How I Was Diagnosed With Ulcerative Colitis: Bayesianism and Eliminative Abduction

My diagnosis of ulcerative colitis was based on clinical history, colonoscopy and CT scan findings, and response to treatment; histopathology was equivocal.

When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.

—James Whitcomb Riley (1849–1916)

I was given a presumptive diagnosis of ulcerative colitis (UC) on March 9, 2018. In this blog post, I recount the symptoms and events that led to this diagnosis.

I was experiencing a few symptoms by the time I presented to my gastroenterologist (Dr TKF). I remember the date well – February 14, 2018. It was the last day before the doctor’s clinic closed for the Chinese New Year period, a big deal in these parts. As much as I loathe going to hospitals as a patient (versus as a consultant), I counted myself lucky to have been able to make an appointment to see my gastroenterologist, who has a busy practice, with less than 24 hours’ notice. If I hadn’t seen him on February 14, 2018, I would have had to wait till his clinic reopened after the Chinese New Year break, i.e. six days. I’m aware, in many places, a wait of six days for an appointment with a specialist physician would be considered acceptable, if not good. In my case, I had already put off seeing him for months (which, in retrospect, was reckless), and by the time I called the clinic (late afternoon of February 14, 2020), things had, at least to my mind, become serious enough to warrant an urgent expert opinion.

By the time I saw him on February 14, 2018, my gastroenterologist and I had known each other for about 12 years. We first met at Singapore’s National University Hospital (NUH), when I saw him for a diagnostic conundrum a few others in town had trouble solving. To summarize, he diagnosed idiopathic gastroparesis, and perhaps more importantly recommended treatment that yielded beneficial effect. Shortly after our first meeting, he joined the hospital where I worked, so we were colleagues until I left the hospital and started my own consulting business in 2009. This prior relationship was important. I trusted his clinical acumen, and he knew about some of my obsessive and compulsive traits, e.g. he knew he needed to eliminate colon cancer from the differential diagnosis, or else I’d “keep thinking about cancer” – his words, not mine.

Main Presenting Complaints and History

The chief complaints that made me want to see my gastroenterologist were, unsurprisingly, gastrointestinal in nature. I’ll describe them below – these were the symptoms that I first reported to my gastroenterologist. There were others (which I’ll also detail) but these either (a) did not seem to be relevant in the first instance or (b) simply escaped my attention until I was told the results of the colonoscopy.

  • Irregular bowel movements. For about 6 months, my bowel movements were highly erratic. On one day, it could be constipation. A couple of days later, I could go through several episodes of watery, sometimes explosive, diarrhoea. I could also have periods (measured in terms of days, not weeks) of relatively normal bowel movements, i.e. formed stools, once a day. There wasn’t any particular pattern I could identify – emotional or psychological stress, dietary triggers, time of day, physical exertion, etc. didn’t seem to have any association with my irregular bowel movements.
  • Left-sided abdominal pain. I had colicky pain on the left side of my abdomen, which could get quite severe, up to 7/10 on the Numerical Rating Pain Scale, usually occurring around bedtime, i.e. between 12 midnight and 2 a.m. The pain would last for a couple of hours and subside spontaneously. It would often be troublesome enough to prevent me from sleeping while I felt the pain. Lying on my left side tended to lessen the severity of the pain but not the duration of the episode. I’m still unsure if this pain was caused by the UC (not likely) or irritable bowel syndrome (IBS) (more likely).
  • Rectal (PR) Bleeding. From around mid-November 2017, I noticed intermittent rectal bleeding – bright blood, often mixed with blood clots. The bleeding looked different from haemorrhoid bleeding which I’ve experienced occasionally since the age of 20.
  • Decreased stool calibre. For at least 3 months, I had noticed a reduction of the calibre of my stools. My understanding was that stool calibre was a non-specific symptom. But in the context of my other symptoms, I thought it could have been significant and reported it to the doctor during our February 14, 2018 appointment.

These symptoms were noticeably worsening over the weeks leading up to my clinic visit, but the final straw was experiencing explosive bloody diarrhoea and left sided abdominal pain simultaneously on the afternoon of February 13, 2018. The fact that I had experienced pain during daylight hours was unusual. But I also had not previously experienced the left-sided abdominal pain while sitting on the throne plus having explosive diarrhoea. It was time to get professional expert assistance, hence the phone call to my gastroenterologist’s clinic to make the appointment.

I had other symptoms, which I now believe were likely to have been associated with UC. Around the time that I was diagnosed with UC, I had had these symptoms for a prolonged period of time (measured in terms of years or decades), so the association wasn’t obvious then.

