which acute
effects of radiation-induced injury target cells of the bowel epithelium, whereas chronic effects of radiation-induced injury target
cells with slower turnover, such as endothelial cells and fibroblasts.
Rapidly dividing cells like those in the gastrointestinal (GI) tract are
most susceptible to radiation injury; as such, radiation affects the
cells of the mucosa first, followed by the submucosa, muscularis, and
serosa. Chronic radiation injury to the bowel is often associated with
ischemic injury. Reaction of fibroblasts to cytokines, growth factors,
and chemokines leads to fibrosis. Cellular death leads to intestinal
atrophy and subsequent malabsorption and stricture formation.
Radiation can also result in vascular damage, leading to dilatation of
small blood vessels presenting as telangiectasias. Furthermore, arteriolar constriction can result in bowel ischemia and necrosis.
Ortiz LA, Zhang B, McCarthy MW, etal. Treatment of enterocutaneous fistu-
las, then and now. Nutr Clin Pract. 2017;32(4):508–515.
Teubner A, Morrison K, Ravishankar HR, etal. Fistuloclysis can successfully
replace parenteral feeding in the nutritional support of patients with
enterocutaneous fistula. Br J Surg. 2004;91(5):625–631.
Histopathologically, acute radiation injury to the bowel is often
characterized by extensive mucosal inflammation, crypt atrophy/
abscesses, nuclear atypia with bizarre mitoses, and eosinophilic submucosal infiltration. Chronic radiation injury to the bowel is often
characterized by obliterative enteritis (irregularly shaped endothelial
cells, fibroblasts, myofibroblasts, and foamy cells within arteries),
small-vessel vasculopathy (dilated, thickened, hyalinized blood vessels), ulceration, fibrous induration, and superimposed episodes of
ischemic changes (Fig. 1).
RISK FACTORS
Risk factors associated with radiation-induced bowel injury include
both patient factors and radiation treatment-related factors. Patient
comorbidities associated with an increased risk for radiation-induced
injury include smoking, diabetes mellitus, hypertension, vascular and
collagen disorders, atherosclerosis, coronary artery disease, inflammatory bowel disease, and prior intestinal surgery. Chemotherapy
such as fluoropyrimidines, taxanes, platinum agents, mitomycin C,
gemcitabine, methotrexate, actinomycin D, topotecan, and doxorubicin can act as radiosensitizers and potentiate the effects of radiation.
Low body mass index (BMI) has also been associated with increased
risk for radiation injury due to higher rate of radiation toxicity.
Radiation treatment-related factors associated with increased risk
for radiation-induced injury include higher radiation dose, longer
length of bowel irradiated, fewer dose fractionation, and larger radiation field size.
FIG. 1 Histopathology (magnification ×20) showing submucosal
fibrosis with atypical fibroblasts, endothelial cells, and increased
inflammatory cell infiltrate. (From Theis VS, Sripadam R, Ramani V, Lal S.
Chronic radiation enteritis. Clin Oncol. 2010; 22[1]:70–83.)
172 MANAGEMENT OF RADIATION-INDUCED INJURY TO THE SMALL AND LARGE BOWEL
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RADIATION THERAPY TOXICITY
GRADING SYSTEMS
Although various radiation toxicity grading systems exist in the
literature, the Radiation Therapy Oncology Group (RTOC) and
the European Organization for Research and Treatment of Cancer (EORTC) grading system is one of the most commonly used
(Table 1). The RTOC/EORTC grading system differentiates acute
radiation morbidity (day 1 through 90) from chronic radiation
morbidity (after day 90) on a scale from 0 to 5 based on presenting
symptoms. Although these grading systems provide a standardized
assessment based on patient symptoms, they do not include endoscopic and histopathologic information. Other available grading
systems include the Late Effects Normal Tissue (LENT) system; the
Subjective, Objective, Management, and Analytic (SOMA) grading
system for chronic radiation injury; and the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE).
CLINICAL FEATURES
Acute radiation-induced bowel injury can occur from the time of
radiation treatment up to 6 months after treatment completion.
