Acute Colorectal and Anoproctology Flashcards
Define “Massive Lower Gastrointestinal Bleeding”
What proportion of massive LGIB is actually UGI in aetiology?
Massive LGIB is defined as bleeding distal to the ligament of Treitz associated with haemodynamic abnormality.
Between 15-20% of massive LGIBs are UGIBs.
This has lead to a recent proposal to reserve the term LGIB for bleeding occuring distal to the ICV.
What is the mortality rate associated with LGIB?
What factors affect this?
A recent UK audit showed a 3-4% mortality associated with LGIB.
This was higher in inpatients who develop LGIB compared with outpatients who present with LBIG, which reflects the underlying comorbidities associated with inpatients who bleed.
Provide an overview of the causes of lower GI bleeding
LGIB is most common in elderly patients with multiple comorbidities; however, causes vary by age. In adolescents, common causes are Meckel’s diverticula, IBD, and benign polyps. LGIB in adults is most often caused by colonic diverticula, cancer, and angiodysplasia.
In a recent audit of UK data:
-
Diverticulosis 20-65%
- Self-limiting 80% of the time
- Often not a formal diagnosis (25% of audit diagnoses)
-
Colitis 15%
- Ischaemic
- Inflammatory bowel disease
- Infectious
-
Haemorrhoids 3-15%
- Rarely cause massive LGIB
-
Angiodysplastic lesions 3-15%
- Over-represented in massive LGIB 20-30%!
- Over two thirds are >70 years old
- More commonly in the right colon (54%)
-
Iatrogenic bleeding 5-10%
- Post-polypectomy; immediate and delayed
- Post-colorectal surgery
- Post radiotherapy
-
Malignancy
- Often occult, rarely massive LGIB
-
Miscellaneous:
- Varices, Rectal ulceration, Dieulafoy lesions, NSAIDS, Meckel’s
What are the key principles in managing LGIB?
Which index should be used in the assessment of potentially massive LGIB? What is its utility?
- Simultaneously assess and resuscitate
- Determine the severity of bleeding
- Determine the location of the bleeding
- Determine the cause of the bleeding.
The British guidelines advocate the use of the shock index (HR/SBP) with a value greater than 1 as an indicator of ongoing bleeding.
Increasing shock index is associated with increasing risk of mortality and it is widely used in the trauma literature.
A shock index >1 is also a predictor of detecting a contrast blush on CT angiography and therefore may be useful in identifying patients who would benefit from CTA and likely need therapeutic intervention.
Describe the key features of a focussed history when assessing a patient with lower GI bleeding.
- HPC:
- Timing, frequency, and volume of the bleeding
- Associated symptoms
- PMHx:
- Anticoagulant / anti-platelet use
- Previous colonoscopy
- History of bleeding diathesis
- History of IBD
- History of irradiation
- History of liver disease
What are the guidelines for NG placement in lower GI bleeding?
The American guidelines recommend placement of a nasogastric tube and lavage to assess for an UGIB source; however, the British guideline advise against this practice as it does not reliably aid diagnosis, affect outcomes and maybe associated with complications in up to a third of patients.
Reliance on a negative nasogastric tube aspirate to exclude an UGIB has poor sensitivity and low negative predictive value (64%).
Describe the principles of blood transfusion in lower GI bleeding.
Cite Hb thresholds and targets in your answer.
- All the guidelines recommend a restrictive approach to blood product transfusion with a threshold haemoglobin of 70g/L in haemodynamically stable patients with a target haemoglobin of 70-90 g/L.
- In patients with ischaemic heart disease or significant comorbidity this threshold can be increased to 80g/L with a target haemoglobin of 80-100g/L.
- Haemodynamically unstable patients should be actively resusciated with a massive transfusion protocol in consultation with a haemotologist to target a haemoglobin of 90g/L.
- There is no randomised data from patients with LGIB to support these recommendations. They are derived from UGIB data where a recent meta-analysis has demonstrated increased survival when a restrictive blood transfusion strategy is adopted.
- A separate systematic review has shown that a restrictive transfusion strategy in patients with ischaemic heart disease, previous stroke and vascular disease have an increased risk of myocardial infarction and death.
What is the evidence for TXA use in lower GI bleeding?
The HALT-IT trial, published in 2020, demonstrated that patients administered 4g TXA after acute GI bleeding experienced more venous thromboembolic events than controls (0.8% vs 0.4%, RR 2.11) without a concomitant reduction in death or rebleeding at 24hrs, 5 days, or 28 days.
