THE BLOAT BATTLE: TAMING YOUR TUMMY TROUBLES

I feel bloated, doctor. My tummy feels like a drum.

This is the most common statement I encounter daily as a practising gastroenterologist in a private hospital in Penang. Even when talking to friends and relatives during my days off, they often sit beside me casually and ask if I can listen to their digestive complaints. I can usually guess it is one of three things: a painful tummy, a bloated abdomen, or nagging heartburn. As much as I enjoy friendly banter, the conversation often quickly shifts to something more serious.

In technical terms, bloating is a subjective sensation of tummy distension, swelling, or fullness felt when the abdominal wall becomes tense and sometimes firm. It does not cause severe, debilitating pain that would drive someone to the emergency department for immediate relief and further assessment, but it is uncomfortable enough to prompt medical consultation. It affects a patient’s quality of life, as they cannot enjoy a full meal, often feeling nauseated, sometimes even vomiting. When it occurs at night, sleep can be disrupted due to the heaviness in the belly. Bloating may result from excess gas, fluids, fecal matter, a solid tumor, or even a pregnancy (undiagnosed). It remains a bit of a mystery when a patient of different age, ethnicity, gender, and body type seeks relief for their ‘bloatedness’.

Figure 1: Bloating is a subjective complaint that necessitates further medical assessment if the symptoms become persistent and troublesome (image courtesy of Alpine Surgical).

While it can be confusing at times, it can also be quite fascinating to help the patient unravel the complex array of symptoms and then provide the right solution to support them. It becomes even more rewarding when they return to tell you that their bloating, which has troubled them for weeks, months, years, and even decades, is now a thing of the past. Although I would like to focus on ‘gastroenterology bloating’ or bloating caused purely by gastroenterological disorders, this is not always the case. Patients often find it difficult to differentiate between symptoms and their underlying causes. Therefore, clinicians must be alert to potential pitfalls and red herrings when taking a detailed history and examining patients with bloating.

What should you expect when visiting a clinician’s office for bloatedness? Or how should you prepare for your consultation with your gastroenterologist? I understand that feeling anxious about the unknown and the fear that the news may be unfavorable is common. There may also be concerns about the numerous tests your doctor might suggest. Writing down your thoughts and organizing your chief complaints in a chronological order can help; your clinician will guide you through your concerns. We aim to demystify the events leading to your bloatedness, identify the cause, and provide an appropriate solution for your ailments.

Here’s some personal sharing…

Since starting private practice in Penang, I have grown and learned from the challenges and the difficult task of understanding bloating. I have encountered multiple causes of bloating unrelated to gastroenterology, including a large ovarian tumor/cyst in a teenage girl, significant uterine fibroids in a middle-aged woman, impacted kidney stones in an obese man, undiagnosed kidney failure in a thin elderly gentleman, heart failure with uncontrolled diabetes mellitus in a portly lady, a liver abscess in a young travelling businessman, a massive liver tumor in an elderly man, an enlarged spleen caused by a blood-related disorder in a young woman, pancreatic cysts, perimenopausal symptoms, and three cases of undiagnosed and unexpected pregnancies.

Such a diagnosis can imitate bloating caused by gastroenterological issues to the extent that patients might seek over-the-counter remedies like antacids, alginates (Gaviscon), and simethicone (e.g., Maalox Plus, Alucid, Gas-X, and GazGo) for relief. Conversely, some, influenced by experiences shared by family or friends, may start experimenting with traditional medications, supplements, prebiotics, probiotics, and proton pump inhibitors (acid-neutralizing agents) for an indefinite period without seeing any improvement. This delay in diagnosis can be an issue later if it turns out to be a malignant cause.

I hope that this column will serve as an aid to inform the public that, should there be doubts, always consult your general practitioner or obtain a referral to see a specialist if your symptoms persist.

