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Surgery > Chapter 12, part 2 > Flashcards

Chapter 12, part 2 Flashcards

1
Q

Purpose of the colon

A

Extracts water, sodium, short-chain fatty acids (SCFAs), and some vitamins from the stool
Excretes potassium

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2
Q

What percentage of water and sodium is recovered by the colon?

A

90% of each

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3
Q

How much water can the colon absorb a day?

Where does most of this absorption occur?

A

6 L/day

Most occurs on the right side

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4
Q

What is the primary energy source of the colon?

A 
SCFAs
-Butyrate
-Propionate
-Acetate
Also creates osmotic gradient, driving solute absorption
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5
Q

Bacterial population of the colon

A

Bacteroides (anaerobe): MC bacteria overall

E. coli is the MC aerobe

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6
Q

What are the three patterns of colonic motility?

A

Retrograde
Segmental
Mass movements

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7
Q

Retrograde colonic motility

A

Anti-peristaltic that starts near the hepatic flexure and moves toward the cecum
Results in slowing of colonic transit and increasing fecal mixing

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8
Q

Where does segmental motility occur?

What does it do?

A

Transverse and left colon

Propels stool forward over small distances (increasing stool mixing)

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9
Q

What do mass movements do?

A

Progress along the length of the colon and can move a column of stool up to 1/3 the length of the bowel
During these, pressure is the highest in the sigmoid colon

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10
Q

What supplies extrinsic control of the colon to stimulate and inhibit motility?

A

Parasympathetic and sympathetic neurons

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11
Q

What are the two plexuses of the intrinsic neurons?

A

Myenteric (Auerbach)

Submucosal (Meissner)

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12
Q

Where is the myenteric (Auerbach) plexus?

A

At junction between longitudinal and circular layers of muscularis propria

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13
Q

How is the submucosal (Meissner) plexus formed?

A

In the submucosa from nerve fibers that perforate the circular muscle layer

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14
Q

Gastrocolic reflex

A

Ingestion of a meal results in increased colonic tone

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15
Q

How does nl defecation occur?

A

Initial trigger leads to rectal distention, which leads to internal sphincter relaxation
Puborectalis relaxes, which leads to strengthening of anorectal junction
External anal sphincter relaxes and intra-abdominal pressure increases
Rectal contents evacuated

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16
Q

What is the purpose of the rectum?

A

Reservoir for stool

Filling of this leads to the urge to defecate as the internal sphincter relaxes

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17
Q

Appendicitis

A

Inflammation of inner lining that can be d/t obstruction of the lumen by a fecalith or d/t infection

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18
Q

Sx of appendicitis

A

Periumbilical pain migrating toward RLQ
Nausea
Anorexia

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19
Q

Labs of appendicitis

A

LFTs

Pancreatic enzymes

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20
Q

Rads of appendicitis

A

CT of abdomen and pelvis

U/s- for peds or pregnant pts (non-compressible tubular structure)

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21
Q

Tx of appendicitis

A

Appendectomy
If small abscess or phlegm: do IV abx initially followed by interval appendectomy after 4-6 wks
Large abscess- drainage catheter in addition to abx therapy

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22
Q

Diverticular dz

A

Outpouchings of the colonic wall
Most commonly d/t high intraluminal pressure in areas of anatomic weakness where small arterioles traverse the colon wall

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23
Q

What is the MC site for diverticular dz?

A

Sigmoid colon

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24
Q

Diverticulosis

A

Usually asymptomatic

Common cause of lower GI bleeding

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25
Q

Diverticulitis

A

Infection and inflammation resulting from perforation of a diverticulum

26
Q

S/sx of diverticulitis

A 
Localized abd pain (at sigmoid, MC)
Change in bowel habits
Anorexia
Nausea
Fever/chills
Urinary urgency
27
Q

Labs/rads of diverticulitis

A

Leukocytosis

Do CT scan of the abdomen

28
Q

Tx of uncomplicated diverticulitis

A

Bowel rest, analgesia prn, and abx
-Can be outpatient if pt is afebrile and stable vital signs
-Must be able to tolerate oral intake
If they don’t meet these criteria: admit for bowel rest, IV abx and serial evaluations
-Abx for 10-14 days
Need colonoscopy 6 wks after resolution of sx

29
Q

What is considered complicated diverticulitis?

