Frequent Urination During a Diverticulitis Flare-Up

“Does anyone else feel intense pressure on their bladder and need to urinate constantly during a flare?”

If you live with diverticulitis, this question may sound all too familiar. While diverticulitis is widely known as a digestive condition, many people are surprised—and often alarmed—when urinary symptoms appear during a flare-up. Sudden bladder pressure, frequent urination, urgency, and even pelvic pain can become just as disruptive as the abdominal pain itself.

For many, these bladder symptoms appear suddenly during active inflammation and subside once the flare settles. For others, bladder sensitivity can linger for weeks or months. Unfortunately, these symptoms are often misunderstood, dismissed, or misdiagnosed as repeated urinary tract infections.

The truth is this: the connection between diverticulitis and bladder symptoms is real, medically recognized, and rooted in anatomy and inflammation. You are not imagining it—and you are certainly not alone.

In this article, we will explore:

Why diverticulitis flare-ups cause bladder pressure and frequent urination
How inflammation spreads through the pelvis
The role of nerves and muscle tension
Why symptoms often mimic urinary tract infections
What may help manage bladder symptoms during a flare

What Is a Diverticulitis Flare?

Diverticulitis develops when small pouches (diverticula) in the colon become inflamed or infected. These pouches most commonly form in the sigmoid colon, which is located in the lower left abdomen.

A flare-up refers to a period of active inflammation or infection and may involve symptoms such as:

Sharp or cramping lower abdominal pain
Fever and chills
Nausea and vomiting
Constipation or diarrhea
Bloating and abdominal pressure
Fatigue
And notably—urinary changes

During a flare, the immune system releases inflammatory chemicals to fight infection. This inflammatory response does not remain isolated to the bowel. Instead, it affects surrounding organs, connective tissue, muscles, and nerves throughout the pelvic region.

Why Diverticulitis Causes Bladder Pressure and Frequent Urination

1. The Colon and Bladder Are Anatomical Neighbors

The sigmoid colon and the bladder sit directly beside one another in the pelvis. When the colon becomes:

Inflamed
Swollen
Thickened
Or filled with inflamed diverticula

it can physically press against the bladder.

This mechanical pressure reduces the bladder’s ability to expand normally as it fills with urine. As a result:

Even small volumes of urine feel uncomfortable
The bladder sends “full” signals much earlier
A constant feeling of urgency develops
The need to urinate becomes frequent and persistent

Many people describe feeling as if their bladder is “always full,” even right after emptying it.

2. Inflammation Spreads Through Shared Pelvic Tissue

The organs of the pelvis are connected through:

Fascia (connective tissue)
Blood vessels
Lymphatic drainage
Shared inflammatory pathways

When diverticulitis triggers localized infection, the inflammatory chemicals released—such as cytokines and prostaglandins—can easily
spread to nearby structures, including the bladder.

This causes:

Irritation of the bladder wall
Increased bladder sensitivity
Heightened urgency and pressure
Pelvic discomfort even without a true bladder infection

In essence, the bladder becomes caught in the “inflammatory crossfire.”

3. Cross-Organ Nerve Sensitization

One of the most powerful mechanisms behind bladder symptoms during a diverticulitis flare is cross-organ sensitization.

The nerves that serve the colon and bladder travel through the same spinal pathways. During active bowel inflammation:

Pain signals intensify along shared nerve routes
The brain struggles to distinguish whether discomfort is coming from the bowel or bladder
The bladder becomes neurologically hypersensitive

This leads to:

Frequent urgency
Pressure with minimal urine volume
A constant feeling of needing to urinate
Pelvic pain without infection

This is why many people report: “I feel like I need to go constantly, but barely anything comes out.”

4. Pelvic Floor Muscle Tension During Flares

Pain and inflammation cause the body to enter a protective muscular response. During a diverticulitis flare, the
pelvic floor muscles often tighten reflexively to guard against pain.

When these muscles remain in a chronic state of tension, they can:

Interfere with complete bladder emptying
Increase bladder pressure
Trigger urgency and frequency
Cause a weak or hesitant urine stream
Create pelvic aching or spasms

Even after the bowel infection resolves, muscle guarding can persist—causing bladder symptoms to linger beyond the flare.

5. Diverticulitis Can Mimic a Urinary Tract Infection

Many people with diverticulitis experience classic UTI-like symptoms, including:

Bladder pressure
Urinary urgency
Frequent urination
Burning sensations
Pelvic pain

Yet urine testing often shows no infection present.

This occurs because:

Inflammation irritates surrounding tissues
Nerves misfire urgency and pain signals
The colon compresses the bladder mechanically

In rare but serious cases, repeated diverticulitis infections can lead to the formation of a colovesical fistula—an abnormal connection between the colon and the bladder.
This causes recurrent UTIs, air or stool in the urine, and requires surgical treatment.

The Role of Stress and the Nervous System

The bladder and bowel are both deeply regulated by the autonomic nervous system. Stress activates the sympathetic “fight-or-flight” response, which:

Increases bladder sensitivity
Intensifies urgency
Heightens awareness of pelvic sensations
Amplifies pain perception

This creates a self-reinforcing cycle:

Diverticulitis flare → bladder urgency → anxiety → worsened urgency → increased distress.

Breaking this cycle is an important part of long-term symptom management.