  • Pus and mucus in stools. I had observed pus and mucus consistently in my stools for several months. I had seen something similar in the past, but only on rare occasions. It was only after the colonoscopy on February 20, 2018 (see below for more details), and upon direct questioning by gastroenterologist, that I realized the significance of the pus and mucus.
  • Rectal pain during defecation. Sometimes, I would experience a sharp, severe pain in my rectum (not my anus) upon defecation. The correct medical jargon for this symptom is odynochezia. I didn’t have it every time I opened my bowels, and it was quite unpredictable. I didn’t identify any antecedent factors.
  • Anal pain. Closer to my initial clinic appointment for my bowel problems, I noticed that my anus felt warm/hot all the time. I never actually tried feeling my anus to confirm it was warm/hot but the sensation in the anus gave the impression it was burning. Initially, I thought it might have been temporary inflammation of my external hemorrhoids, a problem I had known about since I was 20. What made this different from previous episodes in which my hemorrhoids played up was the nature of the pain (constant burning versus a localized “itch” of a thrombosed external hemorrhoid) and that it never seemed to subside even after a couple of weeks. This sensation would last a further three weeks after commencement of treatment for UC before it went away for good.
  • Fatigue. I had suffered from fatigue for several years, particularly upon returning from work trips out of town. These “expeditions”, which usually last about a week and no longer than a month at a time, really drained me of my energy, which I felt only upon my return home. Often, I found myself lying on the sofa for most of the day, usually doing nothing productive at all. The debilitating fatigue I went through on those occasions, which happened at least monthly (partly because I was travelling at least that frequently), usually lasted 4–5 days. During those years, I just brushed off my fatigue with different excuses: giving 110% for my clients on my expeditions, insufficient sleep on the road, less than ideal diet (e.g. a combination of airport, airline, and fast food), a side effect of ageing, stress from being in a foreign environment, etc. My wife used to liken my need for recovery time to the downtime artists take after a tour. There might have been an element of truth in that hypothesis, but it doesn’t explain those periods of fatigue which occurred spontaneously when I was working out from my office only, and not doing any special performance in the form of a talk, workshop, or on-site visit to a hospital 7000 kilometers from home. Paradoxically, I have never experienced fatigue during any of my assignments. Right from Day 1 of my consulting business, I have always felt excited and energetic while on the job, regardless of location on the planet, duration or type of the assignment (ranging from a 1-hour speaking engagement to a 2-day workshop, to a 25-day expedition in the heart of South Asia), or even how busy my calendar was. It seems like the adrenaline rush from the consulting/coaching/training assignments, and the determination to provide maximum value to my clients, keeps me going strong! :muscle: But afterwards, I would need convalescence time, up to a week for business trips and perhaps only a day or two for 1-day speaking/training events. For those times in which I experienced fatigue without an obvious trigger (such as out-of-town travel or speaking engagement), I might need between a few days and a couple of weeks to regain my energy and motivation.
  • Diminished exercise tolerance. I was fit in my teens and early twenties. I engaged in competitive sports – tennis and swimming – without much trouble at all. In my late teens, I could run 13 kilometers in about 60 minutes, immediately followed by 30 minutes of resistance training at home, and then a 1000-metre swim in the nearby public swimming pool – all this in one evening, at least five times per week for at least 2 consecutive years. I’d say that was when I was at my fittest. However, something strange happened after about the age of 22. Since then, on innumerable occasions, I tried to embark on a regular exercise routine a number of times over the years but could never sustain it for more than a month. I’d give up due to physical injury (e.g. manifesting as back pain), wheezing on mild exertion, or prolonged period of perceived fatigue. Each time this happened, I gave myself time to “recover” and I’d try again, the interval between attempts ranging between a couple of months and up to about 3 years. Needless to say, I never managed to attain the level of fitness I was hoping for.
  • Low back pain. I had been troubled by low back pain for more than two decades. I first sought medical help when I was around 24. At that time, I received physiotherapy for a few weeks but that didn’t really seem to help much. Over the years, the back pain has waxed and waned spontaneously but sometimes exacerbated by physical activity. There have been some notable episodes in which it was severe, once requiring hospital admission in 2007. An MRI at that time showed degenerative changes as well as early signs of fusion of the lumbar vertebrae. As correctly pointed out by a friend (Dr RS), my low back pain could have been referred from my rectum, sigmoid colon and/or descending colon. However, how this low back pain was related to my proctitis (see below) was indicated by its dramatic improvement after commencement of specific treatment of UC. I now believe I have a form of spondyloarthropathy, possibly ankylosing spondilitis, associated with UC.
  • Bronchial hyperresponsiveness. Another problem I had for more than a decade was the occasional episode shortness of breath and wheezing. These instances of presumed airway obstruction were usually precipitated by exercise or certain foods, like some brands of curry powder, and responded well to inhaled Ventolin. I sometimes gave myself a course of oral Prednisolone if the episode was bad. Like the back pain, this respiratory dysfunction disappeared after I started taking specific medication to treat UC. For this reason, I suspect my airway obstructive disease was a pulmonary manifestation of UC.

