Acute Cholecystitis on CT: Imaging Biomarkers, AI-Assisted Diagnosis, and Clinical Decision-Making for Emergency Radiology

 

Acute Cholecystitis on CT: Imaging Biomarkers, AI-Assisted Diagnosis, and Clinical Decision-Making for Emergency Radiology

Keywords: Acute Cholecystitis, Gallbladder CT, Emergency Radiology, Medical Imaging AI, Radiology AI, Abdominal CT, Gallstones, CT Interpretation, AI Healthcare, Clinical Decision Support

When Right Upper Quadrant Pain Becomes a Surgical Emergency

A 56-year-old man presented to the emergency department with sudden-onset severe abdominal pain localized to the right upper quadrant. He reported nausea and progressive discomfort that had worsened over several hours. Physical examination demonstrated marked tenderness over the gallbladder fossa with a positive Murphy sign, while laboratory evaluation revealed inflammatory changes suggestive of an acute infectious process.

Contrast-enhanced computed tomography (CT) demonstrated several characteristic imaging findings:

• Marked gallbladder distension
• Diffuse gallbladder wall thickening
• Mucosal hyperenhancement
• An obstructing calculus within the cystic duct

Together, these findings established the diagnosis of acute calculous cholecystitis, a common yet potentially life-threatening abdominal emergency requiring prompt clinical management.

Although acute cholecystitis is frequently encountered in emergency departments, delayed recognition can result in gangrenous transformation, gallbladder perforation, biliary peritonitis, abscess formation, or septic shock. Consequently, rapid and accurate radiologic diagnosis plays a decisive role in determining patient outcomes.

---

Why This Disease Matters

Acute cholecystitis is among the most common indications for emergency abdominal surgery worldwide.

Most cases develop after obstruction of the cystic duct by gallstones, leading to:

• Progressive gallbladder distension
• Increased intraluminal pressure
• Impaired venous and lymphatic drainage
• Ischemic injury
• Secondary bacterial infection
• Acute inflammation

Without timely intervention, inflammation may progress to tissue necrosis and perforation.

---

Clinical Presentation

The uploaded case describes a 56-year-old male presenting with acute abdominal pain. Typical clinical manifestations include:

• Right upper quadrant pain
• Pain worsening after meals
• Fever
• Nausea
• Vomiting
• Positive Murphy sign

Laboratory abnormalities commonly include:

• Leukocytosis
• Elevated CRP
• Elevated ESR

When biliary obstruction extends beyond the cystic duct, serum bilirubin, alkaline phosphatase, and gamma-glutamyl transferase may also become elevated. However, neither laboratory findings nor physical examination alone can definitively diagnose acute cholecystitis; imaging remains essential.

Imaging Evaluation

Early imaging is the cornerstone of diagnosing acute cholecystitis because clinical symptoms and laboratory findings often overlap with numerous other causes of acute abdominal pain. While ultrasonography remains the preferred initial examination for suspected gallbladder disease, contrast-enhanced CT has become increasingly important in emergency departments because it not only demonstrates the gallbladder but also evaluates surrounding organs and identifies life-threatening complications. In the uploaded case study, CT was the key modality that established the diagnosis by demonstrating multiple characteristic findings simultaneously.

---

Hallmark CT Findings of Acute Cholecystitis

1. Gallbladder Distension

Gallbladder distension is usually the earliest morphologic manifestation of cystic duct obstruction. As bile outflow is blocked, the gallbladder progressively enlarges because intraluminal pressure continues to rise.

In this case, CT demonstrated a markedly enlarged gallbladder consistent with acute obstruction. The source document notes that a gallbladder measuring approximately 5 × 8 cm or larger can be considered distended in the appropriate clinical setting.

Radiologic significance

• Indicates persistent cystic duct obstruction
• Reflects increasing intraluminal pressure
• Often represents the earliest objective imaging sign

---

2. Gallbladder Wall Thickening

A normal gallbladder wall is extremely thin. Acute inflammation produces vascular congestion, edema, and inflammatory cellular infiltration, resulting in diffuse wall thickening.

The uploaded case identifies wall thickness greater than 4 mm as an important diagnostic criterion. However, wall thickening alone is not diagnostic because similar findings may occur in numerous systemic diseases.

