Sabiston 1 Flashcards
(161 cards)
1
Q
What is the site most likely to perforate in the presence of large bowel obstructions
A
acute dilation of the cecum to a diameter of more than 12 cm, which can be measured on a plain abdominal radiograph, is associated with risk of ischemic necrosis and perforation
2
Q
In cases of large bowel obstruction, the ileocecal valve is clinically important.
A
An ileocecal valve that does not allow reflux of colonic contents into the ileum (competent ileocecal valve) can result in a closed-loop obstruction, a surgical emergency,
whereas a valve that allows retrograde flow into the ileum (incompetent ileocecal valve) will result in less colonic distension and a less acute clinical scenario.
3
Q
The bloodless fold of Treves
A
it is the only part of the ileum that has a fold on the antimesenteric side of the bowel, it can help in the recognition of the ileocecal region and the base of the appendix
4
Q
When releasing the hepatic flexure and lifting the colon medially, one must be aware of
A
the proximity of the second part of the duodenum, which can be inadvertently injured
5
Q
surgical landmark for the underlying left ureter
A
The mobile portion of the sigmoid colon is attached by the sigmoid mesocolon to the posterior abdominal wall and pelvis in the pattern of an inverted V creating the intersigmoid fossa. When mobilizing the sigmoid colon, this mesenteric fold is a surgical landmark for the underlying left ureter
6
Q
The ileocolic artery
A
is the most constant of these arteries. It runs toward the ileocecal junction within the mesentery giving off the anterior and posterior cecal arteries and the appendicular artery, supplying the terminal ileum, cecum, and appendix. The avascular space between the SMA and the ileocolic artery is a safe region to begin vascular dissection
7
Q
right colic artery, middle colic artery
A
The right colic artery, absent in up to 20%, usually arises from the SMA but may be a branch of the ileocolic or left colic vessels.
The middle colic artery enters the transverse mesocolon and divides into right and left branches, which supply the proximal and distal transverse colon, respectively.
When lifting the transverse colon, the middle colic artery can be tracked to the base of the mesentery just to the right of the ligament of Treitz, and into the proximal SMA
8
Q
The marginal artery of Drummond
A
runs along the mesenteric margin of the colon from the cecocolic junction to the rectosigmoid junction
9
Q
The meandering mesenteric artery, or “arc of Riolan,”
A
is an uncommon finding described as a thick tortuous collateral vessel that runs close to the base of the mesentery and connects the SMA or middle colic artery to the IMA or left colic artery.
It can have an important role in blood delivery in cases of SMA or IMA occlusion
10
Q
IMV
A
continues beyond the IMA along the base of the mesentery to the left of the ligament of Treitz and into the portal vein
The IMV can be divided to achieve extra colonic length for low pelvic anastomoses.
11
Q
The rectum
A
begins at the rectosigmoid junction and ends at the level of the anus.
Anatomists define the distal border as the dentate (pectinate) line based on the mucosal surface, whereas surgeons define it as the proximal border of the anal sphincter complex at the level of the levator ani (about 2 cm above the dentate line).
12
Q
Structurally, the rectum lacks
A
taeniae coli, epiploic appendices, and haustra.
13
Q
Dissection deep to the presacral fascia
A
can cause severe bleeding from the underlying presacral venous plexus. Such bleeding can be very difficult to control, as the torn vessels tend to withdraw into the sacral foramina
14
Q
Waldeyer fascia , Denonvilliers fascia
A
The rectosacral fascia, or Waldeyer fascia, is a thick condensation of endopelvic fascia connecting the presacral fascia to the fascia propria at the level of S4 that extends to the posterior-inferior rectum. Dividing Waldeyer fascia during dissection from an abdominal approach provides access to the deep retrorectal pelvis.
Denonvilliers fascia, located anterior to the rectum
15
Q
“lateral stalks” or ligaments.
A
Laterally, the rectum is connected to the pelvic sidewall
These are found in the low pelvis at the level of the prostate or mid-vagina. It is important to remember that in about a quarter of the cases, a branch of the middle rectal artery traverses them and may cause bleeding when cutting through them.
16
Q
Rectum draining
A
The superior rectal vein drains the upper two thirds of the rectum, draining into the IMV and portal system.
The lower rectum and anus drain into the middle and inferior rectal veins, which are connected to the internal iliac and systemic circulation.
This drainage pattern explains the higher rate of lung metastases observed with low rectal cancers as compared to mid and upper rectal cancers, which are much more likely to metastasize to the liver.
17
Q
Lymph nodes Drain
A
The lymph from the upper two thirds of the rectum drains upward toward the inferior mesenteric and paraaortic nodes.
The lower part of the rectum drains in two directions, cephalad toward the inferior mesenteric nodes and laterally and inferiorly toward the internal iliac nodes.
Below the dentate line, lymph drains toward the inguinal lymph nodes.
18
Q
sympathetic innervation
A
The sympathetic innervation of the rectum is derived from sympathetic nerves exiting at the level of L1–3, forming the superior hypogastric plexus.
At the level of the sacral promontory, they divide into left and right hypogastric nerves, traveling on both sides of the pelvis. These nerves supply the rectum and send branches to supply the genitourinary system anteriorly
19
Q
high IMA ligation
A
A high IMA ligation injuring the superior hypogastric plexus or severing the hypogastric nerves near the sacral promontory may result in sympathetic dysfunction characterized by retrograde ejaculation in men.
Division of the lateral stalks too close to the pelvic sidewall may injure the pelvic plexus and nervi erigentes and cause erectile dysfunction, impotence, and atonic bladder.
Injury to the periprostatic plexus when dissecting anteriorly can also cause sexual and bladder dysfunction.
20
Q
Antibiotics and lactulose on Ammonia
A
Antibiotics and lactulose decrease the amount of ammonia absorbed by lowering the concentration of bacteria and reducing the pH, respectively
21
Q
choleretic, diarrhea
A
Deconjugated bile acids can then interfere with sodium and water absorption, leading to secretory, or choleretic, diarrhea.
