Bowel Obstruction

Dr. Isa BasukiDepartment of Surgery, AWS General Hospital

Introduction• Bowel obstruction was recognized, described, and

treated by Hippocrates• one of the most common intra-abdominal problems

faced by general surgeons in their practice• intestinal obstruction continues to be a major cause of

morbidity and mortality • early recognition and aggressive treatment can

prevent irreversible ischemia and transmural necrosis decreasing mortality and long-term morbidity

Definition• Bowel obstruction when the normal propulsion and passage

of intestinal contents does not occur• can involve:

• only the small intestine (small bowel obstruction), • the large intestine (large bowel obstruction)• the small and large intestine (generalized ileus)

• Intestinal obstruction can be classified according to:• etiopathogenesis (mechanical or functional obstruction)• time of presentation and duration of obstruction (acute or chronic

obstruction), • the extent of obstruction (partial or complete),• type of obstruction (simple, closed-loop, or strangulation obstruction).

Cont’d• Complete intestinal obstruction can be categorized as:• simple obstruction

• obstruction without any vascular compromise

• closed-loop obstruction• both ends of the involved intestinal segment are obstructed (e.g.,

volvulus)

• strangulation obstruction• the blood supply to the affected segment is compromised

ANATOMY• Gross Anatomy• Microscopic Anatomy

Gross Anatomy• The entire small intestine ~ 270 to 290 cm• duodenal length ~ 20 cm• jejunal length ~ 100 to 110 cm• ileal length ~ 150 to 160 cm

• jejunum begins at the duodenojejunal angle, which is supported by ligament of Treitz (peritoneal fold)• no obvious line of demarcation between the jejunum

and the ileum• Jejunum two fifths of the small intestine• Ileum three fifths of the small intestine

Cont’d• In the jejunum, only one or two arcades send out long,

straight vasa recta to the mesenteric border, whereas the blood supply to the ileum may have four or five separate arcades with shorter vasa recta• The mucosa of the small bowel is characterized by

transverse folds (plicae circulares), which are prominent in the distal duodenum and jejunum

Neurovascular-Lymphatic Supply• The small intestine is served by rich vascular, neural,

and lymphatic supplies, all traversing through the mesentery• Base of the mesentery attaches to the posterior

abdominal wall to the left of the second lumbar vertebra and passes obliquely to the right and inferiorly to the right sacroiliac joint• The blood supply of the small bowel, except for the

proximal duodenum, which is supplied by branches of the celiac axis, comes entirely from the superior mesenteric artery

• superior mesenteric artery courses anterior to the uncinate process of the pancreas and the third portion of the duodenum, where it divides to supply the pancreas, distal duodenum, entire small intestine, and ascending and transverse colons

Microscopic Anatomy• consists of four layers:

1. serosa, 2. muscularis propria, 3. submucosa, 4. Mucosa

• Serosa consists of visceral peritoneum that encircles the jejunoileum, and the anterior surface of the duodenum• muscularis propria consists of two muscle layers:• Thin outer longitudinal layer• Thicker inner circular layer of smooth muscle

Cont’d• Ganglion cells from the myenteric (Auerbach) plexus

are interposed between the muscle layers and send neural fibers into both layers• The submucosa consists of a layer of fibroelastic

connective tissue containing blood vessels and nerves• Strongest component of the intestinal wall and

therefore must be included in anastomotic sutures• contains elaborate networks of lymphatics, arterioles,

and venules and an extensive plexus of nerve fibers and ganglion cells (Meissner plexus)

Cont’d• mucosa can be divided into three layers:

1. Muscularis mucosae 2. lamina propria, 3. epithelial layers

• muscularis mucosae is a thin layer of muscle that separates the mucosa from the submucosa• lamina propria is a connective tissue layer between the

epithelial cells and muscularis mucosae• contains a variety of cells, including plasma cells,

lymphocytes, mast cells, eosinophils, macrophages, fibroblasts, smooth muscle cells, and noncellular connective tissue.

