Welcome to First Incision, the podcast about preparing for the General Surgery Fellowship exam. I'm your host, Amanda Nikolic. Let's get started with our team timeout. Our patient today is the colorectal module from the general surgical curriculum and the operation or topics we'll be covering today are anal fistulas and hemorrhoids. So starting off with a definition. An anal fistula is an abnormal communication between the inside of the anus and the epithelium outside the anus.
A fistula in general is a tract connecting two epithelial surfaces. So in this situation, it's from the anal canal or the rectum to the skin around the anus. These are relatively common and occur mostly in people in their 30s, 40s, and 50s, with a higher incidence in men compared to females.
Theory of the pathophysiology or etiology of perianal fistula is... the cryptoglandular hypothesis which is the same as we were talking about for perianal abscess and it's thought that most fistula are actually a consequence of perianal sepsis. The thought is that this is a pathological process that affects the anal glands at the dentate line. These anal glands get blocked, leading to infection, which leads to an abscess within the gland, which then tracks.
either in the intrasphincteric plane, transphincteric superficial area, or supra lovata, and that the tracking of this infection then leads to a tract, which can become chronic and turn into a fistula. Saying that though, there are some fistulas that are not related to this cryptoglandular hypothesis. And these are considered secondary fistulas. Conditions that are associated with secondary fistulas include Crohn's disease.
malignancy, which can cause fistulas or can also be a consequence or arise within a fistula, tuberculosis, trauma from a hemorrhoidectomy or episiotomy, for example. a foreign body injury, in radiation damage, and also sometimes in hydro adenitis superativa. Risk factors for the formation of anal fistulas include being a man, smoking, having an immunocompromised state, and also diabetes, which are actually all mostly risk factors for developing a perianal abscess. Approximately...
10 to 30% of patients who have a perianal abscess are thought to subsequently develop a fistula. Because the exam is a sucker for classification systems, of course there is a classification for perianal fistulas. And it's worth having a look at the PARCS classification by Googling it and having a look at a picture online if you haven't seen this before while I go through and describe the four types of perianal fistulas.
So type 1 is an inter-sphincteric fistula. This is the most common and it runs in a line between the sphincters, so between the internal and external anal sphincters. Type 2 is a trans sphincteric fistula and this fistula traverses both sphincters and then goes through to the ischiorectal fossa to end at the perianal skin.
If it passes through the muscle at a low level, it may be readily treated. But if it's through a lot of the muscle, it makes it much more difficult to manage. The third type is a suprasphincteric fistula. These are very uncommon. They travel through the intersphincteric plane superiorly.
And then go laterally through the puborectalis or levator ani muscle and then down through the ischia rectal fossa to the perianal skin. This sort of fistula can actually happen through iatrogenic means. So if you have a supra levator...
abscess and you drain this through the skin, you can create this sort of tract versus if you have a supra levata abscess, you could consider draining it with a mushroom catheter through that intersphincteric plane or even into the rectum itself to avoid creating.
this type of complex fistula. Type 4 is extremely rare and this is where you have an extra sphincteric fistula and this is where the internal tract is quite high up in the rectum and it traverses through the levator muscle and through the ischiorectal fossa to then finish in the skin. These are very difficult to manage and they're quite long fistulas and they're more likely to be associated with other problems such as Crohn's disease, malignancy or diverticular abscesses, for example.
Another way to think about fistulas or to classify fistulas is considering them as simple versus complex. A simple fistula is a nice low fistula with a tract that doesn't involve a lot of the muscle and it could be that intersphincteric type of fistula. Pretty much all of the others are complex. So if you have a tract that involves more than a third of the external sphincter, if it's very high and transphincteric, if there's multiple tracts, if it's anterior in a female, if it's recurrent.
