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Figure 20.20 Meckel’s diverticulum. A, Common location and gross appearance. B, Resected segment of the small intestine shows an
outpouching which on section is seen communicating with the intestinal lumen. The lumen contains necrotic debris.

INTESTINAL OBSTRUCTION Peritoneal Adhesions and Bands

Conditions which interfere with the propulsion of contents Adhesions and bands in the peritoneum composed of fibrous
in the intestine are considered under the heading of intestinal tissue result following healing in peritonitis. Rarely, such
obstruction. The causes of intestinal obstruction can be fibrous adhesions and bands may be without any preceding
classified under the following 3 broad groups: peritoneal inflammation and are of congenital origin. In either
case, peritoneal bands and adhesions result in partial or
1. Mechanical obstruction. It can occur as a result of the complete intestinal obstruction by outside pressure on the
following causes: bowel wall.
i) Internal obstruction (intramural and intraluminal):
SECTION III
Inflammatory strictures (e.g. Crohn’s disease) Hernias
Congenital stenosis, atresia, imperforate anus Hernia is protrusion of portion of a viscus through an
Tumours abnormal opening in the wall of its natural cavity.
Meconium in mucoviscidosis
External hernia is the protrusion of the bowel through a
Roundworms defect or weakness in the peritoneum.
Gallstones, faecoliths, foreign bodies
Ulceration induced by potassium chloride tablets Internal hernia is the term applied for herniation that
prescribed to counter hypokalaemia. does not present on the external surface.
Two major factors involved in the formation of a hernia
ii) External compression: are as under:
Peritoneal adhesions and bands i) Local weakness which may be congenital e.g. at the
Systemic Pathology
Strangulated hernias umbilicus, inguinal and femoral canals, and in surgical scars
Intussusception called ‘incisional hernia’.
Volvulus ii) Increased intra-abdominal pressure that is produced by
Intra-abdominal tumour. coughing, straining and exertion.
2. Neurogenic obstruction. It occurs due to paralytic ileus Inguinal hernias are more common, followed in
i.e. paralysis of muscularis of the intestine as a result of shock decreasing frequency, by femoral and umbilical hernias.
after abdominal operation or by acute peritonitis. Inguinal hernias may be of 2 types:
3. Vascular obstruction. Obstruction of the superior mesen- Direct when hernia passes medial to the inferior
teric artery or its branches may result in infarction causing epigastric artery and it appears through the external
paralysis. The causes are as under: abdominal ring.
Thrombosis Indirect when it follows the inguinal canal lateral to the
Embolism inferior epigastric artery.
Accidental ligation. When the contents of hernia such as loop of intestine can
Out of the various causes listed above, conditions be returned to the abdominal cavity, it is called reducible.
producing external compression on the bowel wall are the When it is not possible to reduce hernia due to large contents
most common causes of intestinal obstruction (80%). Some or due to adhesions in the hernial sac, it is referred to as
of these are described below. irreducible.