Because acute radiation damage leads to mucosal inflammation
and damaged mucosal surface, diarrhea is one of the most common
symptoms. Injury to the mucosal barrier also increases the risk for
bacterial translocation and subsequent bacteremia and sepsis. Other
symptoms of acute radiation-induced bowel injury include nausea,
bloating, cramping, abdominal pain, and GI dysmotility. Acute radiation colitis and proctitis can present with additional symptoms of
bleeding, mucus discharge, urgency, and tenesmus.
Chronic radiation-induced bowel injury can continue from
the acute phase or present after a latent period. Chronic radiation
injury symptoms typically present 8 to 12 months after treatment
completion; however, symptoms have been reported up to 30 years
after a latent period. Like acute radiation-induced injury, diarrhea is
one of the most common symptoms. Chronic radiation proctitis can
also commonly present with rectal bleeding due to telangiectasias.
Patients with chronic radiation-induced bowel injury can also have
ulcerations from ischemia, abscesses, and fistula formation. Chronic
ischemic changes can lead to stricture formation and subsequent
bowel obstruction. Full thickness necrosis of the bowel can result in
fistulae or free perforation.
DIAGNOSIS
Acute radiation-induced injury to the small intestine, colon, and
rectum is generally diagnosed based on the patient’s presenting
symptoms and history. Chronic radiation-induced bowel injury is
diagnosed not only by symptoms but also may require additional
imaging such as a CT scan or MR enterography to evaluate the anatomy and assess for strictures, fistulae, or bowel wall thickness abnormalities. Patients with suspicion for radiation colitis or proctitis may
occasionally undergo barium and water-soluble contrast enemas,
which can reveal shortening, narrowing, lack of distensibility, and
absent haustral/mucosal folds of the bowel. Fistulae may need to be
further evaluated with MRI, fistulograms, cystograms, and pelvic
examinations.
Definitive diagnosis can be made endoscopically with biopsies
demonstrating histologic features pertaining to radiation injury,
as described previously. Upper endoscopy may be considered for
suspected radiation injury to the duodenum; however, lower endoscopy may not be effective in reaching more distal areas of radiation
enteritis. Capsule endoscopy should only be considered if intestinal
strictures have been excluded. Lower endoscopy via colonoscopy or
sigmoidoscopy is beneficial in diagnosing radiation colitis and proctitis. These are characterized by neovascularization with fragile vessels on lower endoscopy (Fig. 2). Other features of radiation-induced
bowel injury include pallor and friability. Rectal biopsies should be
performed judiciously, as they have been associated with increased
risk of rectal fistula formation.
MANAGEMENT STRATEGIES
Medical Management
Between 50% and 75% of patients with acute radiation-induced
bowel injury present with symptoms. Fortunately, these symptoms
are often self-limited and can be managed medically. Diarrhea can
be managed with antidiarrheal medications such as loperamide and
fiber supplements, and with dietary modifications (e.g., lactose-free
diet, low-fat diet, low-residue diet, or elemental diet). Patients with
severe diarrhea, dehydration, and nutritional deficits may need to
be admitted to the hospital for intravenous fluids and/or parenteral
nutrition. If first-line antidiarrheals are ineffective, octreotide may
be given. Nausea can be managed with antiemetics. Anticholinergics,
TABLE 1 RTOG/EORTC Radiation Toxicity Grading System
Grade 1 2 3 4 5
Acute radiation
morbidity
(Days 1–90)
Late radiation
morbidity
(Days >90)
RTOG/EORTC, Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer
• Increased frequency or
change in bowel habits
•
Rectal discomfort
• No medication
• Mild diarrhea and
cramping
•
Bowel movement
≤5 times daily
• Slight rectal discharge
or bleeding
• Diarrhea requiring
parasympatholytic
drugs
•
Mucus discharge not
requiring sanitary
pads
•
Rectal or abdomi-
nal pain requiring
analgesics
Moderate diarrhea and
•
cramping
•
Bowel movement
>5 times daily
•
Excessive rectal
mucus or intermittent
bleeding
•
Diarrhea requiring
parenteral support
•
Severe mucus or blood
discharge requiring
sanitary pads
•
Abdominal distension
Obstruction or bleed-
•
ing requiring surgery
• Acute/subacute
obstruction, fistula, or
perforation
•
GI bleed requiring
transfusion
•
Abdominal pain or
tenesmus requiring
tube decompression
or bowel diversion
• Necrosis, perforation,
or fistula
•
N/A
Death
•
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FIG. 2 Endoscopic appearance of radiation proctitis showing tel-
angiectasias. (From Hogan NM, Kerin MJ, Joyce MR. Gastrointestinal compli-
cations of pelvic radiotherapy: medical and surgical management strategies. Curr
Probl Surg. 2013; 50[9]:395–407.)
antispasmodics, bile acid–binding agents like cholestyramine, and
antisecretory agents can also be considered.
