Colon

Colon

All are true statements regarding appendices epiploicae EXCEPT

Extends the whole length of colon except rectum

More prominent in sigmoid colon

Flat in right sided colon

Absent in appendix

Ans - a

Ans - a

2

Length of colon longer in females (155 vs 145 cm) difference mainly due to length of transverse colon

Jacksons membrane flimsy adhesions between abdominal wall and anterior taenia of ascending colon

Narrowest portion of colon rectosigmoid no sphincter

Cecum breadth more than length (7.5cm vs 6 cm)

Ileocecal valve

Bauhn

Both circular and longitudinal muscle

Misnomer sphincter function in terminal ileum

Cecocolonic junction true sphincter

All are true statements regarding Vermiform appendix EXCEPT

Appendicular artery is a branch of posterior cecal artery

Bloodless fold of treves represent superior ileocecal fold

Most common location is retrocolic

Gerlachs valve at appendicular orifice is not a true valve

Ans - b

Vascular supply of colon

SMA branches ileocolic most constant

Right colic most variable & Absent in 2-18%

Most common variation of right colic from middle colic

Middle colic absent in 4-20%

SMA L1

IMA L3

Arch of riolan (MMA)

Between left colic and middle colic

present in 2/3 of patients

Synonyms - Arch of treves, Artery of drummond

Lymph nodes along middle colic artery are

Epicolic nodes

Paracolic nodes

Intermediate nodes

Principal nodes

Ans - c

Risk of volvulus is low in which type of rotation anomaly

Non rotation

Reverse rotation

Nonrotation of duodenal jejunal limb with normal rotation and fixation of cecocolic limb

Normal rotation of duodenal jejunal limb with non rotation of cecocolic limb

Ans - c

Difference in presentation of malrotation in adults and neonates volvulus uncommon in adults

Barium meal follow through investigation of choice birds beak

Management of old asymptomatic patients with malrotation diagnosed preop

Incidental malrotation detected intra-op always corrected

Malrotation associated with life threatening disorders (CDH) not corrected

Doppler finding SMA and SMV, ladds procedure

11

All are true statements regarding right mesocolic hernia EXCEPT

a) Caused by failure of the small bowel to rotate to the left with the right coloncontinuing to rotate anterior to it

b) Should be treated even detected incidentally

c) Opening of the herniasac lies above the ascending branch of the left colic artery andthe inferior mesenteric vein.

d) Superior mesenteric artery forms the anterior edge of the herniasac

Key c

Mesocolic hernias

Left mesocolic hernia occurs through vascular arch of treitz formed by IMA and left colic artery

Left mesocolic hernia more common than left

IMA and IMV lies on the right margin of sac

Right mesocolic hernia SMA lies on medial border of sac

Should be treated even detected incidentally as the lifetime riskfor bowel incarceration is approximately50%.

All are true statements regarding CT colonography Except

Requires bowel preparation

Done in prone position

Requires bowel inflation with air

Accepted as the leading imaging technique for colorectal cancer screening

Key - b

MR colonography

Specific contraindications - claustrophobia, metallic implants, or cardiac pacemakers

Preparation and position similar to CT colonography

Antispasmodic glucagon (IC valve reflux poor distension) or buscopan

MR colonography types

Bright-lumen MR colonography

Administration of a gadolinium chelatespiked enema

Less popular

Filling defects, including air bubbles and residual stool, that fail to displace despite dual positioning can be mistaken for true polyps

Precludes the intravenous administration of gadopentetate dimeglumine as a trouble-shooting approach to helping differentiate stool from polyps and cancer

Dark-lumen approach - administration of water, carbon dioxide, room air, or fat.

The principal short chain fatty acid in large intestine

a) Acetate

b) Propionate

c) Butyrate

d)Succinate

Key a

The three primary fatty acids produced are acetate, propionate, and butyrate in a ratio of 3 : 1: 1.

If the question is SCFA which is the primary energy source for colonic epithelial cells then Butyrate is the answer.

Myenteric plexus and interstitial cells regulate motility

Submucous plexus (Henles) regulate mucosal absorption

Na only absorbed

K & Cl absorbed and secreted

Hco3 only secreted

All are true statements regarding scintigraphic assessment of colonic transit study EXCEPT

Faster than radiopaque marker study

Radiation exposure less compared to radiopaque marker study

High geometric center is suggestive of pelvic outlet obstruction

Radiolabelled delayed release activated charcoal or polystrene pellets used

Key - b

Geometric center = proportion of counts x weighing factor

Colonic transit study - methods

Radioopaque marker

capsule containing 24 radiopaque markers on days 1, 2, and 3

count remaining markers on a plain abdominal radiograph on days 4 and 7.

68 or fewer markers remaining in the colon - normal

More than 68 markers indicates - slow transit constipation

Retention of more than 20% of the markers at 120 hours is indicative of prolonged colonic transit.

Wireless Motility Capsule

pH rises abruptly (by >2 units) when the capsule exits the stomach

drops rapidly (by >1 unit) when it crosses the ileocecal valve.