In addition to the above, I also had other gastrointestinal symptoms, which I think were more related to IBS than UC.

  • Abdominal Bloating. I had intermittent episodes of abdominal bloating, which were probably most closely related to what I ate. Emotional and psychological stress also played a role as to (a) whether I would experience bloating and (b), if I did experience bloating, to what degree.
  • Intermittent Nausea. Nausea and vomiting were my main symptoms when I was diagnosed with idiopathic gastroparesis in 2006. Since then, I’ve had intermittent, spontaneous episodes of nausea and anorexia, usually lasting up to a fortnight. I was having some bouts of nausea in the months before my clinic appointment on February 14, 2018, but I don’t think they were linked to UC.

Other Pertinent Information

In the months leading up to the clinic visit, my weight was stable – I certainly wasn’t losing weight – and my appetite was unchanged, though I was testing different diets to see if they helped my symptoms. During that time, my body mass index (BMI) was about 27.5, so I might have been considered overweight. (:warning: Disclaimer: I don’t believe the BMI is a good indicator of my nutritional status or adiposity.)

I’m a lifetime non-smoker.

Although I travelled extensively, especially within Southeast and South Asia, since I started my healthcare consulting firm in 2009, my travel had been limited to fairly developed locations (e.g. Singapore, Kuala Lumpur) in the previous few months. I had also been careful with the foods and water I consumed during my expeditions. Therefore, in my opinion, an infectious cause for my woes was unlikely.

Another important point to clarify is my sexual orientation: I’m a straight guy. I’ve never engaged in homosexual activity. For the record, I have nothing against the LGBT community. I’m just adding this bit to exclude the possibility my medical problems were somehow connected to homosexual sexual activity. The latter, e.g. anal sexual intercourse, anal fisting (aka “fist fornication”, “handballing”), insertion of foreign bodies, is a recognized cause of some forms of anorectal disease.

I’ve never had any radiation treatment.

I have no family history of colorectal cancer.

Physical Examination

Physical examination did not find any abnormality. A digital rectal exam wasn’t done, consistent with local practice.

My Differential Diagnosis

For months, I had considered the possibility of three conditions:

  1. Diverticulosis. The only real symptom that would support this diagnosis was the rectal bleeding. Uncomplicated diverticulosis isn’t usually associated with abdominal pain. Other symptoms could not be explained by diverticulosis alone.
  2. Diverticulitis disease. Before seeing the doctor, I actually thought I probably had diverticulitis. The bloody diarrhoea and abdominal pain were somewhat suggestive of this condition. But the location of the pain was not typical of diverticulitis and the history of my symptoms didn’t quite fit the typical picture for this disease.
  3. Colon cancer. I’d be lying if I said I did not seriously consider the possibility of cancer, in particular colon cancer. It didn’t help that a non-blood relative in his eighties told me only a couple of months before my visit to my gastroenterologist that the only symptom he had from his colon cancer was decreased stool calibre. I was only in my mid-forties without any family history (of colon cancer), and my weight had been stable – these factors seemed to go against the diagnosis of colon cancer.

Provisional Diagnosis and Rationale for Colonoscopy and CT Scan of Abdomen and Pelvis

Based on my story and his physical exam, my gastroenterologist’s provisional, or pre-test, diagnosis was IBS. He told me my previous diagnosis of gastroparesis and IBS both fall under the spectrum of functional gastrointestinal disorders. It didn’t sound like cancer to him. Nevertheless, because IBS was a diagnosis of exclusion, he recommended a colonoscopy and a CT scan of my abdomen and pelvis. I was fully prepared to be told I had to undergo these two tests; I was fine with them welcomed them. He didn’t need to convince me that a colonoscopy was justified, but he offered two other indications for it:

  • Being in my mid-forties, my age was close enough to being 50, the age at which most guidelines recommend to start regular colorectal cancer (CRC) screening in persons with an average risk of CRC. Interestingly, the American Cancer Society, in its 2018 guideline for CRC screening, made a “qualified recommendation” to begin screening in average-risk adults at age 45 years.
  • As mentioned above, my doctor knew I wanted a colonoscopy, without which I would constantly wonder about the possibility of CRC.

