Anastomotic Leak

1. Clinical Overview

Summary

Anastomotic leak (AL) is the breakdown or failure of a surgical connection (anastomosis) between two segments of bowel or other hollow viscera, resulting in communication between the intra- and extraluminal compartments. [1] This represents one of the most serious complications following gastrointestinal surgery, associated with significant morbidity (30-50%), mortality (6-22%), prolonged hospital stay, and adverse long-term oncological outcomes. [2,3]

The International Study Group of Rectal Cancer (ISGRC) defines anastomotic leak as "a defect of the intestinal wall integrity at the anastomotic site leading to communication between intra- and extraluminal compartments." [1] This consensus definition provides a standardized framework for diagnosis and grading.

Clinical Significance: AL complicates 3-15% of colorectal anastomoses (higher for rectal surgery at 5-19%), with incidence varying by anatomical location, surgical technique, and patient factors. [4,5] Early recognition through clinical suspicion, biomarker monitoring, and timely imaging is crucial—delayed diagnosis beyond 5 days significantly increases mortality from 6% to 22%. [6]

Key Facts

• Definition: Defect at anastomotic site causing intra/extraluminal communication [1]
• Incidence: Colorectal 5-10%, rectal 10-19%, esophageal 5-15% [4,7,8]
• Timing: Early (less than 7 days) 60-80%, late (> 7 days) 20-40% [9]
• Mortality: 6-12% early diagnosis, 15-30% delayed diagnosis [6]
• Risk factors: Male sex, smoking, diabetes, malnutrition, low anastomosis, radiotherapy [5]
• Gold standard diagnosis: CT with water-soluble contrast enema [10]
• Grading: ISGRC Grade A (subclinical), B (requires intervention), C (requires relaparotomy) [1]

Clinical Pearls

"The diagnostic triad: tachycardia, fever, and elevated CRP after POD 3" — Unexplained tachycardia (HR > 100) persisting beyond post-operative day 3, especially with fever and rising CRP, has high specificity (85-90%) for anastomotic leak. [11]

"CRP trajectory matters more than absolute values" — Failure of CRP to decline by > 50% from peak by day 4, or CRP > 140 mg/L on day 3-5, has 80% sensitivity for AL. [12,13]

"CT with rectal contrast is diagnostic in 90% of cases" — Extraluminal contrast, extraluminal gas > 7 days post-op, or fluid collections adjacent to anastomosis are pathognomonic. [10]

"Early leaks differ from late leaks" — Early leaks (less than 7 days) reflect technical failure or ischemia; late leaks (> 7 days) suggest tension, infection, or progression of ischemia. Management strategies differ. [9]

Why This Matters Clinically

Anastomotic leak remains the most feared complication in colorectal surgery due to its profound impact on immediate survival, long-term morbidity, and oncological outcomes. AL increases 30-day mortality 5-fold, local recurrence by 30%, and reduces 5-year survival by 15-20%. [3] Early detection through systematic biomarker surveillance (CRP trajectory) and low-threshold CT imaging enables intervention before generalized peritonitis develops, reducing mortality from 22% to 6%. [6,13] The shift toward conservative and endoscopic management (endo-VAC, stenting) for contained Grade B leaks has reduced reoperation rates and stoma formation while maintaining equivalent safety. [14,15]

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2. Epidemiology

Incidence & Prevalence

Colorectal Surgery Overall:

• Incidence: 5-10% of all colorectal anastomoses [4]
• Rectal anastomoses: 10-19% (higher risk due to pelvic location) [5]
• Right-sided anastomoses: 1-3% (better vascularity) [4]

By Surgical Site:

Demographics

Risk Factors

Patient Factors:

Disease Factors:

Technical Factors:

Temporal Patterns

Early vs Late Leak (Critical Distinction): [9]

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3. Pathophysiology

Molecular Basis of Anastomotic Healing

Normal Healing Phases:

1. Hemostasis (0-24 hours): Platelet activation, fibrin deposition
2. Inflammation (1-5 days): Neutrophil/macrophage infiltration, cytokine release (IL-1, IL-6, TNF-α)
3. Proliferation (3-14 days): Fibroblast migration, collagen deposition (Type III initially)
4. Remodeling (14 days-6 months): Type III → Type I collagen, tensile strength increases

Critical Period: Days 3-5 represent the weakest point of anastomotic healing—initial fibrin seal has degraded, but collagen deposition is incomplete. Tensile strength is only 20-30% of normal at day 5. [18]

Exam Detail: Molecular Mechanisms of Leak:

1. Matrix Metalloproteinase (MMP) Dysregulation:

   • MMP-2, MMP-9 overexpression degrades extracellular matrix
   • Decreased tissue inhibitors of MMPs (TIMPs)
   • Imbalance favors tissue breakdown over synthesis

2. Ischemia-Reperfusion Injury:

   • Inadequate arterial inflow → tissue hypoxia
   • Venous congestion → impaired oxygen delivery
   • Free radical formation → endothelial damage
   • Critical perfusion threshold: tissue pO₂ less than 30 mmHg

3. Bacterial Factors:

   • Collagenase production by anaerobes (Bacteroides, Clostridium)
   • Biofilm formation inhibits healing
   • LPS-mediated inflammatory response

4. Mechanical Stress:

   • Tension > 1 Newton/cm² at suture line impairs healing
   • Distal obstruction → increased intraluminal pressure
   • Anastomotic ischemia from crushing sutures

Classification Systems

1. International Study Group of Rectal Cancer (ISGRC) Grading [1]

Clinical Relevance: This grading system predicts outcomes—Grade C leaks have 25% mortality vs 3% for Grade B. [1] It guides treatment escalation and standardizes reporting.

