Intestinal Obstruction: Frequency

INTESTINAL OBSTRUCTION Definition Is a partial or complete blockage of the bowel (small or large intestine) that prevent the feces and gas from passing distally

Frequency Among patients who are admitted to the hospital for severe abdominal pain, 20% have an intestinal obstruction

INTESTINAL OBSTRUCTION Frequency Bowel obstruction can affect individuals of any age Different conditions occur at higher rates in certain age groups ►Children under the age of two, for example, are more likely to present with: intussusceptions or congenital defects ►Elderly patients, on the other hand, have a

higher rate of colon cancer

INTESTINAL OBSTRUCTION Morbidity and mortality rates The mortality rate of small bowel obstruction ranges from : 2% for a simple obstruction to 25% for a strangulation obstruction that: compromises the blood supply and is treated after a lapse of 36 hours Large bowel obstruction carries a mortality rate of: 2% for volvulus to 40% if part of the bowel is gangrenous

INTESTINAL OBSTRUCTION

Etiology There are two types of intestinal obstructions: mechanical and non-mechanical, called paralytic ileus Mechanical obstructions occur because the bowel is physically blocked Unlike mechanical obstruction, non-mechanical obstruction, occurs because peristalsis stops

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction Three types of abnormalities may produce mechanical obstruction I) Obstruction of intestinal lumen may be caused by several kinds of diseases, such as:

► Intussusception Is an invagination of the bowel lumen, with invaginated portion (the intussusceptum) passing distally into the ensheathing outer portion (the intussuscipiens) by peristalsis

Illustration

• Intussusception

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction ► Intussusception Unrelieved intussusception can occlude the blood supply of the intussusceptum In adults, intussusception is usually caused by an abnormality of the bowel wall, such as: tumor or Meckel’s diverticulum

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction ► Intussusception In infants and children, intussusception may occur without apparent anatomic cause

► Large gallstone (biliary ileus) Can enter the intestinal lumen via a cholecystoenteric fistula, can cause obstruction to produce a rare condition called gallstone ileus

Illustration Large gallstone (biliary ileus)

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction ► feces meconium or bezoars may obstruct the intestine Bezoars occur more frequently in: children the mentally retarded and the toothless, and in patients after gastrectomy

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction 2) Intrinsic bowel lesion Producing intestinal obstruction are often congenital such as: Atresia Stenosis Duplication They occur most commonly in: infant and children

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction 2) Intrinsic bowel lesion Neoplasm carcinoma of the sigmoid colon Inflammation Chrohn’s disease

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction 3) Lesions extrinsic to the bowel cause intestinal obstruction ► Adhesion of the intestine by adhesions from: previous operations or inflammation is the leading cause of small intestinal obstruction ► External hernias Are the second most common cause of mechanical small intestinal obstruction

Illustration Small bowel obstruction by adhesion

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction ► Internal hernia due: to congenital abnormalities of the mesentery or to surgical defects in the mesentery cause bowel obstruction ►Extrinsic masses such as: neoplasms and abscesses may cause mechanical bowel obstruction

Illustration Internal hernia

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction ► A volvulus Is an extrinsic abnormality in which a portion of the alimentary canal rotates or twists about itself The twist usually involves the blood supply of the twisted portion of the bowel

Illustration • Volvulus:

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction ► A volvulus A volvulus usually accompanies an underlying abnormality: midgut volvulus is caused by mesenteric abnormality of malrotation Cecal volvulus occurs when the cecum or right colon is on a mesentery rather than being retroperitoneal

Etiology Mechanical Obstruction ► A volvulus Sigmoid volvulus develops when the sigmoid is abnormally long Another type of volvulus occurs when adhesion fix the intestinal to a point that acts as a pivot for the volvulus

INTESTINAL OBSTRUCTION Etiology Mechanical Obstruction ► A volvulus The most common causes of intestinal obstruction in adults are adhesions, usually from previous operations: hernias and neoplasms Neoplasms are the most common cause of colon obstruction

Illustration Neoplasm

Etiology Paralytic Ileus (or non-mechanical obstruction) It is a common disorder, occurs to some extent in most patients undergoing abdominal operations Several neural, humoral, and metabolic factors cause this abnormality; such as: ►Intestinointestinal reflex, result from prolonged intestinal distention *Distenstion of other organs, such as the ureter, can inhibit intestinal motility *Spine fracture, retroperitoneal hemorrhage, or trauma can also produce paralytic’s ileus

INTESTINAL OBSTRUCTION Etiology Paralytic Ileus (or non-mechanical obstruction)

►Clinically, peritonitis causes paralytic ileus ►Electrolyte imbalance, particularly hypokalemia, contribute to paralytic ileus by interfering with the normal ionic movements during smooth muscle contraction ► Finally, ischemia of the intestine rapidly inhibits motility

INTESTINAL OBSTRUCTION Etiology Idiopathic Intestinal Pseudo-Obstruction (IIPO) IIPO is a chronic illness characterized by symptoms of recurrent intestinal obstruction without demonstrable mechanical occlusion of bowel The patients with this disease have:

* impaired motor response to intestinal distension * duodenal and colonic slow waves may be normal * some patients have aperistalsis of the esophagus

INTESTINAL OBSTRUCTION

Etiology Idiopathic Intestinal Pseudo-Obstruction (IIPO) In IIPO, the heredity plays a role in this disorder The symptom IIPO include: Cramping abdominal pain Vomiting Distension Diarrhea Steatorrea

INTESTINAL OBSTRUCTION Etiology Idiopathic Intestinal Pseudo-Obstruction (IIPO) Physical examination reveals abdominal distension IIPO is distinguished from mechanical intestinal obstruction by the absence of the radiological findings of mechanical obstruction Surgery treatment for IIPO should be avoid Intravenous hyperalimentation may help manage these patients