Choleretic diarrhea is seen early after right hemicolectomy as a transient phenomenon and more permanently after extensive ileal resection. This diarrhea can often be effectively treated by administration of cholestyramine,
22
Q
The main source of energy for intestinal bacteria is
A
dietary fiber, composed of complex carbohydrates (i.e., starches and nonstarch polysaccharides).
Dietary recommendations (i.e., “adding fiber”) generally refer to bulking agents, such as lignin and psyllium, which are nonabsorbable and nonfermentable by colonic bacteria.
23
Q
Bulking agents benefits
A
Bulking agents decrease intracolonic pressures and increase colonic transit time, which help prevent the formation of colonic diverticula and minimize colonic exposure to toxins
24
Q
the principal source of nutrition for the colonocyte
A
Butyrate, an SCFA, is the principal source of nutrition for the colonocyte. Because mammalian cells do not produce butyrate, the colonic epithelium and luminal bacteria form an essential and elegant symbiotic relationship.
Antibiotics disrupt this cohabitation—decreased bacteria leads to less butyrate, which, in turn, negatively affects colonocyte function leading to diarrhea.
Likewise, mucosal atrophy is seen after fecal diversion (i.e., diversion colitis)
Butyrate may also play an important role in maintaining cellular health by arresting the proliferation of neoplastic colonocytes
25
two other SCFAs
Besides butyrate ,acetate and propionate, are produced in the colon, with acetate being the most common of all three.
Hepatocytes metabolize SCFAs for use in gluconeogenesis, and muscle cells oxidize acetate to generate energy.
26
acetate
acetate is the primary substrate for cholesterol synthesis. The production of acetate is reduced by nonabsorbable, nonfermentable dietary fiber, such as psyllium, which in turn has a beneficial effect on cholesterol levels.
27
propionate
Similarly, propionate, which has a glycolytic role in the liver, may also lower serum lipid levels by inhibiting cholesterol synthesis.
28
Lactobacillus and Bifidobacterium
Studies have indicated that probiotics may have widespread health benefits, including stimulation of immune function, anti-inflammatory effects, and suppression of enteropathogenic colonization
they may increase the digestibility of dietary proteins and enhance absorption of amino acids.
Probiotics have been shown to prevent Clostridium difficile–associated diarrhea,
29
Prebiotics
Prebiotics are nutrients that support the growth of probiotic bacteria.
Prebiotics are nondigestible oligosaccharides (e.g., inulin)
30
The autonomic nervous system
The autonomic nervous system is comprised of parasympathetic and sympathetic innervation.
Parasympathetic innervation is excitatory, and it reaches the colon via the vagus nerve and the rectum via the sacral nerves (S2–S4) through the pelvic plexus.
Sympathetic innervation is, conversely, inhibitory. Sympathetic fibers originate from lumber ventral roots (L2–L5), postganglionic hypogastric nerves, and the splanchnic nerves (T5–T12),
31
intrinsic colonic nervous system
The intrinsic colonic nervous system consists of the myenteric (Auerbach) plexus and the submucosal (Meissner) plexus.
These plexus regulate colonic motility, as well as colonic blood flow, absorption, and secretion.
The interstitial cells of Cajal are the primary pacemaker cells governing the function of the enteric nervous system and are important for colonic motility
32
Nutritional and Risk Assessment
patients with an albumin less than 3 are considered higher risk.
There is a growing field of immunonutrition suggesting that consumption of nutritional supplements rich in arginine may, in fact, boost the immune system and lead to a reduction in postoperative infectious complications, such as surgical site infection (SSI).
Patients who are at particularly high risk are those who have chronic partial bowel obstruction and cancer and those who have lost a significant amount of weight (greater than 10% of body weight) in unintentional weight loss
33
Regarding Bowel Prep
Generally, many surgeons believe that a formal mechanical bowel preparation is not required for patients undergoing surgery for IBD since these patients are already having numerous liquid bowel movements.
Bowel preparation is also not used for patients with partial obstruction.
34
Stoma
mark the patient for a preoperative stoma site.
The area of the abdomen that usually is chosen for a stoma, the infraumbilical fat mound
may not look the same in a patient who is sitting up as it does when they are recumbent.
It is essential to mark the patients in a sitting position and to avoid old scars and any skin folds
35
temporary diversion
Loop ileostomies are often chosen for temporary diversion due to their lack of odor, ease of care, and ease of closing.
Loop descending or sigmoid colostomies can similarly easily be closed.
Transverse loop colostomies should seldom be used, as they are large, very prone to prolapse, and can be difficult to maintain pouch adherence, frequently being located in an area around the patient’s belt line or mid-upper abdomen.
36
A key aspect to creating a good stoma
A key aspect to creating a good stoma is to create a large enough aperture in the abdominal wall to allow the stoma to reach to the skin without tension, but not to create such a wide opening that the patient will develop a hernia at the site.
Typically, creating an aperture that will admit two fingers is adequate
muscle-splitting stoma aperture within the rectus muscle and sharply divide the rectus sheath
37
In constructing an end colostomy
In constructing an end colostomy, typically this does not need to protrude more than 0.5 to 1 cm above the level of the abdominal skin.
However, there are some circumstances where the patient may be expected to have a more liquid effluent (e.g., due to receiving chemotherapy), and one may wish to have the stoma protrude more to permit easier pouch placement and adherence.
In the presence of a liquid effluent, a protruding “spout-like” stoma is always easier to maintain pouch adherence compared with a flatter stoma
38
Ileostomy
Ileostomy effluent usually has no odor, in contrast to colostomy effluent, which usually has odor associated with colonic flora.
However, in contrast to a colostomy, an ileostomy will empty continuously and has a high rate of associated chemical dermatitis due to the more alkaline pH associated with small bowel effluent as opposed to the stool of the colon.
There is also a much higher risk of dehydration with an ileostomy, which is a frequent reason for hospital readmission following elective colorectal surgery.
Prior to hospital discharge, one should ensure that the 24-hour stoma output is less than 1000 mL. If the output is greater than this amount, the patient is at high risk of hospital readmission.
39
Seprafilm
In patients in whom temporary ileostomy diversion is contemplated, wrapping the segment of diverted bowel in hyaluronate-carboxymethylcellulose membrane (Seprafilm) at the time of stoma creation facilitates stoma closure
40
Most common reason for readmission after an ileostomy
dehydration is the most common reason for readmission after an ileostomy creation.