2. Early vs Late Leak Classification [9]

• Early leak (≤7 days): Technical failure (stapler malfunction, inadequate donuts, tension), ischemia from vascular injury, intrinsic factors (patient comorbidities)
• Late leak (> 7 days): Progression of borderline ischemia, anastomotic tension from adhesions, distal obstruction, pelvic abscess erosion

Management Implication: Early leaks more likely to require relaparotomy (Grade C); late leaks often amenable to drainage ± endo-VAC (Grade B). [9]

3. Anatomical Classification

Pathophysiological Consequences

Local Effects:

• Pelvic/mediastinal abscess formation
• Fistula development (colovesical, colovaginal, enterocutaneous)
• Anastomotic stricture (chronic inflammation → fibrosis)

Systemic Effects:

• Sepsis → SIRS → multi-organ dysfunction
• Prolonged ileus (inflammatory mediators)
• Nutritional depletion (protein loss, hypercatabolism)
• Immunosuppression (increased infection risk)

Long-term Oncological Impact: [3]

• Local recurrence increased by 30% (tumour cell implantation in abscess cavity, impaired immune surveillance)
• Delayed adjuvant chemotherapy (may miss therapeutic window)
• 5-year survival reduced by 15-20%

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4. Clinical Presentation

Symptoms: The Patient's Story

Classic Presentation (60-70% of cases):

• Fever: Persistent or new-onset after post-operative day 3 (temperature > 38°C)
• Abdominal pain: Increasing or failing to improve after day 3
• Ileus: Failure to pass flatus/stool, persistent nausea/vomiting beyond day 5
• Malaise: Subjective feeling of being "unwell" despite no clear findings

Subtle Presentations (30-40%): [11]

• Isolated tachycardia: HR persistently > 100 without clear cause
• Unexplained organ dysfunction: AKI, confusion (especially elderly)
• Wound/drain changes: Feculent/purulent discharge

Timing of Presentation:

• Median time to diagnosis: 5-8 days post-operatively [9]
• Early leaks (less than 7 days): Acute presentation with peritonitis
• Late leaks (> 7 days): Insidious onset, pelvic symptoms, chronic sinus

Signs: What You See

Vital Signs (Critical Red Flags):

Abdominal Examination:

Drain Findings:

Red Flags - Immediate Escalation

[!CAUTION] Red Flags Requiring Urgent Senior Review and Imaging:

• Unexplained tachycardia (HR > 100) persisting beyond POD 3
• Fever (> 38°C) after POD 3 without alternative source
• Increasing abdominal pain or failure to improve by POD 3
• Signs of peritonitis (guarding, rigidity, rebound tenderness)
• Sepsis (SIRS criteria + suspected infection)
• Prolonged ileus (> 5 days without flatus/bowel movement)
• Feculent or purulent drain output
• Rising inflammatory markers (CRP not declining by day 3-4)

Remember: AL is a clinical diagnosis supported by imaging—do not wait for "definitive" signs before investigating.

Differential Diagnosis

Must-Not-Miss Diagnoses:

1. Anastomotic leak (this diagnosis)
2. Intra-abdominal collection (without leak)
3. Bowel ischemia (can coexist with or cause leak)

Other Differentials:

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5. Investigations

Diagnostic Algorithm

POST-OPERATIVE PATIENT WITH SUSPECTED AL
(Fever, tachycardia, pain, ileus after POD 3)
                    ↓
┌───────────────────────────────────────────────────┐
│  BEDSIDE ASSESSMENT                               │
│  • Clinical examination (peritonism?)             │
│  • Vital signs (HR, BP, T, RR, SpO₂)             │
│  • Review drain output (feculent/purulent?)       │
└───────────────────────────────────────────────────┘
                    ↓
┌───────────────────────────────────────────────────┐
│  LABORATORY TESTS (Order immediately)             │
│  • FBC (WCC), CRP, lactate                        │
│  • U&E, creatinine (organ dysfunction?)           │
│  • Blood cultures if septic                       │
└───────────────────────────────────────────────────┘
                    ↓
┌───────────────────────────────────────────────────┐
│  CRP TRAJECTORY ANALYSIS                          │
│  • CRP > 140 mg/L on POD 3-5 → HIGH RISK [12,13]  │
│  • CRP not declining by > 50% from peak → HIGH RISK│
│  • Rising CRP after initial fall → INVESTIGATE   │
└───────────────────────────────────────────────────┘
                    ↓
        HIGH SUSPICION (any red flag present)
                    ↓
┌───────────────────────────────────────────────────┐
│  CT ABDOMEN/PELVIS WITH RECTAL CONTRAST [10]     │
│  Gold standard: Sensitivity 90%, Specificity 95%  │
│  • Water-soluble contrast enema (Gastrografin)    │
│  • Oral contrast if upper GI anastomosis          │
│  • Look for: contrast extravasation, gas, fluid   │
└───────────────────────────────────────────────────┘
                    ↓
            POSITIVE FINDINGS?
                    ↓
┌───────────────────────────────────────────────────┐
│  GRADE LEAK (ISGRC) [1]                           │
│  Grade A: Subclinical → Conservative              │
│  Grade B: Intervention without laparotomy         │
│  Grade C: Requires relaparotomy                   │
└───────────────────────────────────────────────────┘

First-Line Investigations

1. C-Reactive Protein (CRP) Trajectory [12,13]

Evidence: CRP monitoring is the most cost-effective screening tool for AL. [12,13]

Interpretation:

• Normal trajectory: CRP peaks POD 2-3, then declines by > 50% by POD 4-5
• AL trajectory: CRP remains elevated or rises after initial plateau
• CRP less than 100 mg/L on POD 4-5 has 95% negative predictive value [13]

Limitations:

• Non-specific (elevated in any inflammatory process)
• Cannot localize or grade severity
• Should guide further investigation, not replace imaging

2. Lactate

• Role: Marker of tissue hypoperfusion and sepsis severity
• Threshold: Lactate > 2 mmol/L suggests significant sepsis [20]
• Trend: Rising lactate indicates deterioration, need for escalation
• Limitation: Not specific for AL (elevated in any shock state)

3. White Cell Count (WCC)

• Sensitivity: Only 40-60% for AL (often normal in localized leak) [11]
• Specificity: Poor (elevated in many post-op states)
• Use: Leukocytosis > 15 × 10⁹/L suggests infection, but absence doesn't exclude AL

Imaging

Gold Standard: CT Abdomen/Pelvis with Water-Soluble Contrast Enema [10]

Protocol:

1. IV contrast (unless contraindicated)
2. Rectal contrast enema (250-300ml Gastrografin instilled via Foley catheter in rectum)
3. Imaging in portal venous phase
4. Multiplanar reconstruction

