INTESTINAL OBSTRUCTION OF SMALL

INTESTINE

BYDR.AKINBI OLUBAYODE.O

OUTLINE Introduction Definition Epidemiology Pathophysiology Signs and Symptoms Etiology Complications Diagnosis Treatment

Introduction The small intestine or small bowel is the part of the gastrointestinal tract between the stomach and the large intestine, and is where much of the digestion and absorption of food takes place. The small intestine has three distinct regions – the duodenum, jejunum, and ileum. The primary function of the small intestine is the absorption of nutrients and minerals from food.

DefinitionSmall Intestinal obstruction occurs when there is a blockage of the small intestine i.e. a blockage in the duodenum, jejunum or ileum. When an obstruction occurs, ingested food, liquids and digestive secretions accumulate above the blockage, the bowel section involved in the blockage becomes distended and the segment can collapse. The normal functions of the bowel wall are compromised and the distended section gets progressively worse. The blockage may be partial or complete.

Epidemiology 20% of patients admitted for acute

abdomen have an intestinal obstruction. Small bowel obstruction is responsible for 80% of these cases.

Adhesion and hernia are the most common causes of small bowel obstruction.

Pathophysiology Small-bowel obstruction (SBO) leads to

proximal dilatation of the intestine due to accumulation of GI secretions and swallowed air. This bowel dilatation stimulates cell secretory activity, resulting in more fluid accumulation.

This leads to increased peristalsis above and below the obstruction, with frequent loose stools and flatus early in its course.

Vomiting occurs if the level of obstruction is proximal. Increasing small-bowel distention leads to increased intraluminal pressures.

This can cause compression of mucosal lymphatics, leading to bowel wall lymphedema. With even higher intraluminal hydrostatic pressures, increased hydrostatic pressure in the capillary beds results in massive third spacing of fluid, electrolytes, and proteins into the intestinal lumen.

The fluid loss and dehydration that ensue may be severe and contribute to increased morbidity and mortality.

Strangulated SBOs are most commonly associated with adhesions and occur when a loop of distended bowel twists on its mesenteric pedicle.

The arterial occlusion leads to bowel ischemia and necrosis. If left untreated, this progresses to perforation, peritonitis, and death.

Bacteria in the gut proliferate proximal to the obstruction. Microvascular changes in the bowel wall allow translocation to the mesenteric lymph nodes.

This is associated with an increase in the incidence of bacteremia due to Escherichia coli, but the clinical significance is unclear.

Etiology Intestinal obstructions are either the result of something blocking part of the intestine and its associated with abdominal pain (mechanical) or due to paralysis of intestinal musculature, there is absence of pain(paralytic ileus). Mechanical obstruction of Small intestine: Intestinal adhesions — bands of fibrous

tissue in the abdominal cavity that can form after abdominal or pelvic surgery

Hernias — portions of intestine that protrude into another part of your body

Etiology Tumors in the small intestine Inflammatory bowel diseases, such as

Crohn's disease Twisting of the intestine (volvulus) Telescoping of the intestine

(intussusception)

Etiology Paralytic ileusParalytic ileus can cause signs and symptoms of intestinal obstruction, but doesn't involve a physical blockage. In paralytic ileus, muscle or nerve problems disrupt the normal coordinated muscle contractions of the intestines, slowing or stopping the movement of food and fluid through the digestive system.

Etiology Paralytic ileus can affect any part of the intestine. Causes can include: Abdominal surgery Pelvic surgery Infection Certain medications, including

antidepressants and pain medications that affect muscles and nerves

Muscle and nerve disorders, such as Parkinson's disease

Signs and symptoms Crampy abdominal pain that comes and goes Nausea Vomiting - Associated more with proximal

obstructions Diarrhea - An early finding Constipation - A late finding, as evidenced by

the absence of flatus or bowel movements Fever and tachycardia - Occur late and may

be associated with strangulation Severe bloating Decreased appetite

Complications Untreated, intestinal obstruction can cause serious, life-threatening complications, including: Tissue death: Intestinal obstruction can cut

off the blood supply to part of your intestine. Lack of blood causes the intestinal wall to die. Tissue death can result in a tear (perforation) in the intestinal wall, which can lead to infection.

Infection: Peritonitis is the medical term for infection in the abdominal cavity. It's a life-threatening condition that requires immediate medical and often surgical attention.

Dehydration Electrolyte and Metabolic imbalance

a) Hypokalemiab) Hypernatremiac) Alkalosis and Acidosis Septicaemia Respiratory failure, respiratory acidosis

from distension of the abdomen Shock

a) Hypovolemic: loss of ECF and or sequestration of blood

b) Endotoxic

Diagnosis The following are adjunctive lab tests used in the evaluation of SBO: Serum chemistries Blood urea nitrogen (BUN) level Creatinine Complete blood count (CBC) Lactate dehydrogenase tests Urinalysis Type and crossmatch

Diagnosis Abdominal CT scan Abdominal x-ray Barium enema Abdominal Ultrasound

Treatment Although urgent relief of the obstruction is the ultimate aim, the general condition of the patient must first be improved by correcting fluid and electrolyte deficiencies and starting antimicrobial treatment.1. GENERAL MEASURESa) Correction of fluid, electrolyte and

metabolic imbalance: fluid and electrolyte deficiencies must be corrected by the administration of Ringers lactate or dextrose/saline and dextrose water. Potassium chloride is added when urine output is greater than 30ml/h.

Pulse and blood pressure are checked quarter-hourly and urine output hourly.

b) Antiemetic's: Used in treatment of nausea and vomiting e.g Promethazine (Phenergan, Phenadoz, Promethegan), Ondansetron (Zofran, Zuplenz) c).Nasogastric decompression: Gastric aspirant must be done to remove swallowed air and intestinal contents which regurgitate into the stomach. It also prevents aspiration into the trachea and bronchi during induction of anaesthesia.d). Sedation: morphine 10-15mg or pethidine 100mg should be given to relieve pain.e). Antibiotics to combat infection: Growth and spread of bacteria should be prevented with broad spectrum antibiotics such as gentamicin with clindamycin or cefuroxime and metronidazole.

Non operative treatment Nonoperative treatment for several types of SBO are as follows: Malignant tumor - Obstruction by tumor is usually

caused by metastasis; initial treatment should be nonoperative (surgical resection is recommended when feasible)

Inflammatory bowel disease - To reduce the inflammatory process, treatment generally is nonoperative in combination with high-dose steroids; consider parenteral treatment for prolonged periods of bowel rest, and undertake surgical treatment, bowel resection, and/or stricturoplasty if nonoperative treatment fails.

Intra-abdominal abscess - CT scan ̶ guided drainage is usually sufficient to relieve obstruction

Radiation enteritis - If obstruction follows radiation therapy acutely, nonoperative treatment accompanied by steroids is usually sufficient; if the obstruction is a chronic sequela of radiation therapy, surgical treatment is indicated

Incarcerated hernia - Initially use manual reduction and observation; advise elective hernia repair as soon as possible after reduction

Acute postoperative obstruction - This is difficult to diagnose, because symptoms often are attributed to incisional pain and postoperative ileus; treatment should be nonoperative

Adhesions - Decreasing intraoperative trauma to the peritoneal surfaces can prevent adhesion formation

Surgical care A strangulated obstruction is a surgical emergency.

In patients with a complete small-bowel obstruction (SBO), the risk of strangulation is high and early surgical intervention is warranted. Laparoscopy has been shown to be safe and effective in selected cases of SBO

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