MEDI7302 Study Guide - Final Guide: Pallor, Intestinal Malrotation, Prednisolone
Benign Colorectal Disease
Learning
objectives
Explain why sigmoid diverticular disease develops and the associated complications
Explain the management options for the complications of diverticulitis, including
simple diverticulitis, perforation, abscess formation, stricture and bleeding
Contrast the pathological features and clinical presentation of Crohn's disease with
Ulcerative colitis
What is the difference between colonic pseudo-obstruction (Ogilvie’s syndrome) and
left sided mechanical large bowel obstruction, in relation to pathology and management
Contrast the pathology and management options of caecal volvulus with sigmoid
volvulus
Anatomy Extra Marginal Artery of Drummond (provides collateral supply to colon
formed from terminal branches of SMA & IMA)
Ascending
colon
Caecum -> right colic/ hepatic flexure
Extraperitoneal
Ileocolic artery (caecum, appendix) + right colic artery (ascending
colon)
Transverse
colon
Hepatic flexure -> left colic/ splenic flexure
Intraperitoneal
Middle colic artery (2/3 transverse) + left colic (1/3 transverse)
Phrenicolic ligament (attaches left colic flexure to diaphragm)
Descending
colon
Left colic flexure -> sigmoid flexure
Extraperitoneal
Left colic artery
Sigmoid colon Sigmoid flexure -> S3 vertebra
Sigmoidal artery
Sigmoid mesocolon (attach sigmoid colon to pelvic wall)
Rectum Superior rectal artery
Anus
Diagram
Diverticular
disease
Definitions
True diverticulum An outpouching covered by all bowel wall layers (eg
Meckel's)
False diverticulum An outpouching lacking muscularis propria (eg
find more resources at oneclass.com
find more resources at oneclass.com
colonic diverticula)
Diverticula Multiple diverticulum
Diverticulosis Presence of (usually colonic) diverticula; usually
asymptomatic (or vague stomach pain, PR bleed)
Incidentally found on CT or colonoscopy
Diverticulitis Inflammation of diverticula
Diverticular disease Complicated diverticulosis (extensive diverticula)
Spectrum
Asymptomatic diverticular disease
Symptomatic uncomplicated diverticular
disease
Complicated diverticular disease 9acute or
chronic diverticulitis)
False diverticula (mucosal/ submucosal herniations that lack normal muscular bowel
layer) throughout colon muscular wall at sites weakened by entry of blood vessels (vasa recta)
Most common region is the sigmoid colon
Epidemiology
40% aged 60+yo people
Risk factors - low fibre diet, constipation, obesity
Etiology
Marfan syndrome & Ehlers Danlos (poor connective tissue reinforcement of
colon)
Low fibre diet -> constipation and poorly distended sigmoid colon
Fatty foods and red meat
Pathogenesis
LaPlace law
Pressure is indirectly related to diameter, whereby smaller diameter
causes increased pressure (and vise versa)
Eg sigmoid colon has smallest lumen diameter = highest pressure in
colon
Abnormal or exaggerated smooth muscle contractions of colon (possibly
related to nature of intraluminal contents), producing high intraluminal pressure unequally
distributed throughout colon
Mucosa herniation at weak bowel wall sites, usually corresponding to areas
blood vessels traverse bowel wall to supply muscular layer
Diverticula formation results in blood vessel supplying that wall region
to become separated from intestinal lumen via mucosa, predisposing to rupture
(painless hematochezia)
Faecal material & undigested food particles collect in diverticum (two theories
follow)
Obstruction -> distension (secondary to mucous secretion &
overgrowth of normal colonic bacteria) -> vascular compromise -> micro or macro
perforation
Increased intraluminal pressure or inspissated/ thickened food
particles erode diverticular wall -> inflammation, focal necrosis, perforation
No hematochezia (blood vessels scarred from inflammation)
+/- perforation
Small - mild, pericolic fat & mesentery may wall off perforation
Large/ extensive - abscess formation, possible intestinal rupture or
peritonitis
+/- fistula formation (after perforation)
Colo-vesical (men)
Colo-uteric (female), less commonly colo-vaginal, colo-cutaneous
Diverticulitis complications
Perforation into different regions [purulent or faecalent matter]
General peritoneal cavity (peritonitis)
Pericolic tissues (pericolic abscess)
find more resources at oneclass.com
find more resources at oneclass.com
Adjacent structures (bladder, small bowel, vagina) forming fistula
Chronic infection + inflammatory fibrosis -> obstruction
Erosion of blood vessels in bowel wall -> acute profuse or chronic occult
haemorrhage
Differentials
Colon cancer (must exclude with colonoscopy!!)
