INTESTINAL OBSTRUCTION

Methas Arunnart MD.

The common Scenario

A 50 year old gentleman presents with abdominal pain, distension and absolute constipation. With repeated episodes of vomiting.His vital sign were stable, abdomen distended with diffuse tenderness but minimal peritonism. Bowel Sounds are hyperactive.

The plain abdominal xray was taken on admission.

Introduction and Definitions

Accounts for 5% of all acute surgical admissions Patients are often extremely ill requiring prompt

assessment, resuscitation and intensive monitoring

Obstruction A mechanical blockage arising from a structural abnormality that presents a physical barrier to the progression of gut

contents.

Ileus is a paralytic or functional variety of obstruction

Patho-physiology I 8L of isotonic fluid received by the small

intestines (saliva, stomach, duodenum, pancreas and hepatobiliary )

7L absorbed 2L enter the large intestine and 200 ml excreted

in the faeces Air in the bowel results from swallowed air ( O2

& N2) and bacterial fermentation in the colon ( H2, Methane & CO2), 600 ml of flatus is released

If mucosal barrier is breached it may result in translocation of bacteria and toxins resulting in bactaeremia, septaecemia and toxaemia.

Patho-physiology IIObstruction results in:

1. Initial overcoming of the obstruction by increased paristalsis

2. Increased intraluminal pressure3. Vomiting 4. Lymphatic and venous congestion resulting

in edematous tissues5. sequestration of fluid into the lumen from

the surrounding circulation6. Factors 3,4,5 result in hypovolaemia and

electrolyte imbalance7. Further: localised anoxia, mucosal depletion

necrosis and perforation and peritonitis.8. Bacterial over growth with translocation of

bacteria and it’s toxins causing bacteraemia and septicaemia.

HOW TO APPROACH?

WHAT ARE YOUR OBJECTIVES?

You should be able to address these questions

1. Is this bowel obstruction?

2. Partial or complete obstruction?

3. Site of obstruction?

4. Cause of this obstruction?

5. Is this a complicated or simple obstruction?

1. IS THIS BOWEL OBSTRUCTION?

The Universal Features

Colicky abdominal pain

Vomiting

Constipation/obstipation

Abdominal distension.

Clinical Findings1. History

Clinical Findings2. Examination

Others

Systemic examination If deemed necessary.•CNS•Vascular•Gynaecological•muscuoloskeltal

Abdominal

•Abdominal distension and it’s pattern•Hernial orifices•Visible peristalsis•Cecal distension•Tenderness, guarding and rebound•Organomegaly•Bowel sounds

–High pitched–Absent

•Rectal examination

General

•Vital signs: P, BP, RR, T, Sat•dehydration•Anaemia, jaundice, LN•Assessment of vomitus if possible•Full lung and heart examination

Radiological EvaluationNormal Scout

Always request: Supine, Upright and CXR

Gas pattern: Gastric, Colonic and 1-2 small bowel

Check gasses in 4 areas:1. Caecal

2. Hepatobiliary

3. Free gas under diaphragm

4. Rectum

Look for calcification,soft tissue masses, psoas shadow

Look for fecal pattern

X-ray finding Different height

in the same loop

Step ladder pattern

Ileus Associated with the following conditions:

Metabolic abnormalities: Hypokalaemia Hyponatremia Uraemia Hypomagnesemia

Postoperative and bowel resection Intraperitoneal infection or inflammation Ischemia Extra-abdominal: Chest infection, Myocardia infarction Endocrine: hypothyroidism, diabetes Spinal and pelvic fractures Retro-peritoneal haematoma Bed ridden Drug induced: morphine, tricyclic antidepressants

Is this an ileus or obstruction

Clinical features Is there an under lying cause? Is the abdomen distended but tenderness is not marked. Is the bowel sounds diffusely hypoactive.

Radiological features: Is the bowel diffusely distended Is there gas in the rectum Are further investigasions (CT or Gastrografin studies)

helpful in showing an obstruction.

Does the patient improve on conservative measures

Example of ileus

2.PARTIAL OR COMPLETEOBSTRUCTION?

http://www.learningradiology.com/images/giimages1/gigallerypages/Adynamic%20ileus.html

3. SITE OFOBSTRUCTION?

Clinical Findings

Persistent pain may be a sign of strangulation Relative and absolute constipation

Colonic•? Preexisting change in bowel habit•Colicky in the lower abdomin•Vomiting is late•Distension prominent•Cecum ? distended

Distal small bowel•Pain: central and colicky•Vomitus is feculunt•Distension is severe•Visible peristalsis•May continue to pass flatus and feacus before absolute constipation

High•Pain is rapid

•Vomiting copious and contains bile jejunal content

•Abdominal distension is limited or localized

•Rapid dehydration

The Difference between small and large bowel obstruction

Small Bowel Large bowel

•Central ( diameter 5 cm max)•Vulvulae coniventae•Ileum: may appear tubeless

•Peripheral ( diameter 8 cm max)•Presence of haustration

4. CAUSE OFOBSTRUCTION?

Small bowel VS Large bowel obstruction

Causes- Small BowelExtraluminal

Mural Luminal

Postoperative adhesions

Congenital adhesions

Hernia

Volvulus

Neoplasm lymphoma carcinoid carinoma lipoma polyps leiyomayoma hematoma secondary

TumorsTBCrohnsStrictureIntussusceptionCongenital

F. BodyBezoarsGall stoneFood

ParticlesA. lumbricoides

Small Bowel Adhesions Accounts for 60-70% of All SBO Results from peritoneal injury, platelet activation

and fibrin formation. As early as 4 weeks post laparotomy. The majority

of patients present between 1-5 years Colorectal Surgery 25% Gynaecological 20% Appendectomy 14%

70% of patients had a single band Readmission in surgically treated patients is 35%

Hernia

Accounts for 10% of SBO Commonest

1. Femoral hernia

2. ID inguinal

3. Umbilical

4. Others: incisional and internal H.

Site of obstruction is the neck of hernia The compromised viscus is with in the

sac. Ischaemia occurs initially by venous

occlusion, followed by oedema and arterial compromise.