In addition, he told me cancer of the tail of the pancreas can present with symptoms like mine. Therefore, he recommended a CT scan (of my abdomen and pelvis) to rule that out.


Here comes the interesting bit: findings of the colonoscopy and CT scan of my abdomen and pelvis. Both were done on the same day, i.e. February 20, 2018. My gastroenterologist told me the results on the same day too.


First, the colonoscopy.

In the rectum, there was “circumferential erythematous mucosa with erosions and slough up to 6 centimeters from the anal verge” on colonoscopy. In layman’s terms, this finding indicated inflammation of the inside lining of my rectum, also known as “proctitis.”

The inflammation was at the bottom part of the rectum, just before the anus, and went all the way round the inside lining of the rectum (i.e. not localized to one, or more, spots). The rest of the colonoscopy, including that of the terminal ileum, was normal. The first photo on the right shows the multiple erythematous erosions on the mucosa of my rectum. These look like tiny red dots in the photo.

Proctitis seen on colonoscopy on February 20, 2018.

In the next photo, you can see thick layer of slough just adjacent to the left edge of the photo. There was presumably a lot more slough that was removed as part of the procedure. (If it wasn’t, we wouldn’t have been able to see what was underneath, would we?)

Another colonoscopic view of the proctitis.

The photo on the right shows the inside of a normal rectum for comparison. I hope my rectum will look like this on my next colonoscopy!

Normal rectum on colonoscopy
Normal rectum on colonoscopy. Photographer: melvil, Rectum-2016-12, CC BY-SA 4.0

Addendum: My colonoscopy on July 15, 2020 was normal.

Contrast-Enhanced Computed Tomography of the Abdomen and Pelvis

Next, the CT scan of my abdomen and pelvis.

The post-contrast images below are only a selection of all that were taken, focusing on the part between the level just below the mid rectum to the anus.

The radiologist who reviewed the CT scan suspected “mucosal thickening in the lower rectum” and suggested a colonoscopy. (He didn’t know I had already undergone the procedure before the CT scan.)


I received the histopathological report three days after my colonoscopy. It basically confirmed the presence of acute proctitis. The reporting histopathologist was of the opinion the “overall features are in favour of an infectious-type proctitis rather than ulcerative proctitis.”

Response to Initial Treatment

Though the clinical history and colonoscopic findings, on the whole, were most suggestive of UC, my initial treatment was based on the histopathology report. (When I questioned why I would have an infection down there, my doc seemed to believe my history of travel could possibly have been a factor.) I was prescribed a two-week course of ciprofloxacin and metronidazole, and a 3-day course of albendazole.

To be sure, I never believed my gastrointestinal symptoms were due to an active infection, but I took the antibiotics and antihelmintic regardless. If the antibiotics and/or antihelmintic could eliminate my symptoms, that would have been a fantastic result.

How did I go? In a word: terrible.

Over the next 14 days, my symptoms steadily worsened, despite me taking those meds religiously. Even after a few days, as my diarrhoea, pus and mucus in the stools, and abdominal pain worsened, I knew the thing in my rear-end was definitely not due to a bacterial or tapeworm infection. Nevertheless, I soldiered on with the entire 14-day course of antibiotic treatment, if not for anything else, to prove a point (i.e. it wasn’t an infectious cause). I called the doctor’s clinic on the 13th day to make an appointment to see him on the last day of the course of antibiotics. By then, my symptoms were quite severe, almost intolerable.

Plan B: Mesalazine to Treat Presumed Ulcerative Colitis

I expected to be told I needed another colonoscopy for more biopsies to be taken and sent for histopathological examination. But my gastroenterologist took a more direct approach, which I thought was far more practical: a trial of mesalazine, also known as mesalamine or 5-aminosalicylic acid (5-ASA), in the form of Salofalk 500 mg tablets, one tablet three times daily. This was actually a reduced dosage, in lieu of the intended dosage of Salofalk 1000 mg three times daily. My gastroenterologist being a little cautious due to my expressed concern over the drug (5-aminosalicylic acid, 5-ASA) being similar, in name and structure, to Aspirin (acetylsalicylic acid, ASA), to which I am highly allergic. He reassured me, and continues to reassure me, that mesalazine is safe for me and for long-term use. My dosage of mesalazine was increased to a more standard one – 1000 mg three times daily, i.e. 3 grams per day – a few days later.

In addition, I was prescribed Salofalk suppository 500 mg, one to be taken at bedtime. I took the suppositories for about two weeks.

