Bloating 101

Bloating is a vague symptom that means different things to different people – including gastroenterologists.    

 It can mean swelling and sticking out of the abdomen, a feeling of fullness or heaviness, or gassiness. The underlying cause depends on the specifics of what you are feeling, so let’s get granular.

When patients come into the clinic with bloating as their main concern, I ask a few key questions to help us get started:

-          What are your stools like? If they are nuggets, a log of nuggets smashed together, or a log with cracks, we may be looking at constipation as the cause.

-          Does your bloating improve when you have a good bowel movement and feel well-evacuated?

-          Do you have a lot of gas? If there is a lot of gas in combination with stools like the above, we may still be looking at constipation.

-          If there is gas, when do you experience it? If it comes on within 30 minutes to an hour, it suggests a histamine, alpha-gal, lactose intolerance, or SIBO/SIFO situation.

-          Is your stomach flat in the morning and get bigger as the day goes by, so that your abdomen is hard by evening and there isn’t a lot of gas, but there is a lot of pressure? This could be functional bloating.

Each of these underlying causes deserves its own attention, but let’s start with the bloating that is related to constipation.

Constipation can be a difficult diagnosis to make on history alone, because there is a wide range of “normal” frequency of BMs, and the worst cases of constipation actually present as diarrhea!

When constipation is present, there is usually gassiness, because the majority of your stool is made up of bacteria. They eat whatever is around them and produce gas as a byproduct for as long as they’re inside you.  Appetite is sometimes reduced and people often feel really full really quickly because there’s no room for food. The body is full of feedback loops, and when your colon isn’t emptying, it sends a signal for the small intestine and the stomach to slow down, too.  Patients often report that they ate half a sandwich and feel like they ate Thanksgiving dinner.   When I examine them, I might be able to feel a stool log in the left lower quadrant of the abdomen, the portions called the descending and sigmoid colon.  It is sometimes tender to my examination.

People with moderate to severe constipation feel bloated all the time – they wake up that way, and it just gets worse as the day goes by.

Sometimes, people present with diarrhea as their main constipation symptom. I get a lot of funny looks when the history suggests this as the main issue - until I explain what’s happening: 

The colon is a much more impressive organ than a simple hollow tube, mainly because it houses the microbiome, my favorite subject in the world, but also because it is tasked with recovering the excess water your body used in the digestive process.

When your small intestine has finished its job, the leftovers, called chyme, trickle into the colon, aka the large intestine. Chyme is very liquidy, and ideally, bacteria work on these leftovers to make amazing health-promoting substances, at the same time that the cells lining the colon reabsorb excess liquid. As the chyme transits through the colon it becomes poop (the line where that happens is fuzzy) and becomes more solid. If a person is really constipated, it’s like the whole tube is filled with rocks that aren’t moving. As chyme trickles in, it has nowhere to sit and dry out, so it just runs through the cracks and crevices and comes out as diarrhea. A clue to this is when people say they are exquisitely sensitive to Immodium, getting constipated for days with just a half dose, for example, or when they are exquisitely sensitive to Miralax – because it makes the chyme even more liquidy and fast-moving.

Often, when I suspect constipation, I order a flat plate Xray of the abdomen. I ask the radiologist to comment on how much stool there is, and where it’s located, because that can give me some clues about the underlying cause.

In cases where constipation is confirmed, I offer short term and long term tools for patients to use to get going, and of course I talk to them about diet. There are several prescription medications on the market but I use them as a last resort, unless the patient wants a quick fix. And sometimes, we test for pelvic floor dysfunction, which could be the subject of a whole other post.