Wee 4/5 - H - Bowel obstruction - adhesion/hernia,/volvulus/tumour/stricture/bolus/intussusception/strangulation/adynamic

Question 1

Let’s talk about the presentation, diagnosis and management of bowel obstruction Any part of the GI tract may become obstructed and present as an acute abdomen. What happens to the bowel proximal to the obstruction?

Answer 1

There is dilatation of the bowel proximal to the level of obstruction with air and fluid

Question 2

We have talked about small bowel obstruction in a previous set of cards so this shall mainly focus on large bowel obstruction Initially however, lets summarise some some bowel obstruction facts * What are the main causes of small bowel obstruction? * What are other less common causes?

Answer 2

Small bowel obstruction - the two main causes occur outside of the bowel Main causes is intra-abdominal adhesions followed by hernias * Other causes are rarer andoccur either within the lumen or within the gut wall * Within the lumen - food / bezoar, gallastone ileus * Within the gut wall - tumours, crohn’s, radiation

Question 3

What is the typical presentation of small bowel obstruction? What may be seen on examination?

Answer 3

ACUTE PRESENTATION * Distention * Vomiting * Borbogymi -rumbling of the stomach (typical sound heard when hungry) * Pain * Faeculent vomiting On examination, may see abdominal scars indicating previous surgery and increases risk of adhesions Also look for both femoral and inguinal hernias

Question 4

How is small bowel diagnosis confirmed?

Answer 4

Usually will involved an Abdominal XRay CT scan of abdomen - gastrografin studies (a radiographic dye) may help confirming the site of the obstruction

Question 5

How is AXR able to differentiate between small and large bowel obstruction?

Answer 5

Small bowel obstruction - will show central gs shadows with valvulae conniventes (plicae circularis) that completely cross the lumen Large bowel obstruction - will show peripheral gas shadows, proximal to the blockage (ie in caecum bt not in rectum)

Question 6

Adhesional small bowel obstruction resulting from previous surgery is treated conservatively in the first instance, with a success rate of around 80% What is the management of small bowel obstruction caused by adhesions?

Answer 6

MANAGEMENT Usually conservative - DRIP AND SUCK method Start IV fluids and correct any electrolyte disturbances (‘drip’) Make the patient nil-by-mouth (NBM) and insert a nasogastric tube to decompress the bowel (‘sucks out air and fluid to relive abdominal swelling’) Urinary catheter and fluid balance Analgesia as required with suitable anti-emetics

Question 7

Why do you not want to carry out surgery for adhesional small bowel obstruction? How long can drip and suck usually be continued up until? Does the drip and suck method treat hernias?

Answer 7

As far as prevention of adhesional small bowel obstruction is concerned, best approach is to avoid operation as any surgical procedure predisposes to adhesions Drip and suck method only treats adhesional small bowel obstruction -up to 72 hour is standard Hernias cannot be treated with drip and suck and usually require reduction - manually - to prevent stangulation and necrosis and if problematic surgical reduction

Question 8

When should you surgically intervene in a patient with small bowel obstruction?

Answer 8

Intervene with emergency surgery if there is a strangulation of the bowel as this can cause ischemia and necrosis Also intervene if there is small bowel perforation

Question 9

What is the surgical management of an obstructed small bowel - carried out if suspecting strnagulation or perforation? What type of incision? Which drugs are given?

Answer 9

Surgical management of small bowel obstruction is usually via a laparotomy using a midline incison Antibiotics and antithromboembolic measures are also taken

Question 10

LARGE BOWEL OBSTRUCTION How does the rate at which vomiting occurs in GI tract obstruction relate to where the obstruction is? Will vomiting still occur even if the patient has / is not eating anything?

Answer 10

The more proximal the obstruction, the earlier vomiting develops. Can occur even if nothing is taken by mouth: GI secretions continue to be produced – Saliva, gastric , pancreatic, bile, small intestine (up to several litres per day).

Question 11

The nature of the vomiting gives clues to the level of the small bowel obstruction What kind of vomiting is seen if it is * A gastric outlet obstruction? * Upper small bowel obstruction? * More distal small bowel / large bowel obstruction?

Answer 11

Gastric outlet obstruction - semi-digested food eaten a day or two previously however no bile Upper small bowel obstruction - copious bile stained fluid (green or yellow) Distal small bowel / large bowel obstruction - thicker, brown, foul smelling vomitus (Faeculent)

Question 12

What are the different presenting features of small bowel vs large bowel obstruction? Why do intermittent episodes of colicky pain occur?

