In which part of the colon do most bowel obstructions occur?

The small intestines

Most common cause of bowel obstructions

Mechanical Bowel obstruction (description)

• Obstruction where something decreases the diameter of the bowel. Could be inside or outside of the lumen of the intestines. Usually found in small intestine at ileum or in ileocecal valve.

% of bowel obstructions which are mechanical

90% of bowel obstructions

Categories of mechanical bowel obstructions

1. Adhesions (50-70%)
2. Hernias  (15%)
3. Neoplasms (15%)

Common cause of obstruction in elderly or a person that is immobile

Fecal impaction.

Adhesions (definition)

Volvulus (def)

Intussusception (def)

One part of the intestine slips into another part located below it.  This occurs most commonly in infants. Analogy is like the way a gloves folds into itself when you remove them.  Causes the intestinal lumen to become narrow and blood supply is strangulated

Hernia (def)

Protrusion of intestines through a weakened area in the abdomen muscle or wall

Functional bowel obstructions

non-mechanical

Intestinal musculature cannot propel the contents along the bowel.

Examples: amyloidosis, muscular dystrophy, endocrine disorders such as DM, or neurological disorders such as Parkinson's, or paralytic ileus  (secondary to surgery)

Amyloidosis

Rare disease where amyloid protein deposits from in many organs and tissues. This decreases the functionality of the intestines.

Muscular dystrophy

Group of hereditary muscle diseases that weaken muscles, including the intestinal walls

Diabates mellitus in bowel obstructions

DM impacts the intestines the same way as the limbs: the intestines, too, are at risk for decreased circulation

Paralytic Ileus

Often secondary to surgery, due to manipulation of the bowel and/or effects of anesthesia. No bowel sounds are heard, or hypo active bowel sounds are heard one day post op. 

The nerves responsible for peristalsis are in the spine, so spinal surgeries are at great risk. However, these patients are often discharged one day post op, so it is important to educate them about the return of gas and bowel movements.

Signs and symptoms of mechanical obstruction

• Initital symptom is crampy pain that is wave-like and colicky
• Minimal distention
• Constipation
• Visible peristlasis
• Borboygmi: high-pitched, tinkling bowel sounds
• Nausea
• Reverse peristalsis/fecal vomiting (if obstruction is in the ileum, this is severe and hopefully obstruction is treated before this point)

Lab work for mechanical obstruction

• Elevated WBC (seen with strangulation or perforation)
• Elevated hematocrit may reflect hemoconcentration
• If we see decreased H&H there is a concern for bleeding
• K, NA, Chloride imbalances may indicate small bowel obstruction

• BUN increase if there is dehydration

• Chronic inflammatory bowel disease that usually affects the ileum and ascending colon
• Increased risk if you smoke

• usually found in 20's or 30's

Most common cause of large intestinal obstruction

Carcinoma

Bowel sounds in any obstruction will be 1)                    above the obstruction and 2)                  below the obstruction

1) hyperactive

2) hypoactive

signs and symptoms of a neurogenic obstruction

absence of bowel sounds

absence of flatus

abdomincal distention

abdominal pain

Psuedo obstruction

Idiopathic obstruction

Apparent mechanical obstruction with no radiological evidence

May be caused by collagen vascular disease, so is treated as a mechanical obstruction

Vascular factors

• There is an interference with blood supply to the intestines

• Most common causes are emboli and atherosclerosis

• May be complete or partial occlusion

Signs and Symptoms of a partial occlusions secondary to atherosclerosis

Intense abdominal pain from ischemi tissue

Passage of stool with blood or mucous

Fever, leukocytosis, shock

s&s of infarcted bowel (bowel death): shock-like, nausea, vomiting, vomiting blood, rectal bleeding, severe back pain as a result of loss of blood supply

S&S of partial occlusion secondary to atherosclerosis

Pain just after eating, or just after taking meds if patient is not eating

Change in bowel habits

Nausea

Vomiting

Weight loss

Bowel sounds of mechanical obstruction

Proximal to obstruction:

                high pitched or hyperactive (borborygmi)

Distal to obstruction:

                     hypoactive or absent

Bowel sounds of non mechanical obstruction

Hypoactive, low-pitched gurgles

Absent bowel sounds suggest paralytic ileus

Etiology of diverticular disease

Low dietary fiber

Age, due to decrease of strength in colon walls

Excess consumption of refined carbs

Inactivity

Smoking

Use of NSAIDs

Obesity

Inherent, weak colon wall

Diverticulum

• May be congentical or aquired

• The outpouching of the mucousa through the muscular intestinal wall. Usually 5-10mm, up to several cm

• Caused by atrophy, weakness of bowel wall, increase of intra-luminal pressure, obesity, and chronic consipation

• Is very common. Many people have these and don't even know until and unless the get diverticulosis.

Diverticulosis

• Presence of multiple outpouches

• Usually non-inflamed

• Often symptom-free, but person may have vague discomfort

Diverticulitis (Part I)

• Inflammation of the diverticula
• Most common in sigmoid colon
• Fecal matter and bacteria collect in a pouch and harden into a fecalith (mass of feces)
• If fecalith develops, it can cause abcess, small perforations, and/or peritonitis
• May result in narrowing from fibrotic stricture, causing obstruction

Diverticulitis (part II: prevalence globally and in genders)

Associated with low dietary fiber and is prevalent in western diets, but almost unheard of in Asia and Africa due to high intake of vegetables and fiber

Affect men and women equally, but men have a higher complication rate

S&S of diverticular disease