---

Intestinal Obstruction with Per Rectal (PR) Bleeding

Clinical Significance of PR Bleeding in Obstruction

• Intestinal strangulation - compromised blood supply leading to mucosal ischemia/infarction
• Intussusception - "redcurrant jelly" stool is classic (especially in children; adults usually have a pathologic lead point)
• Colorectal malignancy causing obstruction with tumour bleeding
• Lymphoma - presents with abdominal pain, mass, PR bleeding, and obstruction/intussusception
• Volvulus with established mucosal ischemia
• Peutz-Jeghers syndrome - obstruction or persistent GI bleeding from hamartomatous polyps

---

Immediate Resuscitation (Always First)

1. Nasogastric decompression - Ryle's (non-vented) or Salem (vented) tube, placed on free drainage with 4-hourly aspiration; reduces aspiration risk at induction
2. IV fluid and electrolyte replacement - Hartmann's solution or normal saline (basic deficit is sodium and water loss); volume guided by clinical, haematological, and biochemical criteria
3. Relief of obstruction - timing depends on clinical picture

---

Indications for URGENT/EMERGENCY Surgery

"The Sun should not both rise and set on a case of unrelieved acute intestinal obstruction." - Bailey & Love's

---

Surgical Treatment Principles

Intraoperative Assessment

1. Site of the obstruction
2. Nature of the obstruction (adhesion, hernia, tumour, volvulus, etc.)
3. Viability of the gut

Bowel Viability Assessment

• If doubtful: wrap in hot packs for 10 minutes, then reassess
• If still uncertain: resect (unless extent risks short bowel syndrome)
• Critically unwell patient or massive infarction: resect necrotic bowel + raise both ends as stomas (avoid anastomosis in unfavourable conditions)
• Multiple ischaemic areas or mesenteric vascular occlusion: second-look laparotomy at 24-48 hours

Operative Decompression

• Insert large-bore orogastric tube and milk small bowel contents in retrograde fashion to stomach for aspiration
• Savage's decompressor within seromuscular purse-string suture if needed (balance against risk of septic complications)

---

Management by Specific Cause

Small Bowel Obstruction with Strangulation

• Emergency laparotomy
• Enterolysis (division of adhesions), excision, bypass, or proximal decompression based on cause
• Resect non-viable bowel; anastomosis or stoma formation depending on patient stability

Large Bowel Obstruction

• Treatment tailored to etiology and patient condition
• Unstable patients with high anastomotic leak risk → diverting stoma or exteriorization as loop ileostomy

Colonic Stents (Bridge to Surgery)

• Useful for malignant large bowel obstruction in high-risk surgical candidates
• Allows patient optimization, preoperative chemotherapy
• Complications: stent migration, perforation, reobstruction
• Mixed results in trials - requires case-by-case evaluation

Adhesion-Related Obstruction

• Initial IV rehydration + nasogastric decompression (occasionally curative)
• Conservative management acceptable for up to 72 hours if no strangulation
• Laparotomy: divide causative adhesion(s); sharp dissection from duodenojejunal junction to caecum if multiple adhesions

---

Strangulation - Key Points (Most Relevant to PR Bleeding)

• Do not delay surgery - strangulation is a surgical emergency
• For volvulus with established infarction: clamp the mesentery before detorsion to prevent reperfusion injury; detorsion before clamping risks a burst of inflammatory mediators causing remote organ injury (reperfusion/lung injury)
• Resect all non-viable bowel
• Second-look laparotomy in 24-48 hours if viability is uncertain across multiple segments

---

Intussusception with PR Bleeding

• Pneumatic or hydrostatic enema reduction under fluoroscopy or ultrasound guidance (first line if no peritonitis)
• If fails or peritonitis present: surgical reduction or resection

• Colonoscopic biopsy + CT for diagnosis
• Surgical resection following oncologic principles - do NOT attempt reduction (malignancy must be excluded/treated)

---

Summary Algorithm

Intestinal obstruction + PR bleeding
         ↓
Immediate: NGT + IV fluids + monitoring
         ↓
Is there peritonitis / perforation / strangulation?
    YES → Emergency surgery (do not delay)
    NO  → Resuscitate, investigate cause
         ↓
    Identify cause:
    - Strangulated hernia → Emergency surgery
    - Volvulus → Endoscopic decompression ± surgery
    - Malignancy → Stent or Hartmann's
    - Intussusception (child) → Enema reduction
    - Intussusception (adult) → Surgical resection
    - Adhesions → Conservative 72h, then surgery
    - IBD → Steroids, drainage

---

Note: PR bleeding with intestinal obstruction must always raise suspicion of strangulation - treat as surgical emergency until proven otherwise.

