Bowel obstruction
Resuscitate, nil by mouth, NG tube on free drainage, correct the electrolytes, CT to find the cause, and look hard for signs of strangulation that need theatre today.
A 58-year-old woman who had a hysterectomy years ago has colicky central pain, a swollen belly and has vomited green fluid six times. She has not passed wind since yesterday. Pulse 104, BP 118/72. Potassium 3.1 mmol/L (mEq/L).
What is "drip and suck", and how do you know if she needs theatre today?
- ResuscitateIV crystalloid. Many patients are very dry.
- Look for strangulationConstant pain, tenderness, fever, fast pulse, high lactate, irreducible hernia.
- Nil by mouth and NG tubeFree drainage. Measure the output.
- BloodsCBC, urea, creatinine, electrolytes (especially potassium), lactate, group and save.
- Catheter and fluid chartHourly urine.
- Examine every hernia siteIncluding femoral and umbilical. Old scars.
- CT abdomen and pelvis with contrastFinds the level, the cause and signs of ischaemia.
- Surgical reviewEarly.
- Constant pain or peritonism
- Fever, fast pulse, high lactate
- Tender irreducible hernia
- Caecum over 9–12 cm on imaging
- Massive distension in an elderly patient
- Strangulation
- Closed-loop obstruction
- Sigmoid volvulus
- Strangulated femoral hernia
- Perforation
- Cancer as the cause
| Drip | IV fluid to replace losses, with potassium once passing urine |
| Suck | NG tube on free drainage. Replace NG losses mL for mL with 0.9% saline and potassium |
| Potassium | Correct low potassium: it worsens ileus |
| Adhesive obstruction, no strangulation | Water-soluble contrast (Gastrografin) 100 mL by NG may be given, then X-ray |
| Strangulation signs | Theatre today |
Check every dose against a current drug reference and your hospital protocol.
On this page
Recognising it
- Colicky central pain
- Early, frequent vomiting (green or bilious)
- Less distension
- Causes: adhesions, hernias, abdominal TB, Crohn's
- Gradual swelling of the belly
- Constipation, no wind
- Vomiting late (may be faeculent)
- Causes: cancer, sigmoid volvulus, diverticular stricture
The four cardinal features: colicky pain, vomiting, distension, and absolute constipation (no stool or wind).
Causes in Pakistan
- Adhesions after previous surgery (including caesarean sections).
- Hernias: inguinal, femoral, umbilical, incisional. A small femoral hernia in an elderly woman is easily missed.
- Abdominal TB: strictures and a matted "doughy" abdomen, weeks of weight loss and fever.
- Sigmoid volvulus: elderly, constipated, often institutionalised or bedbound. Huge distension.
- Colorectal cancer: older patients, weight loss, change in bowel habit, anaemia.
- Intussusception (mostly children), gallstone ileus (elderly women), worms (Ascaris) in children.
Strangulation: the danger
- Pain becomes constant rather than colicky.
- Tenderness, guarding or peritonism.
- Fever, fast pulse, low BP.
- Raised white count and lactate.
- A tender, irreducible hernia.
- CT signs of ischaemia or a closed loop.
Any of these: surgeon now, theatre today. Strangulated bowel can perforate within hours.
Drip and suck
- Explain and positionSitting up, chin slightly down.
- MeasureNose to ear to just below the xiphisternum.
- Insert gentlyAsk the patient to swallow sips if allowed.
- Confirm positionAspirate pH (5.5 or less) or X-ray. Never use the "whoosh" test.
- Free drainageBag below the patient. Aspirate 4-hourly. Chart the volume.
See NG tube insertion for the full procedure.
Investigations
| Test | Why |
|---|---|
| CBC, CRP, lactate | Infection, strangulation |
| Urea, creatinine, electrolytes | Dehydration, low potassium, kidney injury |
| Group and save | Surgery likely |
| Abdominal X-ray | Dilated loops. Small bowel above 3 cm, large bowel above 6 cm, caecum above 9 cm. "Coffee bean" in sigmoid volvulus |
| CT abdomen and pelvis with contrast | Level, cause, ischaemia, closed loop, perforation |
Treatment by cause
- Adhesive small bowel obstruction, no strangulation: conservative care for up to 72 hours. Water-soluble contrast (Gastrografin 100 mL by NG) helps predict who will settle and may speed recovery: contrast in the colon on X-ray within 24 hours means it will likely settle.
- Hernia: urgent surgery, especially if tender or irreducible.
- Sigmoid volvulus: endoscopic decompression (flexible sigmoidoscopy with a flatus tube) if no ischaemia, then elective surgery. Surgery now if ischaemic.
- Large bowel obstruction from cancer: surgery or a stent, senior decision.
- Abdominal TB: surgery for complete obstruction, plus anti-TB treatment.
Common mistakes
- Not examining the femoral canal.
- Forgetting potassium.
- Not measuring and replacing NG losses.
- Waiting days with a tender belly and rising lactate.
- Giving metoclopramide in mechanical obstruction.
- Missing abdominal TB as the cause in a young patient with weight loss.
Frequently asked questions
What is drip and suck?
IV fluids with electrolyte replacement ("drip") and a nasogastric tube on free drainage to decompress the bowel ("suck"), with the patient nil by mouth.
What are the signs of strangulation in bowel obstruction?
Constant pain, tenderness or peritonism, fever, fast pulse, raised white count and lactate, a tender irreducible hernia, and CT signs of ischaemia.
What is Gastrografin used for in small bowel obstruction?