41
Prep Pre OP
clear liquid diet up until 2 hours before the induction of anesthesia.
However, there is weaker evidence to support the use of per os carbohydrate loading prior to surgery.
Mechanical bowel preparation alone has not shown to be beneficial (strong recommendation based on high-quality evidence, 1A).
In the United States, mechanical bowel preparation plus oral antibiotics preparation has become the preferred preparation to reduce complications, including SSIs, especially when left-sided and rectal resections are anticipated
42
Periop Intevention Plan
Colorectal surgery patients have up to a 20% risk of developing a SSI postoperatively.
-preoperative chlorhexidine shower
-mechanical bowel preparation with oral antibiotics,
-prophylactic antibiotic administration within 1 hour of incision
-the use of wound protectors during surgery
-changing gown, gloves, and instruments before fascial closure
-euglycemia, and normothermia.
43
Pain managements and fluids
-multimodal, opioid-sparing, pain management plans starting before the induction of anesthesia.
-Minimizing opioids is associated with earlier return of bowel function and shorter length of stay.
Acetaminophen, nonsteroidal antiinflammatory drugs (NSAIDs), and gabapentin have all been incorporated into various ERPs.
Transverse abdominis plane block with local anesthetic, including liposomal bupivacaine, have shown promising results.
Epidural analgesia is generally recommended for open, but not laparoscopic, colorectal surgery.
The use of goal-directed fluid therapy in the intraoperative and postoperative phases of care is associated with a reduction in time to return of bowel function and length of stay
44
Post Op
Early patient mobilization with early feeding has good evidence to support its role in an ERP.
Alvimopan use has been shown to hasten return of bowel function after open surgery, but not with MIS.
In addition, intravenous (IV) fluids and urinary catheters should be discontinued early
45
Diverticula
Diverticula are classically formed on the mesenteric side of the colonic wall in regions where vasa recta traverse through the muscular layer to provide blood to the mucosa
The sigmoid and descending colon are typically affected, whereas the rectum, having an extra layer of muscle, is generally not affected.
This has implications for surgery and is why the distal anastomosis margin in operations for diverticulitis should always be within the rectum.
46
risk of diverticulitis
Western dietary patterns high in red meat, fat, and refined grains are associated with an increased risk of the disease
whereas increased fiber intake, with abundant fruit, vegetables, and whole grains, reduces the risk of diverticulitis.
Central obesity and smoking increase the risk
whereas physical activity such as running has been correlated with a decreased risk
47
Modified Hinchey classification system
see
48
In Abscess
Following recovery, elective surgery is generally recommended; however, some of these patients, especially those with smaller abscesses that were treated without drainage, can probably be managed nonoperatively
49
Fistula
The most common type, especially in men, is a colovesical fistula to the dome of the bladder.
Patients will present with recurrent urinary tract infections, which are in many cases polymicrobial.
Pneumaturia and fecaluria may also be present.
CT can reveal air or contrast in the bladder in the absence of prior instrumentation.
Cystoscopy will usually disclose inflammation at the site of the fistula
50
Colovaginal fistulas , Colocutaneous fistulas
Colovaginal fistulas occur almost exclusively in women who have undergone previous hysterectomy and present with vaginal discharge and passing of air per vagina.
Colocutaneous fistulas usually present at a previous drain site in patients who have undergone percutaneous drainage
51
Tx for Fistula
Initial management includes broad spectrum antibiotics to decrease the inflammation.
Patients are then investigated with colonoscopy and appropriate imaging (i.e., cystoscopy) to exclude malignancy and Crohn disease.
Surgical principles then encompass resection of the involved colon and fistula tract with primary anastomosis.
If possible, the fistula opening into the secondarily involved organ is primarily suture repaired
52
Fistula to Bladder, Small Bowel Tx
In the case of the bladder, with small fistula openings, drainage of the bladder with a Foley catheter for 7 to 10 days will usually allow for healing. A cystogram can be done to confirm fistula healing prior to Foley removal.
Fistulas to the small bowel will characteristically require resection and primary anastomosis.
53
Obstruction
Patients with a partial obstruction can usually be initially treated with a nasogastric tube for decompression, antibiotics, fluids, and bowel rest.
If the obstruction resolves, elective resection can be planned.
It is usually important, prior to resection, to perform a colonoscopy to rule out malignancy.
54
Surgical Emergency
Hinchey grades 3 and 4 are considered a surgical emergency
55
Perforation Tx
The mainstay of treatment in these cases has traditionally been the Hartmann procedure, which removes the involved colon and exteriorizes an end colostomy.
Reversing the colostomy, however, requires a second major surgical procedure with its own significant morbidity and mortality. Practically, up to 50% of patients will never be reversed
56
Another Options
laparoscopic lavage
> irrigation of the abdominal cavity to reduce the abdominal contamination and placement of drains without resection (mainly for Hinchey grade 3 diverticulitis).
> results in lower stoma rates
> significantly higher rates of ongoing and recurrent sepsis and emergency reoperations.
Another option is performing a resection with a primary anastomosis and diverting ileostomy
> found to be safe and significantly simplifies and shortens the second operation.
> Overall morbidity and mortality are similar
> much higher proportion of patients will have their stomas reversed (94%–96% for primary anastomosis vs. 65%–72% for Hartmann).
attractive option for patients who are stable enough to withstand the additional time of the initial surgery.
57
Uncomplicated Diverticulitis Tx
clear liquids
followed by a low-residue diet until the inflammation subsides.
Antibiotics have traditionally been prescribed to cover colonic bacteria.
A systematic review and metaanalysis assessing the effect of antibiotic administration in patients with uncomplicated diverticulitis has not shown the usage of antibiotics to accelerate recovery or prevent complications or subsequent surgery.
58
After recovery
it is recommended that patients undergo a colonoscopy after 4 to 8 weeks to exclude malignancy.
59
recurrence
Following the initial episode of acute, uncomplicated diverticulitis, only 10% to 35% of individuals will have another episode.
60
Now A days they Recommend
recurrences in general tend to follow the severity of the initial episode.
