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8 Colon
Clostridium difcile Infection (CDI)
• Consider fecal microbiota transplant in multiple recurrent CDI
• Mortality rates for CDI requiring surgery are greater than 50%
Stop antibiotics if able
Severity Findings Initial episode First recurrence
Management
Non-severe CDI WBC <15,000 cells/
mL and creatinine
<1.5.
PO vancomycin or PO
daxomicin for 10days
241
Pulse-tapered PO
vancomycin or
daxomicin
Severe CDI WBC >15,000 and/
or creatinine
≥1.5mg/dL
Fulminant colitis Hypotension, shock,
ileus, or toxic
megacolon
PO vancomycin 125mg QID
or daxomicin 200mg BID
Total abdominal colectomy
and end ileostomy
Alternatively, loop
ileostomy+colonic
lavage+intracolonic antegrade
vancomycin+IV
metronidazole
• If ileus➔rectal vancomycin
PO vancomycin
• PO
vancomycin+IV
metronidazole
• If ileus➔rectal
vancomycin
Other causes of infectious colitis
Pathogen Presentation/management
Bacterial Salmonella (causes constipation followed by diarrhea), shigella (causes bloody diarrhea), yersinia
(can mimic appendicitis in children by mesenteric adenitis or terminal ileitis), campylobacter, E.
coli (different strains present differently with O157:H7 being the most common and causing
dysentery)
Viral CMV in immunocompromised patients. Need mucosal biopsy for diagnosis as only 30% of patients
have CMV viremia
Parasites • Cryptosporidium (severe diarrhea in AIDS versus milder watery diarrhea in immunocompetent
hosts)
• Entamoeba histolytica (amebic dysentery): Travel to South America; treat with metronidazole
Research about CDI
Reference Findings
Juo YY, Sanaiha Y, Jabaji Z, Benharash P.Trends in
diverting loop ileostomy vs total abdominal colectomy as
surgical management for Clostridium difcile colitis.
JAMA Surg. 2019;154(10):899–906
Petrof EO, Gloor GB, Vanner SJ, Weese SJ, Carter D,
Daigneault MC, Brown EM, Schroeter K, Allen-Vercoe
E.Stool substitute transplant therapy for the eradication
of Clostridium difcile infection: ‘RePOOPulating’ the
gut. Microbiome. 2013;1(1):3. https://doi.
org/10.1186/2049- 2618- 1- 3. PMID: 24467987; PMCID:
PMC3869191
Loop ileostomy procedures increased from 11.16% in
2011 to 25.30% in 2015. There was no signicant
difference in in-hospital mortality rates between
patients undergoing loop ileostomy versus total
abdominal colectomy
Stool transplant is capable of curing antibioticresistant CDI
242
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Ischemic Colitis
Ischemic colitis
H. Hakmi et al.
Pathophysiology
Risk factors Hypercoagulable states, peripheral artery disease, diabetes, hypertension, smoking history,
Presentation • Cramping abdominal pain along with bloody diarrhea
Diagnosis
Acute ischemia ➔ necrosis of mucosa and submucosa
Chronic ischemia➔necrosis of the deeper layers, leading to colon strictures
The areas of the colon that are more susceptible to ischemia include the splenic exure
(Grifth point) and the rectosigmoid region (Sudeck point)
high risk after cardiac and endovascular aortic surgery (ligation or injury of inferior
mesenteric artery)
• Elevated WBC and metabolic acidosis
Sigmoidoscopy is the rst choice,
unless peritonitis or free air on
imaging
Early ndings: Mucosal edema
and erythema
Late: Cyanotic or black mucosa,
indicating full thickness necrosis
CT ndings: Wall thickening or
possible free air if perforation
