Intestinal Obstruction Flashcards
How can we classify IO into two?
- Mechanical Obstruction
- Functional Obstruction
What is the range of clinical manifestations of IO?
Simple Obstruction –> Bowel Ischemia –> Gangrenous Bowel –> Perforation
What is the pathophysiology of IO?
- Collapse of the bowel distal to obstruction with proximal dilatation
- Resulting in gas accumulation and fluid accumulation (impaired absroption from gut leading to sequestration of fluid into the bowel lumen
- Later, proximal bowel dilation increases which compromises venous return, leading to increased capillary pressure with resultant compromised arterial supply causing bowel ischemia
- Bowel undergoes hemorraghic infarction (risk of bacterial translocation into the peritoneal cavity)
- Bowel perforation leading to peritonitis, sepsis and eventual septic shock
Name the 4 cardinal symptoms of IO?
Pain - colicky, centred on umbilicus (small bowel) or lower abdomen (large bowel)
Vomiting
- Proximal SM: Greenish blue, bile stained
- Distal SM: Brown and foul smelling
- Large Bowel: Uncommon to have vomiting
Abdominal Distention - suggestive of large bowel or distal SB; large bowel closed loop obstruction –> RIF bulge that is hyper-resonant
Constipation/Obstipation
What history should be taken?
History of PC
1. Pain - colicky, centred on umbilicus (small bowel) or lower abdomen (large bowel)
2. Vomiting
- Proximal SM: Greenish blue, bile stained
- Distal SM: Brown and foul smelling
- Large Bowel: Uncommon to have vomiting
3. Abdominal Distention - suggestive of large bowel or distal SB; large bowel closed loop obstruction –> RIF bulge that is hyper-resonant
4. Constipation/Obstipation
5. GI Bleeding
6. Bowel Habits
7. Constitutional Symptoms (LOA, LOW, Fever)
Past Medical History
1. Previous pelvic/abdominal surgeries, irradiation
2. Previous IO
3. Previous Hernias, GI Disorders (IBD, Gallstones)
4. Risk factors for Ischemic Bowel
Drug History
1. Loperamide
Family History
1. Cancers
What should be performed on physical examination?
- Vitals - especially signs of dehydration (Hallmark of SBIO)
- General Inspection - Distension, Cachexia, Confusion
- Peripheries - Signs of Dehydration (CRT, Dry Tongue, Lymph Nodes
- Abdomen
- Abdominal Distension
- Scars
- Visible Peristalsis (Severe IO)
- Hernia
- Bowel Sounds (Initially hyperactive, later sluggish or absent; tinkling BS = SBIO
- Succussion Splash & Epigastric Tenderness: Gastric Outlet Obstruction - DRE - Intraluminal Mass, Impacted Stools, Blood
What are the causes for IO?
Mechanical Causes
- Intra-luminal:
1. Intussusception (SB neoplasm usually as lead point)
2. Impaction
3. Bezoars (PICA Syndrome)
4. Gallstone ileus
5. Foreign Body
6. Parasites
- Intra-mural:
1. Malignancies
2. Strictures (2’ malignancy, inflammatory conditions, anastomoses, ischemic)
3. Congenital Malformations or Atresia
- Extra-mural
1. Intraperitoneal bands and adhesions
2. Hernia
3. Volvulus
4. Peritoneal Carcinomatosis
5. SMA Syndrome
Functional Causes
- Absent Peristalsis
1. Paralytic ileus
- 2’ to postoperative ileus, infection, infarction, reflex ileus (Trauma, spinal cord injury > T5), metabolic
2. Pseudo-obstruction
- Acute: Toxic Megacolon or Oglivie Syndrome
- Chronic: Hirschprung Disease, Paraneoplastic (SCLC), Infection (Chagas’ Disease)
What is the pathophysiology of SMA Syndrome? What is the treatment?
Rapid weight loss leading to the loss of duodenal fat pad resulting in narrowing of the aorto-mesenteric angle and obstruction of duodenum as it passes under the SMA.
