CT scan finds the site and cause of bowel obstruction and shows whether the bowel is in danger. Learn when it is urgent and what the scan can show.
A CT scan of the abdomen is the best test to find a bowel obstruction. It shows where the bowel is blocked, what is causing it (adhesions, hernia, tumour or twisting) and whether the bowel is losing blood supply, which is an emergency. Symptoms include colicky belly pain, vomiting, swelling of the belly and not passing stool or gas.
Symptoms of Bowel Obstruction
- Cramping pain that comes in waves
- Repeated vomiting, sometimes green or faeculent
- Swollen, tight belly
- Not passing stool or gas
- Fever, fast heartbeat or severe constant pain may signal strangulation
This needs urgent medical care. See CT abdomen and pelvis.
What CT Shows
CT shows enlarged bowel above the blockage and collapsed bowel below it, the exact point of obstruction, and the cause. With intravenous contrast, it shows signs that the bowel wall is not getting enough blood, such as poor enhancement, swelling and fluid. This helps surgeons decide between waiting with treatment and emergency surgery.
CauseHow CT helpsAdhesions (scar bands after surgery)Shows transition point and dilated bowelHerniaShows trapped loopTumourShows mass and spreadTwisting (volvulus)Shows twisted loopsInflammatory narrowingShows thick-walled bowelContrast and Preparation
In an emergency, no preparation is needed. IV contrast is usually given if kidney function allows. Oral contrast is often not needed in complete obstruction. Tell the team about earlier surgery, hernias, allergies and kidney disease. See CT scan with contrast.
Treatment After the Scan
Partial obstruction from adhesions often improves with fasting, a nasogastric tube to drain the stomach, intravenous fluids and observation. Complete obstruction, strangulation, a trapped hernia or a tumour often needs surgery. Early treatment prevents bowel loss and serious infection.
Alternatives
X-ray of the abdomen can show dilated bowel but not the cause. Ultrasound may help in children and in some cases. MRI is rarely used in emergencies. See CT scan for hernia and CT scan for appendicitis.
A Practical Example
Mukesh, 56, had an abdominal operation years ago and now has colicky pain and vomiting for two days. A CT shows dilated small bowel with a transition point caused by an adhesive band, with good blood flow. He is treated with a drip and tube drainage, and the blockage clears in two days. Another patient with similar symptoms has signs of strangulation on CT and goes straight to surgery.
After the Scan and Next Steps
Take the CT report to a surgeon without delay. After recovery, eat small, soft meals and increase fibre slowly as advised. Report vomiting, belly swelling, no stool or gas, or fever early. If you have had previous abdominal surgery, you may be at risk of repeat adhesions, so do not ignore these symptoms.
Questions to Ask Your Doctor
- What is causing my bowel obstruction?
- Is the bowel at risk and do I need surgery?
- What can I eat and when?
- How can I prevent a recurrence?
Common Mistakes to Avoid
- Waiting at home with vomiting and belly swelling.
- Taking laxatives for a suspected blockage.
- Ignoring a painful hernia that cannot be pushed back.
Booking, Timing and Report
Most CT scans can be booked on the same day, and the visit takes 20 to 40 minutes. Carry your prescription, old scans and a recent creatinine report if contrast is planned. Reports are usually ready within 24 hours, and images can be provided on a CD or digital link for your doctor.
Key Facts at a Glance
- Colicky pain, vomiting, swelling and no stool or gas suggest obstruction
- CT shows the site, cause and bowel blood supply
- Strangulation needs emergency surgery
- Do not take laxatives for suspected blockage
After surgery on the abdomen, adhesions can cause blockage even years later, so keep your surgery records and report symptoms early.
Frequently Asked Questions
How is bowel obstruction diagnosed?
Examination, X-ray and CT scan.
Why is CT the best test?
It shows the site, cause and bowel blood supply.
Is it an emergency?
Yes, it needs urgent care.
Is oral contrast needed?
Often not.
Does everyone need surgery?
No, some improve with drip and tube treatment.
Can adhesions cause it years later?
Yes.
Is CT safe in this setting?
Yes; benefits outweigh risks.
How long does it take?
Minutes.
When is the report ready?
Immediately in emergencies.
Book Your Test at Ganesh Diagnostic
Ganesh Diagnostic & Imaging Centre in Rohini, Delhi offers this test with trained radiology staff and clear reports. You can book an appointment online, check our branches across Delhi NCR, contact us for current rates, or explore all our services. Reports can be downloaded online through our patient portal, so you do not need to make a second trip just to collect them.
This article is for general information only. It does not replace advice from your doctor. Always follow your doctor's instructions for your test.