GASTROENTEROLOGY CAUSES

Now let us focus on the core issue of bloating caused by gastroenterological factors. This is a systematic and non-exhaustive list of causes, which I find useful in a busy clinic setting. I prefer to write this article from a first-hand perspective when I see a patient:

Figure 2: The gut efficiently balances the production, reabsorption, and excretion of gaseous matter. This delicate process involves many key players, much like an orchestra is conducted. Any disruption to these mechanics, in any form, results in either excessive gas production, reduced gas reabsorption and elimination, and thus causes bloating (image courtesy of Lacy et al. Clinical Gastroenterology and Hepatology 2021).

1. Functional dyspepsia (FD) – a common gastrointestinal problem where patients experience severe upper abdominal pain, significant bloating, or both. Based on symptoms, authorities classify FD into two subtypes: postprandial (after meals) distress syndrome (PDS) and epigastric pain syndrome (EPS). Patients with FD-PDS mainly present with bloating, while those with FD-EPS exhibit severe burning discomfort in the upper abdomen. Some individuals may display both symptoms equally and are classified as having mixed PDS/EPS. The primary causes of functional dyspepsia include visceral hypersensitivity (an increased awareness of nerves serving the stomach and upper digestive tract), impaired stomach motility and emptying (leading to bloating), and a disconnection between the gut and brain axis (triggered by emotions, mental or physical stress, as well as mood disorders such as anxiety and depression). Lifestyle factors such as chronic smoking, poor diet, irregular eating habits, sleep deprivation, and excessive alcohol intake can also worsen the condition. The brain releases chemicals like dopamine, serotonin, and noradrenaline, which help regulate motility and digestion within the digestive tract. Disruptions in the brain-gut axis can cause various functional symptoms, with conventional tests often appearing normal.
2. Helicobacter pylori infection – a most common bacterial infection of the stomach, transmitted through the fecal-oral route. Overcrowding, poor sanitation, and unhygienic practices are common causes of transmission. Prolonged infection results in ongoing inflammation, ulcer development, indigestion (bloating, abdominal pain, and diarrhea), and increases the risk of stomach cancer.




Figure 3: Image depicting the Helicobacter pylori bacterium colonizing the stomach wall and over time leading to chronic inflammation, stomach ulcers, and cancers (image courtesy of the RACGP website).



3. Supragastric belching – a condition where gas is quickly drawn in and expelled immediately from the food pipe, leading to excessive belching. It is strongly linked to anxiety and stress, and often overlaps with other functional gastrointestinal disorders. The first few belches may be involuntary, but with time, the efforts can be easily reproduced and made voluntarily. A thorough assessment followed by counselling is essential to identify the underlying cause, potentially requiring further psychological and psychiatric support. It is important to differentiate between belching (burping) and hiccupping, as they have different causes and underlying mechanisms.
4. Food intolerance, e.g. lactose intolerance or carbohydrate malabsorption – oftentimes, patients can observe a pattern of certain foods or beverages that trigger their symptoms. It is also useful to include how the food is prepared and cooked; oily, greasy, and fried foods are digested more slowly than usual, which can lead to underlying abdominal discomfort and bloating. Patients can be introduced to a low FODMAP diet, which they can follow for a set period before gradually reintroducing foods into their diet over subsequent months. As a side note, constant consumption of a high FODMAP diet can also cause bloating in otherwise healthy individuals. When modifications are made to limit such food groups in low-risk individuals, additional tests often become unnecessary once symptoms resolve.




Figure 4: A common chart displaying categories of low and high-FODMAP diets. It is advisable and possibly important to consult a gastroenterologist and a dietitian before starting such a dietary approach. Beyond trying to follow this diet yourself, it is necessary to understand how and when to reintroduce these foods after a period of food group elimination. A low FODMAP diet is not intended to be followed strictly for a long time, as it does not provide sufficient nutrition (image courtesy of the Gastroenterology Associates of New Jersey website).