Conditions that may also produce gallbladder wall thickening include:

• Liver cirrhosis
• Congestive heart failure
• Renal failure
• Hypoalbuminemia
• Acute hepatitis
• Sepsis

Therefore, radiologists should always interpret wall thickening together with additional CT findings rather than relying on a single imaging feature.

---

3. Mucosal Hyperenhancement

One of the most valuable findings on contrast-enhanced CT is mucosal hyperenhancement.

Inflammation increases vascular perfusion of the gallbladder mucosa, producing intense enhancement that frequently precedes more advanced inflammatory changes.

The uploaded case highlights mucosal hyperenhancement as one of the principal diagnostic imaging biomarkers of acute cholecystitis.

Clinical importance

• Indicates active inflammatory hyperemia
• Helps differentiate acute from chronic gallbladder disease
• Increases diagnostic confidence when combined with wall thickening

---

4. Obstructing Cystic Duct Stone

The defining feature of this case is direct visualization of a gallstone obstructing the cystic duct.

More than 90% of acute cholecystitis cases are associated with gallstones, making calculus identification a major component of CT interpretation. The source emphasizes that radiologists should evaluate not only the presence of gallstones but also their location, size, number, and whether they obstruct the cystic duct.

This finding explains the underlying pathophysiologic mechanism responsible for the patient's acute inflammatory process.

---

5. Pericholecystic Fat Stranding

Inflammation extending beyond the gallbladder wall produces increased attenuation of the surrounding fat, commonly referred to as pericholecystic fat stranding.

This finding suggests that inflammation has spread outside the gallbladder and supports the diagnosis of acute rather than uncomplicated cholelithiasis.

---

6. CT Rim Sign

Another important imaging feature described in the uploaded case is the CT Rim Sign, characterized by increased enhancement of hepatic parenchyma adjacent to the gallbladder fossa.

This phenomenon reflects altered hepatic perfusion secondary to adjacent inflammation and further strengthens the diagnosis when interpreted together with other CT findings.

Figure 1. Contrast-Enhanced Coronal CT of Acute Calculous Cholecystitis

Figure 1. Contrast-enhanced coronal CT demonstrates marked gallbladder distension, diffuse gallbladder wall thickening, mucosal hyperenhancement, and an obstructing cystic duct calculus. These combined findings are highly characteristic of acute calculous cholecystitis and support the need for urgent clinical management. 

---

Integrated Radiologic Interpretation

Rather than relying on any individual abnormality, radiologists evaluate the constellation of findings demonstrated in this case:

• Gallbladder distension
• Diffuse wall thickening
• Mucosal hyperenhancement
• Obstructing cystic duct stone
• Pericholecystic inflammatory change
• CT Rim Sign

According to the uploaded case review, the coexistence of these imaging features strongly supports the diagnosis of acute calculous cholecystitis and provides critical information for determining the urgency of treatment.

Figure 2. Coronal CT Highlighting Progressive Inflammatory Changes

Figure 2. Coronal CT shows persistent gallbladder wall thickening with extensive pericholecystic inflammatory changes and continued cystic duct obstruction by a gallstone. These imaging findings indicate progression of acute inflammation and underscore the importance of evaluating for complications such as gangrenous cholecystitis or perforation. 

---

Clinical Pearl

A gallstone alone does not establish the diagnosis of acute cholecystitis. Likewise, isolated gallbladder wall thickening is nonspecific. The uploaded case emphasizes that the diagnosis should be based on the combined presence of gallbladder distension, wall thickening, mucosal hyperenhancement, obstructing cystic duct stone, and associated inflammatory changes, interpreted in conjunction with the patient's clinical presentation.

Why CT Has Become Indispensable in the Emergency Department

Ultrasonography remains the recommended first-line imaging modality for suspected acute cholecystitis because of its excellent ability to detect gallstones and evaluate a sonographic Murphy sign. However, emergency physicians increasingly request contrast-enhanced CT because patients often present with nonspecific abdominal pain, multiple comorbidities, or atypical clinical manifestations.

The uploaded case review emphasizes that CT is particularly valuable when clinicians need to evaluate the extent of disease, identify complications, or exclude alternative abdominal emergencies. Common indications include:

• Equivocal abdominal pain
• Elderly patients
• Patients with diabetes mellitus
• Obese patients
• Suspected gallbladder perforation
• Possible pericholecystic abscess
• Suspected sepsis
• Differential diagnosis of other acute abdominal disorders

In practical terms, ultrasonography establishes the initial diagnosis, whereas CT defines disease severity and guides therapeutic planning.