---

Diagnosis: Intestinal Obstruction with Per Rectal (PR) Bleeding

Step 1 - Clinical Significance of the Combination

---

Step 2 - History

Cardinal Symptoms of Obstruction

1. Colicky abdominal pain - crampy, intermittent, periumbilical (SBO) or lower abdomen (LBO)
2. Abdominal distension - greater with distal obstruction
3. Vomiting - earlier and more pronounced with proximal obstruction; feculent vomiting indicates bacterial overgrowth (distal/late)
4. Obstipation - absolute (no stool or flatus) in complete obstruction; patients may still pass residual downstream contents early

Key Red-Flag History Points

• Character of bleeding: Bright red (large bowel/anorectal), dark red/maroon (small bowel ischaemia), "redcurrant jelly" (intussusception)
• Onset: Sudden vs. progressive
• Prior abdominal surgery - adhesions most common cause of SBO
• Cancer history - especially colorectal, ovarian, gastric
• IBD history
• Herniorrhaphy history
• Age: Intussusception in infants/children; malignancy more common in adults over 50
• Weight loss, altered bowel habit, iron-deficiency anaemia - strongly suggest malignancy
• Guaiac-positive stools + iron-deficiency anaemia - strongly suggestive of underlying malignancy

---

Step 3 - Physical Examination

Vital Signs

Abdominal Examination

All surgical scars must be examined - port-site hernias (even 5mm) from laparoscopic surgery can cause obstruction and strangulation.

Rectal Examination

• Redcurrant jelly stool - classic for intussusception
• Bright red blood - lower GI source; consider colonic tumour
• Empty rectum in complete obstruction
• Palpable rectal mass - rectal carcinoma
• Blood on finger - always warrants investigation for underlying pathology

---

Step 4 - Laboratory Investigations

No single lab test reliably distinguishes simple from strangulated obstruction. Metabolic acidosis, high WBC with immature forms, and elevated lactate are the most worrying combination.

---

Step 5 - Imaging

1. Plain Abdominal X-Ray (AXR) - First Line

2. CT Abdomen/Pelvis with IV ± Oral Contrast - Gold Standard

• Site and level of obstruction
• Cause of obstruction (adhesion, hernia, mass, faecal impaction)
• Closed-loop obstruction - two adjacent collapsed loops with C-shaped or U-shaped configuration
• Strangulation - altered/absent bowel wall enhancement, bowel wall thickening, mesenteric oedema, ascites, pneumatosis intestinalis
• Volvulus - "bird's beak," "C-loop," or "whirl sign" (twisted mesentery) at point of torsion
• Perforation - free air, free fluid
• Malignancy - obstructing mass, lymphadenopathy, metastases

CT with oral + IV contrast appearing in the caecum within 4-24 hours of administration strongly predicts resolution with conservative management (~95% sensitivity and specificity).

3. Water-Soluble Contrast Studies (Gastrografin/Hypaque)

• Use when diagnosis is unclear or to assess completeness of obstruction
• Gastrografin is hyperosmolar (1900 mOsm/L) - draws fluid into bowel lumen, may therapeutically facilitate resolution in incomplete SBO
• Barium is CONTRAINDICATED in suspected complete obstruction, perforation, or gangrene:
  • Leaks into peritoneum → severe chemical peritonitis
  • Creates barium concretions that worsen obstruction
  • Renders CT/angiography uninterpretable

4. Ultrasound

• Less accurate but appropriate for pregnant patients or when radiation must be avoided
• Can show dilated fluid-filled loops, free fluid, intussusception (target/doughnut sign in children)
• Difficult to interpret in bowel obstruction due to gas

5. Colonoscopy / Sigmoidoscopy

• Useful for large bowel obstruction - can visualise tumour, take biopsy
• Flexible sigmoidoscopy - first-line diagnostic AND therapeutic for sigmoid volvulus (confirms diagnosis + decompresses)
• Contraindicated if peritonitis or perforation is suspected

---

Step 6 - Differentiating Simple vs. Strangulated Obstruction

"Even though small-bowel obstruction with strangulation can be especially difficult to diagnose promptly, early recognition allows earlier treatment, which decreases the risk of morbidity and mortality." - Harrison's Principles of Internal Medicine, 22nd ed.