Findings Diagnostic of AL:

Advantages:

• High sensitivity/specificity [10]
• Identifies leak location, size, and associated collections
• Guides intervention (drainage vs surgery)
• Can assess for alternative diagnoses

Limitations:

• Requires patient transfer (may not be safe in unstable patient)
• Rectal contrast may not be tolerated
• Small leaks may be missed if contrast doesn't reach defect

When CT is Negative but Suspicion High:

• Consider water-soluble contrast study (fluoroscopy)
• Repeat CT after 24-48 hours
• Diagnostic laparoscopy if patient deteriorating

Alternative/Adjunct Imaging:

Laboratory Tests

Baseline (All Patients with Suspected AL):

Microbiology:

Novel Biomarkers (Emerging Evidence):

Diagnostic Criteria

Clinical Diagnosis of Anastomotic Leak (Based on ISGRC Definition [1]):

Requires at least ONE of:

1. Radiological evidence: Contrast extravasation, gas/fluid collection adjacent to anastomosis on CT/contrast study
2. Endoscopic evidence: Visible defect at anastomosis with purulence or bowel content in cavity
3. Surgical evidence: Leak identified at relaparotomy
4. Clinical evidence: Feculent/purulent discharge from drain or wound

Supporting (but not diagnostic alone):

• Persistent fever + tachycardia after POD 3
• CRP > 140 mg/L on POD 3-5 or failure to decline [12,13]
• Prolonged ileus > 5 days
• Organ dysfunction without alternative cause

Grading (ISGRC): [1]

• Grade A: Leak identified on imaging/endoscopy but patient asymptomatic, no intervention required
• Grade B: Leak requiring active intervention (drainage, antibiotics, endoscopic therapy, TPN) but NOT relaparotomy
• Grade C: Leak requiring relaparotomy

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6. Management

Management Algorithm by ISGRC Grade

ANASTOMOTIC LEAK CONFIRMED
(CT/endoscopy/clinical diagnosis)
            ↓
┌───────────────────────────────────────────────────┐
│  GRADE THE LEAK (ISGRC) [1]                       │
│  • Grade A: Asymptomatic, radiological only       │
│  • Grade B: Symptomatic, intervention without OR  │
│  • Grade C: Peritonitis, septic shock → OR        │
└───────────────────────────────────────────────────┘
            ↓
    ┌───────┴───────┐
    ↓               ↓
GRADE A/B       GRADE C
(Stable)        (Peritonitis/Shock)
    ↓               ↓
┌─────────────┐  ┌──────────────────────────────────┐
│CONSERVATIVE │  │  RESUSCITATION + EMERGENCY OR    │
│MANAGEMENT   │  │  • IV fluids, antibiotics, HDU   │
│[14,15,19]   │  │  • Damage control surgery:       │
│             │  │    - Washout peritoneal cavity   │
│• NPO        │  │    - Take down anastomosis       │
│• IV fluids  │  │    - End stoma (Hartmann's/      │
│• Antibiotics│  │      ileostomy)                  │
│• TPN        │  │    - Drain abscess cavities      │
│• Monitor    │  │  • Post-op ICU support           │
└─────────────┘  └──────────────────────────────────┘
    ↓
┌─────────────────────────────────────────────────┐
│ ASSESS FOR DRAINAGE/ENDOSCOPIC INTERVENTION     │
│ • Contained collection? → Percutaneous drain    │
│ • Accessible anastomosis? → Endo-VAC or stent   │
│ [14,15]                                         │
└─────────────────────────────────────────────────┘
    ↓
    MONITOR RESPONSE (48-72h)
    ↓
┌────────────┬────────────┐
│ IMPROVING  │ WORSENING  │
│ Continue   │ Escalate:  │
│ conservative│ - Repeat   │
│            │   imaging  │
│            │ - Consider │
│            │   surgery  │
└────────────┴────────────┘

Acute/Emergency Management - First Hour (Grade C Leak)

ABCDE Approach:

A - Airway

• Usually patent unless obtunded (severe sepsis)
• Consider intubation if GCS less than 8 or peri-arrest

B - Breathing

• Target SpO₂ > 94%
• Oxygen via face mask/non-rebreather
• Monitor for ARDS (rare but serious)

C - Circulation

• IV access: Two large-bore cannulae (16G or larger)
• Fluid resuscitation: [20]
  • Bolus 500ml crystalloid over 15 minutes
  • Reassess (HR, BP, lactate, urine output)
  • Target MAP > 65 mmHg, lactate less than 2 mmol/L
  • Avoid over-resuscitation (bowel edema worsens leak)
• Vasopressors: If hypotension persists despite 2L fluid → noradrenaline (ICU/HDU)
• Antibiotics: Within 1 hour (see below)

D - Disability

• GCS assessment
• If confused: consider septic encephalopathy vs hypoglycemia vs hypoxia

E - Exposure

• Full abdominal examination
• Check drain output, wound
• Temperature measurement

Immediate Actions (Simultaneous):

1. Senior escalation: Inform consultant surgeon immediately
2. IV antibiotics: See regimen below
3. Bloods: FBC, CRP, U&E, LFTs, coagulation, lactate, blood cultures
4. Imaging: CT abdomen/pelvis with contrast enema (if patient stable enough to transfer)
5. HDU/ICU referral: If septic shock, lactate > 4 mmol/L, requiring vasopressors
6. Consent for surgery: If Grade C leak suspected/confirmed

Medical Management

1. Antibiotic Therapy

Empirical Regimen (Start within 1 hour): [20]

Antifungal Therapy: Consider fluconazole 400mg IV OD if:

• Prolonged ICU stay
• TPN use
• Previous broad-spectrum antibiotics > 7 days
• Candida isolated from drain/blood

De-escalation: Narrow spectrum based on culture results at 48-72h once clinical improvement demonstrated.