Barostat better than manometry for measuring colonic motility

All are risk factors for colonic ischemia EXCEPT

a) Cocaine abuse

b) Long distance running

c)Epstein Barr virus infection

d) E. coli O157:H7 infection

Key c

Colonic ischemia predisposing factors

aortic surgery, arteriosclerotic disease, and conditions causing transient hypotension

oral contraceptives, cocaine abuse, hereditary coagulopathies, long distance running, and certain bacterial pathogens, including cytomegalovirus (CMV) and E. coli O157:H7.

True statement regarding Colonic ischemia

A) Angiography is a valuable investigation to plan management

B) Revascularisation should be attempted if the patient is hemodynamically stable at the time of surgery

C) Symptomatic colonic stricture secondary to colonic ischemia usually affects splenic flexure colon

D) Resection of the strictured segment secondary to colonic ischemia with primary anastomosis is safe.

Key d

Colonic ischemia

Arteriography is not indicated unless it is believed that acute mesenteric ischemia involves the small intestine.

Arteriography does not change the management or outcome of clinically apparent Colonic ischemia.

Unlike mesenteric ischemia involving the small bowel, revascularization procedures to establish blood flow to the colon are not indicated.

Chronic sequelae of CI include stricture formation and chronic segmental colitis.

Strictures can be symptomatic, depending on their location and diameter.

Strictures usually affect the sigmoid colon.

Resection of the strictured segment with primary anastomosis is generally advocated for relatively healthy patients.

Colonic ischemia

Special features of colonic circulation

Increased motor activity is associated with decreased flow

Most affected by autonomic circulation

Segment of colon more prone for ischemia sigmoid followed by splenic flexure

Colonoscopy with minimal air insufflation inv. Of choice

Thumb printing sign

Ba enema /x-ray

Corresponds to hemorrhagic bullae (due to bleeding into submucosa) seen in colonoscopy

Usually disappears in 1-2 weeks. If it persists s/o lymphoma or amyloidosis

Treatment of choice for colonic inertia/slow transit constipation

a) Total colectomy with IPAA

b) Subtotal colectomy with Ileorectal anastomosis

c) Subtotal colectomy with Ileosigmoid anastomosis

d) Subtotal colectomy with cecorectal anastomosis

Key - b

constipation

Etiology for STC decrease in interstitial cells of cajal

Algorithm for constipation evaluation

Rule out organic cause colonic transit study do pelvic floor assessment with EMG or defecography

Segmental colonic transit study no adv segmental resection dilatation of remaining segments

Small bowel transit study should be done before surgical treatment of STC

Breath hydrogen

Plasma sulfapyridine

Scintigraphic study

50 year old male with abdominal distension and constipation. On examination there is tenderness in the left lower quadrant. Abdominal x-rays reveal a markedly dilated sigmoid colon that resembles a bent inner tube. Next line of management is

A) CT abdomen

B) Contrast enema

C) Tube decompression

D) Exploratory laparotomy

Key d

Colonic volvulus

Pregnancy risk factor for sigmoid volvulus

Sigmoid volvulus

Most common cause of large bowel obstruction in pregnant females

Second most common cause of bowel obstruction after bowel adhesions

Cecal and sigmoid volvulus clockwise rotation

Cecal bascule cecopexy, cecal volvulus right hemicolectomy

Colonic volvulus with vomiting as earliest feature transverse colon volvulus compression of DJ junction

Transverse colon volvulus treatment

Extended right hemicolectomy or subtotal colectomy with IRA

Colonic intussusception

Most common type of intussusception in adults with increased incidence of subacute or recurrent attacks

Attempt to reduce only in long segment intussusception without gangrene

Predisposing factors

Previous abdominal surgery

Pregnancy

constipation

Recurrent volvulus rule out STC

All the following signs are seen in sigmoid volvulus EXCEPT

A) coffee bean sign

B) birdsbeak sign

C) whorl sign

D) coiled spring sign

Key d

Coiled spring sign seen in colonic intussusception

33

All are true statements regarding ileosigmoid knotting EXCEPT

Common in India

High fiber diet is a predisposing factor

Long small bowel mesentry is a risk factor

Long redundant sigmoid is a risk factor

Key d

A short, redundant, omega-shaped sigmoid is a risk factor

34

All are true statements regarding colonic pseudo obstruction EXCEPT

A) Secondary more common than primary pseudoobstruction

B) In Acute pseudoobstruction sigmoid colon is most commonly affected

C) Chronic colonic pseudoobstruction also affects small bowel

D) Neostigmine is useful for treatment

Key b

Reason for decrease in colonic transit after left colectomy

Colonoscopic decompression vs neostigmine

Earliest sign of colonic vascular ectasia in angiography

A) Dilated tortuous submucosal vein

B) Vascular tufts

C) Early filling submucosal vein

D) contrast extravasation from dilated submucosal vein

Ans - A

Vascular ectasia - pathogenesis

Coagulation with heater probe/NdYAG laser treatment of choice

Angiographic treatment

Vasopressin iv and intra-arterial equal results left colon bleeding

Intra-arterial vasopressin right colon bleeding

Surgery right hemicolectomy

Type of surgery not changed by presence of diverticula in left colon

Etiology of lower GI bleed

West

India

Rule out upper GI source

Children intussusception and meckels diverticulum

40

Colonoscopy issues?