Butyrate enemas have been shown to provide some benefit for
the management of acute radiation proctitis due to the provision of
short chain fatty acids as nutrient for colonocytes; however, they have
had mixed results for the management of chronic radiation proctitis. Recent Multinational Association of Supportive Care in Cancer
FIG. 3 Argon plasma coagulation of rectal ulcer.
(From Araujo IK, Muñoz-Guglielmetti D, Mollà M. Radiation-induced damage in the
lower gastrointestinal tract: Clinical presentation, diagnostic tests and treatment
options. Best Pract Res Clin Gastroenterol. 2020; 48–49:101707.)
(MASCC) guidelines for patients with chronic proctitis in patients
with rectal bleeding recommend the use of sucralfate enemas, given
sucralfate’s ability to evoke a protective barrier and promote epithelial healing. Other enemas such as mesalamine (5-ASA) enemas,
short-chain fatty acid enemas, and steroid enemas have had mixed
findings and require further investigation.
neodymium-doped yttrium aluminum garnet (Nd:YAG) laser therapy, radiofrequency ablation, and cryotherapy are alternative endoscopic treatments that can be performed to treat bleeding, they are
now rarely performed due to the effectiveness of APC.
Formalin therapy has been found to be an effective form of
topical treatment for bleeding from chronic radiation proctitis by
chemically cauterizing telangiectasias and ulcers. Formalin (4%–10%
concentration) can be delivered via irrigation with aliquots of 20 to
50 mL for a total volume of 400 to 500 mL or via direct application of
formalin-soaked gauze onto mucosa via rigid proctoscopy. Washout
with formaldehyde is typically recommended after application of formalin. Although formalin therapy is effective, multiple application
sessions may be required. It is important to avoid direct contact of
formalin to the anoderm because this may cause irritation and pain.
Potential complications of formalin therapy include anal/pelvic pain,
stricture, rectal wall necrosis, and fistula formation.
Other medical treatments that can be considered for radiation-induced bowel injury include antioxidants (vitamins E and C),
probiotics, and hyperbaric oxygen to facilitate angiogenesis. A few
studies have suggested that a 4-week course of oral metronidazole
may be associated with decreased bleeding, ulceration, and diarrhea
in radiation proctitis.
Surgical Management
More than 30% of patients with chronic radiation-induced bowel
injury will require surgical intervention. Surgery is indicated for
patients whose symptoms are unable to be managed medically or
endoscopically, as well as for patients with complications including
perforations, fistulae, strictures, obstruction, intractable pain, and
incontinence. Surgery for patients with radiation-induced bowel
injury is fraught with technical challenges and a high potential for
complications. Morbidity and mortality rates after surgical intervention can range from 30% to 65% and 6.7% to 25%, respectively. The
irradiated abdomen can contribute to a hostile operative environment with friable tissue, extensive adhesions, and high risk for bowel
injury and poor healing. Careful preoperative planning based on
individual patient factors in a multidisciplinary/specialized setting
and a structured approach to operative intervention is therefore
critical to achieving safe and effective surgery. It is important to
also appreciate the risk of recurrence or de novo malignancy in the
Endoscopic Management
Endoscopic therapy can play an important role in the treatment of
chronic radiation-induced bowel injury. Argon plasma coagulation
(APC) is currently the treatment of choice for bleeding, before considering the use of formalin therapy. APC has been found to stop
bleeding in 80% to 90% of cases and is a safe approach because it
coagulates at a superficial depth (Fig. 3). Some studies also demonstrate improvement of bowel function after APC. However, like
formalin therapy, patients may require multiple APC treatments. It is
important when performing APC to avoid the dentate line because
contact may result in anorectal pain. Potential complications for
APC include anorectal pain and abdominal cramping. Although
irradiated bowel segment during preoperative planning. Once the
decision to proceed with surgery is made, effort must be made to
correct modifiable factors and optimize the patient preoperatively.