Cont’d• Lamina propria serves a protective role in the intestine

to combat microorganisms that penetrate the overlying epithelium• epithelial layer is a continual sheet of epithelial cells

covering the villi and lining the crypts• main functions of the crypt epithelium are cell renewal

and exocrine, endocrine, water, and ion secretion• main functions of the villous epithelium are digestion

and absorption

Cont’d• Four main cell types are contained:

1. goblet cells2. Paneth cells3. Absorptive enterocytes4. enteroendocrine cells

• Villi are tallest in the distal duodenum and proximal jejunum and shortest in the distal ileum• Absorptive enterocytes represent the main cell type in

the mucosa and are responsible for digestion and absorption

Mechanical Bowel Obstruction• a physical blockage of the intestinal lumen• may be intrinsic or extrinsic to the wall of the intestine

or on occasion may occur secondary to luminal obstruction arising from the intraluminal contents (e.g., an intraluminal gallstone)• Partial obstruction the intestinal lumen is narrowed

but still allows the transit of some intestinal content aborally• Complete obstruction the lumen is totally

obstructed, and none of the intestinal contents can move distally

Lesions Extrinsic to the Intestinal Wall

Lesions Intrinsic to the Intestinal Wall

ADHESIONS CONGENITAL

Postoperative Intestinal atresia

Congenital Meckel's diverticulum

Postinflammatory Duplications/cysts

HERNIA INFLAMMATORY

External abdominal wall (congenital or acquired)

Crohn's disease

Internal Eosinophilic granuloma

Incisional INFECTIONS

CONGENITAL Tuberculosis

Annular pancreas Actinomycosis

Malrotation Complicated diverticulitis

Omphalomesenteric duct remnant NEOPLASTIC

NEOPLASTIC Primary neoplasms

Carcinomatosis Metastatic neoplasms

Extraintestinal neoplasm Appendicitis

Lesions Extrinsic to the Intestinal Wall

Lesions Intrinsic to the Intestinal Wall

INFLAMMATORY MISCELLANEOUS

Intra-abdominal abscess Intussusception

"Starch" peritonitis Endometriosis

MISCELLANEOUS Radiation enteropathy/stricture

Volvulus Intramural hematoma

Gossypiboma Ischemic stricture

Superior mesenteric artery syndrome INTRALUMINAL/OBTURATOR OBSTRUCTION

  Gallstone

  Enterolith

  Phytobezoar

  Parasite infestation

  Swallowed foreign body

Epidemiology• 80% of bowel obstructions occur in the small intestine; the

other 20% occur in the colon• Colorectal cancer 60–70% of all large bowel obstructions• diverticulitis and volvulus 30%• Mortality rates

• 3% for simple obstructions; • 30% when there is vascular compromise or perforation of the

obstructed bowel

• Recurrence rates:• after primary conservative treatment 12%• after operative management for adhesive bowel obstruction 8%

- 32%

Pathophysiology

•Distention, Absorption, and Secretion• Intestinal Motility•Circulatory Changes•Microbiology and Bacterial Translocation

Distention, Absorption, and Secretion• Most of the gas distending the small bowel in the early

phases of obstruction accumulates from swallowed air• Dilatation and inflammation activated neutrophils and

macrophages causing damage to secretory and motor processes increase in the local release of nitric oxide • first 12 hours water and electrolytes accumulate within

the lumen secondary to a decrease in net absorption• 24 hours intraluminal water and electrolytes

accumulate more rapidly secondary to a further decrease in absorptive flux and a concomitant increase in net intestinal secretion (secretory flux)

Intestinal Motility• early phase of bowel obstruction intestinal

contractile activity increases in an attempt to propel intraluminal contents past the obstruction• Later contractile activity diminishes probably

secondary to intestinal wall hypoxia and the exaggerated intramural inflammation• Some investigators have suggested alterations in

intestinal motility are secondary to a disruption of the normal autonomic parasympathetic (vagal) and sympathetic splanchnic innervation

Circulatory Changes• Ischemia of the bowel wall can occur by several different

mechanisms • Extrinsic compression of the mesenteric arcades by adhesions,

fibrosis, a mass, or a hernia defect; • an axial twist of the mesentery; • local chronic serosal-based pressure on a segment of the bowel

wall (e.g., a fibrous band) • progressive distention in the presence of a closed-loop bowel

obstruction

• vascular compromise is more acute in large bowel obstruction 40% of people have a competent ileocecal valve closed-loop obstruction

Microbiology and Bacterial Translocation• in the presence of obstruction a rapid proliferation of

bacterial organisms occurs proximal to the point of obstruction, consisting predominantly of fecal-type organisms• In persistent bowel obstruction bacterial

translocation can occur secondary to impairment of the barrier function of the intestinal mucosa• Reduction of perfusion of the intestinal wall further

compromises the mucosal defenses

Etiology• Adhesions• Hernia• Malignant Bowel Obstruction• Granulomatous Diseases and Crohn's Disease• Intussusception• Volvulus• Other Causes

