Chapter17: Intestinal Obstruction

Question 1

Obstruction of the GI tract may occur at any level but which is mostly affected?

Answer 1

, but the small intestine is most often involved
because of its relatively narrow lumen.

Question 2

Why is the intestine most commonly involved in the obstruction of GIT?

Answer 2

because of its relatively narrow lumen.

Question 3

What collectively accounts for the 80% of mechanical obstructions?

Answer 3

Collectively, hernias, intestinal adhesions,
intussusception, and volvulus account for 80% of mechanical obstructions ( Fig. 17-22 )

Question 4

What accounts for the only about 10% to 15% of small bowel obstructions?

Answer 4

tumors and infarction account

Question 5

What are the clinical manifestations of intestinal obstruction?

Answer 5

The
clinical manifestations of intestinal obstruction include :

• abdominal pain and distention,
• vomiting, and constipation.

Question 6

What is usually required in cases of mechanical obstruction or

severe infarction?

Answer 6

Surgical intervention

Question 7

Answer 7

FIGURE 17-22 Intestinal obstruction.

The four major causes of intestinal obstruction are:

• (1) herniation of a segment in the umbilical or inguinal regions,
• (2) adhesion between loops of
• intestine,
• (3) volvulus, and
• (4) intussusception.

Question 8

What is a hernia?

Answer 8

Any weakness or defect in the wall of the peritoneal cavity may permit protrusion of a serosalined
pouch of peritoneum called a hernia sac.

Question 9

Acquired hernias most commonly occur where?

Answer 9

anteriorly, via the inguinal and femoral canals or umbilicus, or at sites of surgical scars.

These
are of concern because of visceral protrusion (external herniation) . This is particularly true of
inguinal hernias, which tend to have narrow orifices and large sacs.

Question 10

Why are acquired hernias are of concerned?

Answer 10

These
are of concern because of visceral protrusion (external herniation).

This is particularly true of
inguinal hernias, which tend to have narrow orifices and large sacs.

Question 11

Which is mostly involved in external herniation?

Answer 11

Small bowel loops are
involved most often, but portions of omentum or large bowel also protrude, and any of these
may become entrapped.

Pressure at the neck of the pouch may impair venous drainage of the entrapped viscus.

The resultant stasis and edema increase the bulk of the herniated loop, leading to permanent entrapment, or incarceration, and, over time, arterial and venous compromise (strangulation) develops that can result in infarction ( Fig. 17-23A ).

Question 12

Answer 12

FIGURE 17-23 Intestinal obstruction.

• A, Portion of bowel incarcerated within an inguinal hernia. Note dusky serosa and hemorrhage that indicate ischemic damage.
• B, Intussusception caused by a tumor. The outermost layer of intestine with external serosa has been removed, leaving the mucosa of the second layer exposed. The serosa of the second layer is apposed to the serosa of the intussuscepted intestine. A tumor mass (right, labelled tumor) is present at the leading edge of the intussusception. Compare to Figure 17-22

Question 13

What are could result to adhesions between bowel segment?

Answer 13

Surgical procedures, infection, or other causes of peritoneal inflammation, such as
endometriosis, may result in development of adhesions between bowel segments, the
abdominal wall, and operative sites.

Question 14

What happens when there is adhesion?

Answer 14

These fibrous bridges can create closed loops through
which other viscera may slide and become entrapped, resulting in internal herniation.
Sequelae, including obstruction and strangulation, are much the same as with external hernias.

Though rare, fibrous adhesions may be congenital, therefore, internal herniation must be
considered even in the absence of a history of peritonitis or surgery.

Question 15

Why internal herniation must be
considered even in the absence of a history of peritonitis or surgery?

T or F

Answer 15

Though rare, fibrous adhesions may be congenital, therefore, internal herniation must be
considered even in the absence of a history of peritonitis or surgery.

Question 16

What is a volvulus?

Answer 16

Complete twisting of a loop of bowel about its mesenteric base of attachment is called volvulus
and produces both luminal and vascular compromise.

Question 17

What are the clinical presentation of volvulus?

Answer 17

Thus, presentation includes features of
obstruction and infarction because it produces both luminal and vascular compromise.

Question 18

Volvulus occurs most often occur where?

Answer 18

in large redundant loops of sigmoid
colon, followed in frequency by the cecum, small bowel, stomach, or, rarely, transverse colon.

Question 19

Why is volvulus often missed clinically?

Answer 19

Because it is rare

Question 20

When does Intussusception occurs?

Answer 20

occurs when a segment of the intestine, constricted by a wave of peristalsis,
telescopes into the immediately distal segment.

Once trapped, the invaginated segment is
propelled by peristalsis and pulls the mesentery along. Untreated intussusception may progress
to intestinal obstruction, compression of mesenteric vessels, and infarction.

Answer 21

When encountered in infants and children, there is usually no underlying anatomic defect and the patient is otherwise healthy, although some cases are associated with rotavirus infection.

Question 22

What virus is associated to intussesception occuring in infants and children?

Answer 22

Rotavirus

Question 23

In older children and adults what generally serves as the point of traction that causes intussusception ( Fig. 17-23B ).

Answer 23

an intraluminal mass or tumor

Question 24

What can effectively reduce the
intussusception in infants and young children?

Answer 24

Barium enema

Question 25

What is usually necessary intervention for older patients with intussusesception?

Answer 25

ay , but surgical intervention is usually necessary in
older patients.