5. Small intestinal bacterial overgrowth (SIBO) – a common gastrointestinal condition involves a build-up of gas-producing bacteria within the small intestines, leading to significant symptoms of indigestion. If left undiagnosed for a long time, patients may not only experience bloating but also develop abdominal pain, diarrhea, constipation, general fatigue, and nutritional deficiencies such as joint pains, skin rashes, and hair loss. SIBO is often misdiagnosed and treated as other conditions like ‘gastritis’, functional dyspepsia, heartburn, reflux disorders, or simply ‘excessive wind’. The causes of SIBO are numerous, including previous gut surgeries, impaired gut motility, offending medications (such as antibiotics, proton pump inhibitors, analgesics, traditional medicines, or immunosuppressants), and other medical conditions that disrupt the gut microbiome (like diabetes mellitus, connective tissue disorders such as scleroderma affecting gut movement, and immunodeficiency illnesses). Although methods like hydrogen and/or lactulose breath tests exist to evaluate SIBO, these can be costly, laborious, time-consuming, and require strict pre-test protocols. Fortunately, diagnosing SIBO can often be achieved through clinical assessment by ruling out other organic issues, such as Helicobacter pylori infection or gastrointestinal malignancies, before prescribing antibiotics.




Figure 5: I enjoy showing this diagram to patients suffering from SIBO – it illustrates an overgrowth of microbes within the small bowel. The small intestines are a pristine environment, with a continuous sweeping motion (peristalsis) that maintains its cleanliness. Motility issues affecting this peristalsis can understandably disrupt the cleaning process and promote the overgrowth of bacteria, leading to SIBO. The ‘bad’ bacteria that have established a foothold in your small bowel will begin to thrive and produce foul gases, causing abdominal distension and bloating (image courtesy of the BioKPlus Canada website).



6. Irritable bowel syndrome (IBS) – a common functional lower gastrointestinal condition where patients experience abdominal cramps or pain, bloating, and diarrhea or constipation. Similar to functional dyspepsia, the cause of IBS is believed to be linked to factors such as past gastrointestinal infections like Helicobacter pylori, food intolerance, dietary choices, emotional distress, altered gut microbiome, disrupted gastrointestinal motility, and stress (mental or physical). Treatment can be challenging for patients, as not all respond well and may require a personalized management approach. Commonly used medications include patient education, counselling, moral support, anti-spasmodic drugs, laxatives or anti-diarrheals bile-acid binders, simethicone, probiotics, and neuromodulators.
7. Chronic constipation – the concept behind constipation as a cause of bloatedness is complex and depends heavily on the underlying mechanism. The combination of mechanical obstruction from impacted fecal matter, overproduction of gas from stool fermentation, and reduced colonic motility all contributes to the buildup and backflow of intestinal contents that precipitate bloating. It is no surprise that immediate relief comes with a good dose of potent laxatives. Treatment may have been frustrating in the past, but with modernized functional and motility testing, we are now able to better manage our patients based on their constipation subtypes.
8. Functional bloating – a condition characterized by abdominal swelling and a subjective sensation of fullness, pressure, or distension, with no identifiable cause or underlying medical condition. Functional bloating is linked to other functional gastrointestinal disorders such as functional dyspepsia and IBS. The exact cause of functional bloating is not well understood but is thought to result from a combination of abnormal reflexes in the abdominal wall muscles, increased pain sensitivity to gut stimuli, gut dysbiosis, a high FODMAP diet, and poor coordination between the diaphragm and abdominal wall muscles in response to gas accumulation. The treatment of functional bloating considers other associated functional gastrointestinal disorders and generally involves dietary modification, behavioral therapies, breathing exercises, abdominal massage, probiotics, gut-specific antibiotics, as well as antispasmodics and prokinetics.




Figure 6: One proposed mechanism in functional bloating involves poor coordination between the diaphragmatic muscles and the abdominal wall muscles. In a healthy individual, the body responds to increased gas by relaxing the diaphragm and contracting the abdominal wall muscles. This mechanism helps distribute the gas evenly, preventing abdominal swelling. However, in patients with functional bloating, these reflexes are not properly activated – the diaphragm contracts, and the abdominal wall musculature relaxes, resulting in significant bloating and protrusion of the abdominal wall (image courtesy of Lacy et al. Clinical Gastroenterology and Hepatology 2021).



9. Intestinal tumors leading to mechanical obstruction – the cause of bloating in this issue is self-explanatory. The symptoms of bloating become more severe with circumferential tumors and a significantly narrowed intestinal pathway.




