I stick my finger up someone’s bum as much as three times a day. It doesn’t get any better with time, it’s always someone else’s shit on my finger. With any problem below the lungs, it seems necessary to insert a gloved digit up the anal passage and have a poke around.

Perhaps unsurprisingly, to me the idea of sticking my finger up a man’s bum for sexual kicks is about as erotic as nasal hair. Firstly, I wear gloves for a reason, and secondly, no matter how much it might make him pant, I can’t help but feel I’m trying to evaluate his haemorrhoids.

In the medical profession it’s called a digital rectal exam. I don’t remember my first time. There have been so many that sometimes it feels like my job is simply a barrage of sphincters to bypass. You learn on a rubber model bum – a quadriplegic, headless arse with changeable prostate parts like Mr. Potato Head. In examinations you have to address it like a person, making idle chit-chat with the severed bum hole. “Excuse me, Mr. Potato Head, I am now going to insert my finger in your back passage. Please try to relax.”

The advantage is the Barbie doll bum hole can’t talk back. My last anal probe was on a voluptuous woman, who bent over the trolley with little ado. I used what is called a proctoscope – an instrument like a plastic ice cream cone with a hole in the end for easy viewing. Halfway through the examination, as I’m perusing her anal cavity trying to be delicate with what could otherwise be termed a torture device, she turns around to me and says, “I run an S&M parlour and my clients would kill for this. Could I tempt you to come down? I could give you £100-an-hour?”

As much as being an anal crusader for the S&M community was always my dream, I politely declined. But if you’re more of a free spirit when it comes to your arsehole and the idea of lube and latex gets your knickers in a twist, then here is a quick guide to getting a rectal exam of your very own.

1. A rectal exam is given to anyone with serious bum bleeding. Bright red spots won’t get you anywhere. They’re from burst haemorrhoids, or just tearing the delicate skin from straining on an oversized turd. The worrying stuff is a dark, tarry goop, like black pudding. It has a sickly sweet smell – not entirely unpleasant but still kind of farty – which I can spot from metres away. If you complain of this you’re past stage one.

2. Most of you will have a preference on what gender doctor performs the duty. GP practices will normally have a picture in the foyer or advertising pamphlet about the doctors, so you can decide whether you want a big matronly toughie or Dr Dreamboat to finger your unborn turd children. If you get a doctor not of your gender preference, you can always say, “I would be more comfortable with a [insert man/woman].” If it suddenly doesn’t seem like it’s going to be as much fun as you had imagined, it is your right to decline an exam at any point.

3. Now you’ll have to undress below the waist. The doctor should help you assume the right position. I put people into a fetal position on the bed with their bum hanging off the edge for easy access. I say, “I am now going to insert my finger in your back passage. It may be a little uncomfortable, but relax if you can.”

4. The actual exam only lasts 60 seconds and involves a sweep around the whole anal cavity looking for anything unusual. It should only really hurt getting past the pursed hag’s lips-esque opening. Sometimes my fingers aren’t long enough, which means I have to really knuckle their arse cheeks to reach. Be warned: male doctors have larger fingers.

5. For the sake of avoiding embarrassment, dump beforehand and please wipe and wash thoroughly. There’s nothing worse than poo-crust, and if you’re getting off on it, it only seems fair that the doctor doesn’t have to smell you on their fingers for a week.

I am not encouraging any of this, though. Most people I deal with find it about as intrusive as being poked in the arse by a stranger. Which, of course, is exactly what the procedure is.

DR MONA MOORE