This may entail correcting electrolyte derangements and providing
enteral nutrition for severely malnourished patients. Surgical options
for radiation-induced bowel injury include limited bowel resection,
bypass/exclusion procedures, stricturoplasty, and fecal diversion.
The choice of surgical incision for patients with chronic radiation
injury should be carefully considered because patients who undergo
radiation therapy have impaired wound healing. Some surgeons may
prefer a low transverse incision inferior to the umbilicus to avoid the
irradiated area. Others may prefer a lower midline incision to allow
for adequate exposure and in case further interventions are needed
174 MANAGEMENT OF RADIATION-INDUCED INJURY TO THE SMALL AND LARGE BOWEL
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in the future. A Pfannenstiel incision may be considered for thin
female patients. The role of minimally invasive surgery for radiation-induced bowel injury is controversial. A diagnostic laparoscopy
with abdominal entry via open Hasson technique would determine
whether a minimally invasive approach is feasible, with dense
adhesions or pelvic fibrosis serving as contraindications. Once the
abdomen is entered and the severity of disease is assessed, dissection
should begin proximally, where radiation-induced damage is less
severe, and move distally. Gentle handling and extreme care of tissue
via sharp dissection using Metzenbaum scissors is recommended to
prevent bowel injury. Blunt dissection can be associated with a high
risk of enterotomy and should be avoided.
For patients with extensive, dense adhesions, limited adhesiolysis
should be performed only in the area of interest and only if the bowel
is resectable because there is increased risk for fistula formation and
bowel injury. Patients with pelvic adhesions generally have small
bowel segments adherent in the pelvis; bowel adherent to the sacrum
may be extracted from the pelvis with careful dissection, although it
is important to avoid damage to the presacral veins and to be able to
deal with any ensuing hemorrhage that could occur. Enterotomies
would commit the surgeon to extracting the bowel from the pelvis.
If a bowel segment were fibrosed to the sacrum, it may be safer to
leave this segment attached while applying diathermy to the mucosal
surface. Hydrodissection via saline injection into dense interloop
adhesions can prevent serosal injuries.
Limited bowel resection of the involved segment is generally preferred over other surgical alternatives such as bypass/exclusion because
it is associated with decreased rates of reoperation and increased survival. During bowel resection, careful consideration is necessary when
selecting the two pieces of bowel to be used for bowel anastomosis.
Grossly irradiated bowel can appear pale, mottled, yellowish/gray, or
telangiectatic with features of vascular insufficiency (Fig. 4). However, irradiated bowel can also appear indistinguishable from normal
bowel. Anastomotic leak rates between two pieces of irradiated bowel
can be as high as 50%; as such, anastomosis between nonirradiated
bowel is recommended when possible. If an anastomosis is necessary,
the cecum and terminal ileum should be avoided as these segments
often experience severe radiation injury. Hand-sewn anastomosis is
favored when possible to avoid staple-line ischemia. Because radiation
can lead to friable, thickened, and foreshortened mesentery, it is also
FIG. 4 Intraoperative comparison of radiation-damaged small
bowel (left) with healthy bowel (right). (From Hogan NM, Kerin MJ, Joyce
MR. Gastrointestinal complications of pelvic radiotherapy: medical and surgical
management strategies. Curr Probl Surg. 2013; 50[9]:395–407.)
recommended to over-sew the mesentery with an interlocking heavy
#1 chromic suture between clamps rather than simply ligating the
mesentery with vessel sealers or a clamp, cut, tie technique.
Although bowel resection is preferred, bypass/exclusion can be
considered in patients with extensive adhesions and/or pelvic fixation in which resection is not possible. Bypass is associated with a
decreased risk of bowel or mesenteric injury and lower anastomotic
leak rate compared with bowel resection; however, it increases the
risk of blind loop syndrome and fistula formation from the affected
segment left behind, which can contribute to further complications.
