Medical Lectures

Making Sense of Abdominal Pain and Bloating (Quiz Included)

Conor Loftus, MD MRCPI discusses cases of abdominal pain and bloating and emphasizes categorizing these patients into groups to facilitate diagnosis and subsequent management. Take the quiz at the end to test your knowledge of gastroenterology.
February 5, 2022
Conor G. Loftus, MD MRCPI

Conor G. Loftus, MD MRCPI, Mayo Clinic
Conor G. Loftus, MD reviews: 
  • What are the really important aspects of the history and physical examination in patients with gas and bloating? 
  • What dietary changes are helpful to these patients? 
  • What types of tests are necessary when tests are necessary? 
  • And what treatments are effective for these patients? 


One of the key elements to figuring out what's going on with any patient is doing a detailed history and physical examination. I like to emphasize that it's very important to do the basics well, by listening to the patient and by performing a thorough clinical examination. Oftentimes, we can have a good sense as to what's going on or begin to put theories together with regards to the etiology of their symptoms simply from the history and physical examination. 

So, when taking the history from patients with abdominal gas and bloating, I like to categorize patients into really three groups. One is what I call the gastric bloater. The second is the small bowel bloater, and the third is the patient with gas bloating combined with constipation. Belching patients are another subgroup that we see, but I'll be speaking less about them today. 


So, the gastric bloater is the patient who will say, “Very quickly or soon after I eat, after a swallow or two, I'm beginning to feel discomfort in my abdomen.” When the symptoms are very rapid and onset anywhere from a minute to 30 minutes after ingesting the food, that suggests that the problem is related to the stomach. 

There are a number of things that can be going on in the stomach. It could theoretically be gastric outlet obstruction, although that diagnosis is rare. Could theoretically be gastroparesis, but again, that diagnosis is rare. Nonulcer dyspepsia or functional dyspepsia is a very common diagnosis involving the stomach; usually, that's what's causing the problems. Occasionally, it's a disorder of gastric accommodation or relaxation of the stomach, but that's quite rare as well. 


In contradistinction from the gastric bloater, the small bowel bloater is the patient who says, “I can eat that plate of food without any difficulty whatsoever, and I feel fine for the first 30 to 60 minutes, but then 60 to 90 minutes after eating, I begin to feel bloated further down in my abdomen and I feel discomfort.” 

Those patients are oftentimes patients who have either irritable bowel syndrome or dietary intolerance, such as gluten intolerance, or dairy intolerance, or sometimes fructose intolerance. The patient may have celiac disease, or they may have SIBO, small intestinal bacterial overgrowth. They may have ingestion that's causing those symptoms, such as chewing gum or artificial sweetener, or theoretically, SBO, which stands for small bowel obstruction, could be a mechanical issue of the small bowel. 


The third group of patients have gas-bloating and constipation. This is the patient who says, “I'll go for four, five, or six days, or a week, or ten days, or three weeks without having a bowel movement. I feel full, uncomfortable, gaseous, and bloated.” And usually, in that circumstance, the constipation is the driver, and our job is to figure out is what's causing the constipation in the first place. 

The differential diagnosis in that situation may be constipation, predominant irritable bowel syndrome. It may be simple constipation secondary to a lack of fluid or lack of fiber. Or theoretically, it may be something like pelvic floor dysfunction. I'll speak about that in the moment. 


This is a picture that is from a paper that we've written in the Mayo Clinic proceedings that describes the different phenotypes: the gastric bloater, the small bowel bloater, and the constipated bloater, as well as the differential diagnosis and the types of tests that we consider for the different groups of patients. 

So, what on the physical examination, then, is important? Belching, we're not speaking too much about today, but if the patient is belching during the conversation, sometimes that can suggest an anxiety-type disorder. 


Signs of abdominal distension on examination: if the abdomen is distended, particularly if bowel sounds are absent, that distension may be due to an ileus of the small bowel. If the bowel sounds are high-pitched, that may suggest a mechanical obstruction in the small bowel. 


And a digital rectal examination is performed usually with the patient in the left lateral decubitus position, and just simply looking at the anorectal area, while we ask the patient to push down like as if they're having a bowel movement, we should see the pelvic floor move, and it should descend. Oftentimes, patients with pelvic floor dysfunction, when they go to push down like having a bowel movement, they actually clinch, and they're squeezing together their gluteal muscles, causing an obstruction to defecation, you can actually see that on examination. 

When you insert a finger into the rectum, you can again feel the muscles of the pelvic floor contracting and relax, contracting and relaxing, in a normal situation. If you don't feel that contraction and relaxation, or if you feel the patient is clenching when they're bearing down, those are hallmark signs on physical examination of potential pelvic floor dysfunction. 