---

Systematic CT Interpretation Workflow

Experienced radiologists do not interpret gallbladder CT examinations by searching randomly for abnormalities. Instead, they follow a structured workflow to minimize diagnostic error.

Step 1. Assess Gallbladder Size

Determine whether the gallbladder is enlarged.

Evaluate:

• Long-axis diameter
• Short-axis diameter
• Bile volume
• Presence of sludge
• Presence and location of gallstones

Persistent enlargement strongly suggests prolonged cystic duct obstruction.

---

Step 2. Evaluate Gallbladder Wall

Measure wall thickness carefully.

Questions include:

• Is thickening diffuse or focal?
• Is enhancement preserved?
• Is edema present?
• Are there irregular defects suggesting necrosis?

Diffuse smooth thickening favors inflammatory disease, whereas focal asymmetric thickening raises concern for malignancy.

---

Step 3. Identify the Obstructing Lesion

Radiologists should determine:

• Whether gallstones are present
• Number of calculi
• Stone size
• Exact location
• Evidence of cystic duct obstruction

Direct visualization of an obstructing cystic duct stone significantly increases diagnostic confidence for acute calculous cholecystitis.

---

Step 4. Examine Adjacent Fat and Liver

Inflammation frequently extends beyond the gallbladder itself.

Evaluate for:

• Pericholecystic fat stranding
• Fluid collections
• CT Rim Sign
• Hepatic inflammatory changes

These findings reflect progression beyond simple gallstone disease and indicate active inflammatory extension.

---

Step 5. Search for Complications

The final—and arguably most important—step is identifying complications that immediately influence surgical management.

The uploaded case specifically highlights evaluation for:

• Gangrenous cholecystitis
• Emphysematous cholecystitis
• Gallbladder perforation
• Pericholecystic abscess
• Hemorrhage

Recognition of these findings frequently changes management from routine laparoscopic surgery to urgent or emergent intervention.

---

Differential Diagnosis

Not every patient with right upper quadrant pain and gallbladder wall thickening has acute cholecystitis. Accurate interpretation requires careful differentiation from several important conditions described in the uploaded case review.

1. Biliary Colic

Patients with uncomplicated biliary colic have gallstones but lack inflammatory changes.

Typical CT findings include:

• Gallstones present
• No significant wall thickening
• No pericholecystic fat stranding
• No mucosal hyperenhancement

Unlike acute cholecystitis, biliary colic reflects transient obstruction without sustained inflammation.

---

2. Acute Pancreatitis

Acute pancreatitis often presents with severe upper abdominal pain, nausea, and vomiting, making it an important clinical mimic.

However, CT demonstrates inflammation centered on the pancreas rather than the gallbladder.

Characteristic findings include:

• Pancreatic enlargement
• Peripancreatic fat stranding
• Fluid collections around the pancreas

Recognition of the primary site of inflammation helps distinguish these entities.

---

3. Acute Hepatitis

Acute hepatitis may produce secondary gallbladder wall thickening because of hepatic inflammation.

However, imaging primarily demonstrates abnormalities within the liver parenchyma rather than an obstructed cystic duct or inflamed gallbladder.

---

4. Gallbladder Carcinoma

Gallbladder carcinoma should be considered when CT demonstrates:

• Focal asymmetric wall thickening
• A discrete soft tissue mass
• Irregular infiltrative growth

Unlike acute cholecystitis, malignant lesions usually do not present with the classic combination of diffuse inflammatory findings described in this case.

---

5. Adenomyomatosis

Gallbladder adenomyomatosis is characterized by:

• Gallbladder wall thickening
• Rokitansky–Aschoff sinuses

Recognition of these characteristic features prevents overdiagnosis of acute inflammation.

---

AI-Assisted CT Interpretation in Acute Cholecystitis

Modern artificial intelligence is rapidly transforming emergency abdominal imaging. Although the uploaded case focuses on radiologic findings rather than AI algorithms, the imaging biomarkers it describes are highly suitable for AI-assisted detection and decision support.