If there's been previous local irradiation, Crohn's disease or pre-existing incontinence, these would all be considered complex fistulas. The other thing to be aware of is the concept of good soul's law or good soul's rule. And this is a rule that tries to give some guidance around where the internal opening of a fistulas tract may be in relation to its... external opening. And so if you draw a line between the ischial spines, fistulas with an external opening in the anterior half.
so above that line or in the anterior aspect of that line, tend to have a direct radial tract into the anus. So if you have an opening in the one o'clock position, you could expect the internal opening to be in the one o'clock position, for example. For fistulist openings that are located behind that line through the ischial spines or in the posterior location, then if that external opening is within three centimetres of the anal canal,
then these tend to have curving tracks with the internal opening located at the six o'clock position. So even if the external opening is at five o'clock, for example, the internal opening will be at the six o'clock. This, however, doesn't apply if the external opening is more than three centimetres away, in which case you may find that there's a long tract and it can open at different places.
This is also not always accurate in inflammatory bowel disease as well, or obviously if there is underlying malignancy, the openings can be anywhere. So how do we find out about these patients who have a fistula? On history, most patients will have some sort of symptoms. Often they'll present with a opening that they may notice themselves with this history of it sort of...
building up and getting swollen and sore and discharging intermittently. On examination, you want to inspect the area looking for previous scars. You want to identify the external opening and its distance from the anal verge. It's good to palpate the external opening and see if you can palpate a tract and also to do a digital rectal examination and see if you can palpate an indurated area of tissue that might be representative of an internal opening.
You should also palpate for the sphincter muscles, especially in a woman who's had previous obstetric trauma, and see if there's any defects, as well as assess the resting and squeeze anal tone to assess their continence and anal function. These patients usually will proceed then to an examination under anesthetic. This should be done in lithotomy position with the use of a headlight. You want to do an...
gentle probe of the external opening using Lockhart mummery probes with a finger in the anal canal to try to guide that probe to the internal opening. You need to be really careful not to create a false tract. If you can't find a pathway easily, then you might try to inject with saline or methylene blue.
or hydrogen peroxide, and have an Eisenhammer retractor in the anal canal to try and see if you can identify an internal opening. You should consider a colonoscopy if there's a concern for an underlying pathology such as Crohn's disease. And if you're unable to find an internal opening or they've got complex disease, you could also consider an MRI to have a look at the location of and involvement of the muscle of any of the tracks.
This is particularly important in patients with Crohn's disease and it can also really help guide surgical planning, how to counsel that patient and also what you should be doing at the time of an operation. An endoanal ultrasound may also be useful to help assess the amount of muscle involved and can help sort of map complex fistula disease.
And a CT is only really used if you have a suspicion for a pelvic abscess or an abdominal source of the cause of the fistula. It doesn't have enough soft tissue information to look at specific tracts. So let's move on to management of perianal fistula. So the key points to management are that you must identify the relation of the fistulas tracts to the sphincter muscle. And this can be aided by using the PARCS classification. The second thing is to accurately identify the location of the...
internal and external opening. The next thing to consider is a balance between getting rid of the fistula and sepsis and preserving the continence of that patient. And specifically, you want to think about what that patient's preoperative continence status is, if it's an anterior fistula in females, and especially if a patient has had any previous operative intervention for the fistula.
You want to try to prevent recurrence and if you're worried about an alternative cause and it not being a straightforward cryptoglandula, abscess and fistula, make sure that you investigate and treat any underlying causes. A rule of thumb that I've heard when talking about the management of fistula is that you should definitely never cut more than a third of the sphincter muscle. With the exception being in women and in anterior fistulas, you should probably not cut any of the muscle.
But if they're a man, for example, it's not an anterior fistula and it's involving less than a third of the muscle, then you could consider laying it open. So I want to talk a little bit about some of the different types of repairs.
but I'm going to talk about them in the context of different types of fistula classifications and which particular treatments may be useful for the different types of fistulas. So for interspinteric... fistulas with a low transphincteric tract, so involving only a small amount of the internal sphincter muscle. The best option for these fistulas is actually simple laying open of the fistula and allowing it to heal by secondary intention.
It needs to be really low down, involve only a small amount of the muscle, and there needs to be no concerns about continence or sphincter function. If the internal opening is above the dentate line, then this increases the risk of having continence issues with laying open a fistula. Laying open or marsupialization of a fistula has a more than 90% success rate.