In select cases, stricturoplasty may be considered as an intestine-preserving alternative to more extensive bowel resection or bypass
techniques to reduce risk of short gut syndrome and avoid total
parenteral nutrition (TPN) dependence.
The management of postradiation enteric and pelvic fistulae are
similar to those employed for other types of fistulae, including sepsis management, nutritional optimization, and fistula maturation/
output optimization. Higher pelvic fistulae (rectovaginal, rectourethral) can be treated with proctectomy and anastomosis of colon
to distal nonradiated rectum or anus. Hand-sewn coloanal anastomosis should only be considered in younger patients with intact
sensation, function, and control. Interposition of well-vascularized
tissue (omentum or rectus pedicle flap) between the affected organ
and anastomosis is highly recommended. Lower pelvic fistulae can
be managed similarly or via a perineal (Kraske) or transsphincteric
(York-Mason) approach. Flap reconstruction (gracilis, omentum,
rectus, bulbocavernosus, or Martius) should be considered for better
healing. In severe circumstances, it may be necessary to perform a
pelvic exenteration.
Fecal diversion has been found to be effective in the management
of pain, tenesmus, incontinence, obstruction, and sepsis and for
patients who are not optimal surgical candidates. Because dissection
can be difficult in an irradiated pelvis with greater risk for bowel
injury, loop ileostomies and transverse/descending colostomies may
be safer to perform than sigmoid colostomies.
PREVENTION
The risk of radiation-induced bowel injury can be minimized with
careful attention to radiotherapy planning and radiation delivery
methods. Recent advances in radiation therapy techniques have
sought to maximize radiation dose to the tumor while minimizing
radiation to adjacent normal tissues. One method for doing so is
3D conformal radiation therapy (3DCRT), which utilizes 3D planning via CT and computer technology to plan and deliver radiation
treatment that matches the shape of the tumor, thereby allowing for
higher dose of radiation delivery to the tumor with less effect on normal tissue. Intensity-modulated radiation therapy (IMRT) is another
technology in which varying intensities of radiation are delivered in a
planned field with clear identification of malignant vs. normal tissue.
Brachytherapy is another method that can be used alone or in conjunction with EBRT to reduce normal tissue injury. Proton therapy
is also a new technology being used by certain tertiary centers as an
option to minimize the amount of radiation to structures and organs
surrounding the target anatomy.
Other strategies to reduce radiation injury include prone positioning, protective belly boards, and ensuring that the bladder is
full during radiation delivery. Amifostine, a prodrug that metabolizes into a thiol metabolite that functions as a free radical scavenger, has demonstrated benefit in some studies to prevent symptoms
of acute radiation proctitis, though these findings have largely
been reported in small, single center studies. Operative maneuvers
including the use of omental slings and tissue expanders to fill
the pelvis can be considered if radiation were to be administered
postoperatively.
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S u g g e S t e d R e a d i n g S
Araujo IK, Muñoz-Guglielmetti D, Mollà M. Radiation-induced damage in
the lower gastrointestinal tract: Clinical presentation, diagnostic tests and
treatment options. Best Pract Res Clin Gastroenterol. 2020;48–49:101707.
Ashburn JH, Kalady MF. Radiation-Induced Problems in Colorectal Surgery.
Clin Colon Rectal Surg. 2016;29(2):85–91.
Hogan NM, Kerin MJ, Joyce MR. Gastrointestinal complications of pelvic
radiotherapy: medical and surgical management strategies. Curr Probl
Surg. 2013;50(9):395–407.
Kennedy GD, Heise CP. Radiation colitis and proctitis. Clin Colon Rectal Surg.
2007;20(1):64–72.
Mendenhall WM, McKibben BT, Hoppe BS, Nichols RC, Henderson RH,
Mendenhall NP. Management of radiation proctitis. Am J Clin Oncol.
2014;37(5):517–523.
Raîche I, Moloo H. Radiation, Microscopic, Ischemic Colitis. In: Steele S,
Hull T, Read T, Saclarides T, Senagore A, Whitlow C, (eds). The ASCRS
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Preoperative Bowel
Preparation: Is It
Necessary?