Adhesions• abnormal connective tissue attachments between tissue

surfaces• can be congenital or acquired (postinflammatory and

postoperative).• Congenital or inflammatory adhesions are infrequent causes• Postoperative adhesions are the leading cause of small

bowel obstruction• adhesions form in response to the initial fibrin gel matrix

combined with the local microenvironment• If the fibrin gel allows apposition of adjacent surfaces, a band

or bridge may form (i.e., an adhesion). dynamic process

Hernia• Incarceration of the bowel in congenital abdominal

wall hernias, internal hernias, or postoperative hernias the second most common cause • 5% of external hernias will require emergency

operation• 10–15% of incarcerated hernias contain necrotic bowel

at exploration• chronically incarcerated hernias can develop

strangulation, but most chronically incarcerated hernias can be managed electively

Malignant Bowel Obstruction• Colorectal, gastric, small bowel, and ovarian

neoplasms are among the most frequent causes of malignant bowel obstruction• the recurrence and morbidity are high• decisions about management need to be

individualized by carefully weighing risks, benefits, and life expectancy• Metastatic cancer can also cause bowel obstruction• The most common form is peritoneal carcinomatosis,

but melanoma and carcinoma of the breast, kidney, or lung can also cause intraperitoneal metastases that can obstruct the bowel

Granulomatous Diseases and Crohn's Disease• Crohn's disease is a chronic, transmural, inflammatory

disease of the gastrointestinal tract that may affect any part of the alimentary tract from the mouth to the anus• responsible for about 5% of cases of small bowel

obstruction secondary to the inflammatory process or to stricture formation• granulomatous diseases causing obstruction

tuberculosis and actinomycosis

Crohn Disease

Crohn disease is an idiopathic infl ammatory bowel disease that can affect any segment of the GI tract but usually involves the small intestine (terminal ileum) and colon.

Young adults of northern European ancestry are more commonly affected.

Transmural edema, follicular lymphocytic infiltrates, epithelioid cell granulomas, and fistulation characterize this disease.

Signs and symptoms include the following:• Diffuse abdominal pain (paraumbilical

and lower-right quadrant)• Diarrhea• Fever• Dyspareunia (pain during sexual

intercourse)• Urinary tract infection (UTI)• Malabsorption

Intussusception• relatively frequent cause of bowel obstruction in

infancy (the first 2 years of life) but only 2% of bowel obstruction in the adult • most common cause of bowel obstruction in central

Africa• median age of presentation in adults sixth to

seventh decade• etiology of adult intussusceptions inflammatory

lesion or a neoplasm that is malignant in almost 50% of patients

Volvulus• axial twist of the bowel and its mesentery• infrequent cause of small or large bowel obstruction• sigmoid volvulus accounts for 75% of all patients with

volvulus• cecal volvulus the remaining 25% of bowel volvulae • Speculation about etiology of primary volvulus of the

small intestine has been related to abrupt dietary changes that occur during the religious holiday when the people celebrating Ramadan fast during the day and then consume a large meal after dark

Sigmoid volvulus. A. Supine abdominal radiograph showing the dilated, volvulated segment of redundant sigmoid colon pointing toward the right upper quadrant; arrows show the space between the sigmoid and hepatic and splenic flexures. B. Contrast enema in sigmoid volvulus showing cut off at distal site of volvulated sigmoid having a "bird-beak" appearance

Cecal volvulus. Dilated volvulated cecum pointing to left upper quadrant. Arrows indicate the cecal tip

Diagnosis• History and Physical Examination• Laboratory• Radiologic Findings• Flat and Upright Abdominal Radiographs• Contrast Studies• Ultrasonography• Computed Tomography

History and Physical Examination• History:• crampy abdominal pain• Distention• acute obstipation• nausea, and vomiting

• Physical examination:• Inspection previous surgical incisions• Auscultation high-pitched metallic "rushes" and

"groans“followed by the metallic tinkling sounds • Palpation rebound, localized tenderness, and involuntary

guarding • rectal exam occult blood

Flat and Upright Abdominal Radiographs• upright chest x-ray combined with supine and upright

abdominal radiographs • chest x-ray is helpful to detect extra-abdominal

conditions • typical findings of small bowel obstruction dilated

loops of small intestine with air-fluid levels • Proximal bowel obstruction little intestinal dilation• Distal bowel obstruction multiple loops of distended

small intestine and/or large intestine

Complete small bowel obstruction. A. Supine abdominal radiograph shows multiple loops of dilated small bowel with colonic gas. B. Upright radiograph shows multiple air-fluid levels in the small intestine (arrows).