Pathogenesis Intestinal Obstruction Mechanical obstruction of the intestine causes accumulation of the fluid and gas proximal to the obstruction producing distention of the intestine Ingested fluid, digestive secretions and intestinal gas initiate the distension Large volume of saliva, gastric secretion, bile, and pancreatic juice enter the gut daily The stomach has a very small capacity for absorbing fluid

Pathogenesis Intestinal Obstruction Obstruction of the bowel 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 both above and below the obstruction with frequent: loose stools and flatus early in its course

Pathogenesis (Intestinal Obstruction) * Vomiting occurs if the level of obstruction is proximal *Increasing 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

Pathogenesis Intestinal Obstruction The fluid loss and dehydration that ensue may be severe and contribute to increased: morbidity and mortality Strangulated bowels are most commonly associated with adhesions and occur when a loop of distended bowel twists on its mesenteric pedicle

Pathogenesis Intestinal Obstruction Bacteria in the gut proliferate proximal to the obstruction Microvascular changes in the bowel wall allow bacterial translocation to the mesenteric lymph nodes ►►► ► cystemic toxicity dehydration and electrolytes abnormalities

Pathogenesis Intestinal Obstruction The arterial occlusion leads to bowel: ischemia and necrosis If left untreated, this progresses to: perforation peritonitis and fecal soilage of peritoneal cavity if left untreated ► death

Clinical Small bowel History Abdominal pain (characteristic with most patients) Pain, often described as: crampy and intermittent is more prevalent in simple obstruction Often, the presentation may provide clues to the approximate: (1) location and (2) nature of the obstruction

Clinical Small bowel History Usually, pain that occurs for: a shorter duration of time and is colicky and accompanied by bilious vomiting may be more proximal bowel obstruction Pain may last as many as several days Progressive in nature and with abdominal distention ►► this may be typical of more distal bowel obstruction

Clinical (Small bowel) History Pain may be changed in the character: ►Example: constant pain, this may indicate the development of a more serious complication (strangulation, or ischemic bowel) Nausea Vomiting, which is associated more with proximal obstructions Diarrhea (an early finding)

INTESTINAL OBSTRUCTION Clinical Small bowel History 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

INTESTINAL OBSTRUCTION Clinical Small bowel History  

Previous abdominal or pelvic surgery previous radiation therapy or both may be part of patient's medical history History of malignancy (particularly ovarian and colonic)

Physical Examination: Small bowel Abdominal distention Duodenal or proximal small bowel has less distention when obstructed than the distal bowel has when obstructed Hyperactive bowel sounds occur early as GI contents attempt to overcome the obstruction Hypoactive bowel sounds occur late

Physical Examination: Small bowel Exclude incarcerated hernias of the groin, femoral triangle, and obturator foramina Proper genitourinary and pelvic examinations are essential ►Look for the following during rectal examination * Gross or * Occult blood which suggests: late strangulation or malignancy

INTESTINAL OBSTRUCTION Physical Examination: Small bowel Check for symptoms commonly believed to be more diagnostic of intestinal ischemia, including the following: Fever (temperature >100°F) Tachycardia (>100 beats/min) Peritoneal signs

INTESTINAL OBSTRUCTION Differential Diagnosis Small bowel Appendicitis, Acute Cholangitis Cholecystitis and Biliary Colic Cholelithiasis Constipation Diverticular Disease Foreign Bodies, Gastrointestinal Gastroenteritis Inflammatory Bowel Disease

Differential Diagnosis Small bowel Obstruction, Large Bowel Ovarian Torsion Pancreatitis Pediatrics, Appendicitis Pediatrics, Gastroenteritis Pediatrics, Intussusception Pelvic Inflammatory Disease Urinary Tract Infection

Lab Study Small bowel 1) Essential laboratory tests Serum chemistries: Results are usually normal or mildly elevated BUN level: If the BUN level is increased, this may indicate decreased volume state (e.g., dehydration) Creatinine level: Creatinine level elevations may indicate dehydration

Lab Study Small bowel CBC: WBC count may be elevated in simple or strangulated obstructions Increased hematocrit is an indicator of  volume state (i.e.: dehydration)

Type and crossmatch: The patient may require surgical intervention Urinalysis

Small bowel Imaging Studies 1) Plain radiography Obtain plain radiographs first for patients in whom SBO is suspected At least 2 views are required: supine or flat and upright

Small bowel Imaging Studies 1) Plain radiography Plain radiographs are diagnostically more accurate in cases of simple obstruction ►Remember The diagnostic failure rates of as much as 30% have been reported

Small bowel Imaging Studies 1) Plain radiography Dilated small-bowel loops with air fluid levels indicate SBO

Small bowel Imaging Studies 2) Enteroclysis ( bowel enema)

*Enteroclysis is valuable in detecting the presence of obstruction and

* in differentiating partial from complete blockages This study is useful when plain radiographic findings are:

* normal in the presence of clinical signs of SBO or

*

if plain radiographic findings are nonspecific

Small bowel Imaging Studies 3) CT scanning CT scanning is useful in making an early diagnosis of strangulated obstruction Sensitivity: 90% in detecting SBO

Small bowel Imaging Studies 4) Ultrasonography Ultrasonography is less costly and less invasive than CT scanning Specificity is reportedly 100%

Treatment Emergency Department Care Initial ED treatment consists: ► aggressive fluid resuscitation ► bowel decompression ► administration of analgesia and antiemetic as indicated clinically ► antibiotics (to cover against gram-negative and gram-positive) and ► early surgical consultation