So for patients with these low fistulas, it is an excellent surgical option. The procedure should be done under a general anaesthetic in lithotomy. You want to prep and drape and give IV antibiotics. I'd start with a rectal examination to feel for the internal opening. Make sure that there's no sepsis. And you want to use a Parkes anal or a Ferguson's retractor in order to identify the internal opening.
You place a probe through the external opening coming out through the internal opening and again, reassess if it really is appropriate for fistulotomy. Have a feel for how much of the sphincter muscle is involved. and make sure that this is minimal and look for the location of the internal opening. Then perform an incision.
through the skin and mucosa down onto that Lockhart mammary probe. And you may need to divide some of the internal sphincter muscle. Remember to have a look at a picture of an intersphincteric fistula tract. to see what I mean. But you need to make sure that you're definitely not cutting more than 30% of it. You can marsupialize the base of the fistula to the skin in order to encourage it to heal by secondary intention.
And usually you want to give the base or the fistulas track a curette to make sure that there's healthy tissue there. And send any tissue that you do excise for histology. I usually then inject local with a pudendal nerve block and place a combine and tape. And postoperatively, you want to manage this patient sort of like a hemorrhidectomy. So stool softeners and bulkers, you can give oral appearance, oral analgesis.
and oral metronidazole to reduce the inflammation and pain associated with this procedure. The next type of fistula I want to talk about is a high transphincteric tract. So if there's more than 30% of the sphincter muscle involved, you do not want to lay open this fistula because you'll be cutting through too much muscle and you're risking incontinence for that patient. And there's a number of options for these sorts of fistulas, which means that none of them are 100%. And there's...
A lot of different opinions, I guess, about what sort of procedures would be done as first line. But I think it depends on your institution experience. So the options include a cutting seat on. sphincter-preserving techniques such as a lift procedure, rectal mucosal advancement flap, fibrin glues and bioprosthetic plugs.
Cutting seton is the first one I mentioned. This isn't really done now due to high incontinence rates, but basically involves placing a seton that's actually usually a silk suture. and tying it down really tight. And basically you progressively tighten that seat on weekly until the seat on has eroded all the way through the muscle layer and falls out.
And the thought is that it slowly cuts through the muscle, allowing fibrosis behind it and keeps the divided muscle ends close so that there's less functional impairment. However, the incontinence rates are between 25% and 50%. So I haven't seen this done much recently. I'm not sure that it's used that often anymore as a first line. So then talking about sphincter preserving techniques.
These are definitely indicated in high fistulas or patients with borderline continence or women, especially with an anterior fistula. So the first procedure I mentioned is called a lift procedure. And this stands for ligation of intersphincteric fistula tract. This procedure involves dissection in the intersphincteric plane until you come across that transphincteric fistula tract.
with suture ligation of the tract internally, and then the external opening is enlarged. In order to perform this fistula procedure, you need to have a fibrose tract. So you need to make sure that all the infection and sepsis has been drained and that acetone is left in place through the fistula for at least six weeks to make sure there's a nice, well-established fibrose tract that you can identify and tie off easily.
And the technique is again with the patient in lithotomy under a general anaesthetic. A curvilinear incision is made over the intersphincteric groove with dissection between the sphincters by using scissors or small Langenbecks. The tract is identified and isolated and ligated with two ovicryl ties and then divided between these. The external opening is curetted and the...
Internal opening can also be sutured shut or left. There's no sphincter muscle division, so these patients have nearly 0% rates of incontinence.
There's obviously issues with wound healing, but this usually is well tolerated. And the excess rate is probably... maybe 50 to 70 percent there were some original series that had quite high success rates but i think the impression was that maybe those series were done on fistulas that were lower and probably didn't need a lift procedure and that the real world outcomes have
been quite as high. The next procedure is a rectal mucosal advancement flap and this is where a partial thickness flap of mucosa, submucosa and some muscle where the width of about two to three centimetres is prepared. adjacent to the fistula with the internal fistula opening cored out and excised and then that flap advanced over that internal opening and sutured in place. The external opening is opened up and widely drained to allow drainage while the internal opening is draining.