As a result, the number of attacks of uncomplicated diverticulitis has fallen out of favor as an indication for surgery.
Currently, an individual assessment is performed on the frequency of attacks, ongoing symptoms, and their effect on quality of life versus the age and medical condition of the patient and their surgical risk
61
Margins ?
When removing the sigmoid colon, the proximal margin should be in soft pliable bowel, but it is not necessary to include all proximal diverticula.
The distal anastomosis, however, should be to the upper rectum, since leaving a section of distal sigmoid colon is associated with a higher risk of recurrent diverticulitis.
62
Immunocompromised Patients
they are more likely to present with free perforation and complicated disease because of their impaired ability to mount an inflammatory response.
Because of this risk, there should be a lower threshold for resection after a single attack of diverticulitis.
Immunocompromised patients who require emergency surgery and resection should probably not undergo primary anastomosis at the initial surgery because of their impaired immune system and healing.
63
Young Patients
Current guidelines do not support treating young patients differently than others.
64
Adult colonic intussusceptions
in contrast to pediatric intussusceptions, are almost always associated with a pathologic lead point, such as a polyp, cancer, Meckel, or colonic diverticulum.
A recent meta-analysis found malignancy as the causative factor in 36.9% of ileocolonic and 46.5% of colonic intussusceptions.
Most authors recommend surgical resection adhering to oncologic principles without reduction
65
Patients with malignant obstruction of the low and mid rectum
usually require an initial diverting stoma to allow for neoadjuvant chemoradiation prior to definitive surgery.
66
Malignant obstructions of the sigmoid and left colon without signs of impending perforation
can be treated with initial endoscopic stenting as a bridge to surgery, or initial surgery.
Surgical options include segmental resection with Hartmann operation (end colostomy with internal closure of the rectal stump) or primary anastomosis with or without a diverting stoma
67
If the cecum is ischemic or nonviable
a subtotal colectomy is performed
68
right-sided obstruction
In cases of right-sided obstruction
a right hemicolectomy is typically performed with primary anastomosis.
69
Patients who are unstable with a high risk for anastomotic failure
should undergo creation of a temporary diverting stoma or exteriorization of the anastomosis as a loop ileostomy.
70
In patients with sigmoid volvulus
endoscopic decompression is often successful using either a rigid or flexible sigmoidoscope with placement of a rectal tube proximal to the point of torsion.
If this is unsuccessful, patients require surgery with resection, colostomy, and a Hartmann procedure.
If decompression is successful, elective sigmoid resection with primary anastomosis
71
With cecal volvulus
primary resection and anastomosis can typically be performed unless the patient is at increased risk of anastomotic leak (e.g., nonviable bowel, sepsis, hypotension, etc.).
72
obstruction as a result of active IBD
will commonly respond initially to steroids.
73
Paracolic abscesses
can be drained percutaneously
74
Foreign bodies
can usually be removed endoscopically.
75
Fecal impaction
is commonly relieved with a combination of stool softeners and laxatives from above and manual disimpaction at the bedside or in the operating room under anesthesia.
76
Hernias causing mechanical large bowel obstruction
usually require surgery
77
Conditions associated with pseudo-obstruction
see
78
suspicion of pseudo-obstruction xray
Dilation and gas continuing all the way down to the distal rectum support the suspicion of pseudo-obstruction in contrast to a mechanical obstruction in which a paucity of gas is commonly encountered distal to the obstruction.
79
signs that may be indicative of colon ischemia, perforation, or impending perforation.
Abdominal tenderness, leukocytosis, fever, and cecal dilation more than 12 cm
80
When to Consider Nonoperative
supportive care is initiated for patients with a cecal diameter that is less than 12 cm without evidence of ischemia or perforation.
81
In cases that do not improve with supportive care or with a cecal diameter of more than 12 cm
without systemic toxicity and abdominal tenderness, colonic decompression is indicated
82
Neostigmine
given as a 2 to 2.5 mg IV bolus injected over 3 to 5 minutes and results in significant parasympathetic stimulation causing strong colonic peristalsis that usually leads to subsequent flatus and bowel movements.
> safe and effective option for patients with acute colonic pseudo-obstruction who have failed conservative management.
> some patients requiring multiple drug administrations.
83
Neostigmine is contraindicated in
mechanical bowel obstruction and in patients with signs of ischemia or perforation.
It should be used with caution among patients with asthma, chronic obstructive lung disease, bradycardia, and recent acute coronary syndrome and in those with renal failure.
Neostigmine should be given in a monitored setting with atropine immediately available
84
Colonoscopic decompression
should be considered in patients with contraindications to neostigmine or for those who are unresponsive to it.
The aim of endoscopic decompression is to advance the scope to the right colon with minimal insufflation and use of narcotics and place a colonic decompression tube while removing as much gas as possible from the colon
85
Colonoscopic perforation rates following decompression
for pseudo-obstruction are in the range of 1% to 3%
86
Patients who do not respond to other lines of treatment or those who demonstrate signs of systemic toxicity, ischemia, or perforation require surgery.
Surgical options are determined according to the condition of the colon and the patient.
If the colon is viable, tube cecostomy or cecostomy can be performed, with high rates of success.
For patients with signs of ischemia or perforation, a resection, usually with a diverting stoma, is recommended.
87
Crohn disease
smoking tends to exacerbate symptoms.
Antibiotic use in early life has also been thought to predispose to IBD, as has NSAID use.
88
in CD , Something Should Always be Performed
Digital rectal examination should always be performed.
89
One of the most serious joint manifestations is
ankylosing spondylitis which runs a course independent of the bowel disease.
These patients are HLA-B27 positive
90
Erythema nodosum
is characterized by red painful swollen nodules that can occur and usually will respond to systemic steroid administration
91
pyoderma gangrenosum
characterized by typically extremely painful ulcerating lesions that frequently occur at sites of repeated trauma such as in the vicinity of surgical incisions or more frequently around intestinal stomas
There is a phenomenon called “pathergy,” which refers to a worsening of the pyoderma with any type of surgical manipulation or debridement.
