6. Bowel Obstructions Flashcards
What is a typical presentation of a patient with an obstructed bowel?
Differentiate between an obstruction and ileus.
What can you see in the abdo-pelvis XR below?
Abdo pain, distension, absolute constipation (no bowel movements or flatus), vomiting, hyperactive bowel sounds
Obstruction: mechanical blockage arising from structural abnormality that presents as a physical barrier to progression of gut contents. Can be partial/complete and simple/strangulated
Ileus: paralytic/functional variety of obstruction
Dilated bowel loops, jejenum-ileum obstruction because looks like stack of coins (if it was large bowel would see haustra)
What might happen if a mucosal barrier is breached and enteric bacteria (coliforms, anaerobes and strep. faecalis) get translocated?
Describe the pathophysiology of obstruction.
How would you correct these occurances?
Bactaeremia, septaecemia, toxaemia.
Increased peristalsis overcomes obstruction -> increased intraluminal pressure by fluid + gas -> vomiting -> sequestration of fluid into lumen from surrounding circulation -> lymphatic + venous congestion resulting in oedematous tissues -> hypovolaemia + electrolyte imbalance -> localised anoxia, mucosal depletion necrosis and perforation + peritonitis -> bacterial overgrowth with translocation of bacteria and it’s toxins -> bacteraemia + septicaemia
Decompress with NGT, replace lost fluid, correct electrolyte abnormalities, recognise strangulation and perfusion, systemic abx
List luminal, mural and extraluminal causes of small bowel obstruction.
What are small bowel adhesions?
What are hernias?
Luminal: foreign body, bezoars, gallstone, food particles, A. lumbricoides
Mural: neoplasms (lipoma, polyps, leiyomayoma, hematoma, lymphoma, carcimoid, carcinoma), Crohn’s, TB, stricture, intussecption, congenital
Extraluminal: post-op adhesions, congenital adhesions, hernia, volvulus
Scar tissue - fibrous bands. 60-70% SBO, results from peritoneal injury, platelet activation and fibrin formation.
20% of SBO, commonest: femoral, inguinal, umbilical. Ischemia initially, then venous occlusion, oedema and arterial compromise. Strangulation: persistent pain, discolouration, tenderness, consitiutional sx
How would you distinguish between small and large bowel obstructions?
Why is CT important for demonstrating abnormalities in bowel walls, mesentery, mesenteric vessels and peritoneum?
Why is barium/gastrografin contrast media used, and when should bariuim not be used?
Large: peripheral (diameter 8cm max), haustration
Small: central (diameter 5cm max), vulvulae coniventae (plicae), ileum - may appear tubeless [Pic - L = LB, R = SB]
Can define level/degree of obstruction, cause (volvulus/hernia/luminal/mural), degree of ischaemia, and free fluid/gas. Triple contrast: IV, oral and rectal
May be able to define level and mural causes, distinguish adynamic and mechanical obstruction. Barium SHOULD NOT be used in a pt with peritonitis
What lab/radiological/other investigations would you do for a patient with suspected bowel obstruction?
How would presentation differ depending on the area of obstruction (high, distal small bowel, colonic)?
Lab: FBC (WCC, anaemia, hematocrit, plts), clotting profile, ABG, U + Crt, Na, K, amylase, LFT, glucose, LDH, G+S
Radiological: plain XR, USS (free fluid, masses, peristalsis pattern, doppler of vasculature etc.), other = CT, MRI, contrast studies
Other: ECG etc. for comorbidities
[Pic]
What would be the initial ER management of a patient with bowel obstruction?
What are the indications for surgery?
What general, abdominal and systemic examinations (if necessary) might you do for a patient with a suspected obstructed bowel?
Resus (airway, lines, IVF - crystalloids), bloods for lab, alert senior, NBM, decompress with NGT and secure, urinary catheter + input/output chart, IV abx, follow up lab results and correction of electrolyte imbalance
Immediate: strangulation evidence, peritonitis resulting from perforation/ischemia. In 24-48h: no resolution of obstruction, dx unclear + virgin abdo
[Pic]
What conditions is an ileus associated with?
Differentiate between examination/radiographic features of an ileus vs obstruction.
Post-op and bowel resection. Intraperitoneal infection/inflammation. Ischemia. Extra-abdo: chest infection, MI. E__ndocrine: hypothyroidism, DM. Spinal and pelvic fractures. Retro-peritoneal haematoma. Metabolic abnormalities: hypokalaemia/natremia, uraemia, hypomagnesemia. Bed ridden. Drug induced: morphine, TCAs
Ileus: gas diffuse through intestine, quiet abdomen, diffuse discomfort and no sharp colicky pain, diffusely dilated bowel on radiograph, distension
Obstruction: intestinal loops + thickened plicae near obstruction and little/no gas after obstruction, crampy pain, high pitched tinkling sounds, localised tenderness
Describe the following:
a) right hemicolectomy
b) extended right hemicolectomy
c) transverse colectomy
d) sigmoid colectomy
e) Hartmann’s (proctosigmoidectomy)
a) Remove R side of colon, attach small intestine to remaining portion of colon (ileocolic anastomosis)
b) right colon and portion of transverse colon removed, then ileocolic anastomosis
c) transverse colon removed, anastamosis between remaining parts of colon
d) removal of sigmoid colon, anastomosis to join remaining L colon and top of rectum
e) resection of rectosigmoid colon with closure of anorectal stump and formation of an end colostomy
Describe 4 types of stomas.
Paralytic ileus may occur 2-3 days post op - what are some features?
What might cause a paralytic ileus?
How would you manage it?
- *1) Ileostomy:** brings ileum out to surface. Loop (temporary) or end, spouted
- *2) Colostomy:** brings colon out to surface. Loop or end, non-spouted
- *3) Mucous fistula:** stoma which allows mucus to be collected in an ostomy bag
- *4) Ileal conduit:** system of urinary drainage using the small intestine after bladder removal
Pain free, abdo distension, bowel sounds absent
Laparotomy, inflammation (e.g. pancreatitis), thoracic conditions (e.g. pneumonia), systemic disorders (e.g. sepsis, hypokalaemia), drugs (e.g. opiates, CCBs)
Mx: rule out mechanical causes, drip and suck (fluids and correct electrolyte imbalances, NG tube), usually resolves spontaneously in 2-4 days
What is Ogilvie’s syndrome?
What are some risk factors and how is it treated?
Acute colonic pseudo-obstruction - colonic obstruction in the absence of a mechanical cause, associated with recent severe illness/surgery and elderly. Symptoms and signs of bowel obstruction.
Risk factors: chest infection, MI, stroke, renal failure, electrolyte disturbances
Tx: correct U&E, colonoscopy allows decompression and excludes mechanical causes. Neostigmine = effective. Surgery rarely needed