A little bit of the internal sphincter muscle needs to be maintained with the flap in order to ensure vascularity. And there is some incontinence rates, although this is relatively low. The success rate of this, again, long-term is maybe 60% to 80%. And this could be used after a lift has failed or even first line before a lift, depending on your institution's preferences.
The last couple I mentioned are fibrin glue and bioprosthetic plugs. These have very poor success rates, about 30% overall, but are sometimes used. Fibrin glue is where you use this glue to plug the tube from the internal opening to the external opening. And it's thought to help healing through fibroblast migration and activation. It needs a thorough curatage of the tract before you insert the glue and, like I said, has a pretty poor overall success rate but can be repeated.
A bioprosthetic plug is the next thing I wanted to talk about. There's a sergesis anal fistula plug which is a porcine intestinal submucosa which is something I've seen used before and this is basically inserted into a debrided tract and pulled through until it's snug. And you can secure this with PDS if you need to and close the mucosa over the top of it if possible.
Again, the success rates are relatively low, around 30%, but obviously neither of these procedures cause any damage to the muscle and can also be repeated. For a suprasphincteric fistula, the options are limited. This is a complex fistula, as I mentioned. You can try all of those other procedures I talked about, so an advancement flap, a lift procedure.
Just good drainage with acetone. You can try and remove the tract and primarily close internally with wide drainage externally. And again, all of these will have varying success rates. For extra sphincteric fistulas, these are very uncommon. And as I mentioned earlier, often due to other reasons such as malignancy, Crohn's disease, or even patients with intra-abdominal sepsis such as anastomotic leaks or abscesses that then drain down through the skin.
The treatment is to treat the cause and drain the sepsis. So to round off our perianal topics, I'm going to finish up this episode with talking about hemorrhoids. Hemorrhoids are super common and definitely easy for a question, especially a spot question in the exam. So what actually are hemorrhoids? So hemorrhoids are vascular arteriovenous plexuses that are part of the normal anorectum.
And they are part of the anal cushions, the purpose of which is not clearly understood. But as we talked about in the continence episode, they appear to be important for... making a seal around the anal canal and also partly to help sense what contents are that are coming down through the rectum. Hemorrhoidal complexes are normally located above the dentate line. and that's the internal hemorrhoidal plexus, and also at the anal verge, which is the external hemorrhoidal plexus.
The internal hemorrhoidal plexus has about one to eight, but an average of six, hemorrhoidal arteries, which originate from the superior rectal artery and drain via the middle rectal veins. External hemorrhoidal plexus drain via the inferior rectal veins into the pudendal vessels and these are covered by the anoderm of modified squamous epithelium and they have pain fibres associated with them.
compared to the internal hemorrhoidal plexus, which as you know, being above the dentate line, should be insensate and be supplied by visceral innervation. The internal hemorrhoids are... Traditionally said to be found in the left lateral right anterolateral and right posterior lateral regions of the anal canal but from experience people don't usually subscribe to what's in the textbooks and they can be found at any location around the anal canal.
Enlargement of these hemorrhoidal plexuses leads to hemorrhoidal disease. The pathophysiology of how hemorrhoids develop is that for internal hemorrhoidal tissue, the tissue supporting the anal cushions deteriorate, allowing them to slide down into the anal canal, which leads to impaired venous drainage, progressive engorgement. local stasis and transudation of fluid. They can also then prolapse, which blocks the venous outflow even more, leading to a cycle of more engorgement.
The risk factors for this occurring include anything that increases the venous pressure or alters the venous drainage. So this could include things that increase your intra-abdominal pressure such as cirrhosis with ascites, pregnancy. constipation and frequent straining and prolonged standing. In addition, abnormal bowel functions such as diarrhoea or constipation, collagen vascular abnormalities, significant pelvic floor dysfunction,
Obesity and a sedentary lifestyle are all considered risk factors for the development of hemorrhoids. How do these patients present? bleeding per rectum usually immediately after or with defecation. They often describe bright red blood mixed around the stool in the toilet bowl or on wiping. They may also complain of perianal itching or discomfort, soiling, which is actually thought to be due to that transudate of fluid, and they can also get a sudden onset of pain due to a thrombosed hemorrhoid.