These lesions are therefore best treated by nonoperative means and can include intralesional steroid injections (i.e., triamcinalone), topical (tacrolimus 0.1%), or systemic biologic therapy (anti-tumor necrosis factor [TNF] antibodies
92
inflammation begins at
With UC, inflammation begins at the level of the dentate line and extends proximally
whereas in Crohn disease, in many cases, the inflammation is more patchy and there can be discontinuous inflammation (i.e., skip areas)
93
One of the most common scoring systems for endoscopic assessment of UC is the Mayo Clinic Scoring System
based upon the severity of the mucosal ulceration or the absence
Grade 1 refers to a normal endoscopic appearance
grade 2 refers to slightly more erythematous
grade 3 refers to even more erythematous area with touch bleeding
grade 4 refers to significant bleeding and friability.
94
Crohn disease is more characterized by
deeper punched-out appearing ulcerations
often longer serpiginous ulcerations covered with fibrin. These can oftentimes extend longitudinally along the lumen of the bowel, in which case they are sometimes referred to as “bear claw” ulcerations
In many cases, Crohn disease ulcers are worse on the mesenteric side of the bowel.
Regarding the distribution of Crohn disease, the most common site of involvement in nearly half of patients is ileocolic, followed by colonic involvemen
95
As a rule, inflammation in UC is restricted to
the surface epithelium
96
In biopsy specimens, the diagnosis of Crohn disease is made in the presence of
non-necrotizing granulomas or the presence of transmural lymphoid aggregates in an area not deeply ulcerated
97
IBD undetermined
refers to a subset of patients who have overlapping characteristics of both Crohn disease as well as UC on endoscopic biopsy. It is thought that up to 10% to 15% of patients
98
indeterminate colitis
is made in patients in whom there is uncertainty of the diagnosis on evaluation of the colectomy specimen, since histologic features of both Crohn and UC are seen.
Overall, this diagnosis is more likely in patients with fulminant disease where the significant amount of inflammation interferes with precise disease diagnosis
99
Thiopurines
“steroid-sparing” class of medication that are usually begun once patients are placed on steroids and perhaps have been unsuccessful in weaning off steroids after one or two attempts at pulse therapy
100
The side effects of this therapy include
leukopenia and pancreatitis.
These side effects are largely seen in individuals who are homozygous for a variant of the enzyme thiopurine methyltransferase responsible for metabolizing these drugs poorly.
For this reason, many physicians now routinely perform thiopurine methyltransferase genotyping of patients to see whether they will be able to metabolize these drugs properly prior to initiating thiopurine treatment.
there is usually a 3- to 4-month lag time until these medications exert their therapeutic effect. For this reason, these medications cannot be used to treat a flare.
Long-term thiopurine use is also associated with a higher risk of developing non-Hodgkin lymphoma
101
The side effects of methotrexate
include elevations in liver function tests, as well as pulmonary fibrosis. When methotrexate is given, patients require folic acid supplementation
102
infliximab SE
reactivation of infections including tuberculosis, histoplasmosis, actinomycosis, and hepatitis.
For this reason, a careful patient history regarding these infections should be taken prior to consideration of treatment. In addition, before starting these drugs, the patient should have either a tuberculin skin test or undergo testing with QuantiFERON gold assay as well as obtain a hepatitis profile
associated with a higher risk of developing non-Hodgkin lymphoma compared to the general population. In addition, anti-TNF-α antibody has been associated with a low risk of hepatosplenic T-cell lymphomas
103
marker to assess disease activity
either fecal calprotectin or lactoferrin that can be used as an inflammatory marker to assess disease activity.
104
toxic megacolon having three or more of the following criteria present:
- tachycardia greater than 100
- leukocytosis greater than 12,000/dL3
- hypoalbuminemia less than 3 g/dL3,
- temperature greater than 38°C
- or a diameter of the transverse colon on a plain abdominal radiograph greater than 5 cm.
Three or more of these criteria meet the definition of toxic megacolon; note that a “megacolon” does not need to be present in order to meet this definition.
105
Patients with longstanding UC (>8 years) have a high risk of developing dysplasia or cancer, as do those who have sclerosing cholangitis.
Once the disease has been present longer than 8 years, patients are advised to undergo regular (yearly) colonoscopic surveillance with or without chromoendoscopy.
106
If multiple areas of low-grade dysplasia or areas of high-grade dysplasia are found
a colectomy is recommended to prevent the development of invasive adenocarcinoma.
The finding of colonic dysplasia in patients with longstanding UC is an indication for surgery
107
There is currently somewhat of a controversy as to exactly who requires surgery and who requires continued observation with close surveillance
due to the development of high-definition colonoscopy, as well as the development of techniques of surveillance such as chromoendoscopy.
Chromoendoscopy involves the performance of colonoscopy with the spraying of dyes such as methylene blue or indigo carmine onto the colonic mucosa at the time of colonoscopy to highlight areas suspicious for dysplasia to permit targeted biopsies rather than just performing the random biopsies that were previously standard of care.
In addition to this, there has been recognition that there are different types of dysplasia.
The flat dysplasia that is difficult to detect and blends in with the surrounding mucosa is very different from the “polypoid” dysplasia that is apparent and can be treated in many cases like a polyp and removed
108
UC Polypectomy
patients with UC have undergone “polypectomy” removal of dysplastic lesions and have been followed long-term without interval development of cancer
109
however, still agreement that if there are multiple areas of flat dysplasia within the colon,
colectomy is indicated
110
if an adenocarcinoma is identified
colectomy is indicated
111
In certain patients, the presence of severe extraintestinal disease is also an
indication for surgery
112
Indications for Surgery for Crohn Disease
- children with Crohn disease when they show failure to grow.
- symptoms of obstruction secondary to fibrostenosing Crohn
- perforating Crohn disease associated with abscess or fistula
- associated cancer or dysplasia, as with patients with UC, are an indication for surgery
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ileal sigmoid fistula , enterocutaneous fistulas, Enteroenteric fistulae
- presence of a symptomatic ileal sigmoid fistula resulting in significant diarrhea bypassing the entire colon can be an indication for surgery.
- The occurrence of enterocutaneous fistulas is an indication for surgery.
- Enteroenteric fistulae are not an indication for surgery unless they are associated with significant symptoms of obstruction or discomfort.