Potential AI applications include:

• Automated gallbladder segmentation
• Measurement of gallbladder wall thickness
• Detection of gallbladder distension
• Identification of cystic duct calculi
• Quantification of pericholecystic inflammatory changes
• Recognition of CT Rim Sign patterns
• Automated complication alerts
• Structured radiology report generation
• Emergency triage prioritization
• Integration with PACS and hospital clinical decision support systems

Rather than replacing radiologists, AI can enhance workflow efficiency by highlighting suspicious examinations, reducing perceptual errors, and accelerating diagnosis in busy emergency settings. These capabilities align well with the imaging biomarkers emphasized throughout the uploaded case review while extending them into next-generation clinical decision support.

CT Complications That Must Never Be Missed

The greatest strength of contrast-enhanced CT lies not merely in confirming acute cholecystitis but in identifying complications that determine the urgency of intervention. As emphasized in the uploaded case review, recognition of these complications directly influences surgical planning and patient prognosis.

---

1. Gangrenous Cholecystitis

Gangrenous cholecystitis represents progressive ischemic necrosis of the gallbladder wall caused by prolonged vascular compromise.

CT Findings

• Irregular gallbladder wall
• Focal wall defects
• Loss of normal mucosal enhancement
• Areas of necrosis
• Extensive surrounding inflammatory change

Because tissue necrosis markedly increases the risk of perforation, gangrenous cholecystitis requires urgent surgical management.

---

2. Emphysematous Cholecystitis

This uncommon but highly lethal complication results from infection by gas-forming organisms.

CT Findings

• Gas within the gallbladder wall
• Air-fluid level inside the gallbladder
• Intraluminal gas bubbles
• Extensive inflammatory changes

The uploaded case notes that emphysematous cholecystitis occurs more frequently in patients with diabetes mellitus and represents a surgical emergency.

---

3. Gallbladder Perforation

Persistent inflammation eventually weakens the gallbladder wall, allowing bile to escape into the peritoneal cavity.

CT Findings

• Discontinuity of the gallbladder wall
• Pericholecystic fluid
• Extraluminal bile
• Localized or diffuse peritonitis

Prompt diagnosis is essential because mortality rises substantially once perforation develops.

---

4. Pericholecystic Abscess

Localized perforation may produce a confined abscess adjacent to the gallbladder.

CT Findings

• Rim-enhancing fluid collection
• Gas-containing abscess cavity
• Severe inflammatory fat stranding

Patients often require image-guided drainage in addition to antibiotic therapy.

---

5. Sepsis

Sepsis represents the most severe systemic consequence of untreated acute cholecystitis.

The uploaded case emphasizes that elderly patients may initially exhibit only subtle symptoms, making imaging particularly important for early diagnosis and timely intervention.

---

Management Strategy

Treatment aims not only to relieve pain but also to eliminate the underlying obstruction, control infection, reduce gallbladder pressure, and prevent life-threatening complications.

Initial Emergency Management

The uploaded case outlines several essential first-line measures:

Nil Per Os (NPO)

Oral intake is withheld to minimize gallbladder contraction and reduce further inflammatory stimulation.

Intravenous Fluid Therapy

Aggressive fluid replacement is administered to:

• Correct dehydration
• Maintain blood pressure
• Restore electrolyte balance
• Reduce the risk of septic shock

Pain Control

Adequate analgesia is considered an integral component of treatment. Contemporary practice prioritizes effective pain relief rather than avoiding opioid medications solely because of theoretical biliary effects.

Antibiotic Therapy

Because bacterial infection commonly accompanies acute cholecystitis, empirical antimicrobial therapy should provide appropriate biliary penetration.

Common pathogens listed in the uploaded case include:

• Escherichia coli
• Klebsiella species
• Enterococcus species
• Enterobacter species

Appropriate antimicrobial therapy is combined with definitive treatment of the underlying obstruction.

---

Early Laparoscopic Cholecystectomy

The uploaded case identifies early laparoscopic cholecystectomy as the current standard treatment whenever feasible.

Advantages include:

• Shorter hospitalization
• Lower recurrence rates
• Fewer complications
• Reduced healthcare costs

Today, laparoscopic surgery is the preferred approach for most patients with uncomplicated acute calculous cholecystitis.

---

When Immediate Surgery Is Required

Urgent surgical consultation is recommended when CT demonstrates:

• Gangrenous cholecystitis
• Gallbladder perforation
• Biliary peritonitis
• Pericholecystic abscess
• Emphysematous cholecystitis
• Sepsis

These imaging findings indicate advanced disease in which delaying intervention significantly increases morbidity and mortality.