I want to speak a little with regard to the pathophysiology of some of the diagnoses we're going to talk about, and I alluded to this earlier, a diagnosis of non-ulcer dyspepsia, or functional dyspepsia involving the stomach. Functional dyspepsia, or non-ulcer dyspepsia, is where there is a change in sensation at the level of the stomach. And this is when I am explaining this diagnosis to patients, I often say, “this is like irritable bowel syndrome but for the stomach.” 

Irritable bowel syndrome is typically a change in sensation involving the small bowel or colon. 

Functional dyspepsia is where there is oftentimes pain or discomfort or a fullness associated with a change in sensation within the stomach. So, our stomachs are continuously sensing the normal physiology of the stomach, and the normal physiology of the stomach is the production of acid, the production of bicarbonate, the production of fluid. That acid, bicarbonate, fluid, food, and other contents within the stomach, stimulate nerve endings within the lining of the stomach, and that stimulation of nerve endings causes some degree of discomfort. But our brains say to us that's normal, and so we don't feel symptoms coming from the stomach ordinarily, typically after we've eaten a normal meal. 

However, that circuit of sensation surrounding the stomach can change, for example, after a viral illness or after major stress in life. That physiology in the stomach, instead of having normal sensation, can be sensed as abnormal, or we can have an increase in sensation being generated in the stomach, and that can be portrayed as nausea, early satiety or fullness, pain from the stomach, or an acid burning sensation. That change in sensation at the level of the stomach is what we call nonulcer dyspepsia, or functional dyspepsia, which is a very common entity. 

I often think about this as what can we do inside the lumen of the gastrointestinal tract? What can we do at the level of the bowel wall? What can we do at the level of nerve endings that are coming out of the gastrointestinal tract? Then, what can we do with the level of the brain? 


So, at the level of the gastrointestinal tract lumen, so inside that stomach, we can treat acid. So, suppression of acid may help these patients usually be effective in about 15% of patients. We can change the type of food that the patient is eating, the quantity of food that the patient is eating, and downstream, ensuring that the patient has good clearing bowel movements on a daily basis, is important for the management of gastric symptoms. 


At the level of the bowel wall, sometimes we'll use medications that are anticholinergic, or relax the bowel wall, such as Hyoscyamine or Dicyclomine. Other times, we'll use medications that are more advanced, neuromodulators-type medications to decrease sensation at the level of those nerve endings. Tricyclic-type medications, or serotonin-specific reuptake inhibitor type medications are utilized to modify sensation. 


Finally, for the patient who has significant anxiety or depression which is contributing into their symptoms, it's important at the level of the brain to be able to treat those coexisting conditions to enhance the patient's outcome. 

When you're faced with patients, I always find it difficult to treat patients with gas and bloating. But it helps me when I was able to categorize these patients into those three main groups:

1. Is it the gastric bloater, that is the patient who has symptoms very early on after eating the food? If it's a gastric bloater, you think about functional dyspepsia, particularly after you've excluded significant abnormalities by performing an upper endoscopy and perhaps a gastric emptying study. 

2. Is the patient a small bowel bloater where the symptoms are more delayed? If the patient is a small bowel bloater, you think about the list of diagnoses that are presented.

3. And then in the patient who has gas bloating with significant constipation, if you've treated constipation and your situation is still having a lot of difficulty, you think about could this be related to a pelvic floor dysfunction?

I hope you are able to take some of the lessons learned back to your clinic and apply them to the patients you're seeing.


This patient also does not take nonsteroidal anti-inflammatory medications as she's had a trial of omeprazole, which did not help. Upper endoscopy was normal. Ultrasound of the gallbladder was normal. She had a HIDA scan which is slightly abnormal, and she's had a gastric emptying study that was normal as well. 

With that clinical picture, which of the following would you recommend? 

A. Take out the gallbladder

B. Gastric emptying study

C. CT scan

D. Treating the patient for functional dyspepsia 

E. 24 pH study 

Which of the following diets is not likely to help this patient?

A. The traditional irritable bowel syndrome diet 

B. Lactose-free diet 

C. Gluten-free diet 

D. FODMAP diet

E. The Paleo or caveman diet 

3. 51-year-old female, who presents with chronic abdominal discomfort and bloating. Patient has had constipation for many years, which has been getting worse. The patient spends a long time in the restroom, straining to have bowel movements. And physical examination, when you examine the abdomen, there's evidence of musculoskeletal abdominal wall tenderness with a positive Carnett's sign. 

What would you recommend for this patient? 

