Bowel Obstruction Flashcards
Mechanical Classification of bowel obstruction? (13)
Intra-luminal:
• stool Impaction
• Gallstone “ileus”
• foreign body
• trichobezoars /phytobezoars
Intra-mural
• malignancy, malignant strictures (15%)
• Inflammatory strictures (TB/ chron’s., diverticulitis, radiation colitis) (15%)
•. intestinal atresia
Extra-mural
• intraperitoneal bands and adhesions (40 %)
• Hernia
• volvulus- sigmoid (more common), cecum
• intussusception
• lymph node compression
• superior mesenteric artery syndrome
Anatomical Classification of bowel obstruction and major differences? (3)
Small bowel obstruction
- high: vomiting early and profuse with rapid dehydration; minimal distention
-Low: pain predominant with central distention, multiple central fluid level seen on AXR
Large bowel obstruction
Distension early and pronounced , mild pain; vomiting and dehydration late; proximal colon and cecum distended (competent ileocecal valve)
Pathological Classification of bowel obstruction and major differences? (4)
Simple
• one obstructive point, no vascular compromise
Closed loop
• obstruct at 2 points forming loop of grossly distended bowel, at risk for perforation (tender and perforation usually at cecum)
• >10 cm require urgent decompression
• strangulation → venous compromise → oedema → arterial compromise → gangrene and potential perforation
• causes: volvulus, bowel herniation, tight carcinomatous stricture of colon with competent ileocecal valve.
3 most common causes small bowel obstruction?
- Adhesions
- Hernias
- Malignancies (but still rare)
3 most common causes large bowel obstruction?
- Cancer
- Volvulus
- Diverticular
4 cardinal symptoms of bowel obstruction and differences between higher and lower obstruction?
- Pain
• visceral colicky pain centered on umbilicus (small bowel) or lower abdomen ( large bowel)
• complete obstruction = constant sharp pain
• volvulus = sudden severe pain
• paralytic ileus = no pain
2 vomiting
• high small bowel = green- blue, bile stained
• low small bowel = brown, foul smell , feculent
• large bowel: uncommon usually late symptom
- Abdominal distension
• prominent in large intestine distal obstruction
• closed loop = rif (right iliac fossa ) bulge, hyper-resonant
• small bowel: high uncommon esp if vomiting; low central distension
4 constipation (flatus) / obstipation (nothing-complete obstruction)
Name 3 risk factors ischaemic bowel
• Atherosclerotic Rh
• heart disease
•Previous stroke
Findings on xray for bowel obstruction in general?
Erect AXR : air fluid levels
• ≥ 5 = intestinal obstruction diagnostic
• in small bowel, number of air fluid levels directly proportional to degree of obstruction and side (more-distal)
Supine AXR: dilatation of bowel
Investigations for bowel obstruction? (5)
• FBC (infections, anaemia) , uce (dehydration due to intraluminal third space loss or vomiting; acute renal failure from dehydration, k loss can perpetuate paralytic ileus)
• ABG (acidosis from bowel ischaemia; alkalosis from vomiting; lactate anaerobic respiration)
• amylase, lipase (acute pancreatitis)
• erect CXR (free air under diaphragm; aspiration pneumonia )
.Axr to assess obstruction site, severity, source etc
Acute Management bowel obstruction? (6)
• ATLS: especially breathing and spo2- may be affected by splinting of diaphragm (give oxygen)
• ngt suction large bore
• iv rehydration: water , k, cl depletion and correct electrolyte abnormalities
• catheter to monitor output: hydration
• if suspect ischaemic bowel or perforation, give prophylactic antibiotics
• surgical decompression! If bowel ischaemic, unresolved mechanical obstruction , dilation > 10cm large bowel
Treatment post-op paralytic ileus? (2)
> 3 days post op
• supportive: “drip and suck” ( Iv and ngt ), wait for peristalsis to restart
• prokinetics: erythromycin, metoclopramide, cisapride
Treatment sigmoid volvulus? (5)
Non-surgical if stable, no signs perforation or ischaemia and necrosis, no signs peritonitis
• sigmoidoscopic decompression followed by flatus tube insertion
• recur in 50%
• semi- elective sigmoidectomy within the same hospital admission
Surgical
• sigmoid colectomy with primary anastomosis (primary anastomosis only if bowel ends viable, no peritoneal contamination, haemodynamically stable)
• sigmoid colectomy with Hartman’s procedure (can be reversed in 3-6 months)
• sigmoid colectomy and formation of double barrel colostomy (paul-mikulicz procedure) with future re-anastomosis
• sigmoidopexy: fix to posterior abdominal wall (rarely done, high risk recurrence)
Treatment caecal volvalus?
Right hemi-colectomy with primary ileocolic anastomosis (not endoscopic decompression like with sigmoid, not often successful)
Define toxic megacolon
Potentially lethal complication of IBD or infections colitis, characterised by total or segmental non-obstructive colonic dilatation plus systemic toxicity
Clinical features and symptoms toxic megacolon? (2)
• Severe bloody diarrhea
• toxic patient: altered sensorium, tachycardia, fever, postural hypotension, lower abdominal distention/ tender/ peritonitis