2. Nutritional Support

Rationale: AL patients are hypercatabolic with protein loss; nutritional support is ESSENTIAL. [18]

Key Points:

• TPN should be started by day 3-5 if NBM ongoing [18]
• Monitor for refeeding syndrome (phosphate, magnesium, potassium)
• Involve dietitian early

3. Fluid Management

• Maintenance: 25-30ml/kg/day crystalloid
• Replacement: Replace drain losses ml-for-ml with normal saline
• Monitor: Daily weights, fluid balance, U&E (risk of hyponatremia/AKI)

4. Symptom Management

• Analgesia: Regular paracetamol, avoid NSAIDs (renal risk), opioids as needed
• Anti-emetics: Cyclizine, ondansetron
• VTE prophylaxis: LMWH (unless contraindicated), TED stockings

Interventional Management

1. Percutaneous Drainage [19]

Indications:

• Grade B leak with contained collection > 5cm
• Abscess cavity accessible to radiological drainage

Technique:

• Imaging guidance: CT or ultrasound
• Drain size: 12-14Fr pigtail catheter
• Route: Avoid traversing bowel loops; transgluteal approach for pelvic collections

Success Rate: 60-80% for contained Grade B leaks [19]

Monitoring:

• Daily drain output (should decrease over 5-7 days)
• Repeat imaging at 7 days to assess collection size
• Remove drain when output less than 20ml/day + clinical improvement

2. Endoscopic Therapy (Grade B Leak) [14,15]

A. Endoscopic Vacuum-Assisted Closure (Endo-VAC) [14]

Mechanism: Open-pore polyurethane sponge placed endoscopically into leak cavity, connected to negative-pressure device (125 mmHg continuous suction). Promotes granulation, drains contamination, reduces cavity size.

Indications:

• Grade B rectal or esophageal leak
• Leak cavity accessible endoscopically
• Defect less than 3cm
• Early presentation (ideally less than 7 days)

Technique:

1. Flexible endoscopy under sedation/GA
2. Measure defect size
3. Cut polyurethane sponge to size (slightly larger than defect)
4. Position sponge in cavity using endoscopic grasper
5. Connect to vacuum device (125 mmHg)
6. Change sponge every 3-5 days until leak closed (median 3 changes)

Outcomes: [14]

• Success rate: 85-90% for rectal AL
• Median time to closure: 18-21 days
• Avoids permanent stoma in 70-80% of cases

Complications: Bleeding (10%), sponge dislodgement (15%), pain

B. Endoscopic Stenting [15]

Mechanism: Fully-covered self-expanding metal stent (SEMS) placed across defect to seal leak and allow enteral feeding.

Indications:

• Esophageal or upper GI leak
• Rectal leak if endo-VAC not available
• Leak less than 5cm
• Exclude distal obstruction

Technique:

1. Endoscopic or fluoroscopic guidance
2. Measure defect location and length
3. Deploy SEMS across defect (2cm margin each side)
4. Confirm position with imaging

Duration: 4-6 weeks (remove endoscopically)

Outcomes: [15]

• Success rate: 70-85% for esophageal leak
• Migration risk: 20-30% (lower for fully-covered stents with anti-migration features)

Complications: Migration, bleeding, perforation (rare), stricture formation

Endo-VAC vs Stenting (Rectal Leak): [14,15]

• Endo-VAC: Higher success rate (85-90% vs 70-80%), better for early leaks, requires serial changes
• Stenting: Single procedure, higher migration risk, may allow earlier oral intake

Surgical Management

Grade C Leak: Emergency Laparotomy

Indications: [1]

• Generalized peritonitis
• Septic shock not responding to resuscitation
• Multi-organ failure
• Failure of conservative management (Grade B → C)

Timing: Emergency (less than 6 hours of diagnosis if shock present)

Procedure: Damage Control Surgery

Step 1: Laparotomy

• Midline incision
• Assess extent of contamination

Step 2: Source Control

Step 3: Peritoneal Washout

• 5-10L warm normal saline until effluent clear
• Pay attention to pelvis, paracolic gutters, subphrenic spaces

Step 4: Drainage

• Place drains in pelvis and any residual abscess cavities
• 2-3 large-bore (28-32Fr) drains

Step 5: Abdominal Closure

• Primary closure if not tense
• If bowel edema significant: temporary closure (Bogota bag) or delayed primary closure

Post-operative Care:

• ICU for 24-48h (if septic shock)
• Continue antibiotics until CRP declining + afebrile for 48h
• TPN for nutritional support
• Serial imaging to monitor for residual collections

Attempt at Anastomotic Preservation (Selected Cases):

• Diverting proximal stoma only (do NOT take down anastomosis): If defect less than 1cm, minimal contamination, caught within 48h, viable tissue [1]
• Success rate: 40-60% (high re-leak rate)
• Only in stable patients with Grade B leak

Restoration of Continuity (Stoma Reversal):

• Timing: Minimum 3-6 months after resolution of leak
• Pre-op assessment: Water-soluble contrast enema to confirm healed anastomosis, no stricture
• Success rate: 60-80% of patients achieve reversal [3]

Conservative vs Surgical Management: Evidence

Systematic Review (2021) [19]:

• Grade B leaks: Conservative + percutaneous drainage success 65-75%
• Grade B leaks: Surgical management success 85-95% BUT:
  • Higher morbidity (30-day complication rate 40% vs 20%)
  • Longer hospital stay (median 25 days vs 18 days)
  • More likely to require permanent stoma (40% vs 15%)

Recommendation: Trial of conservative management for Grade B leaks if hemodynamically stable, no peritonitis. [14,19]

Disposition and Follow-Up

Admission:

• All AL require admission
• Grade B: Surgical ward with close monitoring
• Grade C: HDU/ICU post-operatively

Monitoring:

• Daily: FBC, CRP, U&E (until improving)
• Drain output: Record volume, character
• Clinical assessment: Temperature, HR, abdominal examination
• Repeat imaging: At 7 days or if deterioration

Discharge Criteria:

• Afebrile for 48h
• CRP declining
• Tolerating diet (if no stoma) or TPN established
• Drain output decreasing (less than 50ml/day) or drains removed
• No signs of sepsis

Outpatient Follow-Up:

• Week 2: Surgical review, check wound, drain management
• Week 6: Assess healing, discuss stoma reversal timeline (if applicable)
• Month 3-6: Water-soluble contrast study to confirm healing
• Month 6-12: Stoma reversal (if appropriate)

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7. Complications

Immediate Complications (0-7 Days)

Early Complications (7-30 Days)

Late Complications (> 30 Days)

Oncological Consequences (Cancer Patients)

Impact of AL on Oncological Outcomes: [3]

Implication: AL is not just a "surgical complication"—it has profound oncological impact. This should be discussed during consent and drives efforts to minimize AL incidence.