Axial abdominal CT image with oral and IV contrast
demonstrates diffuse colonic wall thickening and
adjacent inammatory changes (arrows)
Case of ischemic colitis Management
Management
Follow-up After acute episode, repeat colonoscopy to look for strictures
Ischemic colitis without
perforation
Ischemic colitis+free air or
sepsis or full thickness necrosis
Ischemic stricture Biopsies to rule out underlying cancer, then endoscopic
Avoid anastomosis if hemodynamically unstable or questionable bowel viability and plan
for second look
IV uids, bowel rest, optimize perfusion by treating
hypotension, anemia, and hypoxia
Non-viable bowel should be resected with possible
stoma creation
dilation or resection
8 Colon
Colonic Volvulus andObstruction
Colonic obstruction (LBO large bowel obstruction)
Cecum is the thinnest and widest part of the colon➔highest risk for perforation (LaPlace’s
law)
Anatomy and
pathophysiology
Causes of LBO Malignancy (most common), diverticulitis, volvulus, radiation, ischemic brosis, internal hernia
Presentation • Abdominal pain, distention) (more than small bowel obstruction), obstipation, sepsis and
Competent ileocecal valve+large bowel obstruction➔closed loop obstruction
Incompetent valve+large bowel obstruction➔large bowel obstruction decompression into the
small bowel with possible vomiting
Sigmoid, transverse colon, and cecum are susceptible to volvulus as they are mobile and
intra-peritoneal. Sigmoid volvulus is by far the most common (elderly, chronic constipation,
neuropsychiatric history), followed by cecal volvulus
Cecal volvulus can be from true volvulus (twisting) or bascule (folding)
As the obstruction progresses➔intraluminal pressure increases➔venous
compression➔bowel wall ischemia➔necrosis
peritonitis if necrotic bowel
CT will show transition point
• Pneumatosis intestinalis➔bowel necrosis
• Peripheral portal air necrosis/severe infection of bowel
243
Diagnosis
Sigmoid
volvulus:
“Omega” or
“coffee-bean”
sign
Axial (A) and coronal (B) abdominal CT image with IV contrast demonstrates
a closed loop, dilated sigmoid colon (arrows) twisted around its mesentery,
creating a swirling mesentery sign (arrowheads, B). (C) Scout view from the
same CT examination demonstrates a “coffee bean” appearance of the dilated
sigmoid colon (arrows)
Cecal volvulus:
Dilated loop of
colon displaced
to left upper
quadrant
Coronal abdominal) CT image with IV contrast demonstrates a markedly
dilated cecal loop (arrows) displaced superiorly into the left upper quadrant.
There is also dilated small bowel (arrowheads)
244
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Colonic obstruction (LBO large bowel obstruction)
Case Management
H. Hakmi et al.
Management
Ogilvie’s
syndrome
Sigmoid
volvulus+nontoxic appearing,
non-peritoneal,
no signs of
bowel ischemia
Sigmoid
volvulus+toxic
or with
peritoneal signs
Cecal volvulus Surgical resection
• Pseudo-obstruction of large bowel
• Risk factors: Elderly, frail, bed-ridden) patients, narcotics, calcium channel blockers
• Presents as bowel obstruction but no signs of obstruction on imaging
Treatment: Electrolyte replacement, stop anti-motility agents (such as narcotics,
anti-cholinergics)
For signicantly distended bowel treatment with rectal tube, nasogastric tube if small bowel
also dilated➔neostigmine➔Colonoscopic decompression
• High risk of perforation if >10cm colonic diameter
Endoscopic reduction and placement of a rectal tube, sigmoid colectomy
during same admission (otherwise 50% recurrence rate)
Emergent resection. Due to colon hypermobility, laparoscopy usually
unnecessary
Case scenarios of colonic obstruction and their management
Case scenario Management
Sigmoid volvulus+no systemic
toxicity
Cecal or transverse colon
volvulus
Obstructing rectal or colon
mass
Endoscopic decompression then sigmoid resection during same admission
(primary anastomosis not favored if patient unstable)
Surgical resection (endoscopic decompression unlikely to succeed)
Colon: Stenting as a bridge to later resection without stoma versus emergent
resection±stoma
Rectum: Diverting colostomy
Colonic Polyps
Types of polyps
Adenoma Premalignant, either tubular (60–85%, least risk of malignancy), tubule-villous (15%) or villous
type (5–10%, with highest malignancy risk and likely sessile)
Hamartoma Benign tumor. Considered neoplastic when part of syndromes as: PJS, juvenile polyposis
syndrome, Cowden disease
Hyperplastic Metaplastic, non-neoplastic polyps. Has low risk of cancer development if <1cm
Inammatory
pseudo polyp
Not true polyps, non-neoplastic, associated with IBD, infectious, and ischemic colitis
Le
Le
Le
Le
Le
is
limited to the head of the polyp
Le
Le
Le
Le
Le
s
of polyp
Le
Le
Le
Le
Le
s
of the stalk
Le
Le
Le
Le
Le
s
but above muscularis propria
8 Colon
Staging of pedunculated polyps
Haggitt level I Haggitt level II Haggitt level III Haggitt level IV
245
vel 0
vel 1
vel 2
vel 3
Submucosa
vel 4
Muscularis propria
Level 1
Invasion of the submucosa but
Colonic polyps
Key points of
polyp
management
Management
Muscular
mucosae
vel 0
vel 1
vel 2
vel 3
vel 4 Submucosa
Muscularis propria
Level 2
Invasion extending into the neck
Musculari
mucosae
vel 0
vel 1
vel 2
vel 3
vel 4
Submucosa
Muscularis propria
Level 3
Invasion into any part
Musculari
mucosae
vel 0
vel 1
vel 2
vel 3
vel 4 Submucosa
Muscularis propria
Level 4
Invasion beyond the stalk
Musculari
mucosae
• Remove all adenomatous/premalignant tissue
• Tattoo suspicious lesions for later identication/resection
• Difcult polyps may require advanced endoscopic techniques (EMR, ESD). If unsuccessful or
malignancy suspected, will need surgical resection
Pedunculated polyp Remove with snare
Sessile polyp Remove in piecemeal fashion or snare with
saline lift (inject saline into
submucosa➔increase distance between
mucosa and muscularis)
Polyps with malignancy features (ulceration,
Biopsy and tattoo for surgical resection
friability, or induration
Polyp case Management
Haggit 1–3 Polypectomy
Haggit 4 and sessile polyps snared with margin
No further resection
≥2mm, no high-risk features
High-risk: Lesions with invasion beyond 1mm or
Appropriate oncologic resection
the upper 1/3 of the submucosa, polypectomy
margin <2mm, lymphovascular invasion,
piecemeal polypectomy, or poor differentiation
Rectal malignant polyps with no nodal disease Stage with MRI rst. Then consider
Transanal or TEMS/TAMIS full thickness
excision if no high-risk features
246
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Polyposis Syndrome
Polyposis syndrome
Lynch syndrome/
Familial
adenomatous
polyposis
Syndrome:
Inheritance: AD AD AD AR AD
“FAP”
hereditary
non-polyposis
colorectal cancer
HNPCC
PeutzJeghers
syndrome
(PJS)
MUTYHassociated
polyposis
(MAP)