The Emotional Toll of Constant Urinary Urgency

Frequent urination and constant bladder pressure affect far more than physical comfort. Many people report:

Interrupted sleep
Anxiety about leaving the house
Constant bathroom planning
Fear during travel
Work disruptions
Embarrassment
Decreased intimacy

Some begin restricting fluids to avoid urinating—ironically worsening bladder irritation. Over time, this constant vigilance creates a heavy mental burden.

These struggles are real, valid, and deserve medical acknowledgment.

What Can Help During a Diverticulitis-Related Bladder Flare?

1. Follow Flare-Appropriate Nutrition

During acute diverticulitis flares, doctors often recommend:

Clear liquids initially
Followed by a low-fiber, low-residue diet

Avoid common bladder irritants such as:

Caffeine
Alcohol
Carbonated drinks
Artificial sweeteners
Spicy foods
Citrus products

These can significantly worsen bladder pressure and urgency.

2. Gentle Hydration

Sipping water regularly:

Dilutes urine
Reduces bladder lining irritation
Eases burning sensations
Prevents constipation (which further compresses the bladder)

Dehydration leads to highly concentrated urine, which worsens urgency and discomfort.

3. Heat Therapy

Applying heat to the:

Lower abdomen
Pelvic region
Lower back

can:

Increase blood flow
Relax pelvic muscles
Calm irritated nerves
Reduce cramping and pressure

4. Pelvic Floor Physical Therapy

Once the flare resolves, pelvic floor therapy can help:

Release muscle guarding
Normalize bladder function
Improve bladder emptying
Reduce chronic urgency
Improve pelvic pain

Many people experience significant improvement after targeted pelvic rehabilitation.

5. Medical Treatment

Depending on severity, doctors may prescribe:

Antibiotics for infection
Antispasmodics for bowel and bladder
Anti-inflammatory medications
Pain management therapies

Never ignore worsening urinary symptoms without medical evaluation.

When to Seek Immediate Medical Attention

Contact your healthcare provider urgently if you experience:

Fever with urinary symptoms
Blood in urine
Severe flank or pelvic pain
Foul-smelling urine
Recurrent UTIs
Air bubbles during urination
Inability to urinate

These may signal serious complications requiring prompt treatment.

You Are Not Alone—And This Symptom Is Medically Valid

If you’ve ever asked:
“Why does my bladder feel like it’s under constant pressure during a diverticulitis flare?”

The answer lies in anatomy, inflammation, nerve signaling, muscle tension, and immune activation—not anxiety, exaggeration, or imagination.

Diverticulitis does not affect only the bowel. It affects the entire pelvic ecosystem. The bladder is simply one of its closest and most sensitive neighbors.

With informed medical care, symptom targeting, and pelvic support strategies, many people find real improvement and regain control over both their digestive and urinary health.

References

Strate, L. L., & Morris, A. M. (2019). Epidemiology, pathophysiology, and treatment of diverticulitis. Gastroenterology.
Tursi, A., et al. (2020). Diverticular disease and its complications. Nature Reviews Gastroenterology & Hepatology.
Berkley, K. J. (2005). A life of pelvic pain. Physiology & Behavior.
Tu, F. F., et al. (2010). Cross-organ sensitization between colon and bladder. Neurogastroenterology & Motility.
FitzGerald, M. P., et al. (2009). Pelvic floor muscle dysfunction and bladder pain. Journal of Urology.
Cleveland Clinic. Diverticulitis: Symptoms, Causes, Diagnosis, and Treatment.
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diverticular Disease Overview.

Bladder Pressure and Frequent Urination During a Diverticulitis Flare: Why It Happens and What You Can Do

Bladder Pressure and Frequent Urination During a Diverticulitis Flare: Why It Happens and What You Can Do

What Is a Diverticulitis Flare?

Why Diverticulitis Causes Bladder Pressure and Frequent Urination

1. The Colon and Bladder Are Anatomical Neighbors

2. Inflammation Spreads Through Shared Pelvic Tissue

3. Cross-Organ Nerve Sensitization

4. Pelvic Floor Muscle Tension During Flares

5. Diverticulitis Can Mimic a Urinary Tract Infection

The Role of Stress and the Nervous System

The Emotional Toll of Constant Urinary Urgency

What Can Help During a Diverticulitis-Related Bladder Flare?

1. Follow Flare-Appropriate Nutrition

2. Gentle Hydration

3. Heat Therapy

4. Pelvic Floor Physical Therapy

5. Medical Treatment

When to Seek Immediate Medical Attention

You Are Not Alone—And This Symptom Is Medically Valid

References

Further Reading

1. Mayo Clinic — Diverticulitis: Symptoms & Causes

2. Mayo Clinic — Diverticulitis: Diagnosis & Treatment

3. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) — Diverticulosis & Diverticulitis

4. Cleveland Clinic — Diverticulitis Overview

5. Cleveland Clinic Health Essentials — Diverticulitis Diet

6. Cleveland Clinic — Urinary Urgency

7. Cleveland Clinic — Cystitis / Bladder Inflammation

8. Cleveland Clinic Journal of Medicine — Acute Diverticulitis Review (PDF)

9. Johns Hopkins Medicine — Diverticulitis Overview

10. Harvard Health Publishing — Diverticular Disease

11. Physiology & Behavior Journal — Pelvic Pain & Cross-Organ Sensitization

12. Neurogastroenterology & Motility — Colon–Bladder Sensitization

13. Journal of Urology — Pelvic Floor Dysfunction & Bladder Pain

14. NIH — Colovesical Fistula (Colon–Bladder Connection)

15. World Gastroenterology Organisation — Diverticular Disease Guidelines

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