The results? Magic. I expected the drug to show some effect, if any, in perhaps a 2–3 weeks. However, in my case, I noticed a remarkable boost in energy and a renewed sense of well-being after only three doses (about 24 hours)! I could confidently say I had not felt that good for over two decades. I’m sure it was not a placebo effect, but I still haven’t quite figured out exactly how this occurred – I guess the drug, through its anti-inflammatory mechanism of action, reduced the production of systemic inflammatory mediators or blunted their effects.

All my other symptoms I believed were linked to UC, listed above, also improved over the ensuing days and weeks. For me, mesalazine was a game changer. Just as tegaserod (brand name: Zelmac) was for my gastroparesis 12 years earlier.

I’ve been taking mesalazine since March 2018 and my UC symptoms have not recurred. So it appears that at least two goals of drug treatment have been achieved: (i) induction of remission, and (ii) maintenance of remission.

I was actually due for a follow-up colonoscopy last month, i.e. approximately 2 years after first starting mesalazine, but the procedure was postponed by 3 months because of limited supply of personal protective equipment (PPE) in the hospital, which forced the hospital to cancel all elective cases (which of course included mine). The lack of supply of PPE in the hospital was mainly due to US export restrictions on five categories of PPE in response to the COVID-19 pandemic. These restrictions are ongoing.

The Diagnosis of Ulcerative Colitis

Ideally, to confirm the diagnosis of UC, the biopsy specimens of my rectal mucosa would have shown architectural and cellular changes typical of UC under the microscope. However, only lymphoplasmacytosis (an inflammatory often change seen in UC) was found. The lack of histopathological confirmation remains a contentious point for some people to whom I’ve told my diagnosis of UC (all of them doctors) – to them, the diagnosis can only be made if a histopathology report backs it up.

There are at least three key points that support the diagnosis of UC:

  1. No viable alternative explanation for the distal rectal proctitis suggested in the history, e.g. infection, homosexual activity, radiation, etc.
  2. The trial of antibiotics and antihelmintic yielded zero beneficial effect. Therefore, an alternative diagnosis to UC (bacterial or tapeworm infection) became less likely.
  3. Excellent response to mesalazine. The only indication for mesalazine is the treatment of UC. Based on the literature available to me, this drug is not approved for treatment of any other bowel condition, though some people diagnosed with Crohn’s disease are also prescribed mesalazine. I’ve checked this fact with my gastroenterologist and others. In short, mesalazine should not have any clinical effect on any disease except inflammatory bowel disease, i.e. UC or Crohn’s disease.

The process of making a diagnosis was also complicated by IBS, which was diagnosed shortly after. More on the latter in a separate post.

The disease appeared to be confined to the distal rectum, i.e. disease extent was proctitis (and not left-sided colitis or extensive colitis).

There were no obvious triggers precipitating onset of disease – I’m a lifetime non-smoker, I never take nonsteroidal anti-inflammatory drugs (NSAIDs) because I’m allergic to them, I did not display any symptoms that suggested enteric infection, etc.

Fix the Problem

Making a diagnosis is a means to an end; a diagnosis guides further management of the patient’s problem. It shouldn’t be the goal; it’s just a necessary step towards addressing the patient’s problem or problems.

I encounter a similar situation in my consulting work. All my clients have a problem they want me to help fix. If they didn’t, they wouldn’t reach out to me. The process of solving their problem usually calls for some combination of knowledge, skills, intuition, and judgment – all of which influenced by length, type, and quality of experience. Sticking to scientific principles and practices, or at least practices regarded as conventional by industry standards, is the most prudent course of action in most situations. However, there are times when one has to knowingly do something which deviates from standard practice. For example, in rare instances, I might (over)simplify an interpretation of an accreditation standard, so that the client will accept the changes I propose – it might not be 100% accurate to the purists or my CPHQ students – but for the purpose of solving the client’s problem (accreditation, in this example), the simplification might be pragmatic and necessary.

Back to my diagnosis. After the presumptive diagnosis of UC and specific treatment for this disease, my symptoms improved quickly, and I was able to function quite normally soon after:

  • No more (unpredictable) episodes of diarrhoea.
  • No more rectal bleeding, pus, or mucus.
  • Stool calibre returned to normal.
  • No more rectal pain.
  • Overall energy level considerably improved.
  • Exercise tolerance much improved, especially after some training. As an illustration, I can now row for 70 consecutive minutes (holding a stroke rate of 18 strokes per minute and decent split time of 2:10/500m throughout) and run 10 kilometres or ride 30+ kilometres, and still have leftover gas in the tank afterwards.
  • Very little back pain or stiffness (not delayed onset muscle soreness (DOMS), which I experience regularly).
  • No more episodes of breathlessness and wheezing.

Problem solved. For now.

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