---

Diagnostic Summary Table

INTESTINAL OBSTRUCTION + PR BLEEDING
              ↓
    CLINICAL ASSESSMENT
    4 Cardinal symptoms:
    Pain + Distension + Vomiting + Obstipation
    + PR Bleeding → narrows to:
    ┌─────────────────────────────────┐
    │ Strangulation                   │
    │ Intussusception                 │
    │ Colorectal malignancy           │
    │ Volvulus with ischaemia         │
    │ Lymphoma                        │
    │ Mesenteric ischaemia            │
    └─────────────────────────────────┘
              ↓
    INVESTIGATIONS
    FBC / Electrolytes / Lactate / ABG
              ↓
    AXR (erect + supine + lateral)
              ↓
    CT ABDOMEN/PELVIS WITH CONTRAST
    (gold standard - ~95% accuracy)
              ↓
    Strangulation signs? → Emergency surgery
    Malignancy? → Staging CT + colonoscopy/biopsy
    Volvulus? → Sigmoidoscopy / surgery
    Intussusception? → Enema (child) / Surgery (adult)

---

• Harrison's Principles of Internal Medicine, 22nd Edition (pp. 2634-2636)
• Mulholland and Greenfield's Surgery, 7th Edition (pp. 2411-2417)
• Bailey and Love's Short Practice of Surgery, 28th Edition (p. 1406-1408)

---

Management of Acute Per Rectal (PR) Bleeding

Definition & Context

---

Step 1 - Initial Assessment & Triage

A - Haemodynamic Evaluation

B - Risk Stratification

• Haemodynamic instability (shock)
• Active ongoing bright red bleeding or passage of clots
• Advanced age (median age of LGIB hospitalisation: 74 years)
• Comorbidities: renal failure, cirrhosis, cardiac disease, malignancy
• Coagulopathy or anticoagulant/antiplatelet use
• Secondary bleeding (onset after hospitalisation for another condition) - carries highest mortality

---

Step 2 - Immediate Resuscitation

IV Access & Fluids

• Insert two large-bore (14-16G) peripheral IV cannulae
• Commence crystalloid resuscitation (normal saline or Hartmann's solution) immediately
• Target: HR <100, SBP >90, urine output >0.5 mL/kg/hr

Blood Transfusion

• Cross-match 4-6 units packed red blood cells (PRBCs)
• Transfuse PRBCs to maintain Hb >70-80 g/L (or >90 in cardiac disease)
• Withhold/reverse anticoagulants (warfarin - give Vitamin K ± PCC; DOACs - specific reversal agents)
• Correct coagulopathy: Fresh Frozen Plasma if INR >1.5, Platelets if <50 x10⁹/L
• Withhold antiplatelet agents as appropriate

Monitoring

• Insert urinary catheter (monitor urine output)
• Continuous cardiac monitoring, pulse oximetry
• Central venous access if haemodynamically unstable or cardiac disease present
• Nasogastric tube insertion - if NGT lavage shows blood/coffee grounds, this identifies an upper GI source (stops further lower GI workup temporarily)

Investigations (Parallel with Resuscitation)

BUN:Creatinine ratio >30 is most suggestive of an upper GI source of bleeding.

Passage of blood clots per rectum is the finding most predictive of a lower GI source.

---

Step 3 - Algorithm by Haemodynamic Status

PATHWAY A: Haemodynamic Instability (Shock)

Active bleeding + Hypovolaemic shock
         ↓
1. Aggressive resuscitation (IVF, blood, reverse coagulopathy)
         ↓
2. Exclude upper GI source (NGT lavage / urgent OGD)
         ↓
3. CT ANGIOGRAPHY (CTA) - FIRST LINE
   • Detects bleeding ≥0.3-0.5 mL/min
   • Sensitivity 85%, Specificity 92%, Accuracy ~100%
   • Localises source before angiography
         ↓
CTA POSITIVE → Extravasation identified
         ↓
4. MESENTERIC ANGIOGRAPHY + EMBOLISATION
   (within 90 minutes of positive CTA)
   • Superselective embolisation - feasibility 98%
   • Complication rate 4.6% (mainly bowel infarction)
   • Superior mesenteric artery examined first (most common source)
         ↓
Bleeding controlled → Inpatient colonoscopy to identify/treat source
Bleeding continues → Consider surgery

PATHWAY B: Haemodynamically Stable (Significant Bleeding)