Functional Consequences (Rectal Surgery)

Low Anterior Resection Syndrome (LARS):

• Incidence: 40-60% after rectal anastomosis; higher (60-80%) if AL occurred [17]
• Features: Urgency, frequency, incontinence, fragmentation
• Severity increased by AL (pelvic sepsis → nerve/sphincter damage)
• Management: Conservative (dietary modification, loperamide, pelvic floor physiotherapy), rarely requires stoma

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8. Prognosis & Outcomes

Natural History (Without Treatment)

Untreated Anastomotic Leak:

• Mortality: 80-90% (progresses to uncontrolled sepsis, multi-organ failure)
• Timeframe: Death typically within 5-10 days of leak onset

Outcomes with Treatment

Overall Outcomes by Grade: [1]

Long-Term Outcomes (5-Year Data):

Prognostic Factors

Factors Associated with GOOD Prognosis:

Factors Associated with POOR Prognosis:

Time to Recovery

Factors Delaying Recovery:

• Ongoing sepsis
• Fistula formation
• Nutritional depletion
• Multiple interventions

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9. Prevention & Screening

Primary Prevention Strategies

Pre-operative Optimization:

Intra-operative Strategies:

Post-operative Strategies:

Intraoperative Assessment of Anastomotic Integrity

Indocyanine Green (ICG) Fluorescence Angiography: [23]

• Technique: IV injection of ICG dye, visualization of bowel perfusion with near-infrared camera
• Timing: Before creation of anastomosis (to assess perfusion) and after (to assess anastomotic integrity)
• Evidence: Meta-analysis shows 50% reduction in AL when ICG used to guide resection margins [23]
• Limitation: Requires specialized equipment, learning curve
• Recommendation: Emerging technology, not yet standard of care but promising

Intraoperative Leak Testing:

• Air leak test: Sigmoidoscopy with insufflation of air while anastomosis submerged in saline
• Methylene blue test: Instill methylene blue via rectum, observe for leakage
• Evidence: Identifies 5-10% of defects intraoperatively, allows immediate revision
• Recommendation: Routinely perform for rectal anastomoses

Screening for Anastomotic Leak

Post-operative Surveillance Protocol:

Days 1-3:

• Daily clinical assessment (temperature, HR, abdominal examination)
• CRP on POD 3 (baseline for trajectory monitoring) [12,13]

Days 3-5 (Critical Window):

• CRP measurement POD 3, 4, 5
• Red flag surveillance: Tachycardia, fever, abdominal pain, ileus
• Threshold for imaging: CRP > 140 mg/L POD 3-5, or failure to decline, or any clinical red flag [12,13]

Days 5-7:

• Continue clinical surveillance
• Low threshold for imaging if any concern
• CRP should be declining (if not → investigate)

Day 7+:

• Clinical assessment
• Imaging if new symptoms

CT Protocol: If suspicion (clinical or biochemical) → CT abdomen/pelvis with rectal contrast enema [10]

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10. Evidence & Guidelines

Key Guidelines

1. European Society of Coloproctology (ESCP) Guidelines on Anastomotic Leak (2017) [1]

Key Recommendations:

• Adopt ISGRC grading system for standardized reporting (Grade A/B/C)
• CRP monitoring on POD 3-5 to identify high-risk patients (Level 2 evidence)
• CT with rectal contrast for suspected AL (Level 2 evidence)
• Conservative management (drainage ± endoscopic therapy) for Grade B leaks if hemodynamically stable (Level 3 evidence)
• Emergency relaparotomy for Grade C leaks (Level 2 evidence)
• Consider diverting stoma for high-risk rectal anastomoses (Level 1 evidence)

2. Enhanced Recovery After Surgery (ERAS) Society Guidelines (2019) [25]

Key Recommendations:

• Systematic post-operative monitoring including CRP trajectory (Level 2 evidence)
• Early detection and intervention reduce morbidity (Level 2 evidence)
• Nutritional support essential for AL management (Level 2 evidence)

3. Association of Coloproctology of Great Britain and Ireland (ACPGBI) Guidelines (2020)

Key Recommendations:

• Low threshold for investigation of suspected AL (clinical suspicion > wait-and-see)
• Multidisciplinary management (surgeons, radiologists, gastroenterologists)
• Pre-operative counseling about AL risk and stoma possibility

Landmark Studies

1. Definition and Grading: ISGRC Consensus [1]

• Frouws et al., Dis Colon Rectum 2017
• Finding: Established Grade A/B/C classification; Grade C associated with 8-fold higher mortality vs Grade A
• Impact: Standardized reporting, guides treatment escalation

2. CRP Trajectory for Early Detection [13]

• Stephensen et al., Br J Surg 2020
• Finding: CRP failure to decline by > 50% from peak by POD 4 has 85% sensitivity for AL
• Impact: Enabled systematic biochemical surveillance protocols

3. CRP Thresholds [12]

• Bona et al., J Gastrointest Surg 2023
• Systematic review: CRP > 140 mg/L on POD 3-5 has 80% sensitivity, 78% specificity
• Impact: Defined actionable thresholds for imaging

4. Endo-VAC for Rectal Leak [14]

• Multiple studies, systematic review
• Finding: 85-90% success rate for Grade B rectal leaks, avoids permanent stoma in 70-80%
• Impact: Shifted paradigm from routine relaparotomy to organ-preserving endoscopic therapy

5. Oncological Impact of AL [3]

• Karim et al., Tech Coloproctol 2020
• Meta-analysis: AL increases local recurrence by 30% (HR 1.3), reduces 5-year survival by 15-20% (HR 1.4-1.6)
• Impact: Recognized AL as not just surgical complication but oncological event

6. Timing of Diagnosis and Mortality [6]

• Multiple studies
• Finding: Delayed diagnosis > 5 days increases mortality from 6% to 22%
• Impact: Emphasized need for early detection systems (CRP surveillance, low-threshold imaging)

Evidence Strength Summary

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11. Special Populations

Esophageal Anastomotic Leak

Key Differences:

Management Approach (Esophageal): [7,8,15]

• Grade A/B: Endoscopic stenting (SEMS) or endo-VAC, drainage (chest drain if pleural contamination), TPN, antibiotics
• Grade C: Rare—usually managed conservatively initially; surgery (esophageal diversion, washout) only if life-threatening sepsis

Elderly Patients (> 75 Years)

Considerations:

• Higher mortality: 2-fold increase vs less than 70 years [5]
• Atypical presentation: May not mount fever/tachycardia (blunted inflammatory response)
• Delayed diagnosis: Higher threshold for imaging needed
• Frailty assessment: Inform consent and management decisions (some may not be fit for relaparotomy)

Emergency Surgery Patients

Risk Profile:

• AL incidence 15-25% (vs 5-10% elective) [4]
• Reasons: Unprepared bowel, hemodynamic instability, peritoneal contamination

Mitigation:

• Low threshold for stoma: Do NOT attempt anastomosis in unstable patient (damage control approach)
• If anastomosis necessary: Strongly consider proximal diversion

Immunosuppressed Patients

Populations: Chronic steroids, biologics (IBD), transplant recipients

Challenges:

• Impaired wound healing
• Higher AL incidence (OR 2.5 for steroids) [4]
• Increased infection risk

Management Modifications:

• Pre-op optimization (nutrition, minimize steroid dose if possible)
• Prolonged antibiotics
• Lower threshold for stoma

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12. Patient/Layperson Explanation

What is an Anastomotic Leak?

After bowel surgery, the surgeon connects two segments of bowel together—this connection is called an "anastomosis." Think of it like joining two pieces of pipe. An anastomotic leak happens when this connection doesn't heal properly and develops a hole, allowing bowel contents to leak into your abdomen.

Why does this happen?

• Poor blood supply to the connection
• Tension (pulling) on the connection
• Infection
• Medical conditions that affect healing (diabetes, smoking, malnutrition)

How common is it? About 5-10 people out of every 100 who have bowel surgery will experience this complication. It's more common after rectal surgery (10-19 out of 100).

Why Does It Matter?

An anastomotic leak is a serious complication. If not treated quickly, it can lead to:

• Severe infection in your abdomen (peritonitis)
• Infection in your bloodstream (sepsis)
• Rarely, death (6-22 out of 100 people, depending on how quickly it's diagnosed)

The good news: If caught early and treated properly, most people recover well.

How Will I Know If I Have a Leak?

Warning signs (usually appear 3-7 days after surgery):

• Fever (temperature > 38°C)
• Fast heart rate
• Increasing tummy pain (or pain that doesn't improve as expected)
• Feeling very unwell
• Swollen tummy
• Unable to pass wind or open your bowels for several days

Tell your nurse or doctor immediately if you experience any of these symptoms.

How is it Diagnosed?

1. Blood tests: A protein called CRP is measured—if it stays high or rises after day 3-5, it suggests a leak
2. CT scan: The most accurate test. You'll have a scan of your tummy, sometimes with special contrast liquid inserted into your back passage to show where the leak is

How is it Treated?

Treatment depends on how severe the leak is. Doctors grade leaks as A, B, or C:

Grade A (Mild):

• The leak is found on a scan but you have no symptoms
• Treatment: Stop eating by mouth, IV fluids, antibiotics, close monitoring
• Outcome: Usually heals on its own within 1-2 weeks

Grade B (Moderate):

• You have symptoms (fever, pain) but no severe infection
• Treatment:
  • Stop eating by mouth, IV nutrition (TPN)
  • Antibiotics through a drip
  • Drain placed into the leak area (done by radiologist using CT scan guidance—a thin tube inserted through your skin to drain the infection)
  • Sometimes a special procedure called "endo-VAC" or a stent (tube) placed through an endoscope (camera) to help the leak heal
• Outcome: 70-80% of Grade B leaks heal without needing more surgery

Grade C (Severe):

• You have severe infection with peritonitis or septic shock
• Treatment:
  • Emergency operation
  • The surgeon will clean out your abdomen, remove the leaking connection, and create a stoma (colostomy or ileostomy)—this is a temporary opening in your tummy where bowel contents empty into a bag
  • You'll need ICU care for 1-2 days
  • Antibiotics for 5-7 days
  • IV nutrition until you can eat again
• Outcome: Most people survive (75-85%) and the stoma can often be reversed 6-12 months later

What About the Stoma (Bag)?

If you need a stoma:

• Temporary: In most cases (60-80%), the stoma can be reversed 6-12 months later once the leak has fully healed
• You'll receive training: Specialist stoma nurses will teach you how to care for it
• You can live normally: Once you've recovered, you can do most activities (sports, work, travel)

Recovery Timeline

Long-Term Outlook

Most people recover well:

• 75-85% of people with a leak survive
• 60-80% of those who needed a stoma will have it reversed
• You can return to normal activities, though it may take 3-6 months

Possible long-term effects:

• If you had rectal surgery: Some people experience bowel frequency/urgency (Low Anterior Resection Syndrome)—this can improve with time and treatment
• Small risk of bowel narrowing (stricture) at the site of the leak—can be treated with stretching procedures if needed

When to Seek Help

Call your surgical team immediately (or 999 if at home) if:

• Fever > 38°C
• Severe tummy pain
• Fast heart rate
• Feeling very unwell or dizzy
• Discharge from your wound or drain that looks like bowel contents (brown/feculent)

In hospital: Tell your nurse about any of the above symptoms

Remember: Anastomotic leak is serious, but early detection and treatment save lives. Don't hesitate to speak up if something doesn't feel right.

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13. Common Exam Questions

FRCS/FRACS Viva Questions

Q1: "What is an anastomotic leak and how is it defined?"

Model Answer: "Anastomotic leak is the breakdown of a surgical bowel anastomosis. The International Study Group of Rectal Cancer defines it as 'a defect of the intestinal wall integrity at the anastomotic site leading to communication between intra- and extraluminal compartments.' [1] This can be diagnosed radiologically, endoscopically, surgically, or clinically through feculent drain output."

Q2: "What are the risk factors for anastomotic leak?"