H. Hakmi et al.
Juvenile
polyposis
Gene Mutation of APC
gene (tumor
suppressor gene)
Cancer risk CRC occur in 100%
at median age of
40years
Screening Colonoscopy
annually starting
age 12
• If rectum is
involved➔annual
proctoscopy
• Endoscopy every
1–5years at age
20–25
Notes • 90% will have
duodenal
adenomas
• Desmoid tumors
in 5%
• Gastric polyps are
hyperplastic
(benign)
Affect DNA mismatch
repair (MLH1, MSH2,
MSH6, and PMS2),
microsatellite
instability
CRC occur in 60–80%
at median age
45–60years
• Colonoscopy every
1–2years beginning
at age 20–25
• Endometrial biopsy
every 1–2years at
age 35in females
Polyps and cancers are
predominantly right
sided and tend to be
mucinous
Affect serinethreonine- kinase
tumor suppressor
gene (STK11)
gene
CRCs occur in
40% of
individuals
Colonoscopy
every 2–3years
beginning in
adulthood
Hamartomatous
polyps in GI
tract and
pigmentation of
buccal mucosa,
lips
• Reproductive,
thyroid, lung,
biliary, breast,
and pancreatic
cancer
Mutations in
MUTYH gene
CRC occurs in
80% at mean age
of 45–55years
Colonoscopy
every 1–2years
starting at age
20–25
• Oligopolyposis
(10–100
adenomatous
polyps
throughout
colon)
Duodenal,
bladder, ovarian,
and endometrial
cancers
Mutations in
the genes
SMAD4 and
BMPR1A
CRC 10–50%
Colonoscopy
every
1–3years
starting at age
12years
• May only
have 4–5
polyps
throughout
their lifetime,
others can
have more
than 100
Management • Classic
FAP➔TPC/IPAA
• Rectal
sparing➔TAC/
IRA
• Rectal polyps
>20➔risk of rectal
metachronous
cancer
• Completion
proctectomy if
dysplasia of rectum
or uncontrolled
polyposis
CRC colorectal cancer, TAC total abdominal colectomy, TPC total procto colectomy, IRA: ileo rectal anastomosis,
IPAA ileal pouch anal anastomosis, TA H total abdominal hysterectomy, AR autosomal recessive, AD autosomal
dominant
• Colon
cancer➔TAC/IRA
Rectal cancer➔TPC/
IPAA
• Women with lynch
syndrome➔TAH
Segmental
colectomy versus
TAC/IRA
TAC/IRA versus
TPC/IPAA
depending on
status of rectum
TAC/IRA
versus TPC/
IPAA
8 Colon
Colorectal Cancer
Screening for colorectal cancer
Screening in average risk patients (>45-year-old, no history of inammatory bowel disease, no history of cancer/
adenoma and –negative family history of colorectal cancer or adenomas
Commonly used screening tests
Colonoscopy • Repeat every 10years, >95% sensitive to colorectal cancer and adenomas. Only
screening modality that is also therapeutic
247
Multi-target stool DNA test
“MSDT,” e.g., Cologuard
Virtual colonoscopy • Repeat every 5years. 90% sensitive to cancer or adenomas >10mm diameter
Sigmoidoscopy • Every 5–10years. 60–70% sensitive. Any abnormality should prompt full
High sensitivity guaiac test • Requires three stool samples annually, and if positive, requires follow-up
Fecal immunochemical test
“FIT”
• Repeat every 3years. 92% sensitive to colorectal cancer, but only 42% for
adenomas
• No prep. Positive result requires colonoscopy
• Requires bowel prep. Positive result requires colonoscopy
Less commonly used screening tests
colonoscopy. 40% of cancers are proximal to area visualized
• Sometimes combined with FIT to boost sensitivity
colonoscopy
• 70% sensitive to colorectal cancer and only 7% sensitive to adenomas
• Done annually. 80% sensitive to nding colorectal cancer but 30% sensitive to
ndings adenomas
• Specic for hemoglobin. Low false positive as no reaction to peroxidase
• Specic for detecting blood in the colon as it does not react to hemoglobin from
upper GI
Colorectal cancer
Epidemiology 3rd most common cancer and second most common cause of cancer related death in USA with 5%
lifetime risk
2–12% risk of synchronous cancer
Risk factors Adenomatous and serrated polyps, familial cancer syndromes, IBD, tobacco use, diet of processed
meat with low ber
Oncologic pathways for colorectal cancer
Oncogenesis
Symptoms
Chromosomal instability
(75%)
Microsatellite instability DNA replication prone to error in highly repetitive sequences
DNA methylation Hypermethylation of DNA promoter regions in tumor suppressor
• Ascending colon: Bleeding, iron deciency anemia, weight loss
• Descending colon: Bowel obstruction, colicky pain, hematochezia
• Sigmoid colon: 20% mimic diverticulitis, with possible Colo-vesicle\vaginal stulae
• Rarely, diagnosed by association with S. bovis (gallolyticus) in blood cultures
Oncogenesis by mutation of APC gene dysplasia➔K-ras
(oncogene) mutation➔uncontrolled cell growth➔DCC gene
mutation➔p53 gene mutation impairing repair
(microsatellites). Mismatch repair (MMR) genes➔repair of errors
genes leads to loss of BRAF, p16, and MLH-1 sequentially
248
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H. Hakmi et al.