Figure 7: Case of advanced stomach cancer with Helicobacter pylori infection as background – the patient presented with bloatedness, abdominal discomfort, early satiety, loss of appetite, and weight loss over three months before seeking treatment.





Figure 8: Case of a large duodenal (first part of the small bowel) tumor in a patient with long-standing abdominal fullness, bloating, and mild crampy discomfort. Although surgical removal was offered due to the size of the polyp, our patient chose a conservative watch-and-wait approach because of her advanced age and multiple medical conditions.





Figure 9: Case of an advanced left-sided colon cancer in a patient who experienced new-onset constipation and bloatedness for six months before consulting a doctor.



10. Diverticular diseases – these are pockets that form on the lining of the intestines, particularly in the large bowel, and can vary in size from small to large, where stools can become impacted and lead to infection (fever), rectal bleeding, abdominal cramps, bloating, and pain. The concept behind bloating in diverticular diseases is likely related to the association with chronic constipation, but also the fermentation of impacted stools.




Figure 10: A case illustrating diverticular disease of the large bowel with impacted stools. Our patient experienced frequent abdominal cramps hours after a heavy meal, along with bloating and constipation. Note the varying sizes of the diverticular orifice, which range from as small as 1 mm in some patients to as large as 10 cm in extreme cases.



11. Intestinal motility disorders – gastroparesis, slow-transit constipation, and pelvic floor dysfunction with dyssynergic defecation can lead to the accumulation of not only solid and liquid matter but also gaseous substances. This group of gastrointestinal disorders was previously underappreciated and often went undiagnosed due to their complexities and the limited understanding and investigation available to evaluate them. Patients frequently leave consultations feeling frustrated because standard tests tend to come back normal. They and their families are also often faced with the belief that their symptoms might be purely psychological. Recently, a network of local and international experts has been collaborating to offer advanced motility tests to better understand gastrointestinal motility issues, their characteristics, and behavior. The goal is to optimize treatment approaches—whether pharmacological, endoscopic, or surgical—by making them more targeted. Such efforts, combined with ongoing medical education, seminars, conferences, workshops, and expert engagement, will further enhance our understanding and improve patient care.




Figure 11: A panel of gastric emptying time scintigraphy images in three patients – (A) a healthy individual with normal stomach emptying time, (B) a patient with rapid gastric emptying following medication, (C) a patient with delayed gastric emptying. A normal stomach empties 60% of its content by 2 hours and 90% by 4 hours. Patients with delayed gastric emptying have gastroparesis, which can be caused by infection, previous stomach surgeries that damage the vagal nerve, uncontrolled diabetes mellitus affecting the autonomic nerve function supplying the stomach, as well as certain neurological and autoimmune disorders, and in some cases, it is idiopathic (unknown) (image courtesy of Borghammer et al. NPJ Parkinson’s Disease 2017).



12. Gallbladder disorders – the forgotten friend, often overlooked in the list of differential diagnoses for bloating, is an infected gallbladder. An acutely inflamed gallbladder secondary to impacted gallstones leads to reduced bile flow into the small intestines, which can disrupt digestion. Additionally, the stagnant bile can become infected, triggering a cascade of inflammatory reactions that cause various symptoms, including right-sided upper abdominal pain or discomfort, jaundice, poor appetite, nausea, vomiting, early satiety, and, indeed, bloating. In some cases, subtle yet prolonged inflammation results in chronic cholecystitis, where the gallbladder no longer functions properly and appears contracted on imaging. These patients often present with indigestion symptoms, such as bloating, abdominal fullness, and mild, persistent discomfort that worsens after consuming greasy meals.




Figure 12: An example of a patient with long-standing gallbladder inflammation caused by gallbladder stones (yellow arrow). One of the stones fell out and became lodged in the bile duct (red arrow), leading to infection and severe, debilitating pain due to obstruction of bile flow into the small bowel (the blue arrow indicates the opening of the bile duct into the small bowel). A timely procedure, endoscopic retrograde cholangiopancreatography (ERCP), was performed to restore bile duct flow by inserting a plastic tube through that opening.