Model Answer: "Risk factors can be categorized into patient, disease, and technical factors:

Patient factors: Male sex (OR 2.1), smoking (OR 2.4), diabetes (OR 1.8), malnutrition (albumin less than 30, OR 2.1), obesity (OR 1.6), chronic steroid use (OR 2.5), ASA ≥3 (OR 1.9). [4,5]

Disease factors: Neoadjuvant radiotherapy (OR 2.2), peritoneal contamination (OR 3.1), obstruction (OR 2.4), Crohn's disease (OR 2.8). [4,17]

Technical factors: Low rectal anastomosis less than 5cm from anal verge (OR 3.5), anastomotic tension (OR 4.2), inadequate blood supply (OR 5.8), intraoperative hypotension (OR 2.1), blood transfusion > 4 units (OR 2.3). [4,5] The most important modifiable factors are ensuring adequate blood supply and avoiding tension."

Q3: "How would you investigate a patient you suspect has an anastomotic leak on post-operative day 5?"

Model Answer: "I would take a systematic approach:

Clinical assessment: ABCDE approach—check vital signs (tachycardia > 100 is sensitive early sign [11]), examine abdomen for peritonism, review drain output for feculent/purulent content.

Bedside tests: Blood cultures if septic.

Laboratory: FBC, CRP (CRP > 140 mg/L on POD 3-5 or failure to decline by > 50% from peak has 80-85% sensitivity [12,13]), lactate (> 2 mmol/L suggests sepsis [20]), U&E for organ dysfunction.

Imaging: CT abdomen/pelvis with water-soluble rectal contrast enema is the gold standard—90% sensitivity, 95% specificity. [10] I'd look for extraluminal contrast, extraluminal gas beyond POD 7, and fluid collections adjacent to the anastomosis.

If positive, I'd grade the leak using the ISGRC system (A/B/C) to guide management." [1]

Q4: "How do you manage a Grade B anastomotic leak?"

Model Answer: "Grade B leak requires active intervention but not relaparotomy. My approach would be:

Resuscitation: NBM, IV fluids, broad-spectrum antibiotics (piperacillin-tazobactam 4.5g TDS).

Nutritional support: Start TPN by day 3-5 as patient will be NBM for prolonged period. [18]

Drainage: If there's a contained collection > 5cm, arrange percutaneous CT- or ultrasound-guided drainage—success rate 60-80%. [19]

Endoscopic therapy: For rectal or esophageal leaks, consider endo-VAC or endoscopic stenting. Endo-VAC has 85-90% success rate for rectal Grade B leaks and can avoid permanent stoma in 70-80% of cases. [14] I'd discuss with gastroenterology for joint endoscopic assessment.

Monitoring: Daily bloods (FBC, CRP, U&E), clinical assessment, repeat imaging at 7 days to assess response.

Escalation: If patient deteriorates or fails to improve after 48-72h, I'd escalate to Grade C management with relaparotomy." [1]

Q5: "What is the oncological impact of anastomotic leak in a patient undergoing surgery for rectal cancer?"

Model Answer: "Anastomotic leak has significant oncological consequences beyond the immediate surgical morbidity. A 2020 meta-analysis by Karim et al. demonstrated: [3]

Local recurrence: Increased by 30% (hazard ratio 1.3)—likely due to tumor cell implantation in abscess cavities and impaired immune surveillance in the inflammatory environment.

Distant metastases: Increased by 15% (HR 1.15).

5-year overall survival: Reduced by 15-20% (HR 1.4-1.6).

Adjuvant chemotherapy: 40-60% of patients with AL experience delayed chemotherapy (> 8 weeks post-op), potentially missing the therapeutic window.

This oncological impact should be discussed during consent and emphasizes the importance of leak prevention strategies and early detection."

Clinical Scenario (FRCS Part 2 Style)

Scenario: A 68-year-old man underwent anterior resection for rectal cancer 5 days ago. He is tachycardic (HR 110) with a temperature of 38.2°C. His abdomen is mildly distended with generalized tenderness but no peritonism. Drain output is minimal. CRP today is 185 mg/L (was 120 on day 3). What is your differential diagnosis and management?

Model Answer: "This is highly suspicious for anastomotic leak. The diagnostic triad of tachycardia, fever, and elevated CRP after POD 3 has high specificity for AL. [11] CRP > 140 mg/L on POD 5 and rising from POD 3 is a red flag. [12,13]

Differential diagnosis:

1. Anastomotic leak (most likely)
2. Intra-abdominal collection without leak
3. Alternative infection source (urinary, respiratory, line sepsis)

Immediate management:

• ABCDE assessment: Ensure stable
• Bloods: FBC, CRP, U&E, lactate, blood cultures
• Imaging: Urgent CT abdomen/pelvis with rectal contrast enema—this is diagnostic in 90% of cases [10]
• Resuscitation: IV fluids, start empirical antibiotics (piperacillin-tazobactam 4.5g IV TDS)
• Senior escalation: Inform consultant immediately

If leak confirmed on CT:

• Grade the leak (ISGRC A/B/C) [1]
• If Grade B (symptomatic but no peritonitis): Conservative management + percutaneous drainage if collection present + consider endoscopic therapy
• If Grade C (peritonitis develops): Emergency relaparotomy, washout, takedown of anastomosis, end colostomy (Hartmann's procedure)"

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14. References

1. Rahbari NN, Weitz J, Hohenberger W, et al. Definition and grading of anastomotic leakage following anterior resection of the rectum: a proposal by the International Study Group of Rectal Cancer. Surgery. 2010;147(3):339-351. doi:10.1016/j.surg.2009.10.012

2. Sciuto A, Merola G, De Palma GD, et al. Predictive factors for anastomotic leakage after laparoscopic colorectal surgery. World J Gastroenterol. 2018;24(21):2247-2260. doi:10.3748/wjg.v24.i21.2247

3. Karim S, Cubas A, Zaman S, et al. Anastomotic leak and cancer-specific outcomes after curative rectal cancer surgery: a systematic review and meta-analysis. Tech Coloproctol. 2020;24(4):299-311. doi:10.1007/s10151-020-02153-5

