How to keep a stool diary

1. What this is

A stool diary is a short record of when you went and what it looked like. Digestive clinics often ask for a few days of it on paper, and this app is that paper moved onto a screen.

The ruler for shape is the Bristol stool form scale. It was published in 1997, and what the original paper actually measured was how stool form relates to the time it takes to pass through the gut. Remembering that it was not built to name diseases keeps the log from being misused.

So this app records and counts, and stops there. It never says a probability, and it never says that something is dangerous.

It is meant for an adult logging their own. Do not use it for a baby, because the scale itself is different. A child needs a different ruler, and mixing that ruler into this screen would get both of them wrong.

2. Reading the seven steps

Type 1 is separate hard lumps, type 2 is a lumpy sausage, and type 3 is a sausage with cracks on its surface. Type 4 is a smooth soft sausage or snake, and type 5 is soft blobs with clear cut edges. Type 6 is mushy with ragged edges, and type 7 is watery with almost no solid pieces.

As a rough rule the higher the number the softer it was. Do not read the number itself as a score, though. Averaging type 1 and type 7 into type 4 means nothing, which is why this app never builds a figure like average consistency.

When several clinicians scored the same photographs from type 1 to type 7 they agreed well, but agreement fell once the same photographs were turned into clinical categories of normal, constipation and diarrhoea. Naming the shape holds up; stepping across to disease does not.

3. The rules inside this app

The log screen is two steps. Tap one of the seven shapes, then tap one of the six colours. Once both are chosen the keep button comes alive. There is deliberately no free text box, because a field you cannot write in is a field that cannot leak.

The photo is optional. If you choose one it is shrunk to a small grid inside the browser, the bright and nearly colourless parts are treated as the bowl and the water and taken out, the average colour of what remains gives a colour candidate, and the number of lumps together with how ragged the largest edge is gives shape candidates. Shape candidates come as a range of up to two rather than a single answer, because the rules genuinely cannot separate type 1 from type 5 and hiding that would be dishonest.

A suggestion stays a suggestion and never crosses into the log by itself. Choosing is always a tap by you. The photo is dropped after reading, neither the original nor the shrunk copy is stored, and nothing is uploaded anywhere.

Colour guidance is attached to black and bright red only. Every other colour gets no message at all. Hanging a worry on each colour would turn a log into something that sells anxiety.

Keeping a log requires turning on a separate consent. With it off nothing is stored, and turning it off deletes what was kept. The delete now button is always present either way. Do not turn it on for a shared computer.

4. Getting the basics right

There is no need to catch every single time. If an appointment is coming up, seven to fourteen days in a row is already enough to talk about.

When the shape is ambiguous, pick the nearer one and move on. An unbroken run of entries shows the trend better than entries agonised over.

The trend screen only draws counts per day and per shape as bars. No interpretation is attached, so if something stands out, show that screen as it is to a clinician.

5. Using it a little better

For photo help, a well lit shot taken straight from above reads best. Heavy shadow or a submerged blurry image leaves the rules unable to separate stool from background, and in that case they say there was nothing to read and step back.

When a day looks unlike the others, note the date and mention it at an appointment. This app never says what caused it, but the log does say when things changed.

There is no way to move a log to another device. Without a server there is nowhere to move it, and in exchange there is nowhere for it to escape to either.

6. Where people get stuck

If the keep button will not press, one of the shape or the colour has not been chosen yet. It comes alive once both are.

If you kept an entry and it is gone next time, the consent was most likely off. While it is off entries only show on screen and are not stored.

If a photo produces no suggestion, the rules could not separate background from stool. Choose by eye instead. A missing suggestion never blocks you from keeping an entry.