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patients with fulminant colitis Surgical Option
Subtotal colectomy and ileostomy and Hartmann procedure
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“toxic megacolon”
- mucosa sloughs, the endotoxins within the bowel lumen are absorbed leading to a septic state characterized by
> 1- leukocytosis, 2- tachycardia, 3- fever, and in severe cases, hemodynamic instability.
> protein-losing enteropathy > 4- hypoalbuminemia.
> If the colitis is severe > colonic ileus > 5- increased diameter of the transverse colon (>5 cm).
The definition of toxic megacolon is made when any three of these five factors ( 3/5 ) are present. It is important to realize that a patient can have toxic megacolon without having a “megacolon” (i.e., they can just be “toxic” or septic from their colitis).
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One of the common complications of this procedure postoperatively is
a “blow out” of the Hartmann stump, resulting in a pelvic abscess.
This complication many times can be avoided simply by leaving a very long Hartmann stump and incorporating this into the fascial closure of the midline abdominal laparotomy wound or the specimen extraction site
if the stump dehisces and a wound infection develops, the wound is opened and there is a controlled mucous fistula rather than a deep pelvic infection. Once the patient has stabilized and weaned off immunosuppressant medications, usually after a period of 3 months, another procedure for restoration of intestinal continuity can be performed.
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Subtotal Colectomy and Ileorectal Anastomosis
- avoids complications of pelvic dissection such as disturbances of sexual function in men and reduced fertility
- Patients with limited rectal involvement do best
- need to undergo continued surveillance for dysplasia because they are at in an increased risk of cancer in the retained rectum over time
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Ileal Pouch–Anal Anastomosis
- S Pouches, W Pouches, and H Pouches
- the simplest and easiest pouch and the one with the least complications is the J Pouch
- This is created using 15-cm limbs of terminal ileum and two firings of a GIA stapler.
- The apex of this J Pouch is then either stapled to the distal rectum, leaving a very short rectal cuff , or hand-sewn to the distal rectum after a 2-cm mucosectomy is performed.
Currently, the stapled approach is preferred simply because it provides superior continence and it is much quicker to perform.
However, in cases of dysplasia or cancer, hand-sewn approaches still may be warranted.
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Two fires of a linear stapler are required; either a
75- or 100-mm stapler can be used.
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IPAA, one stage vs two stage
- Many patients who are undergoing this operation are on immunosuppressives at the time of surgery or in poor nutritional state, this operation is commonly performed with temporary fecal diversion (temporary loop ileostomy).
- This is in place for 2 to 3 months, during which these immunosuppressant medications are weaned and the patient regains their normal nutritional state. The temporary ileostomy can then be closed, typically without requiring a laparotomy.
- In patients who are not on immune suppression and in good nutritional state (this usually refers to patients undergoing surgery for the findings of colonic dysplasia), the operation can safely be done in one stage without fecal diversion provided that there is no tension on the IPAA.
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Several technical maneuvers can be performed to lessen the tension on the IPAA.
- mobilization of the small bowel mesentery to the level of the pancreas
- If distal traction is placed on the apex of the J pouch, it should easily reach just below the symphysis pubis
- When this maneuver is performed, one can either feel or visualize which small bowel mesenteric vessel is under more tension, the superior mesentery vessels or the ileocolic vessels. The vessel with the greater amount of tension can be divided
- “Peritoneal windowing” can also provide mesenteric length. This is a maneuver whereby small slits are created in the anterior and posterior peritoneum covering the mesenteric vessels.
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RF for Tension in IPAA
- obese
> more difficult to obtain sufficient mesenteric length for the small bowel to reach tension-free to the pelvis.
- Very tall individuals and those with a long torso, tension can be an issue as well.
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Fashioning of stapled ileal pouch–anal anastomosis
- circular stapler is used; typically a 29-mm stapler is selected.
- A common error is to leave too long a segment of rectum, resulting in the persistent symptoms due to this retained segment of mucosa affected with inflammatory bowel disease (cuffitis).
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Common early complications of IPAA include
- nonhealing of the IPAA:
> pelvic sepsis
> ileal pouch–anal anastomotic fistulae
> ileal pouch–vaginal fistulae
> ileal pouch–anal anastomotic sinuses
> ileal pouch–anal anastomotic strictures (often a reflection of anastomotic tension).
Late complications include the diagnosis of Crohn disease, which is more common in patients who undergo emergent colectomy and in those patients who have a diagnosis of indeterminate colitis.
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With a “good” result, patients with IPAA will have up to
- six bowel movements within a 24-hour period, usually including one nocturnal bowel movement.
- at about 6 months, there will be significant enlargement of the ileal pouch, allowing patients to reduce the amount of antidiarrheal medication they take to control their output.
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Continent Ileostomy
instead of continence being maintained by the anal sphincter, continence was maintained by an intussuscepted segment of ileum positioned between this reservoir and the end ileostomy
A continent ileostomy is air and water tight;
very prone to dessusception, rendering the stoma incontinent and requiring revisional surgery. This procedure works best in individuals with a thin body habitus as with heavier individuals the thicker mesentery also predisposes to dessusception
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in CD for Ileocolic Resection margins
In deciding margins of resection, one should select areas of bowel that feel normal and are not thickened and have a normal thickness of the bowel-mesenteric junction. The ability to palpate a discrete small bowel-mesenteric junction is usually a good indicator that the lumen is free of significant Crohn inflammation.
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in ileocolic anastomosis, the authors prefer a hand-sewn end-to-end anastomosis. Why ?
While there are many ways to construct the ileocolic anastomosis, the authors prefer a hand-sewn end-to-end anastomosis. Postoperatively, these anastomoses are very easy to evaluate endoscopically and to dilate in the event of recurrent disease, which is not true of side-to-side stapled anastomoses
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Proctocolectomy and Ileal-Pouch–Anal Anastomosis in CD
- providing that they do not have obvious perianal disease.
- With the advent of newer and more potent immunosuppressive drugs, this procedure is considered an option in an educated patient who is aware of the increased risk of morbidity and the less favorable functional results (i.e., greater number of bowel movements) as compared to when this operation is performed for patients with UC.