Anna Chudnovets, MD, and Sandy Hwang Fang, MD
atients who undergo colorectal surgery for cancer and inflammatory bowel disease often have associated risk factors that impair
P
wound healing, such as chemoradiation therapy, steroid therapy, and
malnutrition. Additional complicating factors include case complexity, perineal wounds, and combined multispecialty cases. Due to the
nature of the colon and rectum yielding high bacterial inoculum and
these contributing factors, the risk of postoperative infections after
surgery is significant, with an incidence approaching 40%.
The overall objective for the use of bowel preparation in colorec-
tal surgery is to reduce postoperative complications:
1. Decrease the rate of surgical site infections (SSIs)
2. Decrease anastomotic leak rates
3. Alter gut microbiome
A bowel preparation accomplishes these goals via two mechanisms: the evacuation of fecal material from the colon and the eradication of stool bacterial load. In addition, a bowel preparation should
not alter the histologic appearance of the mucosa.
Historically, bowel preparations have created a harsh physiologic
response to the human body. Newer bowel preparation formulations
are smaller in volume, ingested in a short period of time with effective
evacuation of stool, while also decreasing gastrointestinal discomfort
and side effects, such as nausea and emesis. In addition, these newer
drugs produce no fluid shifts, electrolyte imbalances, or dehydration,
which optimizes the patient, leading into the operative stage of colorectal
surgery with goal-directed fluid therapy (GDFT) as part of the enhanced
recovery pathway or enhanced recovery after surgery (ERP or ERAS).
This chapter discusses the bowel preparation types, the efficacy of
mechanical bowel preparations (MBP) versus oral antibiotics (OA)
versus no bowel preparation, colorectal disease pathology and indications for bowel preparation, and its role in ERAS.
TYPES OF BOWEL PREPARATION
There are two types of bowel preparation: mechanical bowel preparation and oral antibiotics. MBPs are oral cathartics that clear feculent
material from the colon. OA decrease intraluminal bacterial load.
Mechanical Bowel Preparation
Two types of MBPs exist: hyperosmotic versus isosmotic (Table 1).
Hyperosmotic MBPs (e.g., magnesium citrate, sodium phosphate)
exert an osmotic effect, drawing fluid into the bowel lumen, as a
mechanism of flushing out colonic contents. Although patients are
able to tolerate ingestion of these lower volume formulations, they
cause electrolyte and fluid imbalances and dehydration. Patients
subsequently become orthostatic and may develop acute kidney
injury. Contraindications to hyperosmotic solutions include renal
failure, acute coronary syndrome, congestive heart failure, bowel
obstruction, ileus, intestinal malabsorption, and ascites. The use of
hyperosmotic MBP solutions is not recommended in current consensus guidelines for ERPs.
ERAS consensus guidelines recommend the utilization of isosmotic MBPs, which consist of osmotically balanced, nonabsorbable
solutions that do not produce significant fluid or electrolyte shifts.
Isosmotic bowel preparations are deemed safe in patients with the
comorbidities of hepatic disease, congestive heart failure, and renal
failure.
Large volume polyethylene glycol (PEG) preparations include
GoLYTELY, Colyte, NuLytely, and TriLyte. Patients have difficulty
tolerating these large-volume solutions as they are not palatable and
cause nausea and emesis in 4% to 17% of patients. New low-volume PEG (1–2 L) preparations combined with other agents have
been developed and include MiraLAX, HalfLytely, MoviPrep, and
BiPeglyte.
There are multiple studies/clinical trials and meta-analyses that
show conflicting results for the effectiveness of MBPs in regard to
surgical outcomes. In a Cochrane review in 2011, 18 randomized
controlled trials were reviewed that included 5805 participants;
2906 patients were administered MBP while 2899 received no bowel
preparation before elective colorectal surgery. There was no statistically significant difference between the MBP and non-MBP groups
in regard to anastomotic leak for colonic resections and low anterior
resection. These results are similar to a recent meta-analysis, published in 2018, evaluating eight studies with 1065 patients. However,
both studies have reported that evidence quality is low due to the
variation in bowel preparations. Because of this, MBP alone is generally not recommended for elective colorectal surgery.