PR bleeding + Haemodynamically stable
         ↓
Resuscitation + Labs + Cross-match
         ↓
INPATIENT COLONOSCOPY (test of choice)
• After adequate bowel preparation
• Performed next-available basis (no proven benefit of <24h vs 24-96h
  for stigmata identification, rebleeding, or transfusion requirements)
• Identifies source in 45-90% of cases
• Allows biopsy AND therapeutic intervention
         ↓
     If normal:
     Consider OGD (exclude upper GI source)
     → Capsule endoscopy (small bowel source)
     → CT angiography
     → Radionuclide (tagged RBC) scan

PATHWAY C: Minor Bleeding / Low Risk

• Arrange outpatient investigations (colonoscopy as outpatient)
• No urgent admission required if haemodynamically stable, self-limiting, low-risk features

---

Step 4 - Endoscopic Management

• Precise localisation regardless of active bleeding or lesion type
• Allows biopsy
• Provides therapeutic intervention

Endoscopic Haemostasis Techniques (at Colonoscopy)

• Injection therapy - adrenaline (1:10,000) injection around bleeding point
• Mechanical clips (endoclips) - for diverticular bleeding, post-polypectomy
• Thermal coagulation - heater probe, APC (argon plasma coagulation)
• Band ligation - haemorrhoids
• After haemostasis of diverticular bleed: place submucosal tattoo at the site (for re-identification if re-bleeding occurs or surgery is needed)

Definitive or potential bleeding source identified in 45-90% of colonoscopies for LGIB. A non-bleeding potential source does not exclude a more proximal source.

---

Step 5 - Radiological Interventions

CT Angiography (CTA)

Mesenteric Angiography

• Requires bleeding ≥0.5-1.0 mL/min (optimal conditions)
• Reserved for: unstable patients unfit for colonoscopy, ongoing bleeding despite colonoscopy
• Must be performed within 90 minutes of a positive CTA (risk of bleeding stopping before procedure)
• Success rate: 25-70% (variable)
• Superselective transcatheter embolisation - has largely replaced vasopressin infusion
• If no prior localisation: examine superior mesenteric artery first (most common LGIB source)

Radionuclide (Tagged RBC) Scan

• Most sensitive for slow bleeding: detects rates of 0.1-0.5 mL/min
• Major disadvantage: only localises to a general abdominal area (poor precision, accuracy 24-91%)
• Used when CTA is negative or bleeding is intermittent/slow
• Requires active bleeding during the scan; follow promptly with angiography if positive

---

Step 6 - Surgical Management

Indications for Surgery in LGIB

1. Persistent haemodynamic instability despite active resuscitation
2. Persistent or recurrent bleeding not controlled by endoscopy/angiography
3. Transfusion >4 units PRBCs in 24 hours with active or recurrent bleeding
4. Exsanguinating haemorrhage

Operative Approach

The morbidity and mortality of surgery without preoperative localisation is significantly higher. All efforts to localise the source before the operating room are mandatory.

---

Step 7 - Source-Specific Management

---

Management Algorithm Summary

ACUTE PR BLEEDING
       ↓
RESUSCITATION: 2x large-bore IV, crystalloids, cross-match
Withhold anticoagulants, correct coagulopathy
Insert urinary catheter, monitor vitals
       ↓
     ┌───────────────────────────────────┐
     │ Haemodynamically UNSTABLE?        │
     └───────────────────────────────────┘
          YES                     NO
           ↓                       ↓
      CTA first             Bowel prep →
      → Angiography +       Colonoscopy
        Embolisation         (next available)
           ↓                       ↓
      Controlled?          Source found?
      YES → Colonoscopy    YES → Endoscopic Rx
      NO  → Surgery        NO  → OGD / Capsule /
                                  CTA / RBC scan
                                       ↓
                                  Still bleeding?
                                  → Surgery

---

Outcomes

• LGIB in-hospital mortality: <4% (most deaths from comorbid conditions, not bleeding itself)
• Worst prognosis: secondary bleed (onset during hospitalisation for another condition), malignancy, coagulopathy, haemodynamic instability, advanced age, male sex
• Best prognosis: haemorrhoids, anal fissures, polyps

---

• Bailey & Love's Short Practice of Surgery, 28th Edition (p. 1405)
• Sabiston Textbook of Surgery (pp. 2189-2191)
• Mulholland & Greenfield's Surgery, 7th Edition (pp. 3197-3200)
• Harrison's Principles of Internal Medicine, 22nd Edition