Clinical Bloating Checker: Differentiate SIBO, IBS, and Gastric Distension

Your results indicate the most probable gastrointestinal zone responsible for your bloating, derived from the timing and nature of your symptoms. This output is designed to help you have a more targeted, productive conversation with your healthcare provider.

• Identify the Zone: Focus on whether your symptoms originate in the upper (stomach), mid (small intestine), or lower (colon) gastrointestinal tract. Each zone corresponds to distinct pathophysiological mechanisms and requires different diagnostic protocols.
• Log Your Data: Use this classification to track symptom triggers, particularly specific fermentable carbohydrates (FODMAPs such as fructans, galacto-oligosaccharides, and polyols) that may exacerbate your specific GI zone dysfunction.
• Guide Clinical Testing: Share this probability report with a gastroenterologist to determine if a lactulose breath test (SIBO confirmation), endoscopy (structural evaluation), or comprehensive stool microbiome analysis is the most appropriate next step.

Bloating is not a single condition, but a symptom of underlying mechanical, chemical, or microbial imbalances in the gut. The timing of your distension is the most critical diagnostic clue, functioning as a temporal map of where along the gastrointestinal tract the dysfunction is occurring.

• Immediate Bloating (0–30 min): Suggests upper GI issues like aerophagia (swallowing air) or delayed gastric emptying. Food has not yet reached the intestines, so bacterial fermentation is not the cause. This is the hallmark of Functional Dyspepsia per Rome IV criteria.
• Postprandial Bloating (1–2 hrs): Strongly correlates with abnormal bacterial fermentation in the small intestine (SIBO or Intestinal Methanogen Overgrowth/IMO). The North American Consensus recommends lactulose or glucose breath testing as the primary non-invasive diagnostic method.
• Delayed or Constant Bloating (>2 hrs): Points toward colonic dysbiosis, IBS (Rome IV subtype: IBS-C, IBS-D, or IBS-M), or pelvic floor dysfunction. Symptom relief following defecation is a key differentiating marker from SIBO.

Underlying Weighted Probabilistic Scoring: The checker calculates a diagnostic score (S) for three GI zones. Inputs are assigned binary weights (W = 1 if present, 0 if absent), scaled by clinical significance multipliers. The category with the highest score determines the primary etiology classification.

S_Upper = (W_onset_imm × 2) + (W_eructation × 1.5) − (W_lower_pain)

S_Mid = (W_onset_post × 2) + (W_distension_sev × 1.2) + (W_nausea)

S_Lower = (W_onset_del × 2) + (W_altered_bowel × 1.5) + (W_flatulence)

Clinical/Scientific Context: Based on the Rome IV criteria for functional gastrointestinal disorders and the North American Consensus protocols for breath testing in suspected SIBO and Intestinal Methanogen Overgrowth (IMO). Symptom weighting reflects evidence-based pathophysiological likelihood ratios.

Conditional Logic & Edge Cases: The algorithm prioritizes safety via a “Red Flag Bypass.” If inputs indicate severe acute pain, GI bleeding, unexplained weight loss, or fever, diagnostic logic is immediately halted and the user is directed to seek urgent medical evaluation. If Mid-GI and Lower-GI scores are equal, the result is flagged as “Complex/Mixed Presentation (Suspected IMO)” to reflect clinically ambiguous presentations requiring multi-modal testing.

Why do I get bloated immediately after eating?
Immediate bloating (within 0–30 minutes) is rarely caused by bacterial fermentation, as food has not yet reached the intestines. It is most commonly caused by aerophagia (swallowing excess air), drinking carbonated beverages, eating too quickly, or functional dyspepsia—a condition of impaired stomach accommodation characterized by hypersensitivity of the gastric wall to normal distension.

What is the difference between SIBO and IBS bloating?
SIBO (Small Intestinal Bacterial Overgrowth) bloating typically occurs 60 to 120 minutes after eating as bacteria prematurely ferment carbohydrates in the small intestine, often causing visible, uncomfortable distension and significant hydrogen or methane gas production. IBS bloating generally occurs later in the digestive process (in the colon) and is heavily associated with alternating periods of diarrhea and constipation, as well as symptom relief following defecation—a key Rome IV diagnostic criterion.

Can stress cause severe abdominal bloating?
Yes. The gut-brain axis is highly sensitive to psychological stress. Chronic stress downregulates the vagus nerve, reducing stomach acid production and slowing gastric motility. This stalled digestion allows standard meals to ferment excessively, leading to gas accumulation and heightened visceral hypersensitivity—a state where normal amounts of intraluminal gas feel extremely painful and produce disproportionate distension responses.