Answer 12

Small bowel obstruction usually presents with early vomiting, distension is less and pain is higher in the abdomen eg umbilical Large bowel obstruction presents with later vomiting, more constant pain and greater distension, more pronounced constipation Intermittent episodes of colicky pain occur as peristalsis attempts to overcome the obstruction.

Question 13

Constipation How is constipation defined by the Rome IV criteria?

Answer 13

Constipation is a common primary functional disorder of the bowel but may, of course, develop secondary to another condition. * ROME IV criteria - defecation that is unsatisfactory because of infrequent stools ( Often passes with difficulty (with straining or discomfort), or seemingly incomplete defecation.

Question 14

What is absolute constipation? What is it pathognomonic of?

Answer 14

Absolute constipation is pathognomonic of bowel obstruction - neither faeces of flatus is passed rectally

Question 15

Consitpation alone often does not advocate further investigation but when occurring with different symptoms, doctors will wan to rule out major pathology What could constipation + rectal bleeding make you suspicious of? What could constipation + distension + active bowel sounds make you suspicious of?

Answer 15

Constipation + rectal bleeding - think possible malignancy Constipation + distension + active bowel sounds - maybe a GI stricture eg Crohn’s or GI obstruction

Question 16

Back to large bowel If the ileo-caecal valve remains competent (50% cases) backward flow of accumulated bowel contents is prevented . What will happen in this case? Why may it be an emergency?

Answer 16

When the ileo-caecal valve remains competent in large bowel obstruction - this will cause the thin walled caecum to become progressively distended with swallowed air and fluids secretions from the GI tract This can potentially lead to rupture - it is known as a closed loop obstruction

Question 17

If the bowel is only partially obstructed, the clinical features may be less clearly defined. Vomiting may be intermittent and bowel habit erratic. What can chronic incomplete obstruction lead to? What is responsible for the colicky pain in this type of obstruction?

Answer 17

Chronic incomplete obstruction can lead to gradual hypertrophy of the muscle of the bowel wall proximally Peristaltic activity in this hypertrophic muscle is responsible for bouts of colicky pain which can be more prominent that in complete obstruction

Question 18

We know that both small and large bowel obstruction can present with pain in the abdomen (more common in large) If the pain is sharp, localised pain and associated with peritonism ( acute abdominal pain, abdominal tenderness, abdominal guarding), what is indicated?

Answer 18

When there is sharp, localised pain and peritonsim this may indicate strangulation of the bowel - urgent surgery required to prevent ischaemia and necrosis

Question 19

What is the most useful sign in the investigation of a suspected bowel obstruction? What is seen?

Answer 19

Most useful investigation is a supine AXR. Bowel proximal to the obstruction is distended with gas Small bowel - distended small bowel loops lie central and have vulvulae coniventes (completely across lumen) Large bowel - distended bowel is perpheral and has hasutraations (not completely across)

Question 20

What is often subsequently performed to confirm the diagnosis and look for a cause? What is the cut off/transition point that is seen on this scan on bowel obstruction?

Answer 20

CT scan is often subsequently performed to confirm the diagnosis and look for a cause. Transition point on CT scan with distended bowel proximal and collapsed bowel distal to the site of obstruction.

Question 21

What are the principles of the initial management of a bowel obstruction? (small or large)

Answer 21

Nil by mouth DRIP AND SUCK * Insert IV cannula and prescribe fluids to rehydrate and correct electrolyte imbalance * Pass a nasogastric tube to decompress the stomach - removing excess air For hernia, will need to manually move the bowel SURGERY IF neither of these work

Question 22

There are many different causes of bowel obstruction - we are going to discuss the mechanical causes What are the two most common causes of small bowel obstruction?

Answer 22

Intra-abdominal adhesions (congenital or resulting from previous abdominal surgery or peritonitis. ) or Hernia (incarcerated hernia)

Question 23

What are the common causes of large bowel obstruction? What are the rare causes of both small and large bowel obstruction?

Answer 23

Common causes of large bowel obstruction * Colon carcinoma * Constipation * Diverticular stricture * Volvulus - sigmoid or caecal Rare causes of both - * inflammatory strictures (crohn’s), * Bolus obstuction - food bolus, impacted faeces (EVEN RARER - gallstone ileus and bezoar) * Intussuception

Question 24

What is volvulus? Where are the two common places it can occur?

Answer 24

Volvulus occurs when a mobile loop of bowel rotates causing obstruction at its neck Can happen in the small or large bowel Commonly either caecal or sigmoid volvulus

Question 25

Which patients are sigmoid volvulus more likely to occur in? Which patients are caecal volvulus more likely to occur in? What is the main worry with volvulus?