Medical (i.e., bowel rest, gastric decompression, nutritional support with IV TPN) or surgical (duodenojejunostomy)
What is the diagnostic criteria for toxic megacolon?
- Radiological evidence of colonic distention + (3 or more of:)
a. Fever
b. HR > 120bpm
c. Neutrophil > 10,500/uL
d. Anemia
+ one of:
a. dehydration
b. altered sensorium
c. electrolyte disturbance
d. hypotensiom
What is Oglivie Syndrome? What is the pathogenesis? Clinical Features? Treatment?
Colonic Pseudo-obstruction. An acute gross dilation of the colon (usually cecum, right and transverse colon > 10cm) without a mechanical cause.
Unknown. Likely due to ANS impairment a/s underlying disease:
a. Trauma
b. Electrolytes (Hypo-Ca, Na, K, Mg, PO4)
c. Drugs (Ca Channel Antagonists, Narcotics, Anticholinergics, TCAs, Steroids)
d. Infections (Pneumonia/Sepsis)
e. Cardiac (MI)
f. O&G (C-Sect, Spinal Anesthesia during childbirth)
g. Retroperitoneal (Malignancy/Hemorrhage)
h. Surgery (Pelvic/Abdominal/Ortho)
i. Others (Neurological Conditions)
Nausea, Vomiting, Abdominal Pain, Constipation/Diarrhoea. Distension. Diagnosis of Exclusion.
Conservative Rx first.
- Treat underlying condition.
- Review Medications,
- Supportive Therapy (NMB, NGT, Rectal Tube, Strict IO Charting, IDC),
- Check and replace electrolyte abnormalities,
- stool culture/C.diff (if diarrhea)
- Serial PE
- Daily AXR
- KIV Gastrografin to ensure no mechanical cause
2nd line.
- Neostigmine
3rd line.
- Colonoscopy Decompression/ Surgical Intervention
– If bowel viable: Decompressive cecostomy tube
– If ischemic/perforated: Bowel Resection
What are the classifications for IO?
- Anatomical
- SBIO (High or Low)
– High: Vomiting occurs early is profuse with rapid dehydration. Distension is minimal.
– Low: Pain predominant with central distention. Multiple central fluid level seen on AXR.
- LBIO.
– Pain mild and vomiting and dehydration is late.
– Distension early and pronounced.
– Proximal colon & cecum distended (competent ileocecal valve).
– Present with constipation and obstipation. - Clinical
- Acute. More SBIO
- Chronic. LBIO, constipation and/or obstipation followed by distension and abdominal colic
- Acute on Chronic. Distension and vomiting against a backdrop of longer standing pain and constipation.
- Sub-acute. Attacks of colic relieved by passing flatus or feces - incomplete obstruction. - Pathological Classification.
- Simple Loop Obstruction. Partial or Complete.
– Partial. One obstructive point, symptoms not as severe, may still be passing flatus
– Complete. One obstructive point, marked symptoms of N/V, distension and constipation.
- Closed Loop Obstruction. Obstruction at 2 points forming a loop of grossly distended bowel. Pain, guarding, tenderness, absence of dilated small bowels. (Surgical Emergency)
What are the causes of a closed loop obstruction?
- Obstructing large bowel lesion (i.e., colonic tumour, bowel stricture) with competent ileocecal valve
- Peritoneal carcinomatosis with obstruction at two points
- Sigmoid volvulus with competent ileocecal valve
- Herniation of Bowel
What are the investigations for IO?
Biochemical.
1. FBC.
2. RP. Any electrolyte imbalances from acute renal failure 2’ dehydration
3. ABG. Acidosis from bowel ischemia
4. Lactate. Important in suspected ischemic bowel
5. ESR/CRP/Procalcitonin.
6. Blood Cultures. If fever, tachycardia, hypotension.
7. Amylase. ? acute pancreatitis
Imaging.