Figure 13: Cartoon illustration summarizing the various functional causes of gassiness and bloating, the most common of which are food and medications, previous gastrointestinal infection, disordered gut motility, bacterial overgrowth leading to gut dysbiosis, heightened perception of pain and gas from disorders of the gut-brain axis, and abdominal muscle wall and diaphragm discordance (image courtesy of Lacy et al. Clinical Gastroenterology and Hepatology 2021).

INVESTIGATIONS

Investigations into bloating are based on the presumed diagnosis and likely cause, but typically involve an abdominal and pelvic ultrasound along with routine blood tests. Occasionally, a CT scan may be chosen over an ultrasound as the initial investigation if the history and clinical examination clearly indicate a disorder best assessed with a CT, or if the patient presents with constitutional symptoms or red flags such as significant appetite loss and unintentional weight loss over a short period. These signs may suggest the possibility of an underlying malignancy. An upper endoscopy and colonoscopy are also performed if a digestive cause is suspected, especially when the patient exhibits other high-risk symptoms such as passing blood, vomiting blood, persistent abdominal discomfort or pain, or a recent change in bowel habits.

Figure 14: An abdominal ultrasound shows a large liver cyst in a patient experiencing early satiety, epigastric discomfort, and bloating. Ultrasonography is a useful initial diagnostic tool in most cases due to its safety, lack of radiation, widespread availability, ease of use, and cost-effectiveness.

Figure 15: CT scans are useful when a detailed assessment is needed to evaluate a known or suspected pathology where an ultrasound is insufficient. CT scans can also be used as the primary modality for suspected malignancy or if surgery might be required later. The figure above shows an abdominal and pelvic CT scan revealing a large benign ovarian tumor in a patient presenting with abdominal fullness, swelling, bloating, and reduced appetite.

Non-invasive tests are reserved for patients who do not exhibit red flag symptoms and are chosen based on the possible underlying cause. The urea breath test, for instance, helps diagnose Helicobacter pylori infection. Conversely, the hydrogen or lactulose breath test is used for patients suspected of having small intestinal bacterial overgrowth or carbohydrate malabsorption. More advanced tests to investigate motility disorders include an esophageal high-resolution manometry to identify esophageal abnormalities, a gastric emptying study using nuclear scintigraphy with a gamma camera to detect gastroparesis (see Figure 11), a colonic transit study with a Sitzmarks capsule and several abdominal X-rays to evaluate the transit time of the large bowel, and anorectal studies employing high-resolution anorectal manometry to assess the function of the anal and rectal muscles.

Figure 16: The Sitzmarks capsule study is a practical, safe, and cost-effective tool to assess constipation subtypes – colonic motility issues (slow-transit constipation) or anorectal muscular dysfunction (dyssynergic defecation). After swallowing the capsule, an abdominal X-ray is taken after five days to examine the number of rings remaining and their distribution (image courtesy of the Sitzmarks.com website).

Figure 17: Image illustrating how anorectal manometry is performed (left) and the data analysis afterwards (right). Such assessments enable the clinician to identify the subtype of constipation caused by discoordination between the rectum and anal muscles, thereby guiding the most appropriate treatment options (image courtesy of the Medspira website and Lee et al. Journal of Neurogastroenterology and Motility 2018).

MANAGEMENT

The underlying cause determines the key management principles, and as we can all appreciate and learn from this article, the causes of bloating are numerous. The journey to unravel the problem is like navigating through a minefield, fraught with potential pitfalls (non-gastroenterological causes). The investigation of choice may not always rely on a single gold-standard tool but often involves a combination of tests to support and confirm the diagnosis. Your doctor will work with you to identify the root cause, which may take time, possibly requiring several clinic sessions and follow-ups. Ultimately, it is worth the patience and effort because bloating is never a pleasant experience, and a prompt, effective solution is greatly appreciated.

In summary, if you are experiencing troubling symptoms of bloating and are unsure of the cause, please visit your nearest doctor’s clinic to get it sorted. Sometimes, a little concern is more valuable than dismissing it. Finally, allow me to share a take-home message – gas may float, but it is not the only one that makes you bloat.