Answer 25

Sigmoid volvulus more likely to occur in edlerly, constipated patients with co-morbidities Caecal volvulus associated with all ages, maybe more common in pregnant women The worry is rapid, severe, strangulated bowel obstruction

Question 26

How is volvulus diagnosed? What is the sign seen on this scan known as? What else may been?

Answer 26

Diagnosis of volvulus (looks like a coffee bean) usually diagnosed on the abdominal xray - plain film caecal volvulus: small bowel obstruction may be seen and coffee-bean sign sigmoid volvulus: large bowel obstruction (large, dilated loop of colon, often with air-fluid levels) + coffee bean sign

Question 27

What are the two causes of inflammatory strictures that can cause bowel obstruction? Are the obstructions usually complete or incomplete?

Answer 27

Two causes Diverticular stricture - usually post-infection - this is the most common stricture cause Crohn’s stricture

Question 28

Bolus obstructions causin a bowel obstruction are rare What are the different causes of bolus obstruction causing bowel obstruction?

Answer 28

* Food bolus obstruction * Impacted faeces * Impacted gallstone ileus - rarae - due to fistulation into duodenum (RARE) * Trichobezoar - A trichobezoar is a bezoar (a mass found trapped in the gastrointestinal system) formed from the ingestion of hair. (RARE)

Question 29

What is intussusception?

Answer 29

Intussusception describes the invagination of one portion of bowel into the lumen of the adjacent bowel, most commonly around the ileo-caecal region - telescoping of the bowel

Question 30

What age group does intussusception occur in? What are the symptoms of intussusception?

Answer 30

It is the most common cause of intestinal obstruction in children usually occurring less than 2 years old Child may present with * Episodic intermittent inconsolable crying with drawing of the legs up * vomiting * bloodstained stool - ‘red-currant jelly’ - is a late sign * sausage-shaped abdominal mass may be palpated

Question 31

What is the diagnosis and management of intussusception?

Answer 31

Intussusception is uaully diagnosed with ultrasound scan and teated with an air enema

Question 32

What is bowel strangulation? What will happen if strangulation is not relieved?

Answer 32

Strangulation occurs when a segment of bowel becomes trapped so that its lumen becomes obstructed (incarcerated) and its blood supply compromised (strangulated) * Venous return becomes obstructed -> * rising local intravacular pressure subsequently compromises arterial inflo If strangulation is not relieved, this will progress to infarction and peforation

Question 33

What is the management for bowel strangulation? When is it usually expected?

Answer 33

Strangulation management - urgent surgical intervention Often suggested by pain over a hernia

Question 34

Adynamic ileus is the failure of passage of enteric contents through the small bowel and colon that are not mechanically obstructed. Essentially it represents the paralysis of intestinal motility. What are the two terms that describe this?

Answer 34

Paralytic ileus and Pseudo-obstruction

Question 35

What is paralytic ileus and when does it occur?

Answer 35

Paralytic ileus is the disruption of normal propulsive activity of the GI tract, due to failure of peristalsis * Paralytic ileus is a common complication after surgery involving the bowel, especially surgeries involving handling of the bowel Paralytic ileus can also occur in association with chest infections, myocardial infarction, stroke and acute kidney injury and electrolyte abnormalities

Question 36

What are the signs and symptoms of paralytic ileus? What is the treatment?

Answer 36

SIgns and symptoms of paralytic ileus are similar to bowel obstruction eg abdo distension, N&V, no flatus or bowel movements - however pain, and high pitched bowel sounds are less common Treatment is - drip and suck while waiting for restoration of peristalsis

Question 37

What is the syndrome known as where there is acute colonic pseudo obstruction? What is it associated with?

Answer 37

Acute obstruction and hence dilatation of the colon in the absence of colonic obstruction in acutely unwell patients. is known as Ogilvie’s syndrome

Question 38

What conditions is Ogilvie’s syndrome associated with?

Answer 38

Hip replacement surgery Coronary Artery Bypass Grafts Spinal fracture Pneumonia Frail / elderly patients

Question 39

How is Ogilvie’s syndrome diagnosed?

Answer 39

AXR +/- CT scan will reveal gaseous distension of the bowel to distal rectum

Question 40

What is the treatment of Ogilvie’s syndrome? What drug has recently been licensed for use?

Answer 40

DRIP and SUCK method If fails -> colonoscopic decompression is usually effective - also allows for exlcusion of mechanical causes Neostigmine - recently been seen as effective (used in the treatment of myasthenia gravis -It works by blocking the action of acetylcholinesterase and therefore increases the levels of acetylcholine) - its effectiveness suggests there may be parasympathetic suppression to blame for this syndrome