Use of TXA is not recommended in the setting of acute LGIB.
How can patients with lower GI bleeding be risk-stratified?
-
The Oakland Score
- Recommended by British Guidelines
- Clinical and demographic data with various weighting
- Safe discharge with OP scope if score is less than 8
-
The NOBLADS score
- Developed in Japan, validated internationally
- 8 parameters, all easily assessed on admission
- Score ≥5 = ~80% severe bleeding risk (≥2URBC)
- Score <4 = ~2% severe bleeding risk
- Safe discharge and OP scope if score less than 2
-
The Strate score
- Derived from multivariate analysis
- Provides OR for severe bleeding
- Similar to NOBLADS parameters.
What proportion of patients presenting with lower GI bleeding are on anticoagulation?
30% are on either anti-platelets or anti-coagulants
5% are on dual antiplatelet therapy or antiplatelets + anti-coagulants.
In the setting of lower GI bleeding, how do you address:
Warfarin?
Dabigatran?
Rivaroxiban / Apixaban?
Aspirin?
DAPT?
Heparin?
- Warfarin
- Cease and reverse with PTX + FFP if INR >2.0
- Recommence 7 days later where feasible
- Bridge with Heparin in high risk patients
- Dabigatran
- Cease and reverse with Idarucizumab
- Rivaroxiban / Apixaban
- Cease and reverse with Adexanet alfa (both direct and indirect Factor Xa inhibitors)
- Aspirin
- Cease in primary prevention
- Continue in secondary prevention
- DAPT
- DAPT for cardiac stents should be discussed with cardio
- In massive LGIB, P2Y12 inhibitors (e.g Cloipidogrel) should be ceased while Aspirin continues
- Patients on DAPT have a 5-fold risk of re-bleeding
- Heparin
- Reverse with Protamine sulfate
- Ciraparantag is a small molecule drug which binds UFH and LMWH - not widely in use
For elective colonoscopy, when should Warfarin, DOACS, and antiplatelets be withheld from and when should they be resumed?
- Warfarin
- withhold from 5 days
- resume same day
- DOACS
- withhold from 2 days
- resume next day
- Aspirin
- do not stop
- P2Y12 agents
- withhold for 7 days
- resume within 24 hours
What is the role of colonoscopy in lower GI bleeding?
- Colonoscopy should be the first-line diagnostic investigation in haemodynamically stable patients to investigate a major LGIB.
- If the bleed is major (Oakland score >8) = inpatient
- If the bleed is minor (Oakland ≤8 points) = outpatient
- A major advantage of colonoscopy is that it can be used simultaneously to provide definitive therapy in up to 60% of cases
- Inpatient colonoscopy requires prep as caecal intubation rates are ~60% without prep. This adds complexity to the case and the risks of inpatient prep following bleeding should be balanced with the expediency of diagnosis.
What colonoscopic therapeutic modalities exist for control of lower GI bleeding?
- Clipping via through the scope clips
- Can be applied to post-polypectomy site
- Can be applied to the base of a bleeding divertic for tamponade
- Adrenaline injection
- 20% re-bleed rate if used as monotherapy!
- Endoscopic band ligation
- Technically more challenging but lower re-bleed rates cf clips
- Argon Plasma Coagulation
- Angioectatic lesions
- 20-60W, 1-2L flow, 1-2 sec pulses, 1-3mm from lesion
- Haemostatic powders
- Hemospray
- Caution with liberal use in heavy bleeding - embolises
Describe the role of interventional radiology in lower GI bleeding.
Overall success rates?
Strengths and weaknesses of the various approaches?
IR can be used to both localise and treat lower GI bleeding, with an overall success rate of 85% with regard to haemostasis.
In the haemodynamically unstable patient experiencing a massive LGIB, CTA is recommended before any therapy is instigated. CTA can detect bleeding as slow as 0.3ml/min. Expedited transfer to angioembolization is required, and some consider this to be a KPI in IR units.
Catheter angiography requires a faster rate of bleeding (1ml/min) for diagnostic purposes. Super selective angioembolization involves the embolization with absorbable gelatin sponges, cyanoacrylate glue, ethylene, or polyvinyl alcohol, and microcoils to control haemorrhage.
A systematic review reported that this technique can be successful in achieving immediate haemostasis in between 40-100% of cases with re-bleeding rates reported between 0-50%
Describe the risks of IR-angioembolization
- Contrast nephropathy
- Bleeding
- Pseudoaneurysm formation
- Thromboembolic events
- Colonic ischaemia
- Can occur if angioembolization is not super-selective.
- This can result in a spectrum of clinical presentation from self-limiting ischaemic colitis to perforation and associated peritonitis
Describe the management algorithm for lower GI bleeding put forward by the British Society of Gastroenterology
What is the cryptoglandular theory and why is it incomplete?
The cryptoglandular theory can be summarised in three steps;
- Cystic dilatation of an anal gland (obstructive or congenital)
- Infection of the anal gland leading to abscess formation
- Surgical or spontaneous drainage in the perianal skin leads to tract formation and epithelisation
Critical points against the cryptoglandular theory include;
- It is unlikely for an abscess to traverse intact skeletal muscle preferentially to an unimpeded path
- Most peri-anal abscesses do not result in fistula
- The theory doesn’t explain why fistula-in-ano is more common in males (12.3/100,000 versus 5.6/100,000)
- A scarcity of bowel derived bacteria in fistula tracts
Describe the pathophysiology of perianal fistulae in Crohn’s
- Based on the Epithelial to Mesenchymal Transition
- EMT is a normal physiological process in embryology and healing
- Indices of EMT include upregulated TGF-1, TGF-2, and β6-integrin with decreased expression of E-cadherin and β-catenin
- This pattern is observed in Crohn’s disease.
- EMT results in activation of matrix remodelling enzymes and induces expression of molecules involved with cellular invasion, creating a fistulating phenotype.
Is there a unifying theory of perianal fistula formation?
- The host’s innate immunity is unable to fully resolve an acute infection of an anal gland
- Persistence of bacterial remnants triggers EMT
- Activation of EMT leads to release of pro-inflammatory cytokines such as IL-1beta and TGFbeta as well as release of MMPs
- This leads to degradation of the extracellular matrix as well as migration of epithelial cells, facilitating fistula formation
What is the evidence for antibiotics in perianal fistula treatment?
-
Randomised evidence to show reduced fistula rates after I+D of perianal abscess (14% versus 31%)
- 7-day course of Cipro and Metronidazole
- There is evidence from small trials in patients with Crohn’s disease that the use of antibiotics alone can lead to fistula closure
- Of note, the original description of the LIFT procedure includes 2 weeks of Ciprofloxacin and Metronidazole post op.
What modifiable factors promote or facilitate perianal fistulisation?
FRIENDS again…
Foreign body (therapeutic Seton!)
Radiation or tissue damage causing chronic inflammatory change
Inflammation around the fistula
Epithelialisation (reflects chronicity)
Neoplasia
Distal obstruction; in this setting the high pressure zone
Sepsis or bacterial load
Classify fistula-in-ano in terms of management categories
Simple (laying open fistula)
- Intersphincteric
- Transphincteric <30% of the sphincter complex involved
Complex (draining Seton for at least 6 weeks…)
- Transphincteric >30%
- Suprasphincteric (cannot have have L.I.F.T)
- Extrasphincteric
- Any fistula with
- Concomittant anorectal disease
- Crohn’s
- TB/HIV
- Radiotherapy
- Cancer
- Multiple tracts
- Recurrent fistula
- Anterior fistula in a woman
- Faecal incontinence
- Concomittant anorectal disease
What factors need to be considered when estimating liklihood of incontinence following fistulotomy?
- Current degree of continence
- Age
- Presence of IBS
- Previous childbirth
- Previous anorectal surgery
- Anoreceptive intercourse
- Previous irradiation
- Underlying neurological disorders.
Describe the most well established “sphincter-preserving” procedures for fistula in ano, their original and subsequently analysed success rates, as well as their main advantages and disadvantages.
- Ligation of the Inter-sphincteric Tract
- Original series 94%
- Meta-analyses 76%
- Pros:
- Down stages the fistula if it fails
- Requires no special equipment
- Cons:
- Technically difficult for high fistulas with success rates from the OG of 60%
- Pros:
- Endoanal advancement flap
- Success proportional to thickness of flap
- 70% for MAF, 81% for PAF, 92% for FAF
- Pros:
- High pressure zone repaired
- Cons:
- Is not actually sphincter preserving with PAF and FAF
- Potential for mucosal ectropion
- Pros:
What are the less well established methods of perianal fistula repair?
What are the approximate success rates?
-
Anal fistula plug
- Simple but expensive
- 54%
-
Fibrin glue
- Success rate reportedly 0-87%!
-
Video-assissted anal fistula treatment
- Requires fistuloscope and cautery
- Reported success rate 82% but little take up
-
Fistula laser closure
- Laser wire destroys the fistula tract epithelium and obliterates the remaining fistula tract through shrinkage
- Success rates of 65%
-
Over the scope clip
- Theorised to more securely close the internal opening
- Success rates of 63%
-
Stem cell treatment
- In evolution, improved cf placebo at 4 weeks but no difference at one year…
Is there a role for anal fistula plugs in the treatment of fistula in ano?
The lack of efficacy in long-term fistula healing when compared to other techniques might be tempered by a lack of detriment to continence, and the conclusion of the position paper by the Association of Coloproctologists of Great Britain and Ireland is that anal fistula plugs may have a niche role in the patient who has some pre-existing incontinence
What are the complications of the LIFT procedure for fistula in ano?
What are the risk factors for failure?
Complications include:
- Wound breakdown and bleeding ~13%
- Failure ~30%; often converts to inter-sphincteric fistula
Risk-factors for failure include:
- Crohn’s disease
- Horseshoe fistulas
- Tracts longer than 3cm
- Diabetes
- Obesity
Describe modifications to the traditional LIFT procedure and state whether these have any evidence.
- Omission of tract excision
- Variable reported outcomes
- Coring out the tract via the external opening
- Small series seem to suggest improved rates of healing
- Placing a Seton to drain the external component
- Small series seem to suggest improved rates of healing
- Addition of a trans-anal advancement flap
- Results disappointing
- Addition of an anal plug
- Single study showed promise but success rates very high in both arms…
- Insertion of a bio-prosthetic mesh between divided tract
- “Biolift” small series, mixed results.
What are the rates of bleeding detectable by:
Catheter angiography?
CTA?
Radionucleotide Scintigraphy?
Catheter angiography = 0.5-1.0ml/min
CTA = 0.3ml/min
Radionucleotide Scintigraphy = 0.1ml/min
Describe the suspensory ligaments of the anal cushions.
Treitz’s muscle maintains the anal cushions in their normal position. It consists of submucosal muscle, which fixes the haemorrhoids to the internal anal sphincter. These muscles will be encountered during haemorrhoidectomy and traverse the plane of dissection.
Park’s ligament is a mucosal suspensory ligament that penetrates the internal sphincter and fixes the sinusoids to the conjoined longitudinal muscle. This ligament is orientated longitudinally and is thought to be pathologically elongated in haemorrhoidal prolapse.
Describe the pathophysiology of haemorrhoidal disease.
- Sliding of the anal cushions
- Loss of the connective anal cushion tissue
- Reduced venous return to the superior and middle rectal veins during defaecation
- Dilated haemorrhoidal plexus with stagnant sinusoidal blood
What is the success rate of rubber band ligation for symptomatic haemorrhoidal disease?
What are the complications?
80% success rate where success is defined as permanent relief of symptoms for follow-up period; marked improvement in symptomatology with rare manifestation of bleeding; symptom relief for a limited period of time.
Complications:
- bleeding (2.8%), secondary bleeding occurs between 5-15 days
- thrombosed external haemorrhoids (1.5%)
- bacteraemia (0.09%)
- Mild bleeding, pain, slippage of bands, and difficulty urination are more common complications and normally minor
What is the role of injection sclerotherapy for haemorrhoids?
How does it work?
What are the complications?
- Limited role given reported complication rate of ~30%
- Theoretical advantage in anti-coagulated patients
- Injection of 5% almond phenol into the submucosal space causes inflammation, apoptosis, and scarring.
- Potential complications include
- urological (prostatitis, haematuria, urinary retention, epididymitis)
- bacteraemia
- haemorrhage
- mucosal necrosis
- injection site ulcer
Describe the complications of surgical haemorrhoidectomy and any interventions/modifications used to mitigate these.
- Pain (opiate use in 40%)
- Reduced pain with regional blockade
- Reduced pain with oral metronidazole (unclear mechanism)
- Multi-modality post operative regimen recommended
- Urinary retention (15%)
- Multifactorial
- May be due to pudendal block
- Assess risk pre-operatively
- Bleeding (2%)
- Primary or secondary
- Infection (<1%)
- Higher rates in immunocompromised patients
- Change in continence (<1% incontinence)
- Even without sphincter damage loss of cushions associated with reduced passive continence
- Anal stenosis (<5%)
- Mitigated by leaving 1cm anodermal/mucosal bridges.
What is the rate of incontinence with lateral spincterotomy?
The rate of long-term faecal incontinence has been reported between 6 and 30%, with a meta-analysis of 22 studies with 4512 patients (prospective + retrospective) identifying that 14% had incontinence of some degree at greater than 2 years.
This is overwhelmingly flatus incontinence only (9/14%), with less than 1% having solid stool incontinence.
What is the mechanism of action of Botox in the treatment of fissure-in-ano?
Botox inhibts contraction of somatic striated muscle by inhibiting the release of Acetylcholine from pre-synaptic motor neurons.
But, in the treatment of fissure in ano, the injection is either into the IAS or into the inter-sphincteric space (IAS = smooth muscle), with proven efficacy; injecting Botox into the inter-sphincteric space is known to reduce both squeeze pressure and resting tone.
Pharmacological studies on porcine IAS concluded that Botox directly inhibits release of NA from sympathetic nerves, abolishing the normal sympathetic action of contracting the IAS.
How can faecal incontinence be classified?
Note any associated aetiology.
Three clinical sub-types
-
Passive incontinence: involuntary leakage of faecal material or gas without awareness.
- Loss of percetion, altered neurology, +/- sphincter injury
-
Urge incontinence: leakage of faecal material or gas in spite of active attempts to retain them.
- Disruption of the sphincter or in compliance/capacity
-
Faecal seepage: undesired leakage of faecal material after normal bowel movement without abnormal continence or evacuation.
- Incomplete evacuation and/or altered rectal sensation.
Define faecal incontinence.
How prevalent is it?
Faecal incontinence is generally defined as either the involuntary passage or inability to control the discharge of faecal material through the anus in individual older than the age of four.
It is a common problem, and likely underreported in the general population due to embarrassment and the associated social stigma. It has an estimated prevalence of 7.7% (IQR 2.0 - 20.7%) in an adult population and is typically seen more commonly with increasing age and in the female patient.
Provide an overview of the causes of faecal incontinence
Anatomical
- Sphincter injury
- Obstetric injury
- Iatrogenic
- Previous rectal surgery (LARS after ULAR)
- Pelvic fractures
Neurological
- Pudendal neuropathy
- Diabetes mellitus
- MS
- Spinal cord lesions
- Central nervous ssytem disorders; CVA, dementia etc
Functional
- IBD
- Faecal impaction with overflow
- Diarrhoea
- Radiation proctitis
- Rectal prolapse
- Fistula in ano
- Hypersecretory rectal tumours.
Describe the Wexner incontinence score
What is the Recto-Anal Inhibitory Reflex?
In what conditions is it pathologically affected?
The rectoanal inhibitory reflex (RAIR) (also known as the anal sampling mechanism, anal sampling reflex, rectosphincteric reflex, or anorectal sampling reflex) is a reflex characterized by a transient involuntary relaxation of the internal anal sphincter in response to distention of the rectum.
This reflex is absent in Hirschsprungs disease, and may be absent in patients following low resection, or those with rectal prolapse.
What parameters are assessed during anorectal manometry?
- Resting and squeeze pressures along the length of the anal canal and sphincter complex (if using station pull-through technique)
- Functional sphincter length can be calculated from this
- RAIR using a 10ml puff of air via catheter-tip syringe
- First sensation of fullness/flatus
- Urge to defaecate
- Maximum tolerance
- Maximum squeeze pressure
- Maximum duration of squeeze
- Cough pressure.
What is the utility of Pudendal Nerve Latency Testing?
The validity of PNTML remains unclear, as this test measures the conduction in the fastest remaining fibres and therefore significant nerve damage may be overlooked.
A normal test does not exclude pudendal neuropathy. The test is also uncomfortable and in many cases the readings are unrecordable or not able to be reproduced.
Most studies have shown a poor correlation between PNTML and clinical symptoms and treatment/surgical outcomes. The routine use of PNTML in the assessment of patients with FI is therefore questionable.
How can colonic injury be classified?
- Destructive
- Wound >50% circumference of colon
- Complete transection
- Significant tissue loss
- Devascularised segment
- Non-destructive
- Wound <50% circumference of colon
- No devascularisation
In blunt trauma:
- Destructive
- Serosal tear >50% of circumference
- Full thickness perforation from blunt injury
- Mesenteric devascularisation
Describe the AAST grading of rectal trauma
How can anorectal-vaginal fistula be classified?
