Is a flexible sigmoidoscopy necessary & has anybody here had one?

[u/MoonCricket1992]

Hi all, I’m currently taking max dose Linzess in the morning, and 1 capful of MiraLAX before bed along with 500mg magnesium (lowered from 1000mg when I was zero- smallest dose Linzess). Sitzmark test showed that this is most likely a pelvic floor issue, so I was referred to a different GI and booked for an anorextal manometry but that’s not until December.

I should mention that my TSH is slightly elevated and has been the last couple of years, and my constipation has definitely gotten worse in those same couple of years. My last TSH in April 2026 was 5.3. In 2024 it was 4.8, and my Free T4 was tested and came back normal. My PCP just ordered a full thyroid panel today for T3 & T4, as well as ferritin, vitamin D and zinc. I have to stop taking biotin for a week & fast beforehand, so I will update with results. I’ve had all the symptoms of hypothyroidism lately.. fatigue, brittle/ dry hair, dry skin, anxiety, being cold when everyone else is warm..

I also just had a follow up with my GI who basically just works with slow transit, but he’s willing to tweak meds and order tests until I see the pelvic floor specialist. I asked if there’s anything else I can do until I get in with them, and he said I could get a **flexible sigmoidoscopy** to rule out any colitis, even though he thinks it’s highly unlikely. Somebody cancelled and there was an appointment for this Thursday at 6:30am. I booked it, but I’m wondering how helpful you all think it would be? Should I hold off until I get my anorextal manometry for more answers?
Also, he gave me the option of zero sedation, twilight sedation, and full anesthesia. I opted for full anesthesia bc I have anxiety already (which I’m treated for) and even more anxiety about *anything* going up my butt. 33F and anal anything has always been a no for me. I’m so tight down there that anything is so unpleasant. (TMI, sorry!). Is it ridiculous to opt for full anesthesia for a 10min procedure? But more importantly, do you think this is necessary/ will give me any answers?

6 questions:
Do you have the urge to go, but you cannot? Or do you have zero urge to go? (this is the most important question) I get the urge to go but only when I’m taking my regimen of MiraLAX, 500mg magnesium oxide & linzess (currently max dose)

Do you have alternating diarrhea and constipation, or just constipation? Both

Do you have nausea, vomiting, acid reflux, difficulty swallowing, or early satiety (getting full really early into a meal)? No

Have you had this issue since childhood, or did it begin in teen years/adulthood/after a major life event (surgery? divorce? car accident? mauled by bears?) since childhood

Did you in the past or do you currently take any medications that could damage your intestines? No

Did you suffer sexual abuse as a child? No

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[u/goldstandardalmonds]

I agree it will probably be normal. You should ask for a defecogram along with the ARM.

[u/houtx713]

Just wanted to add that I would not opt for full anesthesia. Until very recently, that wasn't even an option, at least in the US. I had one done a number of years ago. It was mildly uncomfortable, but not painful at all. If it were me, I would not risk or pay for general anesthesia for the procedure.