- In addition, there is, of course, a higher risk of fistulizing disease and the need to convert to an end ileostomy.
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Cancer Risk
in patients in whom there has been a cancer identified, total colectomy should be performed, as there have been studies showing colonic procarcinogenic mutations tracking along the colon and the risk of a subsequent cancer in other areas of the colon is high
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Postoperative Recurrence
- Crohn patients who smoke are at higher risk of early disease recurrence
- as are patients younger than 30 years old and those who have already had two or more operations for fistulizing disease.
early intensive medical treatment beginning very soon postoperatively may successfully reduce the risk of recurrence.
Regular endoscopic monitoring of the lower GI tract for signs of recurrent disease is important to allow therapeutic intervention prior to the development of therapy-resistant fibrosis.
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C. difficile
- anaerobic, spore-forming, gram-positive bacillus.
- Transmission routes include person-to-person spread through the fecal-oral route or through exposure to a contaminated environment by ingestion of spores from other patients and transmission via healthcare personnel’s hands
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Toxin A and B
Binding of toxin A or B to colonocyte glycoprotein receptors leads to colonocyte death and release of inflammatory mediators
C. difficile Ribotype 027 strain in the mid-2000s resulted in significant outbreaks and Deaths
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RF for C.Diff
Virtually all antibiotics have been associated with C. difficile, but particularly
third and fourth generation cephalosporins,
fluoroquinolones
clindamycin
carbapenems
have been linked to a higher risk of CDI.
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Other RF
immunodeficiency (including human immunodeficiency virus infection)
chemotherapy treatment
use of acid suppressing medications such as proton pump inhibitors
GI surgery or manipulation of GI tract including tube feeding
prolonged hospitalization or lengthy stay in nursing homes or rehabilitation units.
Patients with IBD have increased rates of CDI, along with worse outcomes [HIV] and higher rates of colectomy
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increased risk for death from CDI include
advanced age
multiple comorbidities
hypoalbuminemia
leukocytosis
acute renal failure
and those infected with Ribotype 027
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When it Begins
begin 4 to 9 days after initiation of antibiotics but can commence 10 weeks or more after antibiotic treatment.
Patients presenting with new-onset, unexplained, watery diarrhea (with three or more unformed stools in 24 hours) should be suspected of having CDI.
Patients may also have abdominal pain, fever, and an associated ileus
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categorized into
asymptomatic colonization
nonsevere disease
severe disease
fulminant disease
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assess clinical severity
Leukocytes of at least 15,000 cells/μL
and/or serum creatinine of at least 1.5 cells/μL are predictors of severe disease according to the Infectious Disease Society of America.
Fulminant or severe CDI is diagnosed in patients demonstrating hypotension or shock, ileus, or megacolon
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Diagnosis Test
enzyme-linked immunosorbent assay for toxin detection,
glutamate dehydrogenase immunoassay for C. difficile antigen detection
nucleic acid amplification test
polymerase chain reaction testing
and stool cultures
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Other Tests
- Flexible sigmoidoscopy
> not a first-line modality , helpful in cases of inconclusive stool testing or to help exclude other etiologies.
> Classically raised, yellowish-white small (2–10 mm) plaques (pseudomembranes) can be observed in approximately half of patients with CDI
> Histologic findings from the plaques reveal an inflammatory exudate with mucinous debris, fibrin, necrotic epithelial cells, and polymorphonuclear cells.
> In fulminant colitis, colonoscopy may increase the risk of perforation
Imaging is not very useful
> assist in assessing disease severity and response to treatment.
> Typical CT findings include significant colonic wall thickening, bowel dilation, pericolonic fat stranding, high attenuation oral contrast in the colonic lumen alternating with low-attenuation inflamed mucosa (accordion sign), and ascites.
> Ultrasound may also be useful, especially among critically ill patients who cannot be transported to the CT scanner in radiology. Ultrasonography may show bowel wall thickening, narrowing of the lumen, as well as pseudomembranes, which are seen as hyperechoic lines covering the mucosa
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Treatment
stopping or minimizing previous antibiotics, parenteral fluids, and correction of electrolytes
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Fecal Microbiota Transplant
for patients with recurrent episodes of CDI
Patients with CDI lack protective colonic microbiota to resist replication and colonization
nasogastric, oral (frozen fecal microbial capsules), rectal enema, and colonic per colonoscopy.
A recent comparison between upper and lower methods of delivery demonstrated the lower approaches being more effective.
multiple FMTs needed to achieve a good clinical response.
Current guidelines recommend FMT for patients with multiple recurrences of CDI, in whom antibiotic treatment has failed
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Monoclonal Antibodies
Bezlotoxumab and actoxumab directed against C. difficile toxins B and A, respectively.
These antibodies limit colonic damage by neutralization of the toxin and block the binding to host cells.
They can be used as coadjuvant treatment with antimicrobial therapy to help prevent recurrence,
especially among patients infected by Ribotype 027, in severe CDI, and in immunocompromised patients.
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abx
Treatment options for recurrent episodes generally include changing antibiotics (from metronidazole to vancomycin or fidaxomicin from vancomycin). In addition, tapered and pulsed regimens are used.
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Surgery
a total or subtotal abdominal colectomy with preservation of the rectum has traditionally been performed.
A newer option with similar results for patients without necrosis or perforation is exteriorization of a diverting loop ileostomy with on-table colonic lavage followed by antegrade vancomycin flushes.
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CMV Colitis
important etiology to consider in
immunocompromised hosts, particularly in advanced HIV infection, transplant patients, patients with IBD, and in those receiving chemotherapy.
CMV colitis commonly presents with watery or bloody diarrhea, fever, and abdominal pain.
Diagnosis is established by serology and by determining viral load in the blood.
Endoscopy demonstrates patchy mucosal erythema in the colon.
Inclusion bodies seen on biopsy are pathognomonic for CMV.
CMV colitis can progress to sepsis, toxic megacolon and colon perforation.
Treatment is usually supportive with the addition of ganciclovir. Patients with severe, complicated disease may require surgery
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ischemic colitis Vs acute mesenteric ischemia
It is important to differentiate ischemic colitis from situations of acute mesenteric ischemia, in which a major vessel of the bowel is obstructed, wherein patients commonly present with severe pain out of proportion to physical findings and require immediate vascular intervention. Ischemic colitis is considered a disease of small blood vessels and typically presents less dramatically, seldom requiring vascular intervention.