1. Erect CXR. Free air under diaphragm, any aspiration pneumonia
2. Erect AXR: 5 or more air fluid levels, (air-fluid levels are proportional to degree of obstruction and to its site)
3. Supine AXR: Look for dilation (Duodenum C-Shaped; Jejunum: Dilated small bowel >3cm, stack-of-coins appearance (plicae circularis/valvulae comniventes); distal ileum: featureless; colon: dilation of cecum >9cm or colon >6cm; Complications: Rigler’s Sign/Double-Wall Sign = Pneumoperitoneum OR Thumb-print Sign/Pneumatosis Intestinalis = Ischemic Bowel
4. XR KUB. Look for rectal gas (r/o if complete IO)
5. CT AP
- Done to: identify transition point, severity of obstruction, any fecalisation in SB proximal to transition, closed-loop obstruction
- Look for: target sign (intussception), Whirl sign (rotation of SB mesentery in volvulus), Air in distal bowel with no transition point - paralytic ileus.
6. Water Soluble Contrast (Gastrograffin meal & follow-through)
- Done to: differentiate between patients who will settle with non-operative management vs those who will require surgery
– Appearance of water soluble contrast in the colon on AXR within 24h predicts resolution of adhesive SBIO
For a sigmoid volvulus, how does it present on X-Rays and with Gastrografin enema. To who do these occur commonly?
Massive colonic distension with dilated loop of bowel running diagonally across the abdomen from right to left. Loop pointing to RUQ. Coffee Bean Sign. Bird’s Beak.
Older, institutionalised patients with neurological disorders and chronic constipation.
What happens in Cecal volvulus? How does it present on X-Rays? What is the pathophysiology? What are its two variants? What is the treatment?
Gas filled ileum and distended cecum, with rotation occuring around the ileocolic blood vessels and vascular impairment occuring early (risk of colonic closed loop obstruction with higher risk of ischemia).
Loop pointing to LUQ. Congenital.
Axial Torsion vs Cecal Bascule Type.
Rught hemicolectomy with ileocolic anastomosis (cecal volvulus cannot be detorted endoscopically).
What is the acute management of IO?
- Rule out surgical emergencies
- Ischemic Bowel with Bowel Necrosis - pneumatosis intestinalis
- Perforation/peritonitis
- Obstructed and Strangulated Abdominal Hernia
- Volvulus
- Closed-loop obstruction - Initial Management
- ABCs
- NBM
- NG Tube (Low intermittent suction)
- IV Resus (Hartman’s) (account of maintenance + deficit + ongoing losses)
- Urinary catheterisation to monitor urine o/p which helps assess hydration status
- Correct electrolyte abnormalities
– RP : Urea: Creat ratio >100:1 = prerenal dehydration; <40:1 suggests intrinsic renal damage
– correct acidosis, replace electrolytes as guided by investigations
- Prophylactic Abx +/-
- IA line/ CVP for monitoring +/- - Definitive Management
- Ischaemic bowel: Exploratory laparotomy with bowel resection if bowel is non-viable (gangrenous or necrotic)
- Bowel Perforation: Exploratory laparotomy: resect lesion & perforated bowel with generous peritoneal lavage (i.e. 10L of wash)
- Closed loop obstruction from left sided tumour: Colonic Stenting vs. Emergency Laparotomy +/- stoma
- Obstructed Inguinal / Femoral hernia: Exploratory Laparotomy +/- bowel resection if ischemic bowel is present
- Intussusception
▪ Children: usually due to hypertrophic Peyer’s patches. Administer air or barium enema: watch intussusception reduce on fluoroscopy
▪ Elderly: usually a/w malignant pathological lead point (i.e. polyp, cancer) in 30-50% of the cases. Barium enema unlikely to work, or if works recurrence rate is high, therefore surgery is 1st line treatment
- Caecal Volvulus: Right hemi-colectomy with primary ileocolic anastomosis is the surgical procedure of choice (caecal volvulus almost never able to be detorsed endoscopically)
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