They may also explain to you that there is a lump that comes out with defecation. Of course, there is a classification system for hemorrhoids. And this is a grading system that grades hemorrhoids from one to four. It's also important to consider whether it's an internal or an external hemorrhoid. Clinically, you can determine this if...
it's proximal to the dentate line, then it's going to be internal. If it's external, it's going to be distal to the dentate line and sometimes you can get mixed disease with both proximal and distal hemorrhoids. So for the grading, this is called the Golliger classification, spelt G-O-L-I-G-H-E-R. And there's grade one to four, as I mentioned.
Grade one is where you have prominent vasculature with some engorgement, but no prolapse. Grade two is where there is prolapse of hemorrhoidal tissue when straining, but it spontaneously reduces. Grade three is where you get prolapse of the hemorrhoidal tissue beyond the dentate line, and this will require manual reduction. And these patients will often be the ones that complain of itching or staining from mucus discharge.
And grade four is where you have a completely prolapsed hemorrhoid below the dentate line that's unable to be reduced manually, and these are often inflamed and ulcerated and commonly bleed. The diagnosis... is usually made with a combination of history and examination. You get history, as we've talked about, and on examination, you may be able to see those hemorrhoids. The other things you should be thinking about is if there's any associated symptoms, whether the lump is...
reducible, whether they've had any changes in their bowel habits or other symptoms suggestive of intra-abdominal pathology. And usually these patients, given they've presented with bleeding, will go forward to have a colonoscopy and examination. where you want to have a look to make sure there's no internal pathology, as well as look for any polyps and examine the hemorrhoids with a colonoscopy, with a retroflexed view, and also on the way out through the anal canal.
It's important to think about differential diagnoses for hemorrhoids. I had a lady the other day who... has come back with recurrent anal cancer, but her original pathology was that she had a hemorrhidectomy and that tissue was sent off and that demonstrated a anal SCC. So anal rectal cancer can present as a lump.
You need to make sure that a hemorrhoid isn't being misdiagnosed. Patients may also just have a perianal dermatitis or a skin tag. This may be a presentation of inflammatory bowel disease. They may have diverticular bleeding. anal warts or polyps or rectal ulceration presenting with bleeding. So treatment of hemorrhoids. It really does depend on symptoms, severity and the amount of hemorrhoidal tissue that is prolapsing.
For most patients with grade one or grade two hemorrhoids, you should start with conservative treatment. So this includes teaching them not to spend more than three minutes max in the bathroom, no straining. and making sure that they're taking a high-fibre diet. You may need to give them some bulking agents, such as psyllium, and you may need to give them appearance to soften the stool.
Patients should, if they have painful hemorrhoids, be given ice and anti-inflammatories in the first instance. You could recommend sitz baths and oral analgesia or even a topical treatment to try and reduce inflammation. If this treatment is not successful, then you can consider interventional treatments. And the goals of this are to decrease the vascularity, remove any redundant tissue.
and increase the hemorrhoidal fixation to the rectal wall in order to minimize prolapse. So for grade one hemorrhoids, especially if patients are on anticoagulation, a good choice is... sclerosing agent injections. This involves injecting phenol in almond oil into the submucosa around the pedicle of the hemorrhoid and this then leads to fibrosis and scarring.
and pulls that hemorrhoidal tissue back up into the anal canal. You want to avoid this if it's in the anterior midline, especially in men, as this can lead to prostatitis and urethral irritation. And there's a risk of introducing sepsis, which can make patients very sick, although this is very rare. And this treatment's about 70% effective for grade one hemorrhoids, and it also can be repeated.
The next treatment, which is good for grade one or grade two, and sometimes even for grade three hemorrhoids, is rubber band ligation. And this is where a rubber band is applied at the apex of the hemorrhoidal tissue above the dentate line. And this is usually done with a proctoscope and a special suction machine with a band applied at the end. This can be repeated as well and is up to 60% to 80% effective for grade 2 hemorrhoids.