Water-soluble contrast given by NG tube in adhesive obstruction without strangulation. If it reaches the colon within 24 hours, the obstruction is likely to settle without surgery.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A woman with a previous hysterectomy has colicky pain, bilious vomiting and a soft, non-tender abdomen. What is the most likely diagnosis and initial management?
Answer: Adhesions: drip and suck, CT. Adhesions are the commonest cause of small bowel obstruction. Conservative treatment works in many; water-soluble contrast helps predict resolution.
- Colonoscopy: Not the test.
- Laxatives: Contraindicated in obstruction.
- Immediate laparotomy: Most adhesive obstructions settle with conservative care.
- Gastroenteritis: oral fluids: Bilious vomiting with prior surgery suggests obstruction.
2. Twelve hours later, the same patient's pain becomes constant, the abdomen is tender, pulse 124 and lactate 4. What has changed?
Answer: Strangulation. Constant pain, tenderness, fever, tachycardia and rising lactate suggest strangulation needing urgent surgery.
- Ileus from opioids: Doesn't explain tenderness and lactate.
- Reassure and continue: Unsafe.
- Normal progress: These are warning signs.
- Dehydration only: Doesn't explain the signs.
3. An elderly man has massive abdominal distension and a "coffee bean" on X-ray. What is the diagnosis and first treatment?
Answer: Sigmoid volvulus: decompression. Sigmoid volvulus is common in elderly men in Pakistan. Flexible sigmoidoscopy with a flatus tube, then plan definitive surgery.
- Toxic megacolon: Different setting.
- Small bowel obstruction: Large bowel pattern.
- Caecal volvulus: colonoscopy: Coffee bean pointing to the right upper quadrant suggests sigmoid.
- Pseudo-obstruction: neostigmine: Not with a coffee bean sign.
4. An elderly woman has small bowel obstruction; abdominal X-ray shows air in the biliary tree and a calcified mass in the right iliac fossa. What is the diagnosis?
Answer: Gallstone ileus. Gallstone ileus: a large gallstone erodes through a cholecystoduodenal fistula and impacts in the terminal ileum (narrowest) → small bowel obstruction in elderly women. Rigler triad: small bowel obstruction, pneumobilia, ectopic gallstone. CT confirms. Treatment: laparotomy, enterotomy proximal to the stone and extraction; cholecystectomy/fistula repair usually deferred.
- Sigmoid volvulus: Sigmoid volvulus gives a coffee-bean large bowel obstruction.
- Obstructed femoral hernia: An obstructed hernia does not cause pneumobilia.
- Caecal carcinoma: Caecal carcinoma does not cause pneumobilia.
5. An elderly woman with a large paraoesophageal hernia has sudden severe epigastric pain and violent retching without bringing anything up; a nasogastric tube cannot be passed. What is the diagnosis?
Answer: Acute gastric volvulus. Acute gastric volvulus: rotation of the stomach (organoaxial — commonest, along with paraoesophageal hernia; or mesenteroaxial) causing closed-loop obstruction and risk of strangulation/necrosis. Borchardt triad: severe epigastric pain, unproductive retching, inability to pass a nasogastric tube. Imaging: CT or contrast study shows ‘upside-down’ stomach. Management: resuscitation, attempt decompression (NG/endoscopic), urgent surgery (reduction, hernia repair, gastropexy; resection if necrotic).
- Boerhaave syndrome: Boerhaave follows vomiting with chest pain and surgical emphysema.
- Acute pancreatitis: In pancreatitis vomiting occurs and an NG tube passes.
- Myocardial infarction: MI does not cause the retching triad or block an NG tube.
6. Persistence of which embryonic structure forms Meckel's diverticulum?
Answer: Vitellointestinal duct. The vitelline duct connects the midgut to the yolk sac and normally disappears by week 7. If its intestinal end persists, it forms Meckel's diverticulum on the antimesenteric border of the ileum. It may contain gastric or pancreatic tissue and bleed.
- Urachus: A patent urachus causes urine leaking from the umbilicus.
- Allantois: Becomes the urachus.
- Ductus arteriosus: Becomes the ligamentum arteriosum.
- Notochord: Becomes the nucleus pulposus.
7. A 9-month-old boy has episodes of screaming with drawing up of legs, vomiting, a sausage-shaped mass in the right upper abdomen and red-currant jelly stools. What is the diagnosis?
Answer: Intussusception. Intussusception (usually ileocolic) peaks at 6–18 months; lead points include hypertrophied Peyer's patches after viral infection, or Meckel's diverticulum or polyps in older children. Ultrasound shows a target sign. Treatment: air or contrast enema reduction if no peritonitis; surgery otherwise. Red-currant jelly stool is a late sign.
- Pyloric stenosis: Projectile non-bilious vomiting at 3–6 weeks.
- Midgut volvulus: Bilious vomiting in neonates.
- Meckel's diverticulum bleeding: Painless bleeding.
- Acute appendicitis: Rare at this age; no jelly stools.
References and dose sources
- WSES Bologna guidelines on adhesive small bowel obstruction (2017 update)
- NELA
- ASGBI — emergency general surgery resources
- WSES — adhesive small bowel obstruction (Bologna guidelines)
- Sodium chloride (normal saline, 3% saline) dosing: Drugs.com: Sodium chloride dosage (see also our sodium chloride (normal saline, 3% saline) dose page)
- Potassium chloride dosing: Drugs.com: Potassium chloride dosage (see also our potassium chloride dose page)
- Ondansetron dosing: Drugs.com: Ondansetron dosage (see also our ondansetron dose page)
- Morphine dosing: Drugs.com: Morphine dosage (see also our morphine dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.