What is the likely diagnosis and treatment for a 36-year-old female patient presenting with stomach pain, bloating, constipation, and swelling for 1 week?

Likely Diagnosis and Initial Management

This 36-year-old woman presenting with bloating, constipation, abdominal pain, and swelling for 1 week most likely has constipation-predominant irritable bowel syndrome (IBS-C) or functional constipation, and should be managed with initial dietary modifications followed by pharmacotherapy if symptoms persist. 1, 2

Immediate Assessment Priorities

Rule Out Alarm Features First

Before proceeding with functional diagnosis, actively screen for red flags that mandate urgent investigation:

• Weight loss >10% suggests malabsorption, malignancy, or serious underlying disease requiring urgent workup 2, 3
• Gastrointestinal bleeding (visible blood or melena) requires immediate evaluation 4, 2
• Persistent or severe vomiting may indicate gastroparesis or obstruction 4, 2
• Iron-deficiency anemia warrants celiac disease testing and possible endoscopy 2
• Family history of inflammatory bowel disease or colorectal cancer increases risk and changes evaluation strategy 1, 4
• In women over 50, consider ovarian cancer as bloating and abdominal fullness are often presenting symptoms 3

Key History Elements to Obtain

• Relationship to meals: symptoms typically worsen after eating in functional disorders 4
• Stool consistency using Bristol Stool Scale: hard, lumpy stools suggest constipation-predominant pattern 4
• Straining during defecation, even with soft stool: suggests pelvic floor dyssynergia rather than simple constipation 1, 4
• Sensation of incomplete evacuation after bowel movements 1, 4
• Complete medication list: many commonly used drugs cause constipation and bloating 4
• Dietary triggers: lactose, fructose, and gluten consumption patterns 4, 3

Diagnostic Approach

When to Limit Testing

If no alarm features are present, reserve abdominal imaging and upper endoscopy exclusively for patients with alarm features, recent worsening symptoms, or abnormal physical examination findings. 2 Over-testing in functional bloating is a critical pitfall, as the absence of alarm symptoms makes extensive imaging, endoscopy, and motility testing unnecessary and low-yield. 2

Appropriate Initial Testing (Only if Indicated)

• Complete blood count and comprehensive metabolic panel: only when alarm symptoms present or systemic disease suspected 2
• Tissue transglutaminase IgA with total IgA levels: for celiac disease screening, particularly if diarrhea or weight loss present 2
• Stool Hemoccult: recommended for screening purposes 1
• Thyroid function and glucose testing: to screen for hypothyroidism and diabetes affecting GI motility 2

Treatment Algorithm

Step 1: Dietary Modifications (3-4 Week Trial)

Implement dietary modifications for 3-4 weeks before considering other interventions. 2

• Low-FODMAP diet trial: lactose intolerance affects 51% and fructose intolerance affects 60% of patients with bloating 2, 3
• Gluten and fructan restriction: may be beneficial as fructans rather than gluten may cause symptoms 2, 3
• Small evening meals with longer intervals between eating and lying down 2
• A 2-week dietary restriction trial can serve as diagnostic approach, with symptom resolution as positive predictor 3

Step 2: First-Line Pharmacotherapy for Constipation-Predominant Symptoms

If dietary modifications fail after 3-4 weeks, initiate pharmacotherapy:

• Fiber supplementation: therapeutic trial may be sufficient for constipation-predominant symptoms 1
• Secretagogues (linaclotide, lubiprostone): effective for abdominal bloating when constipation is present 2
  • Lubiprostone 24 mcg twice daily demonstrated significant improvement in spontaneous bowel movement frequency and reduced abdominal bloating, discomfort, and straining versus placebo 5
  • Patients experienced first bowel movement within 24 hours in 57-63% of cases 5

Step 3: Antispasmodics for Pain

• For patients with pain as predominant symptom: plain abdominal radiography during acute episode to exclude bowel obstruction, then therapeutic trial of antispasmodic if negative 1

Step 4: Consider Pelvic Floor Dysfunction

Do not ignore pelvic floor dysfunction, as straining with soft stool or need for manual assistance suggests dyssynergia, not just constipation. 2, 3

• Digital rectal examination: identify increased/decreased sphincter tone, pelvic floor dyssynergia, rectal prolapse, anal stricture, or rectocele 1
• Anorectal physiology testing with balloon expulsion: confirm diagnosis of pelvic floor dyssynergia 1
• Particularly important for women with IBS-C not responding to standard therapies or suspected pelvic floor disorders based on history or examination 1

Step 5: Advanced Therapies if Refractory

• Psychological therapies (hypnotherapy, cognitive behavioral therapy): effective for many patients' symptoms, as up to one-third with IBS experience anxiety or depression 1, 2
• Tricyclic antidepressants or SSRIs: good efficacy for long-term therapy 6
• Rifaximin: may be effective for SIBO-related bloating in high-risk patients with chronic watery diarrhea, malnutrition, or systemic diseases causing dysmotility 2, 3

Critical Pitfalls to Avoid

• Do not assume gastroparesis based on symptoms alone: bloating, nausea, and fullness do not correlate with degree of gastric emptying delay on scintigraphy 2, 3
• Do not use probiotics to treat abdominal bloating and distention, as they are not recommended for this purpose 2
• Do not use opioids for chronic abdominal pain management 7
• Avoid over-testing in the absence of alarm features 2

Follow-Up Strategy

Reevaluate patient in 3-6 weeks after initiating treatment. 1 If treatment unsuccessful or further evaluation needed, additional studies based on symptom subtype can be undertaken, including confirmation of slow colonic transit with whole gut transit test or evaluation for obstructed defecation with anorectal motility testing. 1