The next option, which I'll briefly mention here, but I don't think I'd mention in the exam, is Doppler-guided hemorrhoidal artery ligation. And this is a procedure with a special proctoscope that's got a Doppler probe on it and it's made to be able to insert a needle holder and a needle. And basically you insert this proctoscope and...
Wait till you find the Doppler probe and then place a needle or suture around the hemorrhoidal artery or the feeding vessel. And this can be done in multiple areas around the anal canal. It obviously avoids the need for an open operation and is mostly done in private because of the cost of the appliance. It also doesn't have a lot of long-term data as it's a relatively new procedure.
For grade three hemorrhoids and definitely for grade four hemorrhoids, a formal hemorrhoidectomy may be required. This can either be done as an open procedure or you can actually close the area as well. So taking you through a open hemorrhoidectomy. This procedure is done in the lithotomy position under a general anesthetic. I use a Hill-Ferguson retractor and an Eisenhammer retractor for exposure.
And I grasp the junction of the internal and external component of the hemorrhoid with two artery forceps. And this is a good handle in order to retract the hemorrhoid away from the sphincter muscle. I always start with the most posterior hemorrhoids first so that any bleeding doesn't trickle down onto my operative field as I do each hemorrhoid in turn.
I make an elliptical incision at the external component of the hemorrhoidal tissue and then carefully dissect the hemorrhoidal tissue away from the underlying sphincter muscles. using either a peanut or the tip of my diathermy in order to avoid any injury to the muscle. I continue my dissection in this plane between the mucosa and the muscle down to the base of the... hemorrhoid and the vascular pedicle, and I ligate this with a 2-ovicryl, usually with a suture ligation.
I then excise the hemorrhoidal tissue and I always send this for pathology. And during this procedure, I'm mindful to make sure I leave adequate mucocutaneous skin bridges between the excision sites. Other options include a hemorrhoid apexi with a stapler. This is really only indicated for moderate-sized internal hemorrhoids, not in a patient with external hemorrhoidal disease. And it involves inserting a proctoscope.
and the placement of a circumferential per-string suture in the submucosa two to four centimeters above the dentate line. A circular stapler is then introduced into the anus and the prolapsing tissue is brought into the stapler, which is then fired in order to resect the hemorrhoids and pexy the tissue back up into the anal canal.
The staple line needs to be above the dentate line, so there should be less pain associated with this procedure. The device is quite expensive though, and I think this procedure is mostly done in the private sector, so I don't think it's something that I would... talk about in the exam. For post-op management, I give these patients oral metronidazole for five days, as well as analgesia, a stool softener, stool bulking agents such as psyllium husk or metamucil.
and I get them to do sits baths or regular wash of the area. Complications of open hemorrhoidectomy are pain, because obviously you're excising skin and tissue that's below the dentate line, so this has sensation. Patients can present with secondary bleeding. Anal stenosis is a potential complication, and this will only occur if you leave insufficient mucocutaneous skin bridges between the hemorrhoids that you're excising.
I just also want to mention that for all of these options this is usually done in an elective setting. So I often get calls from ED saying that there's patients presenting with painful hemorrhoids. In the absence of a necrotic or infected hemorrhoid, which is very rare, these patients should be settled down with...
conservative management, laxatives, stool softeners, sits baths, ice packs, oral and topical analgesia, and then an elective operation done if it needs to be performed. The risk in the setting of an inflamed... prolapsed external hemorrhoid is that you can cause possible sphincter damage and also that you may excise more tissue than you mean to because it's all inflamed and that you'll have a higher risk of long-term stenosis of the anal canal. you
And that's it for today's episode on fistula and hemorrhoids. I think that rounds out the perianal component of the colorectal module. So I'll be moving on to more glamorous topics in the next few weeks. Like always, remember to rate, review and subscribe so that other people can find this podcast. It's time to close up. Thanks for listening to First Incision. send us a message at firstincisionpodcast at gmail.com or follow us on Instagram at firstincision. Happy studying!