Small and large bowel obstruction: causes, clinical features, NG decompression, strangulation warning signs, and surgical nursing management
Bowel obstruction is the interruption of the normal transit of intestinal contents, leading to distension proximal to the obstruction and collapse distally. It is a surgical emergency requiring rapid assessment and management.
| Type | Mechanism | Examples |
|---|---|---|
| Mechanical obstruction | Physical blockage of the lumen | Adhesions, hernias, tumours, volvulus, intussusception, bezoar |
| Functional (ileus / pseudo-obstruction) | Failure of bowel motility without mechanical blockage | Post-operative ileus, electrolyte imbalance, medications (opioids, anticholinergics), Ogilvie's syndrome |
80% of mechanical obstructions
Common causes:
20% of mechanical obstructions
Common causes:
Understanding the consequences of obstruction guides nursing priorities:
| Feature | Small Bowel Obstruction (SBO) | Large Bowel Obstruction (LBO) |
|---|---|---|
| Pain | Central, colicky, frequent waves (every 4–5 min) | Lower abdominal, less frequent waves |
| Vomiting | Early, profuse, bilious (green/yellow) → faeculent late | Late, may not occur; if closed loop — faeculant |
| Distension | Central distension (mild–moderate) | Peripheral/global distension (massive) |
| Absolute constipation | May pass flatus/stool initially | Complete — no flatus, no stool (late sign) |
| Bowel sounds | High-pitched, tinkling, active early; absent late | Decreased; may have high-pitched sounds |
| AXR findings | Dilated central loops; valvulae conniventes (go fully across) | Peripheral dilated loops; haustra (partially across) |
| Risk of perforation | Lower (unless strangulated) | Higher — especially caecum if Ileocaecal valve competent |
| Investigation | Purpose |
|---|---|
| Erect CXR + AXR (erect and supine) | Dilated loops, air-fluid levels, free air (perforation) |
| CT abdomen with contrast | Gold standard — identifies level, cause, strangulation, closed loop |
| FBC | Raised WCC (infection/strangulation) |
| U&E | Electrolyte imbalances (hypokalaemia from vomiting) |
| Lactate | Raised lactate = bowel ischaemia/sepsis |
| ABG | Metabolic acidosis in severe obstruction |
| Group and save / crossmatch | Pre-operative preparation |
Suitable for simple SBO without strangulation (especially adhesional SBO). May resolve within 24–72 hours with conservative management.
Surgery indicated for: strangulation, closed-loop obstruction, LBO (colorectal cancer/volvulus), failure to resolve after 48–72 hours of conservative management.
Colorectal cancer (CRC) is the most common GI malignancy in many GCC countries and is increasingly presenting in younger patients (under 50). Risk factors prevalent in GCC: low-fibre high-fat Western diet, sedentary lifestyle, obesity, type 2 diabetes. Late presentation is common due to reluctance to discuss rectal symptoms. LBO from CRC is therefore a common surgical emergency. Nurses should promote colorectal cancer awareness and bowel screening programmes.
Post-surgical adhesions are the most common cause of SBO globally. With rising surgical volumes in GCC (caesarean sections, appendicectomies, laparoscopies), post-adhesion SBO is increasingly seen in younger adults and women of reproductive age. Early post-operative mobilisation, adhesion barrier agents, and laparoscopic techniques reduce adhesion formation.
Sigmoid volvulus is disproportionately common in East African populations (Ethiopia, Somalia, Sudan) and in communities with high dietary fibre intake from indigenous food staples (injera, teff). The large sigmoid colon twists on its mesentery causing LBO. Initial management is endoscopic detorsion (sigmoidoscopy); recurrence is high without sigmoid colectomy. GCC hospitals serving East African expat communities should be aware of this presentation.
Functional ileus after abdominal surgery is common. GCC surgical nurses play a key role in ERAS (Enhanced Recovery After Surgery) protocols which reduce ileus: early mobilisation (within 6 hours), early oral fluids (within 4–6 hours), multimodal analgesia minimising opioids, gum chewing (stimulates bowel motility), prokinetics if prolonged ileus. Early return of bowel function (passage of flatus) should be documented and celebrated in nursing handover.
Q1. A patient with previous appendicectomy presents with colicky central abdominal pain, vomiting, distension, and high-pitched tinkling bowel sounds. What is the most likely cause of their small bowel obstruction?
Q2. A patient with SBO being managed conservatively develops constant (non-colicky) abdominal pain, fever of 38.5°C, tachycardia, and abdominal rigidity. What does this indicate?
Q3. What does "drip and suck" conservative management for SBO involve?
Q4. The MOST common cause of large bowel obstruction in adults is: