GP Life is a study guide written by a GP Registrar in NSW. As such, the focus is largely on NSW and central Australian communities for the purpose of studying for the ACRRM CGT StAMPS exam. The below is not to be taken as medical advice or relied upon for the diagnosis or management of real-life patients.
Perianal pain and PR bleeding can be confronting presentations in general practice. The conflict between trying to constrain healthcare resource utilisation and practicing safely and defensively is real, and not every patient can be sent for colonoscopy. However, separating out concerning cases requires substantial knowledge and experience.
The first step is to differentiate melaena from dark red blood mixed with the stool from bright red PR bleeding. Of course, we are told melaena is black black. But differentiating dark from bright red PR bleeding is clearly not an exact science.
Causes of bright red PR bleeding include haemorrhoids, anal fissures, distal colorectal polyps, and cancer. Don’t forget also that it’s entirely possible to have multiple different pathologies.
Assessment
History
- If blood is present on toilet paper or dripping into the bowl, this is suggestive of an anal/rectal cause.
- Anal pain is not particularly helpful in determining a cause of PR bleeding, as it can be suggestive of fissures, but can also be from rectal cancer and peri/anal infections.
In men who have sex with men and other people who engage in receptive anal sex, consider HSV, syphilis (condylomata lata), and HPV (condylomata accuminata).
- Clearly systemic symptoms (weight loss, fever, night sweats) are suggestive of malignancy, but could also herald PR bleeding from inflammatory bowel disease.
Red flags: melaena (upper GI pathology), abdo pain, weight loss, systemic symptoms, or bowel changes (malignancy), or family history suggesting a colon cancer syndrome (familial polyposis or HNPCC).
Interestingly, a longer duration of bleeding is associated with a lower risk of cancer however conservative investigation is indicated for many of the reasons listed above.
Examination
Inspection of the anus and digital rectal examination are mandatory (as we all learned in med school, “if you don’t put your finger in it, you’ll put your foot in it”). Proctoscopy can also be considered in a skilled provider.
Don’t confuse anal skin tags and perianal haematomas.
Investigations
Anaemia or iron deficiency are suggestive of malignancy.
Imaging is not useful as an initial investigation.
Flexi-sig and colonoscopy are the two most useful tests in patients with persistent symptoms, atypical symptoms, or features suggestive of colorectal or anal cancer.
When to refer
It depends on the cause, and guidelines vary. South Australian guidelines suggest referring new PR bleeding in anyone >40 years or if persistent for 6 weeks after treatment with fibre supplementation/stool softeners and topical haemorrhoid cream. Of course red flags (abdo pain, bowel changes, iron deficiency anaemia, abdo/rectal mass) should prompt immediate urgent referral.
Causes of Perianal Disease
Haemorrhoids
Internal haemorrhoids form above the dentate line and are graded I-IV based on their degree of prolapse. They are normally painless but do bleed. External haemorrhoids can refer to a variety of perianal diseases but in this context usually refer to perianal haematomas. These emerge from venous injury below the dentate line. They are subject to pain and irritation, particularly when thrombosed, but don’t usually bleed.
Initial management of haemorrhoids should include:
- Fibre supplementation (20-30 g) plus adequate water intage.
- Considering cessation of any agents likely to cause constipation. Think about opioids but also things like drugs with anticholinergic side effects, iron supplements, and ondansetron.
- GTN creams (eg Rectogesic) act as antispasmodics on the (internal) anal sphincter. Watch for headaches as a side effect.
- Sitz baths can also be use similarly to relax the anal sphincter but also to reduce inflammation around the haemorrhoids and also helps with pruritus.
- Itch can be controlled with hydrocortisone suppositories (but don’t use for longer than a week due to the risk of mucosal atrophy).
- Bleeding haemorrhoids should be treated conservatively in the first instance.
- Thrombosed haemorrhoids should also be treated conservatively and patients can be reassured that clot resorption usually happens within 3-7 days. Severe pain from an “external haemorrhoid” may be treated with incision and drainage. Thrombosed prolapsed internal haemorrhoids (grade III and IV) will often require definitive treatment.
Indications for referral (gen surg) for haemorrhoids are: symptomatic grade I and II internal haemorrhoids not responding to conservative management over a 6 week period, and symptomatic high-grade internal haemorrhoids. Some GPs are skilled in office-based treatment techniques for prolapsed internal haemorrhoids like sclerosant injection and rubber band ligation. However specific training with these techniques is required.
Patients on anticoagulant therapy or DAPT will often present with bleeding haemorrhoids. They still usually respond to conservative management and do not require cessation or dose reduction of the anticoagulation. They should not have rubber band ligation; sclerotherapy would be the preferred office-based approach and would obviate the need for withholding the medication for a week before colonoscopy in patients for whom this would present an unacceptable thrombosis risk.
Anal Fissure
These start as a tear in the anal lining and often become chronic, with significant pain and bleeding being significant symptoms. Causes include constipation, receptive anal sex, excoriation from diarrhoea, Crohn’s disease, malignancy, and infection. The most common site is the posterior midline.
As for haemorrhoids, treatments include fibre supplementation and adequate fluid intake. Sitz baths should also be used in all patients. Topical GTN with or without lignocaine can also be used. Further management of underlying constipation or diarrhoea should also be implemented, including use of a stool softener like docusate.
Patients without resolution after 2 months of treatment should be referred for scope. Patients with atypical features should be referred for colonoscopy and surgical management earlier.
Anorectal Fistula
Despite being in the minds of every medical student deeply connected to Crohn’s, 90% of anorectal fistulas are related to infection and abscess formation. Anorectal fistulas may also be related to persistent infection, obstetric trauma, and radiation proctitis. They are classified in relation to the sphincter and the dentate line (distal = anal, proximal = rectal).
The classic presentation is persistent purulent drainage >2 months after perianal abscess drainage. This is of course also associated with pain. Differentials include pilonidal disease and hidradenitis suppurativa.
Treatment is surgical (except for Crohn’s disease related fistulas, which clearly also require medical management and aggressive control of the Crohn’s).
Perianal and Ischiorectal Abscesses
These arise usually from anal crypt glands. Patients present with severe pain and fluctuant, indurated skin around the anus. Deeper abscesses may only be detected on PR exam.
Treatment is with drainage of the lesion: this should be done as close to the anal verge as possible to minimise the length of any potential fistula formation. Most GPs are spooked about instrumenting butt pus, but it’s generally recognised that this is a safe (if uncomfortable) thing to do. Don’t take my word for it, here’s a colorectal surgeon talking about it:
My practice in a small rural town a couple of hours away from the nearest surgical centre is to do some shared decision-making with the patient. In my experience, usually people do opt for local management. Recurrent abscesses clearly require formal drainage.
Wound packing has no benefit in preventing abscess recurrence or fistula formation and increases pain scores: see the PPAC2 trial.
The definitive treatment is drainage (“if there’s pus about, let it out”), but empiric antibiotics are also recommended. Ensure you’re covering bowel stuff: I use Augmentin DF BD for 5 days (or trimethoprim/sulfamethoxazole + metronidazole in allergic patients).
Ensure you’re getting patients back for review in 4-6 weeks for resolution.
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