Large Bowel Obstruction

You are the general surgery CT1 asked to see a 75-year old gentleman who has presented with 2-week history of constipation and 2-day history of being unable to pass wind. He has back pain and has been taking regular codeine without laxatives.  

Example answer introduction
In this scenario I would be most worried about a large bowel obstruction, although my differentials will include constipation, paralytic ileus and lower GI malignancy. I would assess this patient using an A-E approach, take a focused history and perform an abdominal examination. I would arrange further investigations to confirm my diagnosis depending on my clinical suspicions and escalate the surgical registrar.

Initial Assessment and Simultaneous Resuscitation


On arrival, manage the patient using an A to E approach according to the Advance Life Support algorithm.

  • Airway 

  • Breathing - check oxygen saturations, respiratory rate, listen to chest, assess work of breathing, breathing depth - if concerns  give high flow oxygen 

  • Circulation

    • Pulse, Blood pressure, capillary refill time, mucus membranes, skin turgor, fluid input/output, catheter is septic

    • IV access - large bore and bloods including CRP

    • Give fluid challenge of 250ml crystalloid solution if evidence of shock 

    • If suspecting bleeding, you may need to activate the Major Haemorrhage Protocol

  • Disability - GCS, pupillary response, blood sugar, temperature

  • Exposure - rashes, systemic signs of shock - expose the whole abdomen - there may be clues!!


During this acute phase state remember to provide constant reassessment

Focused history

  • Allergies

  • Medications – Opiates, laxatives, new medications, anticoagulants

  • Past medical history, including previous abdominal surgery, OGDs, smoking and alcohol, psychological, gynaecological

  • Last meal

  • Events leading up to this point - nature of pain, nausea and vomiting, diarrhoea, constipation, weight loss, PR bleeding

Abdominal examination

  • Inspect – Distention, surgical/traumatic scars

  • Auscultate – “Tinkling” bowel sounds

  • Palpate – Tenderness, hernia

  • Percussion – Normal or hyper-resonant

  • Digital rectal examination – obturator hernia, malignant masses, blood – can suggest late strangulation

  • External genitalia - hernia 

Initial Investigations

  • Abdominal x-ray – bowel obstruction, ileus – I would look for dilated loops of bowel.

    • Small bowel has valvulae conniventes, which pass the entire diameter of the bowel.

    • Large  bowel has haustra, is peripherally situated and you can sometimes see faeces

  • Erect chest x-ray – perforated viscus, I would look for air under the diaphragm

Example questions to progress the station



He is emaciated and tells you that he has lost 2 stone in weight over the past 3 months. His abdomen is distended and you feel an ulcerated mass just inside the anal sphincter. Which investigations would you order?

Q1 Answer 

I would the following baseline tests


  • Urine dip – looking for blood, leukocytes, nitrites glucose, ketones

  • ECG 

  • Abdominal x-ray – Evidence of bowel obstruction

  • Erect chest x-ray – Air under diaphragm signifying perforated viscus. 

However finding of an ulcerated mass is concerning for a colorectal malignancy. I would discuss this case with the registrar as he needs a CT Thorax, abdomen and pelvis to assess for malignancy and metastatic spread. He may also be a candidate for further investigations including an MRI pelvis and perineum, flexible sigmoidoscopy or colonoscopy. 

Q2 - How would you manage this patient?

Initial management

  • Adequate fluid resuscitation, correct electrolyte imbalances   

  • Analgesia according to WHO ladder

  • Keep nil by mouth

  • Inform General Surgery Registrar 

  • Prep for theatre – Bloods, P-Possum score, Anaesthetist, Emergency theatres 

  • Keep patient and any relatives informed

  • Document, document, document!!!


Consider discussion with:

  • General surgical registrar

  • Radiologist if required

  • Anaesthetics +/- ICU

  • Theatres

​This is a sensitive topic and care must be taken to manage the patient and relatives. In a busy on-call communication is key as this can be a harrowing time. 

Useful Resources
NICE Colorectal cancer: diagnosis and management. Clinical guideline [CG131]

BMJ Best Practice 
Association of Coloproctology of Great Britain & Ireland (ACPGBI): Guidelines for the Management of Cancer of the Colon, Rectum and Anus (2017)–Surgical Management.
Note: You may need an institutional or personal access to view some of these resources. Your medical education department or local NHS library may be able to help with access.
core surgical training interview

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