Small Bowel Obstruction

You are the general surgery CT1 asked to see a 60-year old woman with presented with 1-day history of central colicky abdominal pain. Over the past 12 hours she has been vomiting food then bilious liquid. She has not opened her bowels or passed flatus in 3 days. How would you proceed?                                   

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

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, whilst large bowel has haustra

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

Example questions to progress the station

Q1 - She is very tired and tells you she has had a surgery on her tummy in the past, but she can’t remember what they were for. On examination you find she is mildly tachycardic and feel this is due to dehydration. Her abdomen is distended and tender and appears like this. Name the scar in the picture and tell us which operations they may be associated with.

This is a mid-line laparotomy scar. This incision provides access to many general surgical and some vascular operations. Specific operations include...

Q2 - Take us through the X-ray of the patient in this case. 




Q2 Answer: 


This is an AP radiograph of an abdomen without demographic details, taken on xyz date. It shows dilation of the small bowel. I can tell this due the central location of the bowel and the presence of valvulae conniventes. It is dilated as it measures >3cm in diameter. 


Q3 - How would you manage this patient? 

See below

Initial management

  • Adequate fluid resuscitation, correct electrolyte imbalances   

  • Analgesia according to WHO ladder

  • Pass Ryle’s nasogastric tube and check position with pH test/x-ray, decompress stomach by suction

  • Keep nil by mouth

  • Inform General Surgery Registrar – they may want CT abdomen with contrast Prep for theatre – Bloods, P-Possum score, Anaesthetist, Emergency theatres, Keep nil by mouth 

  • Keep patient and any relatives informed

  • Document, document, document!!!

Remember to document your findings and management plan and inform the patient/parents.


Majority of small bowel obstructions are due to intra-abdominal adhesions due to previous abdominal surgery and are managed conservatively the “drip and suck”, nasogastric tube, correction of electrolyte imbalances, IV fluids and analgesia. These patients will need serial x-rays to ensure they are improving. If there is any deterioration or failure to improve then they will need to go to theatre for surgical resolution.  

Useful Resources

​Evaluation and management of intestinal obstruction

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.
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