Rectum Flashcards
Inspect the Anus
A gaping anus suggests a neuropathy or a megacolon, look for symmetry (a tender unilateral bulge suggests an abscess), prolapsed piles, a prolapsed rectum (descent of >3cm when asked to strain as if to pass motion) or anodermatitis (occurs with frequent soiling).
Rectal Examination
Test the anocutaneous reflex (tests both motor and sensory innervation) – on lightly stroking to anal skin does the external sphincter briefly contract.
Then perform a rectal examination – feel for masses e.g. impacted stool or a tumour and feel for the cervix or prostate - note size, consistency and symmetry of the prostate. If there is faecal incontinence or any concern about the spinal cord ask the patient to squeeze your finger.
Note stool or blood on the glove and test for occult blood and wipe the anus. Next you could consider protoscopy (for the anus) and sigmoidoscopy (for the rectum).
Haemorrhoids - Definition and Classification
Probably a vascular cushion covered in a layer of mucosa and containing a branch of the superior rectal artery and a tributary of the superior rectal vein.
Haemorrhoids occur at the point where the superior rectal branches enter the muscle – their position is described in relation to the anus imagined as a clock face with the patient on their back and the penis or vagina at 12 o’clock position.
- Classification – first (do not prolapse), second (prolapse on defecating and straining but return spontaneously) or third degree (remain prolapsed unless they are manually repositioned).
Haemorrhoids - Presentation and Management
- Presentation – may be asymptomatic but they can cause bright red bleeding, minor pain or itching. If they are severely painful suspect prolapse or thrombosis.
- Management – treat with injection of 5% phenol in almond oil (the haemorrhoid shrinks by causing scar formation), rubber band ligation or coagulation with infrared devices.
Pruritis Ani
Itch occurs if the anus is moist or soiled, there are fissures, incontinence, poor hygiene, tight underwear, threadworm, fistula, lichen sclerosis, anxiety or contact dermatitis (e.g. caused by perfumed goods).
Management – involves careful hygiene, anaesthetic cream, moist wipe post defecation, avoiding spicy food and no steroid or antibiotic creams. Capsaicin cream can be helpful.
Fissure in Ano - Definition and Causes
A tear in the squamous lining of the lower anal canal – 90% are posterior (anterior occur after parturition). If chronic often associated with an external ‘sentinel pile’ or mucosal tag.
- Causes – most are due to hard faeces which makes defecation painful. Spasm may constrict the inferior rectal artery causing ischaemia making healing difficult and perpetuating the problem.
- Rare causes include syphilis, herpes, trauma, Crohn’s, anal malignancy or psoriasis.
Fissure in Ano - Management
- Conservative management – 5% lidocaine ointment, increase dietary roughage and fluids, GTN ointment (0.2-0.4% - can cause headaches), Botulinum toxin or topical 2% diltiazam.
- Surgical management – lateral subcutaneous sphincterotomy – partial division of external sphincter.
Fistula in Ano - Definition and Causes
A track communicates between the skin and anal canal or rectum. Blockage of deep intramuscular gland ducts is thought to predispose to the formation of abscesses which then discharge to form a fistula.
- Causes – usually abscesses but also Crohn’s disease, TB, diverticular disease, rectal carcinoma or immunocompromised.
Fistula in Ano - Investigation and Management
- Investigations – diagnosis is made with an MRI and endoanal ultrasound scan.
- Management – fistulotomy and excision – a high fistula (involving the continence muscles of the anus) require a seton - a suture to be tightened over time to maintain continence.
Goodsalls Rule
A fistula anterior to the anus usually opens to the anus in a straight line whereas a fistula posterior to the anus usually have a curving track and open in the midline posteriorly – 6 o’clock
Anorectal Abscess - Cause and Presentation
Usually caused by gut organisms (or rarely staphylococci or TB) – 45% are perianal, 30% are ischiorectal, 20% are intermuscular (between sphincters) and 5% are supralevator. They may develop from infected anal glands or simple skin infections.
Presentation – severe throbbing pain which gets worse on sitting and signs of fever and tachycardia.
Anorectal Abscess - Associations and Management
Associations – abscesses are thought to be associated with diabetes, Crohn’s or malignancy.
Management – involves surgical drainage, packing and healing by secondary intention. Patient should be followed up as 30% develop a fistula in ano.
Perianal Haematoma
Aka thrombosed external haemorrhoid – it is actually a clotted venous saccule caused by subcutaneous bleeding around the anal margin caused by the passage of constipated stool.
It appears as a 2-4mm ‘dark blueberry’ under the skin and causes acute perianal pain which may be worsened by defecation.
It may be evacuated under anaesthetic or just treated with analgesia.
Pilonodal Sinus
Obstruction of the natal cleft hair follicles (around 6cm above the anus) leads to ingrowing hair which causes a foreign body reaction and may cause secondary tracks to open laterally ± abscesses with foul smelling discharge.
The male to female ratio is 10:1 and more common in obese.
Management – pre-operative antibiotics, excision of the sinus tract and primary closure.
Rectal Prolapse - Definition
The mucosa (in type 1) or all 3 layers (in type 2 – more common) may protrude through the anus – incontinence occurs in 75%.
It can be due to a lax sphincter, prolonged straining and related to chronic neurological and psychological disorders.
It can present as a semi-emergency as a prolapse that has become oedematous and ulcerated.
Rectal Prolapse - Management
Partial thickness prolapse can be treated by phenol injection (to induce scarring), rubber band ligation or by simple excision of the mucosa with plication of the underlying tissues (Delorme’s procedure).
A full thickness prolapse usually needs surgical intervention – abdominal rectoplexy where the rectum is stitched to the sacrum.
Perianal Warts
Condylomata acuminate - viral warts – treat with podophyllin, cryotherapy or surgical excision.
Condylomata lata - secondary to syphilis – treated with penicillin.
Proctalgia Fugax
Idiopathic, intense, brief, stabbing rectal pain is worse at night – give reassurance.
Anal Ulcers
These are rare consider in Crohns disease, anal malignancy, tuberculosis and syphilis.
Skin Tags
These seldom cause trouble but are easily excised.
Anal Malignancy - Risk Factors and Presentation
300 cases occur each year in the UK – risk factors include syphilis, anal warts (HPV is implicated) or anoreceptive homosexuals.
Presentation – bleeding, pain, change in bowel habit, pruritis ani, a mass or a stricture.
Anal Malignancy - Histology
80% are squamous cell tumours – anal margin tumours are usually well differentiated, keratinising lesions with good prognosis whereas anal canal tumours above the dentate line are poorly differentiated with a *poor prognosis. *
Anal Malignancy - Spread and Management
Tumours above the dentate line spread to pelvic lymph nodes where tumours below spread to inguinal lymph nodes.
Radio and chemotherapy is usually preferred to anorectal excision and colostomy - 75% retain normal function.