Contrast Studies• The use of contrast is helpful when :

• diagnosis is uncertain in patients with a nonresolving partial small bowel obstruction

• to differentiate between partial and complete bowel obstruction

• can also identify the specific site and often the cause of the obstruction• barium enema can be useful in the patient with suspected

large bowel obstruction • contraindicated in patients with a clear diagnosis of

complete bowel obstruction and when strangulation or perforation is suspected

Barium enema showing complete large bowel obstruction in the ascending colon

Ultrasonography• more sensitive and specific than plain abdominal films

for the diagnosis of bowel obstruction• operator-dependent• diagnosis of small bowel obstruction is made when the

intestinal loops measure more that 25 mm in diameter and the distal ileum is found to be collapsed• useful for the early recognition of strangulation in

several Japanese and European studies2

Computed Tomography• Advantages:• allows imaging of structures other than just mucosal detail• sensitivity of 93%• specificity of up to 100%• accuracy of 94%• the ability to visualize the entire intra-abdominal

compartment • can demonstrate changes in the intestinal wall and

associated mesentery

• CT findings diagnostic of bowel obstruction include intestinal loops greater than 25 mm in diameter and a transition zone between dilated and collapsed bowel loops

Detection of Ischemia• Primary concern in the patient with an intestinal

obstruction • Clinical judgment and laboratory findings unreliable

for early detection of intestinal vascular compromise• Acidosis, leukocytosis with left shift, and increased

serum amylase activity and lactate concentration may indicate strangulation• Abdominal US and pulsed Doppler US have been

reported to be useful in identifying patients with strangulation• The presence of peritoneal fluid was also sensitive for

strangulation

Management• Small Bowel Obstruction• aggressive fluid resuscitation• Decompression• prevention of aspiration• correct metabolic or electrolyte imbalances

• Large Bowel Obstruction• resuscitated aggressively • Electrolyte and acid-base abnormalities should be corrected• Nasogastric decompression • bladder catheter should be inserted • require prompt surgical intervention because of the high risk of

perforation

Nonoperative Management• Only uncomplicated small bowel obstruction should be

considered for a trial of nonoperative management• Contraindications to nonoperative management:• suspected ischemia, • large bowel obstruction, • closed-loop obstruction, • strangulated hernia, • Perforation

• relative contraindication complete small bowel obstruction

When to Convert to Operative Management• evidence of a complicated obstruction:

• fever, • tachycardia, • leukocytosis, • localized tenderness, • continuous abdominal pain, • Peritonitis

• any three of the signs above 82% predictive value for strangulation obstruction (four signs 100%)

• develop free air or signs of a closed-loop obstruction on abdominal radiograph• evidence of ischemia, strangulation, or vascular

compromise is noted on CT

Operative Management• Preoperative preparation

• assessing and addressing the medical fitness of the patient• optimize the patient's medical status• administration of beta-blockers to patients with cardiovascular

comorbidities• appropriate antibiotics

• The choice of operative approach and incision is important• early postoperative period the original incision should be

reopened• midline celiotomy affords the best exposure to all four

quadrants of the abdomen

Cont’d• Once within the abdominal cavity, first step identify

the site and cause of obstruction• Nonviable bowel needs to be identified and resected

with caution• Abdominal closure may be difficult when the small

bowel is massively dilated intraoperative intestinal decompression will facilitate closure• In patients with malignant small bowel obstruction or

if the obstruction is unable to be released intestinal bypass can be performed

Post Operative Care• Management of Pain and

Delirium• Opioid Analgesia• Epidural Analgesia• Analgesia with Nonsteroidal Anti-

Inflammatory Drugs• Postoperative Delirium

• Cardiac Evaluation• Risk Assessment• Coronary Disease• Congestive Heart Failure and

Arrhythmia• Valvular Disease

• Pulmonary Evaluation

• Gastrointestinal Evaluation• Postoperative Ileus• Early Postoperative Bowel

Obstruction

• Renal Evaluation• Hematological Evaluation• Infectious Complications• Nutritional Evaluation

References1. Zinner M, Ashley JS. Maingot’s Abdominal

Operations. 11th ed. McGraw Hill Professional; 2007. 2. Hansen JT. Netter’s Clinical Anatomy. 2nd ed.

Elsevier Health Sciences; 2009. 3. Jr CMT, Beauchamp RD, Evers BM, Mattox KL.

Sabiston Textbook of Surgery: Expert Consult Premium Edition: Enhanced Online Features. 19th ed. Elsevier Health Sciences; 2012.

Thank You