A. Trigger point injection at that point where there were particularly tender with the Carnett's sign positive 

B. CT scan of the abdomen and pelvis 

C. Anorectal manometry looking for pelvic floor dysfunction 

D. Stimulant laxative or another form of laxative known as Linaclotide

Answers and explanations below!

  1. D, Treating the patient for functional dyspepsia 
  2. E, The Paleo or caveman diet 
  3. C, Anorectal manometry looking for pelvic floor dysfunction 

1. The correct answer here is that we would treat this patient for functional dyspepsia. The patient does not have symptoms suggestive of reflux and did not respond to PPI, so we would not recommend further evaluation for reflux with the 24-hour study. The CT scan is less likely to be high yield. The gastric emptying study was already done, which was normal. Taking out the patient's gallbladder for these types of symptoms is not likely to help. 

As I touched on earlier, patients who have viral gastroenteritis can be left with a hypersensitivity syndrome involving the stomach, whereby when the patient eats, they feel uncomfortable very soon after eating. If they're full, if they can feel a burning sensation or early satiety, that condition is functional dyspepsia or nonulcer dyspepsia. 

So, what can you do for the patient who has a gastric bloater? As I said, within the lumen of the stomach, you can modify what the patient is eating and how the patient is eating it. So oftentimes fatty or greasy foods are discouraged. Eating small meals frequently may help. Minimizing caffeine, chewing gum, and artificial sweeteners may help. Treating coexisting constipation is very important by increasing dietary fluid and fiber intake usually, and it's reasonable to consider Helicobacter pylori. A small group of these patients will have coexisting Helicobacter pylori.

It's probably reasonable to look for Helicobacter pylori and eradicate that if present, and also acid-suppressive therapy may be used. As I said earlier, sometimes relaxing the bowel wall, particularly if the patient has spasmodic-type pain with medication such as anticholinergics may help. 

Occasionally, if the patient is has a lot of fullness after eating and has had a viral illness, there may be a disorder of gastric accommodation, and allowing the stomach to relax more, more easily after eating with a medication called Buspirone 5-10 mg twice daily may be helpful. Neuromodulator-type medications such as amitriptyline 25 mg at night time, increasing to 50 mg after two to three weeks may be reasonable. Or for patients who have a really poor appetite, you're trying to stimulate their appetite as well, Mirtazapine, or Remeron, in a dose of 7.5 mg going to 50 mg after two to three weeks is reasonable. You may be familiar with an over-the-counter preparation called FDgard or IBgard. That's F D G A R D it's a peppermint preparation that can be helpful for some of these patients. 

2. So the one diet here that's not likely to be helpful is a Paleo diet. There is reasonable evidence to suggest that each of the other diets may be helpful. This patient is able to eat with their symptoms, but then 30 minutes or an hour later, an hour and a half later they feel full in their mid-abdomen, that patient may have irritable bowel, it may be dietary, maybe due to ingestions that I eluded to earlier, maybe due to celiac disease, or a mechanical problem of the small bowel, or small bowel bacterial overgrowth. So, I touched on FODMAPs, and we hear a lot about FODMAPs nowadays. FODMAPs are Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols. That's a very fancy term for basically sugars. And sugar it's particularly in fruits and vegetables, and FODMAPs diet has gained a lot of traction over recent years, in addition to the gluten-free diet, and oftentimes patients who have had sequential trials of dairy-free and gluten-free irritable bowel type syndrome will pursue a trial of FODMAPs diets, which is low sugars, and oftentimes excluding many foods and then reintroducing foods after hopefully improvement has been seen. 

The IBS diet was described in gastro back in November of 2015 is pretty simple. It’s basically focusing on three meals and three snacks a day, avoiding fatty foods and spicy foods, reducing caffeine, alcohol, and gas-forming foods such as cabbage, broccoli, cauliflower, beans, and onions. The FODMAPs diet is low on sugars, low in fruits and vegetables that I just spoke about. And the gluten-free diet is avoiding gluten. 

So, each of these diets, in addition to the lactose-free diet, have been shown to be helpful in patients with irritable bowel syndrome. So how do you manage irritable bowel syndrome? You think about what you can do inside the lumen of the bowel, what you can do with the bowel wall, and what you can do with the nerve endings coming out of the bowel, and then at the level of the brain. 

So, inside the lumen of the bowel, again, we think about what we're eating and how we're eating it. So small meals frequently, oftentimes working through the different diets that I spoke about. So the irritable bowel diet, lactose-free, gluten-free, and FODMAPs diet. Minimizing ingestions again, caffeine, artificial sweeteners, and chewing gum. Very important to treat constipation if there's coexisting constipation, and if there is coexisting diarrhea. Sometimes a bulking agent such as Metamucil or Citrucel may be helpful in that situation, or a bile salt binder may be helpful if there is excess bile in the stool. 

