ACUTE INTESTINAL OBSTRUCTION

DR. DANIEL B.YIDANA

OUTLINE

• Definition• Epidemiology• Classification• Pathophysiology• Causes• Clinical presentation/Causes of death• Management• Conclusion

Definition

Acute intestinal Obstruction(AIO) is a condition in which there is a sudden stoppage of the onward passage of intestinal contents-i.e. Gas, digestive juices and food.

Epidemiology

• Although exact countrywide figures may not be available, it is an established fact that AIO is by far one of the commonest surgical emergencies.

Classification

• AIO is usually of the dynamic type- where peristalsis is working against a mechanical obstruction.

• AIO is classified based on the (A) site or (B) nature of Obstruction.

The intestines

Classification

A. Site of Obstruction1. High IO- near the ampulla- jejunum and

proximal ileum.

2. Low IO- distal to the ampulla- distal ileum and colon.

Ampulla of Vater

Classification

B. Nature of Obstruction1. Simple Obstruction- the bowel lumen is occluded ,blood

supply however remains intact. The source of obstruction is usually intra-abdominal. ( Eg. Intra-abdominal adhesions, very rarely gallstones, ball of worms, bezoars).

2. Strangulation- the bowel lumen together with its blood supply is cut-off. Eg. Strangulated inguinal hernias. Pure strangulation without bowel luminal narrowing is usually due to mesenteric embolism/thrombosis.

Classification

3. Closed loop obstruction- The bowel is obstructed both proximally and distally. Here the blood supply may be impaired.A classic example is seen in an obstruction of the colon with a competent ileo-caecal valve.NB: All the 3 types spoken about can occur at the same time for example in a strangulated inguinal hernia.

Closed loop obstruction

Other types of intestinal Obstruction

-Chronic Obstruction-Usually seen in large bowel obstruction. The symptoms may arise from the cause and the subsequent obstruction.-Acute on Chronic Obstruction- sudden obstruction in a previously incomplete obstruction.Sub-acute Obstruction- There is a partial obstruction.

Pathophysiology

Irrespective of the aetiology or acuteness of onset, the proximal bowel dilates and develops altered motility. The distal bowel exhibits normal peristalsis and absorption until it becomes empty, contracts and becomes immobile.

Pathophysiology

The proximal distension is due to i) Gas- produced by an overgrowth of aerobic and anaerobic organisms, 90% of which is nitrogen, and then hydrogen sulphide.ii) Fluid- accumulation of digestive juices and intraluminal secretions from the bowel wall as a result of increased intraluminal pressure and venous congestion.

Pathophysiology

Strangulation: The viability of the bowel becomes compromised, and severity depends on the length of bowel involved.The first to suffer is the venous system, before the arterial system.Subsequently, there is sequestration of large quantities of blood, fluid, together with multiplying bacteria into the bowel wall, peritoneum and circulation with resultant effects.

Pathophysiology

Once the arterial circulation is affected, there is the risk of gangrene in as little as 6 hours, with subsequent perforation and florid peritonitis.

Closed Loop: With proximal and distal obstruction, faeces, gas and fluid build up very rapidly with subsequent perforation and peritonitis.

Causes

A. Intraluminal-Faecal impaction-8%-pedunculated tumours/carcinoma- 15%-Rarely- foreign bodies/ball of ascaris worms

B. Intramural-Inflammatory-15% ( Crohns, diverticulitis, ileo-caecal TB ).-Atresias and anorectal anomalies-Intussusception-Aganglionic megacolon

Ball of Ascaris worms

Causes

C. Extramural - Strangulated external hernia- 12%-Adhesions- 40%-Volvulus

Clinical presentation

The clinical presentation varies according to;- The location of the obstruction- The age of the obstruction- Underlying pathology- Presence or absence of intestinal ischaemia.

Clinical presentationThere are however 4 cardinal features.1. Abdominal pain2. Distension3. Vomiting4. Absolute constipation; this may not apply in -Richter’s hernia-gallstone obturation-mesenteric vascular occlusion-Obstruction associated with pelvic abscess-Partial obstruction ( faecal impaction/colonic neoplasms in which case diarrhoea may even occur ).

Clinical presentation

Other manifestations include;1. Dehydration- seen early in small bowel obstruction.2. Electrolyte imbalance- hypokalaemia,

hypochloraedia, metabolic acidosis/alkalosis.3. Pyrexia- this may signify the onset of ischaemia,

intestinal perforation or inflammation associated with the obstructing disease. Hypothermia may indicate septic shock.

4. Peristaltic movement from left to right.

Causes of death

1. Shock- hypovolaemia/endotoxic2. Electrolyte and metabolic imbalances3. Peritonitis4. Septicaemia5. Renal failure6. Respiratory failure

Management

A. Investigations(i) Supportive- FBC, BUE+Cr. Other investigations may be requested on the basis of clinical suspicion.

(ii)Diagnostic -Plain abdominal x-rays- Erect and Supine-CXR-Enema-Endoscopic techniques

Erect and Supine X-rays

Large Bowel Obstruction

ManagementTreatment(i) Supportive-Resuscitation including fluid and electrolyte replenishment.-NG tube insertion.-Urethral catheterisation-Pain medication-pethidine/morphine-Broad spectrum antibiotics

(ii) Conservative treatment-is useful in simple obstruction. This should be quickly abandoned in the presence of increasing distension, worsening abdominal pain, rising pulse

Management

SurgeryTiming is based on the clinical picture. The type of surgical procedure- adhesiolysis- hernia repair- Laparotomy - Endoscopic decompression

Conclusion

• AIO is a surgical emergency• Adequate resuscitation and monitoring is key

to keeping patients alive.• Conservative management should be

promptly abandoned within 72 hours or less if patient is not improving.

Acknowledgement

• God Almighty• Bailey and Love’s Short practice of surgery,25th

edition.• Principles and practices of surgery,4th edition.• Dr. Kofi Semua Ayensu