Oral Antibiotics
First-line antibiotics include a combination of oral neomycin sulfate plus oral erythromycin base or oral neomycin sulfate plus oral
metronidazole (Table 2). The most common side effects are nausea
and emesis. Multiple randomized controlled trials have reported
a significant improvement in SSIs with the use of OA. Two large
studies from American College of Surgeons National Surgical Quality Improvement Program (NSQIP) (>300,000 patients) and one
large meta-analysis of prospective studies (69,000 patients) have
confirmed that many medical centers are using OA alone for their
bowel preparations before colorectal surgery. These studies suggest
that OA alone is associated with similar SSI rates to OA plus MBP
and lower SSI rates as compared with both MBP alone and no bowel
preparation.
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178 PREOPERATIVE BOWEL PREPARATION: IS IT NECESSARY?
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TABLE 1 Mechanical Bowel Preparations
Adjuncts to Mechanical
Preparation Agent Volume/Dose Mechanism Use
PEG (electrolyte lavage) Colyte*
GoLYTELY*
Sulfate-free PEG
(improved smell/
taste, more palatable
for patients)
Low-volume PEG and
bisacodyl tablets
(decrease volume-related discomfort
[e.g., bloating,
cramping])
Aqueous NaP solutions Fleet 90 mL with
Oral sodium phosphate
(tablet)
NuLYTELY*
TriLyte*
HalfLytely and
bisacodyl tablet
bowel prep
MiraLAX
Visicol
(discontinued)
3785 mL
4000 mL
4000 mL
4000 mL
2000 mL
255 g in
2000 mL
48 oz
additional
liquid
32–40 tablets
with 48 oz
clear liquid
No solid food for at least 2 hours
before ingestion of the solution; 240 mL (8 oz) every 10
minutes until rectal output is
clear or 4 L are consumed
No solid food for at least 2 hours
before taking the solution; 240
mL (8 oz) every 10 minutes
until rectal output is clear or 4
L are consumed
Only clear liquids on the day of
the preparation. Dosage is
four bisacodyl delayed-release tablets (5 mg) at noon.
Wait for bowel movement or
maximum of 6 hours; 240 mL
(8 oz) low-volume PEG (i.e.,
HalfLytely) or 240 mL (8 oz) of
clear liquid containing one capful of MiraLAX or other PEG3350 regimen every 10 minutes
until 2 L are consumed.
Only clear liquids can be con-
sumed on the day of preparation. Two doses of 30–45 mL
(2–3 tbsp.) of oral solution
are given at least 10–12 hours
apart. Each dose is taken with
at least 8 oz of liquid followed
by an additional minimum of
at least 16 oz of liquid. The second dose must be taken at least
3 hours before the procedure.
Dosage is 32–40 tablets: 20 tab-
lets on the evening before the
procedure and 12–20 tablets
the day of the procedure (3–5
hours before). The 20 tablets
are taken as 4 tablets every 15
minutes with 8 oz of clear liquid. Bisacodyl is prescribed by
some physicians as an adjunct.
Divided dose regimens (3 L the night
Similar efficacy to PEG
Equally effective as 4 L solutions;
May cause significant fluid shifts.
Early tablet composition included
before procedure, 1 L morning of
procedure) may improve patient tolerance. PEG is considered safer than
osmotic laxatives/NaP for patients
with electrolyte/fluid imbalances,
renal or liver insufficiency, CHF, or
renal or liver failure.
additional studies needed regarding safety
Not for use in pediatric or elderly
patients or those with bowel
obstruction, gut dysmotility, other
structural intestinal disorders, renal
or liver failure, or congestive heart
failure. NaP may cause ulceration or
mucosal abnormalities; do not use
in patients with inflammatory bowel
disease. Patients with compromised
renal function or those taking ACE
inhibitors or ARBs are at risk for
phosphate nephropathy. In 2006, the
FDA issued an alert regarding the
risk for acute phosphate nephropathy, a type of acute renal failure,
with use of oral sodium phosphate
solution or tablets.
higher concentration of microcrystalline cellulose per tablet, which
left residue obscuring the mucosal
surface. Later tablet composition
decreased microcrystalline cellulose concentration. Overall, tablet
NaP is not associated with significantly improved patient tolerance
when compared with aqueous NaP.
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