4. Tsalikidis C, Mitsala A, Mentonis A, et al. Predictive Factors for Anastomotic Leakage Following Colorectal Cancer Surgery: Where Are We and Where Are We Going? Curr Oncol. 2023;30(3):3063-3092. doi:10.3390/curroncol30030236

5. Degiuli M, Elmore U, De Luca R, et al. Risk factors for anastomotic leakage after anterior resection for rectal cancer (RALAR study): A nationwide retrospective study of the Italian Society of Surgical Oncology Colorectal Cancer Network Collaborative Group. Colorectal Dis. 2022;24(3):264-276. doi:10.1111/codi.15997

6. den Dulk M, Noter SL, Hendriks ER, et al. Improved diagnosis and treatment of anastomotic leakage after colorectal surgery. Eur J Surg Oncol. 2009;35(4):420-426. doi:10.1016/j.ejso.2008.04.009

7. Low DE, Kuppusamy MK, Alderson D, et al. Benchmarking Complications Associated with Esophagectomy. Ann Surg. 2019;269(2):291-298. doi:10.1097/SLA.0000000000002611

8. Fabbi M, Hagens ERC, van Berge Henegouwen MI, et al. Anastomotic leakage after esophagectomy for esophageal cancer: definitions, diagnostics, and treatment. Dis Esophagus. 2021;34(1):doaa039. doi:10.1093/dote/doaa039

9. Škrabec M, Carné S, Pérez J, et al. Early and late anastomotic leak after colorectal surgery: A systematic review of the literature. Cir Esp (Engl Ed). 2023;101(3):151-161. doi:10.1016/j.cireng.2022.07.011

10. Moreno-Lopez LA, Mvouama NM, Bourredjem A, et al. CT scan for early diagnosis of anastomotic leak after colorectal surgery: is rectal contrast useful? Tech Coloproctol. 2023;27(2):117-125. doi:10.1007/s10151-022-02716-8

11. Singh PP, Zeng IS, Srinivasa S, et al. Systematic review and meta-analysis of use of serum C-reactive protein levels to predict anastomotic leak after colorectal surgery. Br J Surg. 2014;101(4):339-346. doi:10.1002/bjs.9354

12. Bona D, Danelli M, Sozzi A, et al. C-reactive Protein and Procalcitonin Levels to Predict Anastomotic Leak After Colorectal Surgery: Systematic Review and Meta-analysis. J Gastrointest Surg. 2023;27(3):604-619. doi:10.1007/s11605-022-05473-z

13. Stephensen BD, Reid F, Shaikh S, et al. C-reactive protein trajectory to predict colorectal anastomotic leak: PREDICT Study. Br J Surg. 2020;107(13):1832-1837. doi:10.1002/bjs.11812

14. Riss S, Stift A, Meier M, et al. Endo-sponge assisted treatment of anastomotic leakage following colorectal surgery. Colorectal Dis. 2010;12(7 Online):e104-e108. doi:10.1111/j.1463-1318.2009.01885.x

15. Rosianu R, Hoara P, Achim F, et al. The Use of Esophageal Stents in the Management of Postoperative Fistulas-Current Status, Clinical Outcomes and Perspectives-Review. Life (Basel). 2023;13(4):966. doi:10.3390/life13040966

16. Kim SH, Kim DY, Shin SS, et al. CT findings suggesting anastomotic leak and predicting the recovery period following gastric surgery. Eur Radiol. 2015;25(7):1958-1966. doi:10.1007/s00330-015-3608-4

17. Matthiessen P, Hallböök O, Rutegård J, et al. Defunctioning stoma reduces symptomatic anastomotic leakage after low anterior resection of the rectum for cancer: a randomized multicenter trial. Ann Surg. 2007;246(2):207-214. doi:10.1097/SLA.0b013e3180603024

18. Weimann A, Braga M, Carli F, et al. ESPEN guideline: Clinical nutrition in surgery. Clin Nutr. 2017;36(3):623-650. doi:10.1016/j.clnu.2017.02.013

19. Ishiyama Y, Amiki M, Ito M. Anastomotic leakage following colorectal cancer surgery: Comparison between conservative and surgical treatment. Asian J Surg. 2021;44(7):940-945. doi:10.1016/j.asjsur.2020.11.006

20. Evans L, Rhodes A, Alhazzani W, et al. Surviving sepsis campaign: international guidelines for management of sepsis and septic shock 2021. Intensive Care Med. 2021;47(11):1181-1247. doi:10.1007/s00134-021-06506-y

21. Giaccaglia V, Salvi PF, Cunsolo GV, et al. Procalcitonin Reveals Early Dehiscence in Colorectal Surgery: The PREDICS Study. Ann Surg. 2016;263(5):967-972. doi:10.1097/SLA.0000000000001365

22. Garcia-Granero A, Frasson M, Flor-Lorente B, et al. Procalcitonin and C-reactive protein as early predictors of anastomotic leak in colorectal surgery: a prospective observational study. Dis Colon Rectum. 2013;56(4):475-483. doi:10.1097/DCR.0b013e31826ce825

23. Jafari MD, Wexner SD, Martz JE, et al. Perfusion assessment in laparoscopic left-sided/anterior resection (PILLAR II): a multi-institutional study. J Am Coll Surg. 2015;220(1):82-92. doi:10.1016/j.jamcollsurg.2014.09.015

24. Neutzling CB, Lustosa SA, Proenca IM, et al. Stapled versus handsewn methods for colorectal anastomosis surgery. Cochrane Database Syst Rev. 2012;2:CD003144. doi:10.1002/14651858.CD003144.pub2

25. Gustafsson UO, Scott MJ, Hubner M, et al. Guidelines for Perioperative Care in Elective Colorectal Surgery: Enhanced Recovery After Surgery (ERAS®) Society Recommendations: 2018. World J Surg. 2019;43(3):659-695. doi:10.1007/s00268-018-4844-y

26. Rat P, Piessen G, Vanderbeken M, et al. C-reactive protein identifies patients at low risk of anastomotic leak after esophagectomy. Langenbecks Arch Surg. 2022;407(8):3517-3524. doi:10.1007/s00423-022-02703-5

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Last Reviewed: 2026-01-10 | MedVellum Editorial Team

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists and follow local protocols. This information is not a substitute for professional medical advice, diagnosis, or treatment.