Notes from the Video

What You're Going to Learn from This Video on Small Intestinal Obstruction

What are the causes of small bowel obstruction? 

How do you take a history in a patient with small intestinal obstruction? 

What are the physical examination findings in a patient with small bowel obstruction?

Small bowel obstruction is a critical topic in general surgery and one of those subjects you'll encounter at least every week if not every day on surgery rounds.  Its important to understand how to think about the causes of bowel obstruction, generate a differential diagnosis and understand the pathophysiology!

What are the most common causes of small bowel obstruction?

Small bowel obstruction is a blockage that occurs in the small intestine that can lead to a variety of symptoms such as abdominal pain, nausea, vomiting, and constipation.

The best way to think about small bowel obstruction is to think about causes outside of the bowel (extraluminal), causes from the bowel wall (intramural) and causes from the bowel lumen (intraluminal).

Here are the most common causes of bowel obstruction:

Adhesions: Adhesions are bands of scar tissue that can form after surgery, infection, or inflammation in the abdomen. Adhesions can cause the small intestine to become twisted or compressed, leading to a blockage.

Hernias: Hernias occur when a portion of the intestine protrudes through a weak spot or tear in the abdominal wall. This can cause the small intestine to become trapped and lead to a blockage.

Intussusception: Intussusception occurs when one portion of the small intestine telescopes into another portion, causing the intestine to become blocked.

Tumors: Tumors can grow in the small intestine and cause a blockage. These tumors can be either benign or malignant.

Inflammatory bowel disease: Inflammatory bowel disease (IBD), such as Crohn's disease or ulcerative colitis, can cause inflammation in the small intestine. This inflammation can lead to scarring and narrowing of the intestine, which can cause a blockage.

Volvulus: Volvulus occurs when a portion of the small intestine twists on itself, causing the blood supply to become cut off and leading to a blockage.

Foreign bodies: Swallowed objects, such as coins or bones, can become lodged in the small intestine and cause a blockage.

What is the pathophysiology of bowel obstruction?

Bowel obstruction is a condition in which the normal flow of intestinal contents is blocked, leading to a range of symptoms and potential complications.

The pathophysiology of bowel obstruction can vary depending on the underlying cause, but generally involves three main mechanisms: obstruction, distention, and ischemia.

Obstruction: The most obvious aspect of bowel obstruction is the physical blockage of the intestinal lumen. This can be caused by a variety of factors, such as tumors, adhesions, or hernias. As the blockage progresses, the pressure inside the intestine can increase, leading to further distention and impairment of function.

Distention: As the obstruction persists, the intestine can become distended due to the accumulation of gas and fluid. This can cause the intestine to stretch beyond its normal limits, which can lead to pain and discomfort.

Ischemia: Ischemia refers to a lack of blood flow and oxygen delivery to tissues. In the case of bowel obstruction, ischemia can occur as a result of the physical obstruction and the resulting distention. Ischemia can lead to tissue damage and cell death, which can further exacerbate the obstruction and lead to potential complications such as perforation, sepsis, and shock.

What are the most common symptoms of small bowel obstruction?

Abdominal pain: Abdominal pain is the most common symptom of small bowel obstruction. The pain may be intermittent or constant, and can range from mild to severe. The pain is typically located in the mid-abdomen and may be accompanied by cramping or bloating.

Nausea and vomiting: Small bowel obstruction can cause nausea and vomiting due to the buildup of fluid and gas in the blocked intestine. The vomit may contain bile or be feculent in odor.

Constipation or diarrhea: Small bowel obstruction can cause changes in bowel movements. Initially, the patient may have diarrhea due to the fluid accumulation, but later on they may develop constipation because the blockage stops food from moving forward.

Abdominal distention: As the intestine becomes obstructed, gas and fluid may accumulate, leading to abdominal distention or bloating.

Loss of appetite: Small bowel obstruction can cause a loss of appetite due to nausea, vomiting, and abdominal pain.

Obstipation: As the bowel becomes obstructed, the patient may be unable to pass flatus or stool.

What are the most common physical examination signs in small bowel obstruction?

Abdominal distention: As the small intestine becomes blocked, gas and fluid may accumulate, causing the abdomen to appear swollen or distended.

Abdominal tenderness: The abdomen may be tender to the touch, especially in the area where the blockage is located.

High-pitched bowel sounds: Bowel sounds are typically present in the abdomen and can be heard with a stethoscope. In cases of small bowel obstruction, the bowel sounds may be high-pitched, indicating increased activity as the body tries to move the obstructed material.

Absence of bowel sounds: In some cases of small bowel obstruction, bowel sounds may be absent or greatly reduced due to decreased peristalsis and intestinal activity.

Visible peristalsis: In some cases, visible peristalsis, or the wave-like movement of the intestines, may be visible in the abdomen due to increased activity as the body tries to move the obstructed material.

Palpable mass: If the obstruction is caused by a tumor or other mass, a palpable mass may be felt in the abdomen.

If a patient has fever, tachycardia, hypotension or signs of SIRS, sepsis or septic shock with a concern of bowel obstruction you need to have a high suspicion for necrotic bowel or a perforated viscus.