Large Bowel Obstruction

Scenario

You are the CT1 on call for general surgery. You are asked to see a 70 year old male in A+E with a 2 day history of constipation, abdominal pain and distension. He has a history of previous diverticulitis requiring hospital admission, HTN, IHD. 

Observations: 

Respiratory rate 19

Oxygen saturation 99% on RA

Heart rate 102 BPM

Blood pressure 125/65 mmHg

Temperature 36.0 C

GCS 15/15

How would you initially assessment this patient? 

A-E Approach using CRISP Principles:

Airway:

• Ensure patent airway with 15L non-rebreather mask. 

Breathing:

• Evaluate central trachea, equal chest expansion, and percussion.

• Perform focused respiratory examination 

• Assess oxygen saturation, respiratory rate

• Perform arterial blood gas analysis and CXR if desaturating

Circulation:

• Check heart rate, blood pressure, and heart sounds.

• Check JVP

• Perform ECG as tachycardic

• Bloods including FBC, U&Es, LFTs, Clotting and X-match

• VBG for lactate (if not performing ABG)

• Urine output and fluid chart

 Disability:

• Assess GCS, glucose levels, and pupil response. 

• AVPU

Exposure:

• Abdominal examination  establish whether patient is peritonitic (see below for examination)

• PR ?empty rectum

• Assess wound

• Look for signs of DVT / cellulitis of lines

Escalate  as appropriate to seniors following initial A-E assessment 

Review history, previous notes, medications and escalate to senior early to inform

What are your differential diagnoses? 

Differentials include:

• Large bowel obstruction

• Small bowel obstruction

• Volvulus

• Ileus / pseudo-obstruction

• Diverticular disease

In this patient the features of absolute constipation, abdominal pain and distension without significant vomiting point towards large bowel obstruction. 

What are the four cardinal features of Large Bowel obstruction?

• Constipation

• Abdominal distension / bloating

• Abdominal pain 

• Vomiting (later sign) 

What would you look for on examination? 

Abdominal examination:

• Auscultate for “tinkling bowel sounds” 

• Abdominal tenderness

• Palpate for any masses

• PR  empty rectum

• Presence of caecal tenderness is a useful sign to elicit 

What investigations would you order in this patient? 

• Bedside Tests

• ECG

• Urine Dip / Wound swabs if indicated

• Blood Tests

• ABG/VBG: To evaluate oxygenation status, lactate acid-base balance.

• Bloods: FBCs, U&Es, LFTs, Clotting, CRP 

• Blood Cultures: If concerns about sepsis / pyrexic

• Radiological Investigations

• Chest X-ray: To rule out alternative causes of respiratory symptoms.

• AXR: assess for evidence of SBO / LBO

• CT / Gastrogaffin enema

Debate long surrounds the use of CT versus gastrograffin enemas. Gastrograffin was the traditional method of determining whether a structural lesion is indeed present. However, in the UK the use of this technique has declined and in most units a CT scan will be the first line investigation, this also has the added advantage of identifying a potential tumour and malignancy staging. 

His AXR comes back please interpret the radiograph and give a diagnosis 

An AXR radiograph is presented in a 70 year old male. It shows multiple dilated loops of bowel with multiple air fluid levels. The dilatation appears to be consistent with large bowel obstruction given the hausta do not cross the midline. The dilatation appears to be >6cm. This is highly suggestive of large bowel obstruction. 

How do the presentation and X-ray of small and large bowel obstruction differ? 

What are the main causes of large bowel obstruction?

• Neoplasm (60%)

• Diverticular Strictures (20%)

• Adhesions

• Volvulus (e.g. sigmoid / caecal)

• Incarcerated hernias

Note: LBO is less common than SBO. Pseudo-obstruction is a potential differential. 

What is the initial management of large bowel obstruction?

Initial treatment involves a “Drip and suck” method:

• IVF resuscitation 

  • Electrolyte disturbances corrected 

• NBM

• NG Tube 

  • Aspirate to remove excessive fluid at regular intervals

• Dietician input 

• Analgesia

Patient should then be reviewed with senior (ST3+) for ongoing management decisions. The patient should be monitored closely with ongoing bloods and VBG to monitor for increasing lactate. 

What are the treatment options for LBO? 

“As a general rule the old adage that the sun should not rise on unrelieved large bowel obstruction still holds true”. In practice it depends on patients physiological status, unstable patients require resuscitation prior to surgery and admission to critical care unit for invasive monitoring + potential inotropic support. 

Surgical intervention is offered when:

• When the LBO is unresolving and trial of conservative measures has failed

• Or for complications such as perforation

• A caecal diameter >12cm with competent ilieocaecal valve + caecal tenderness  closed loop obstruction  indicates impending perforation and is a relative indication for prompt surgery

The surgery performed is dependent on the site of the obstruction: 

Right Sided / Transverse Colon

• Right sided hemicolectomy Or Extended right sided hemicolectomy (If involves hepatic flexure / transverse colon)

• In these cases a ileocolic anastomosis can be constructed even in the emergency setting as it has a low risk of anastomotic leak 

Left sided lesions

• Subtotal colectomy

• Left sided hemicolectomy - with Primary anastomosis OR End colostomy

• Hartmann’s procedure - with end colostomy and formation of rectal stump

Recto-sigmoid lesions

• Sigmoid lesions  are amenable to sigmoidectomy (Hartmann’s Procedure) / high anterior resection  

• Lesions below the peritoneal reflection  causing obstruction should generally be treated with a loop colostomy. PRIMARY RECTAL ANASTOMOSES have a HIGH ANASTOMOTIC LEAK RATE

How can the large colon be identified intra-operatively?

HAT

H Haustra

A Epiploic Appendages

T Taenia coli 

What are the taenia coli and epiploic appendage? 

Taenia Coli: 

• Longitudinal outer muscle bands of the colon

• NOT found at the rectum / appendix

Epiploic appendage:

• Small sacs of fat covered in peritoneum and hanging from colon (large bowels)

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