---

Percutaneous Cholecystostomy

Not every patient is an appropriate surgical candidate.

For elderly patients or those with severe comorbidities, the uploaded case describes percutaneous cholecystostomy as an alternative treatment.

Under ultrasound or CT guidance, a drainage catheter is inserted into the gallbladder to:

• Reduce intraluminal pressure
• Control infection
• Stabilize critically ill patients
• Serve as bridge therapy before definitive surgery

This minimally invasive procedure plays an important role in high-risk surgical populations.

---

Radiologist's Reporting Checklist

Before issuing the final report, radiologists should systematically document:

• Presence, size, and location of gallstones
• Evidence of cystic duct obstruction
• Gallbladder distension
• Gallbladder wall thickness
• Mucosal hyperenhancement
• Pericholecystic fat stranding
• CT Rim Sign
• Common bile duct dilatation
• Choledocholithiasis
• Gallbladder perforation
• Hepatic abscess
• Pericholecystic abscess
• Emphysematous change
• Hemorrhage
• Overall severity and suspected complications

A structured reporting approach ensures that surgeons receive all clinically relevant imaging information needed for optimal treatment planning.

Prognosis and Long-Term Outcomes

The prognosis of acute cholecystitis largely depends on the timing of diagnosis and intervention. According to the uploaded case review, most patients recover completely when the disease is recognized early and treated appropriately. However, delayed treatment may result in:

• Gallbladder necrosis
• Gallbladder perforation
• Peritonitis
• Sepsis
• Increased mortality

This highlights why rapid imaging evaluation and prompt surgical consultation are critical components of patient care.

---

The Four CT Findings Every Radiologist Must Remember

The uploaded case repeatedly emphasizes that diagnosis should not rely on a single imaging abnormality. Instead, radiologists should recognize the characteristic combination of findings.

The four most important CT findings are:

1. Gallbladder Distension

Reflects persistent cystic duct obstruction and increasing intraluminal pressure.

2. Gallbladder Wall Thickening

Represents inflammatory edema and vascular congestion.

3. Mucosal Hyperenhancement

Indicates active inflammatory hyperemia.

4. Obstructing Cystic Duct Stone

Provides direct evidence of the underlying etiology.

When these four findings occur together, acute calculous cholecystitis becomes the leading diagnostic consideration.

---

Clinical Pearls for Daily Practice

Pearl 1: Do Not Diagnose Acute Cholecystitis Based Solely on Gallstones

Gallstones are extremely common and may remain asymptomatic for years.

The presence of a gallstone alone does not establish acute cholecystitis.

Radiologists must determine whether inflammatory findings accompany the stone.

---

Pearl 2: Gallbladder Wall Thickening Is Not Specific

Many systemic diseases may cause gallbladder wall thickening without true cholecystitis.

Important mimics include:

• Cirrhosis
• Congestive heart failure
• Renal failure
• Hypoalbuminemia
• Acute hepatitis
• Sepsis

Therefore, wall thickening should always be interpreted in the broader imaging and clinical context.

---

Pearl 3: CT Is the Best Tool for Detecting Complications

The uploaded case strongly emphasizes that CT plays a crucial role not only in diagnosis but also in identifying severe complications such as:

• Emphysematous cholecystitis
• Gangrenous cholecystitis
• Gallbladder perforation
• Abscess formation
• Hemorrhage

This information directly influences treatment strategy and surgical urgency.

---

Future Directions: AI-Driven Emergency Gallbladder Imaging

As healthcare systems increasingly adopt artificial intelligence, emergency abdominal imaging is becoming one of the most promising applications of radiology AI.

Future AI-enabled workflows may include:

Automated Gallbladder Segmentation

Deep-learning algorithms can automatically outline the gallbladder and calculate volumetric measurements.

Automated Wall Thickness Quantification

AI may provide objective and reproducible wall-thickness measurements, reducing interobserver variability.

Stone Detection Systems

Computer vision models can identify gallstones and determine their likelihood of causing cystic duct obstruction.

Complication Prediction Models

By integrating imaging findings with laboratory data and electronic health records, AI systems may predict:

• Gangrenous transformation
• Perforation risk
• Sepsis development
• Need for urgent surgery

Clinical Decision Support Integration

Future systems may integrate:

• CT findings
• Ultrasound findings
• Laboratory values
• Vital signs
• Clinical history

to generate real-time risk stratification and treatment recommendations.