Hernia

Followed by oedema and arterial compromise. Attempt to distinguish the difference between:

Incaceration Sliding Obstruction

Strangulation is noted by: Persistent pain Discolouration Tenderness Constitutional symptoms

Intussusecption

Intussusception is an "internal prolapse" of the bowel

This occurs when a mass or lead point in the bowel is pulled forward by normal peristalsis

Intussusception is rare in adults, 1-5% of SBO. Adult intussusception commonly involves a distinct

pathologic lead point, which is malignant in over half of the cases.

Pediatric intussusception is usually due to a benign etiology and can usually be managed with non-operative reduction.

Intussusecption

Symptoms are often chronic; intermittent abdominal pain is the most common presentation in adults.

The diagnosis is most often made with CT A "target sign" may be seen on CT on perpendicular

view, while the intussusception will appear as a sausage shaped mass when the CT beam is parallel to the longitudinal axis.

An increased incidence of intussusception has been reported in patients with AIDS. This is due to the high incidence of conditions, such as lymphoid hyperplasia, Kaposi's sarcoma, and non-Hodgkin's lymphoma.

Intussuseption in CT

Other causes

IBDGall stone IleusIntussusception

Large Bowel Obstruction

Aetiology:1. Carcinoma: The commonest cause, 18% of CA colon

present with obstruction2. Benign stricture: Due to Diverticular disease, Ischemia,

Inflammatory bowel disease.3. Volvulus: 1. Sigmoid Volvulus

2. Caecal Volvulus4. Hernia:5. Congenital : Hirschusbrung, anal stenosis and agenesis

•Distinguishing ileus from mechanical obstruction is challenging

•According to Leplac’s law: maximum pressure is at the it’s maximum diameter. Cecum is at the greatest risk of perforation

Sigmoid Volvulus Colonic Obstruction

Sigmoid volvulus

Role of CT Used with iv contrast, oral and rectal contrast

(triple contrast). Able to demonstrate abnormality in the bowel wall,

mesentery, mesenteric vessels and peritoneum.

It can define the level of obstruction The degree of obstruction The cause: volvulus, hernia, luminal and mural causes The degree of ischaemia Free fluid and gas

Ensure: patient vitally stable with no renal failure and no previous allergy to iodine

CT SCAN

Role of barium gastrografin studies

As: follow through, enema Limited use in the acute setting Gastrografin is used in acute

abdomen but is diluted Useful in recurrent and chronic

obstruction May able to define the level and

mural causes.

Barium should not be used in a patient with peritonitis

5. IS THIS A SIMPLE OR COMPLICATEDOBSTRUCTION?

Who suspected complicated obstruction?

Patients suspected on admission of having complicated obstruction with

complete or closed-loop obstruction patients with fever, leukocytosis,

tachycardia, metabolic acidosis continuous abdominal pain or peritonitis those who develop these signs and

symptoms during the course of nonoperative Mx.

Closed loop obstruction

Small bowel Large bowel

MANAGEMENT

INITIAL MANAGEMENT 

 The primary goals in the initial management of patients with SBO are to determine:

The degree of volume depletion and metabolic derangement

The severity, cause, extent and location of the obstruction

Whether nonoperative management can be considered

The need for and timing of operative intervention

INITIAL MANAGEMENT 

Adequate intravenous (IV) access should be obtained for fluid resuscitation. should be given until the patient makes urine or is clinically euvolemic. A Foley catheter should be placed to monitor urine

output. If necessary, a central venous catheter or Swan-Ganz catheter can be inserted

Bowel decompression – NPO +NG tube insertion Antibiotics are not indicated in the routine.

Patients who indicate the need for surgery should receive prophylactic antibiotics perioperatively.

OPERATIVE MANAGEMENT The timing of surgical intervention requires careful consideration.

Approximately one-quarter of patients admitted for small bowel obstruction will require operation. Patients suspected on admission of having complicated obstruction with complete or closed-loop obstruction, patients with fever, leukocytosis, tachycardia, metabolic acidosis, continuous abdominal pain or peritonitis, or those who develop these signs and symptoms during the course of nonoperative management warrant prompt surgical exploration [45]. Although prophylactic antibiotics are not routinely administered for uncomplicated small bowel obstruction, antibiotics may be warranted for patients with complications (eg, perforation) (table 2) [52-54].

Every patient considered for exploration due to a suspected small bowel obstruction, whether open or laparoscopically, should be appropriately resuscitated prior to surgery with IV fluids and have their electrolytes repleted, as indicated. This is especially important for patients with copious emesis resulting from more proximal obstruction, obstruction lasting several days, or obstruction causing large-volume intraluminal fluid sequestration. These patients may have severe metabolic acidosis, volume depletion, and electrolyte abnormalities, and need resuscitation prior to operation.