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Arterial Blood Supply
SMA and the IMA
The SMA gives off the ileocolic, right colic, and middle colic arteries.
The IMA gives rise to the left colic and sigmoid arteries and ends as the superior rectal (hemorrhoidal) artery
There are two well-described collateral networks that aid in preventing colonic ischemia by providing “backup” both within the territories of the two major arteries and between them.
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collateral vessel
The main collateral vessel is the marginal artery of Drummond, which runs parallel and close to the mesenteric margin of the colon from the cecocolic junction to the rectosigmoid junction.
The colon can receive collateral blood supply through this artery when one of the larger arteries is obstructed. It is important when resecting a section of colon to preserve this artery since only the vasa recta are located between it and the colon. When it is compromised, ischemia of that section of colon may result.
The second collateral circulation can be found in the proximal region of the large arteries.
The “arc of Riolan” (meandering mesenteric artery) is an infrequent finding, traversing close to the mesenteric root and connecting the SMA or middle colic artery to the IMA or left colic artery. It can have a critical role in situations of SMA or IMA occlusion. The presence of a large arc of Riolan commonly indicates an obstruction of one of the major mesenteric arteries.
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watershed areas
two well-described watershed areas where the collateral circulation is classically inconsistent and vulnerable to ischemia.
The first > splenic flexure (Griffiths point). In some studies, up to 50% of specimens were found to lack a marginal artery in the region where the SMA and IMA circulations meet.
> Commonly, surgeons avoid making anastomoses in this area for fear that the impaired blood supply will not be sufficient to permit anastomotic healing, leading to anastomotic leaks.
A second potential watershed area is the rectosigmoid junction (Sudeck’s point). This region receives it blood supply from the superior hemorrhoidal artery and distal sigmoid branches, both terminal branches of the IMA and prone to atherosclerotic changes.
The right colon, although not classically considered a watershed area, it is also vulnerable to ischemia from embolic occlusion because the ileocolic artery is the terminal branch of the SMA. For this reason, the right colon is also particularly prone to low-flow conditions such as heart failure, hemorrhage, and sepsis.
The rectum, which has a good blood supply from both the IMA and the iliac circulation, as well as a strong collateral network, is rarely the victim of ischemic injury.
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Drugs causing Ischemic Colitis
Constipation-inducing drugs can cause ischemic colitis, most likely as a result of reduced blood flow and increased intraluminal pressure.
Immunomodulator drugs such as anti-TNF-α inhibitors can affect thrombogenesis,
and illicit drugs such as cocaine and methamphetamines cause ischemia through vasoconstriction, hypercoagulation, and direct endothelial injury
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patients present with isolated right-sided ischemic colitis
These patients are more likely to present with abdominal pain without bleeding and more commonly have atrial fibrillation, coronary artery disease, and/or chronic renal failure.
Patients with isolated right-sided ischemic colitis have a higher chance of requiring surgery and have a poorer prognosis.
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“thumbprinting,” and The “single-stripe sign,”
- Abdominal plain films may show bowel distension and “thumbprinting,” which are rounded densities along the sides of a gas-filled colon indicative of submucosal edema
- “single-stripe sign,” a single linear ulcer running along the longitudinal axis of the colon is rare but considered specific for ischemic colitis.
Segmental distribution, with abrupt transition between injured and noninjured mucosa, and sparing of the rectum support ischemia over IBD
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Why bacterial translocation happens ?
Colonic ischemia can result in failure of the intestinal epithelial barrier with bacterial translocation leading to overt sepsis. For this reason, empiric broad-spectrum antibiotics against both anaerobic and aerobic
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When to Perform Surgery for Ischemic Colitis
-Patients who fail to improve or have worsening symptoms within a few days should raise the concern for the development of full-thickness ischemia and should have repeat imaging or endoscopy to help guide treatment.
-A small proportion of patients with mild to moderate symptoms will develop a chronic colitis, with ongoing or recurrent bouts of symptoms of abdominal pain, bloody diarrhea, and sepsis. These patients have a higher rate of complications and commonly require surgical resection of the involved segment.
- Some patients who initially recover from partial-thickness ischemic colitis will eventually develop a chronic stricture at the involved segment. These patients may complain of constipation, narrowed stools, and abdominal pain. Diagnosis can be confirmed with a contrast enema, CT, or endoscopy. Symptomatic patients or those in which malignancy cannot be excluded should undergo elective resection
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What can Exacerbate or lead to perforation
Cathartics
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Risk factors independently identified as associated with perioperative mortality after colectomy for ischemic colitis include
the elderly
poor functional status
multiple comorbidities
preoperative septic shock
preoperative blood transfusions
preoperative acute renal failure
and delay from hospital admission to surgery.
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During Surgery
- visualize and assess the entire small and large intestine for signs of ischemia and gangrene.
- frequently in watershed areas. In these cases, an anatomic resection should be performed to allow sufficient blood supply to the remaining colon with minimal reliance on stressed collaterals.
- Deciding how much to resect or whether a specific segment is likely to survive can be difficult. Visual examination tends to be inaccurate, especially when the bowel is ischemic but still viable. Intraoperative infrared angiography
> indocyanine green is injected intravenously and distributes throughout the circulation. Then, using a variety of commercially available imaging systems, the indocyanine green undergoes laser excitation, demonstrating real-time tissue perfusion
- Creation of an anastomosis is usually not recommended in the acute setting, due to the concern for evolving ischemia and the existence of hemodynamic instability and sepsis commonly encountered in these situations.
- A temporary abdominal closure with a planned second-look after 24 hours
- Staple the ends and leave them in the abdomen, avoiding complications of a stoma as in very obese patients.
- Pancolic ischemia is rare, but such cases require total colectomy with ileostomy.
- In contrast to mesenteric ischemia of the small intestine, there is usually no indication for revascularizing the large bowel in primary colonic ischemia, which is not generally related to large artery obstruction.
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Ischemic Colitis Tx Alg
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