In patients with irritable bowel syndrome who have a lot of spasm-type pain, a lot of cramping in the left floor quadrant, using anticholinergic medications such as those listed may help. And for some of the more complex patients with irritable bowel syndrome with coexisting significant pain, again, neuromodulators-type medications such as amitriptyline may be helpful. 

Finally, at the level of the brain, cognitive behavioral therapy, relaxation techniques, and so on and so forth, may be necessary for patients who have significant and difficult to treat abdominal symptoms. 

I mentioned small bowel bacterial overgrowth as we went through in terms of parts of the differential diagnosis in patients who have small bowel bloating. I want to emphasize that small bowel bacterial overgrowth gets kinda blamed for everything, but if you really think about small bowel bacterial overgrowth, is there is a true risk factor for getting excess bacteria growing in the small bowel? If there is a structural abnormality of the small bowel, such as a small bowel diverticular, small bowel structuring; if the patient has had surgery of small bowel in the past; if they've got true risk factors for small bowel dysmotility such as scleroderma; they're the real higher risk scenarios where small bowel bacterial overgrowth is predisposed to. 

Decreased acid in patients with acid-suppressive therapy or with atrial hydria, gastric resection, there is a somewhat decreased risk. And then patients with advanced age, celiac disease, and occasionally we'll see patients with idiopathic small bowel bacterial overgrowth, but the higher risk situations are the structural, the surgical, and dysmotility risk factors listed there. 

3. The answer here is to evaluate this patient for pelvic floor dysfunction. So, patients who have constipation, I want you to think about it, particularly if they have a history of lengthy restroom visits where they spend 10, 15, 20 minutes in the restroom, really forcing down to have a bowel movement. 

Incomplete evacuation is the second hallmark symptom, or a difficult symptom to ask about, but it's very useful to ask a patient if they manually digitate, so if they manually use their finger to remove stool from the rectal vault, that's a hallmark symptom of pelvic floor dysfunction.

And physical examination, as I spoke about earlier, you're looking for movement of the pelvic floor, a movement of the pelvic floor muscles with bearing down and with contraction, relaxation. If you suspect the patient has pelvic floor dysfunction, then performing an anorectal manometry, that's a little catheter device that we introduced into the rectum, it's got a little balloon on the end of it, and we ask the patient to push down and see if they can evacuate that balloon. 

We also perform pressure measurements to see if we can see if the muscles of the pelvic floor are working properly. So pelvic floor dysfunction is a diagnosis to keep in mind in a patient with refractory constipation. Another differential diagnosis in the patient with constipation and bloating, simple constipation, constipation predominantly in irritable bowel syndrome, mechanical issues with the colon of course have to be considered. Less so in the younger person, but for a person who is at risk for colon cancer, a colonoscopy may be necessary. And rarely slow transit constipation, but that's a diagnosis of exclusion, it's quite rare. \

Other risk factors for pelvic floor dysfunction include unfortunately a history of physical and sexual abuse, environmental stressors. Another aspect of the history that can suggest this diagnosis is if the patient has worsening abdominal symptoms with use of osmotic laxatives, such as MiraLAX. 

The physical examination, again, is important, I explained that earlier. Look for bearing down when the patient is in the left lateral decubitus. Look for movement of the pelvic floor muscles when you ask the patient to squeeze and relax. Really, it's about retraining those muscles of the pelvic floor to be able to contract and relax, contract, relax and move. 

At Mayo Clinic, we have a very dedicated program. It's a two-week program where the patient attends biofeedback therapy two to three times a day/ week one, two, or three times a day/week two. It's in a concentrated manner, it's a very effective program, and 70 to 80 percent efficacy. Patients will see improvement with a sustained biofeedback program. So how do you manage the patient with gas bloating and constipation? 

Again, go back to what can you do at the intra luminal level, and it's really the treatment of constipation. My rule of thumb for constipation is four Fs. Number one, make sure the patient is taking enough dietary Fiber with fruits and vegetables. Number two, make sure the patient is drinking enough Fluid. Number three, make sure the patient is getting exercise/Fitness. And number four, make sure that the patient is getting enough supplemental Fiber, usually soluble fiber in the form of psyllium which is Metamucil, or methylcellulose which is Citracil. 

In addition to that, if that's not effective, the patient can use an osmotic laxative such as MiraLAX. If patients are not responding to those measures, then you may bump up to a stimulant laxative, particularly in patients who are on narcotics, or if they've got dysmotility or other agents have failed. And then the specific medications, Linaclotide and Lubiprostone, are really reserved for patients in whom the other steps fail. 

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