A

Presence of abscess, fistula, obstruction, or free perforation

30
Q

Tx of complicated diverticulitis

A

Greater than or equal to 4 cm pericolonic abscess: percutaneous drainage
Smaller abscesses: abx and observation
Once resolved, should consider elective colectomy

31
Q

What can abscesses in diverticulitis lead to?

A

Erode adjacent organ

Fistula

32
Q

What is the most common fistula in diverticulitis?

How is this confirmed?

A 
Colovesical fistulas (pneumaturia and recurrent UTIs)
Confirm with CT (air in the bladder without previous cath= colovesical fistula)
33
Q

Tx of abscess in diverticulitis

A

Broad spectrum abx until inflammation resolves then elective resection

34
Q

Hinchey classification

A

Stratify severity of diverticular dz complicated by perforation

35
Q

Hinchey classification I

A

Small, confined pericolonic or mesenteric abscess

36
Q

Hinchey classification II

A

Larger, walled-off pelvic abscess

37
Q

Hinchey classification III

A

Generalized purulent peritonitis

38
Q

Hinchey classification IV

A

Generalized fecal peritonitis

39
Q

Tx for Hinchey classification I-II

A

Abx and percutaneous drainage

Then elective colectomy and anastamosis

40
Q

Tx for Hinchey classification III-IV

A

Surgical emergencies that require immediate exploration
Hartmann’s procedure: segmental resection, proximal end colostomy, and closure of the rectal stump
Could also do laparoscopic lavage- treats diverticulitis with purulent peritonitis

41
Q

Cause of large bowel obstruction

A

Typically caused by neoplasms

42
Q

Sx of large bowel obstruction

A 
Similar sx to SBO
Abd pain
Distention
Obstipation
N/V
43
Q

What is the MCC of nonmechanical colonic obstruction?

A 
Colonic pseudo-obstruction
Can cause a closed-loop obstruction btwn the valve and point obstruction
Leads to progressive distention
Leads to vascular compromise
Leads to possible perforation
44
Q

When would you need prompt surgical exploration in a large bowel obstruction?

A

If s/sx of sepsis or peritonitis

45
Q

Imaging for large bowel obstruction

A

Plain abdominal XR and upright CXR adequate to show free intra-abdominal air
Profound dilation of cecum (10-12 cm) indicates impending perforation
Can do CT- if not obvious dx, can do water soluble contrast enema

46
Q

Volvulus- what is it?
What area is most common in the rest of the world?
What area is most common in the US?

A

Twisting loop of colon around the axis of its mesentary
Causes closed loop obstruction
Sigmoid area
Cecum: rotation of the cecum and terminal ileum around the mesentery

47
Q

Sx of volvulus

A

Acute or chronic abdominal pain
Distention
Vomiting

48
Q

Initial tx of volvulus

A

Prompt IV resuscitation followed by detrosion of the sigmoid

49
Q

When will a rigid protoscopy or flexible endoscope be successful for a volvulus?

A

Rush of gas and stool from dilated proximal colon

50
Q

Cecal bascule

A

Variant of cecal volvulus that occurs when floppy cecum flips anteriorly and superiorly, becoming fixed

51
Q

S/sx of cecal volvulus

A

Abdominal pain
Distention
N/V

52
Q

Rads of cecal volvulus

A

X-ray

Coffee bean sign

53
Q

Tx of cecal volvulus

A

Surgical resection with right colectomy

54
Q

Most pts with ______ will present with obstruction

A

Colon CA

55
Q

What is the mainstay of tx for malignancies causing obstruction?

A

Surgery

56
Q

What is the tx for proximal lesions in malignant obstructions?

A

Right colectomy

57
Q

Tx for distal lesions in malignant obstructions

A

Proximal diversion with loop colostomy
Other option: Hartmann’s procedure (resection of colonic segment and creation of an end proximal colostomy)
Can also do endoluminal stenting for palliative care

58
Q

Sx of colonic pseudo-obstruction (Ogilvie’s syndrome)

A

Similar sx to LBO, but characterized by large dilation proximal to the colon WITHOUT mechanical obstruction

59
Q

Dx of colonic pseudo-obstruction

A

Water soluble enema to r/o mechanical etiology

60
Q

Tx of colonic pseudo-obstruction

A

Initial tx- NG tube decompression, NPO, IVF, cessation of narcotics and anticholinergics, and correct electrolyte abnormalities
If it doesn’t resolve, neostigmine and endoscopic decompression

Surgery (30 decks)

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