Colorectal cancer
• Colonoscopy
• Unfavorable histology: Poor differentiation, lymphovascular or perineural invasion, or resection
Workup
Metastasis
Management
margin <1–2mm
• CT chest, abdomen and pelvis with contrast, CEA
• PET not indicated for initial staging
• Nodal status is an important prognostic factor (rst metastasis to lymph nodes)
• 5% risk of drop metastases to ovaries “Krukenberg”
• Liver is most common metastatic site (via portal veins) and lung is second (via iliac veins)
• Rectal cancer can metastasize to the spine directly via Batson’s venous plexus
Cecal, ascending colon, and hepatic exure CRC➔right hemicolectomy
Transverse colon CRC➔extended right hemi-colectomy (including middle colic artery) or
transverse colectomy
Adjuvant chemotherapy is indicated following surgery for: High-risk stages II and III CRC
Chemotherapy regimens for colorectal cancer: FOLFOX or CAPEOX
Simplied colon cancer staging and treatment
Stage T N M Treatment 5-year survival
0 In situ 0 0 Endoscopic resection NA
I and II I: T1–2
II T3–4
III Any N1–2 0 Surgical resection and
IVA, B, C Any M1a, b, c Systemic chemotherapy <25%
CRT: Chemoradiotherapy
0 0 Surgical resection
For high-risk stage II, adjuvant
chemotherapy
Adjuvant chemotherapy
75–90%
45–75%
Follow-up
Stage I Colonoscopy in 1year, then repeat every 3years, then every 5years
Advanced adenoma
Stages II and III • CEA and ofce visit every 3–6months for 2years; then every 6months for 5years
Stage IV • CEA and ofce visit every 3–6months for 2years; then every 6months for 5years
1 adenoma >10mm, villous, or grade 3–4➔follow-up colonoscopy in 3years
• CT chest, abdomen, and pelvis every 6–12months for 5years
• Colonoscopy 1year postop, except if no preoperative colonoscopy, then colonoscopy
in 3–6months
• If no advanced adenoma on colonoscopy: Repeat in 3years and then every 5years, if
advanced adenoma, repeat in 1year
• CT of the chest, abdomen, and pelvis every 3–6months for a total of 5years
• Colonoscopy same as stages II and III
Subtotal colectomy • After an ileorectal anastomosis, the retained rectum should be examined via exible
sigmoidoscopy every 6–12months
Total Procto
colectomy+ileal pouch
anal anastomosis
• Annual pouchoscopy+digital rectal exam
8 Colon
Case scenarios of colorectal cancer management
Case scenario Management
249
Sigmoid and synchronous ascending
colon cancer
CRC with peritoneal metastasis Chemotherapy, complete cytoreductive surgery, and intraperitoneal
CRC with positive margins Chemotherapy, consider radiation in select cases
CRC involving surrounding organs En-bloc resection+adjuvant chemotherapy
CRC with micro- satellite instability Adjuvant immunotherapy
CRC stage IV with metastasis to one
organ amenable to resection
Subtotal colectomy or 2 separate resections (may have difculty with reach,
increased leak risk)
chemotherapy in select cases
• Surgical resection of both primary and met+adjuvant chemotherapy
• Neoadjuvant chemotherapy if borderline resectable or aggressive disease
Research about surgical management of colon cancer
Reference Findings
US Preventive Services Task Force, Davidson KW, Barry
MJ, Mangione CM, Cabana M, Caughey AB, Davis EM,
Donahue KE, Doubeni CA, Krist AH, Kubik M, Li L,
Ogedegbe G, Owens DK, Pbert L, Silverstein M,
Stevermer J, Tseng CW, Wong JB.Screening for
colorectal cancer: US preventive services task force
recommendation statement. JAMA. 2021;325(19):1965–
77. https://doi.org/10.1001/jama.2021.6238. Erratum in:
JAMA. 2021;326(8):773
Routine screening for colorectal cancer starting at
age 45years and continuing until age 75years
André T, Boni C, Navarro M, Tabernero J, Hickish T,
Topham C, Bonetti A, Clingan P, Bridgewater J, Rivera F,
de Gramont A.Improved overall survival with oxaliplatin,
uorouracil, and leucovorin as adjuvant treatment in
stage II or III colon cancer in the MOSAIC trial. J Clin
Oncol. 2009;27(19):3109–16
Quénet F,; UNICANCER-GI Group and BIG Renape
Group. Cytoreductive surgery plus hyperthermic
intraperitoneal chemotherapy versus cytoreductive
surgery alone for colorectal peritoneal metastases
(PRODIGE 7): a multicentre, randomised, open-label,
phase 3 trial. Lancet Oncol. 2021 Feb;22(2):256–266.
