Gastrointestinal Tract III

Question 1

What is the signs of a large bowel obstruction?

Answer 1

•Large bowel obstruction tends to be
located in the periphery.
•Increased intra luminal gas
•Presence of haustra

To understand bowel obstruction think of the GI tract as a tube. Obstruction at any point along the tube would cause the part of the tube proximal to the point of the obstruction to be dilated and the part located distally to be flattene

Question 2

What is the clinical significance of a large bowel obstruction?

Answer 2

• Nausea and vomiting
• Abdominal distention.
• On physical examination increase bowel sounds
• No passage of gas per rectum (obstipation

Question 3

Describe the structure of the rectum

Answer 3

• Continuation of the GI tract into the pelvis .
• Begins at the rectosigmoidal junction
• Terminates at the anorectal junction
• The rectum has no mesentery

• Superior 2/3 is retroperitoneal and forms
the posterior surface of the rectovesical
and rectouterine pouches

• Inferior 1/3 is sub peritoneal

Internal structure :
• 3 transverse folds
2 on the left and 1 on the right

Question 4

Describe the ampulla of the rectum

Answer 4

Ampulla

• most distal part of the rectum stores feces until defecation.
• Stores feces until defecation
• Puborectalis forms a sling around the anorectal junction

Question 5

How does the anal canal above the pectineate line differ from below the pectineate line?

Answer 5

The anal canal above the pectinate line differs in its embryonic origin, arterial supply ,innervation, venous and lymphatic drainage

Question 6

What are the arterial supply of the rectum and anal canal?

Answer 6

Rectum & anal canal are supplied by superior, middle and inferior rectal arteries

• Superior rectal artery branch of the Inferior mesenteric.
• Middle rectal artery branch of the internal iliac
• Inferior rectal artery branch of the internal pudendal

Therefore around the rectum there is a rich anastomosis due to branches of :
• Inferior mesenteric
• Internal iliac
• Internal pudenda

Question 7

Describe the veinous drainage of the rectum

Answer 7

• The internal rectal plexus drains in both directions at the level of the pectinate line
• Superior to the pectinate line the internal venous plexus drains into the superior rectal vein (inferior mesenteric portal vein).
• Inferior to the pectinate line the external venous plexsus drains into the inferior rectal veins (caval system i.e. IVC)

Question 8

Describe the types of hemorrhoids

Answer 8

Internal hemorrhoids :
Prolapses of the rectal mucosa containing dilated veins of the internal rectal plexus.

External hemorrhoids :dilations of the external rectal plexus.

Predisposing factors for hemorrhoids : Any disorder that impedes venous return
Increase in intra-abdominal pressure

Question 9

What is the clinical correlate of Portal & Caval Anastamosis?

Answer 9

Clinical correlate :
• Rectal route for drugs –
(Rectal suppositories)

• Portal Hypertension : In this condition the portocaval anastomoses between the superior middle and inferior rectal veins become varicosed.

Hematochezia- the passage of fresh blood per anus, usually in or with stools.

Question 10

How does lymphatics differ for above and below tye pectineate line?

Answer 10

• Above the pectinate
line lymph drains to the internal
iliac nodes.

• Below the pectinate
line lymph drains to the superficial horizontal inguinal lymph nodes

Question 11

What is Diverticulosis?

Answer 11

• Outpouching of colonic mucosa and submucosa that herniate through muscular layer. Generally found in the sigmoid colon
• May erode into colonic vessels causing bleeding
• May be asymptomatic. If erosion into the colonic vessels take place painless rectal bleeding occurs

Question 12

What labs are done for diverticulosis?

Answer 12

anemia or positive stool guaiac test during bleeding.

Radiology: diverticular seen on barium enema and colonoscopy.

Question 13

What complications does diverticulosis pose?

Answer 13

Diverticulitis: Obstruction of the diverticulum leading to infection. If rupture occurs it may lead to peritonitis /fistula formation

Question 14

What is the clinical picture of diverticulosis?

Answer 14

Clinical picture:
Left lower quadrant pain

Abdominal tenderness

Fever

Abdominal distention.

Terms to remember : melena, hematochezia a9n11d364 meconium

Question 15

What is a sigmoid vulvus?

Answer 15

Sigmoid volvulus is a twisting of the sigmoid colon around its mesentery, causing obstruction of the colon

Question 16

What is the clinical features and complications of the sigmoid vulvus?

Answer 16

Clinical features:
• Abdominal pain
• Nausea and vomiting
• History of constipation

Complications:
Colonic ischemia
Colonic Perforation
Peritonitis

Question 17

What are the radiological signs of sigmoid vulvus?

Answer 17

• Double loop obstruction.
• “Coffee bean” sign
• May have symptoms of both large and small bowel obstruction depending on severity of the obstruction.
• No gas seen in the rectum

Question 18

Describe the lymphatic drainage of the viscera

Answer 18

Stomach – Pancreatico splenic, left gastric & right gastroepiploic nodes > celiac group

Duodenum - pancreatico duodenal group > celiac group

Question 19

What is the significance ofthe thoracic duct?

Answer 19

Thoracic Duct
Drains lymph of lower half and upper left quadrant of the body and ALL of the
viscera.

There is a node called Left supraclavicular node (Virchow’s node) that can be
abdominal wall and contents, enlarged on physical examination due to distant metastasis from abdominal organs

Question 20

What is a Hematochezia?

Answer 20

The passage of fresh blood per anus, usually in or with stools

Question 21

What is the significance of Portal & Caval rectal anastamosis?

Answer 21

Clinical correlate :
• Rectal route for drugs –
(Rectal suppositories)

• Portal Hypertension : In this condition the portocaval anastomoses between the superior middle and inferior rectal veins become varicosed.

Question 22

Differentiate the rectal lymphatic drainage below abd above the pectineate line

Answer 22

Lymphatics
• Above the pectinate
line lymph drains to the internal
iliac nodes.

• Below the pectinate
line lymph drains to the superficial horizontal inguinal lymph nodes

Question 23

What are the innervations of the rectum?

Answer 23

Question 24

What are the folds of the rectum?

Answer 24

Question 25

What are the hemmrhoidal veins?

Answer 25

Question 26

What is a sigmoid volvulus sign?

Answer 26

Question 27

Describe veinous drainage of rectum

Answer 27

Question 28

Describe arterial supply of the rectum

Answer 28