Inflammation - acute gastritis, acute pancreatitis, acute pyelonephritis,
cystitis, appendicitis
Biliary - biliary colic, cholecystitis, obstruction, cholangitis
Constipation, UTI
IBD, IBS, peritonitis and abdominal sepsis
Ovarian cyst, PID
Clinical presentation
Factors - location of affected diverticulum, severity of inflammation, presence
of complications
Asymptomatic (diverticulosis)
Symptomatic (diverticular disease)
Acute diverticulitis LIF pain (sigmoid diverticula) or sometimes RIF
pain (right sided diverticulitis; exclude appendicitis)
Vague mass
Change in bowel habits (constipation, diarrhoea,
flatulence)
Haematochezia - diverticulosis, not diverticulitis
Fever, nausea, vomiting, bloating
Local tenderness + guarding
If perforation, peritonitic signs (generalized
tenderness, rebound tenderness, guarding, abdominal distension,
tympanic percussion, absent BS, pneumoperitoneum)
If pericolic abscess, tender mass + swinging fever
and leukocytosis
Chronic
diverticular
disease
Change in bowel habits (constipation, diarrhoea,
flatulence)
Large bowel obstruction (colicky abdominal pain,
constipation, vomiting, abdominal distension)
Blood and mucus per rectum
Fistula Colovaginal - purulent vaginal discharge
Colovesicular - tenderness, pneumaturia (gas
bubbles in urine), fecaluria (faeces in urine)
Investigations
Laboratory - leukocytosis, electrolyte abnormalities (vomiting or diarrhoea),
urinalysis (colovesical fistula - RBC, WBC), b-HCG (rule out pregnancy)
CT abdomen (best imaging modality)
Pericolic fat stranding via inflammation
Colonic diverticula
Bowel wall thickening & soft tissue inflammatory masses
Peri-divercular abscess (complicated)
Barium enema
Do not perform in acute episode (perforation risk), only in mild-
moderate uncomplicated cases
Globular outpouchings with signet-ring appearance (filling defect
produced by faecoliths)
Staging (Hinchey's classification)
Stage I disease - phlegmon or localized pericolic or mesenteric abscess
Stage II disease - walled-off pelvic, intra-abdominal, or retroperitoneal abscess
Stage III disease - perforated diverticulitis causing generalized purulent
peritonitis
Stage IV disease - rupture of diverticula into the peritoneal cavity with fecal
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Explain why sigmoid diverticular disease develops and the associated complications. Explain the management options for the complications of diverticulitis, including simple diverticulitis, perforation, abscess formation, stricture and bleeding. Contrast the pathological features and clinical presentation of crohn"s disease with. What is the difference between colonic pseudo-obstruction (ogilvie"s syndrome) and left sided mechanical large bowel obstruction, in relation to pathology and management. Contrast the pathology and management options of caecal volvulus with sigmoid volvulus. Marginal artery of drummond (provides collateral supply to colon formed from terminal branches of sma & ima) colon) Ileocolic artery (caecum, appendix) + right colic artery (ascending. Middle colic artery (2/3 transverse) + left colic (1/3 transverse) Phrenicolic ligament (attaches left colic flexure to diaphragm) Sigmoid mesocolon (attach sigmoid colon to pelvic wall) An outpouching covered by all bowel wall layers (eg false diverticulum. An outpouching lacking muscularis propria (eg colonic diverticula) Diverticular disease asymptomatic (or vague stomach pain, pr bleed)