Early colonoscopy should be done?

Major bleeding that has caesed and non major bleeding

Should colonoscopy be done after bowel preparation?

preferable

Radionuclide scanning

Technetium labelled RBC (preferred because of long t1/2) or sulphur colloid scan (uptake by liver /spleen obscures bleeding from flexures)

Sensitive (0.1ml/min) less specific

Role in acute lower GI bleed

Guide in hemodynamically stable major lower GI bleed who is a candidate for angiography

Selective mesenteric angiography

Order SMA IMA CA

Flush aortography no role

Provocative measures - vasodilators, heparin or thrombolytic agents

Techniques vasopressin infusion or superselective embolization

Risks - Hematoma, arterial thrombosis, contrast reaction, acute renal failure and complications related to therapy

True statement for the management of diverticulitis

a) Elective sigmoidectomy should be performed in young patients after one episode of diverticulitis to prevent recurrence

b) Elective sigmoidectomy should be performed in patients > 50 years after two episodes of diverticulitis to prevent complications

c) Elective sigmoidectomy is recommended after single attack of diverticulitis in immunocompromised patients

d) Need for a colostomy to be fashioned increases with the increase in the attacks of diverticulitis

Key c

Elective sigmoidectomy should be performed in young patients after one episode of diverticulitis was the earlier recommendation however recent studies do not support it.

Elective sigmoidectomy should be performed in patients > 50 years after two episodes of diverticulitis to prevent complications was the earlier recommendation which is not universally accepted.

Need for a colostomy to be fashioned is highest with the first attack of diverticulitis.

Elective sigmoidectomy after a single attack of diverticulitis should be considered in immunocompromised patients since these patients have diminished ability to combat an infectious insult.

Most common cause of colovesical fistula

A) Diverticulitis

B) Colonic cancer

C) Bladder cancer

D) Crohns disease

Key a

Right sided diverticula

Common in Asia

Usually mild and respond to medical therapy

Thorsen and Ternent classification

Grade I - discrete, inflamed diverticulum.

Grade II - simple cecal wall mass.

Grade III - localized abscess or fistula.

Grade IV -peritonitis (purulent or feculent).

Grade I/II medical therapy or diverticulectomy +/- appendectomy

III/IV - resection

Giant diverticula

Due to ball valve mechanism

Majority asymptomatic

Treatment in all cases resection preferred over diverticulectomy

Diverticulitis with small pericolic/pelvic abscess After PCD resection in same admission

Ureteral stents decrease operative time not ureteral injury

All are risk factors for malignancy in ulcerative colitis EXCEPT

A) Duration of colitis

B) Extent of colonic involvement

C) Associated primary sclerosing cholangitis

D) Younger age at onset of disease

Key d

Whether age at onset of UC is a risk factor for malignancy independent of duration of disease remains controversial

50

Carcinoma in UC

Evenly distributed throughout the colon

More likely to be mucinous and poorly differentiated

Higher likelihood of synchronous tumors

No significant differences between sporadic and UC-related CRC with respect to prognosis.

UC with rectal tumor

Upper third IPAA can be done

Middle and lower third -IPAA contraindicated

Dysplasia in rectum (even lower third) - IPAA can be done

No stapled anastomosis. Anorectal mucosectomy must

All are true statements regarding Dysplasia associated with lesion or mass (DALM) in ulcerative colitis EXCEPT

A) Associated with higher incidence of malignancy compared to high grade dysplasia

B) Flat dysplasia more common than polypoid dysplasia

C) DALM is not an absolute indication for proctocolectomy

D) Polypoid dyplasia can be managed with endoscopic polypectomy

Key - b

Recent studies suggest that certain polypoid dysplastic lesions can be managed via endoscopic polypectomy.

Prerequisite for endoscopic management - Lesion is well defined and amenable to endoscopic polypectomy, and if biopsies of the flat mucosa immediately surrounding the polypectomy site do not demonstrate dysplastic change.

For lesions that are not amenable to endoscopic polypectomy or have surrounding dysplasia, colectomy is recommended.

Approximately 25% of carcinomas in patients with ulcerative colitis are not associated with dysplasia elsewhere in the colon

All are true statements regarding toxic megacolon in ulcerative colitis EXCEPT

Colonoscopy is contraindicated

Gastrografin enema is contrainicated

Steroids are contraindicated

Antibiotics are routinely indicated as part of conservative treatment regime

Ans - c

Criteria for diagnosis of toxic megacolon

Radiological - colonic diameter >5.5 cm on plain films

presence of any three of the following - fever higher than 38.5 C, tachycardia (>120 beats/min), leukocytosis (>10,500 cells), and anemia (hemoglobin