Such technologies align with the emerging paradigm of precision emergency medicine and AI-assisted radiology.

---

Key Takeaway from This Case

This case of a 56-year-old man with acute abdominal pain demonstrates the classic CT appearance of acute calculous cholecystitis.

The most important imaging findings include:

✔ Gallbladder distension

✔ Gallbladder wall thickening

✔ Mucosal hyperenhancement

✔ Obstructing cystic duct stone

✔ Pericholecystic inflammatory change

✔ CT Rim Sign

Together, these findings form a highly characteristic imaging pattern that allows confident diagnosis and guides urgent clinical management.

For radiologists, emergency physicians, surgeons, and healthcare AI developers, this case highlights an important principle:

Acute cholecystitis is not diagnosed by a single imaging sign. The diagnosis emerges from recognizing a constellation of findings that reflect the underlying pathophysiology of cystic duct obstruction, inflammation, and progressive gallbladder injury.

As medical imaging continues to evolve through artificial intelligence, structured reporting, and clinical decision support systems, the accurate interpretation of these imaging biomarkers will remain essential for improving patient outcomes and reducing potentially fatal complications.

---

References

[1] R. L. Trowbridge, N. K. Rutkowski, and K. G. Shojania, “Does this patient have acute cholecystitis?,” JAMA, vol. 289, no. 1, pp. 80–86, 2003. DOI: https://doi.org/10.1001/jama.289.1.80

[2] J. S. Shakespear, A. M. Shaaban, and M. Rezvani, “CT findings of acute cholecystitis and its complications,” AJR American Journal of Roentgenology, vol. 194, no. 6, pp. 1523–1529, 2010. DOI: https://doi.org/10.2214/AJR.09.3640

[3] J. Fidler, E. K. Paulson, and L. Layfield, “CT evaluation of acute cholecystitis: Findings and usefulness in diagnosis,” AJR American Journal of Roentgenology, vol. 166, no. 5, pp. 1085–1088, 1996. DOI: https://doi.org/10.2214/ajr.166.5.8615248

[4] M. Hirota et al., “Diagnostic criteria and severity assessment of acute cholecystitis: Tokyo Guidelines,” Journal of Hepato-Biliary-Pancreatic Surgery, vol. 14, no. 1, pp. 78–82, 2007. DOI: https://doi.org/10.1007/s00534-006-1159-4

[5] M. Yokoe et al., “New diagnostic criteria and severity assessment of acute cholecystitis in revised Tokyo Guidelines,” Journal of Hepato-Biliary-Pancreatic Sciences, vol. 19, no. 5, pp. 578–585, 2012. DOI: https://doi.org/10.1007/s00534-012-0548-0

[6] T. Takada et al., “TG13: Updated Tokyo Guidelines for the management of acute cholangitis and cholecystitis,” Journal of Hepato-Biliary-Pancreatic Sciences, vol. 20, no. 1, pp. 1–7, 2013. DOI: https://doi.org/10.1007/s00534-012-0566-y

[7] M. Yokoe et al., “Tokyo Guidelines 2018: Diagnostic criteria and severity grading of acute cholecystitis,” Journal of Hepato-Biliary-Pancreatic Sciences, vol. 25, no. 1, pp. 41–54, 2018. DOI: https://doi.org/10.1002/jhbp.515

[8] K. Okamoto et al., “Tokyo Guidelines 2018: Flowchart for the management of acute cholecystitis,” Journal of Hepato-Biliary-Pancreatic Sciences, vol. 25, no. 1, pp. 55–72, 2018. DOI: https://doi.org/10.1002/jhbp.516

[9] M. A. Mauro, W. H. McCartney, and J. R. Melmed, “Hepatobiliary scanning with 99mTc-PIPIDA in acute cholecystitis,” Radiology, vol. 142, no. 1, pp. 193–197, 1982. DOI: https://doi.org/10.1148/radiology.142.1.7053532

[10] A. Brodsky et al., “Laparoscopic cholecystectomy for acute cholecystitis,” Surgical Endoscopy, vol. 14, no. 8, pp. 755–760, 2000. DOI: https://doi.org/10.1007/s004640000182