https://doi.org/10.1016/S1470-2045(20)30599-4. Epub 2021
Jan 18. PMID: 33476595
When comparing treatment of patients with stage II
and II, this study found that the 5-year survival is
67% in patients treated with5-FU versus 73%
treated with FOLFOX
Cytoreductive surgery alone should be the treatment
of choice with intent to cure for colorectal cancer
with peritoneal metastases (compared to
cytoreduction with intraperitoneal chemotherapy)
250
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Inammatory Bowel Disease
Ulcerative colitis (UC) Crohn’s disease
H. Hakmi et al.
• Continuous mucosal inammation of
Anatomy
Gross
appearance
Histology Crypt abscesses, plasmacytosis, paneth cell
Presentation
Diagnosis • 15% of colon IBD can’t be differentiated between ulcerative colitis and Crohn’s
colon and rectum
• Starts distally and spreads proximally
• Can have reux terminal ileitis
Granular mucosa, petechiae, friable tissue,
pseudopolyps
metaplasia, effects mucosa and submucosa
(skipping muscularis)
• Recurrent abdominal pain±bloody
diarrhea and weight loss
• Can present with complications of bowel:
Obstruction, perforation, or bleeding
• Spares the anus, can cause ileitis due to
backwash
• Can present with toxic megacolon
• Colon dilation in megacolon for UC is
dened as >5.5cm
• Fecal lactoferrin and calprotectin
• Upper and lower endoscopy
• CT or MR enterography (MRI better at differentiating stricture versus inammation)
• Segmental, transmural inammation
• Terminal ileum most common location inamed
• Three types: Penetrating, strcturing, and
inammatory
Creeping fat, skip lesions, cobblestoning, oral
ulcers, enlarged lymph nodes
Transmural bowel wall inammation, non-caseating
granuloma and giant cells
• Recurrent abdominal pain±diarrhea and weight
loss
• Perianal or oral disease
• Can be fulminant or quiescent
• Can present with complications of bowel:
Obstruction, perforation, stulas, bleeding, or
abscesses depending on type
• Extra-intestinal symptoms: Erythema nodosum,
pyoderma gangrenosum, arthritis, uveitis,
hepatitis, primary sclerosing cholangitis (PSC),
ankylosing spondylitis (all but ankylosing
spondylitis and PSC improve after resection
• Can present with toxic megacolon
Management • Indications for surgery: Most common indication is medically refractory disease, but also
malignancy, perforation, peritonitis, progressive sepsis, toxic megacolon, massive
gastrointestinal bleeding,, inability to tolerate medical therapy, malnutrition, and growth
retardation
• Biologics have risk of lymphoma and squamous cell carcinoma
Screening
• UC has 20% risk of colorectal cancer after 30years from diagnosis➔colonoscopy 8years after
diagnosis and screening every 1–3years thereafter, with random biopsies every 10cm using
chromoendoscopy
• Only 6% of patients with Crohn’s disease develops colorectal cancer at 30years
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