None of the diagnostic tests available can exclusively diagnose interstitial cystitis
(IC). These tests along with history and physical examination assist in excluding
conditions which have a similar symptom profile as the IC, and thereby aid in early
diagnosis of the syndrome. The diagnostic tools routinely used as discussed below.
Voiding Dairy
The voiding dairy is an important tool to determine baseline symptoms. All the patients
are asked to maintain a voiding dairy, which records daily fluid intake and urine
output. Certain foods such as alcohol, caffeine and carbonated drinks can cause
irritation of the bladder. Awareness on this helps in exclusion of such food items
and prevent worsening of symptoms. This also helps to evaluate the effectiveness
of therapy.2
Urinalysis
Urinalysis in a patient with IC is usually within normal limits.
Urine culture reports are ideally negative in a patient with IC.
Few patients may, however, show evidence of microscopic haematuria and pyuria.
There is a limited role of urinalysis in patients with IC, as cytology findings
cannot definitively diagnosis this syndrome. 1,
Potassium Sensitivity Test
It is a highly specific diagnostic test in patients with IC to identify the bladder
origin of the symptoms.
Data available from published studies show that almost 80% of patients with IC have
positive potassium sensitivity test.
This test is based on the hypothesis of dysfunctional bladder epithelium causing
increased permeability to certain intravesical constituents including potassium.
The test rates the degree of pain or urgency in a patient after instillation of
sterile water into the bladder. The degree of pain is rated on a scale of zero to
five.
The test is positive when an increase in the baseline score by two or more points
on instillation of potassium chloride solution is noted.
A patient with IC experiences severe acute pain during the procedure.
A patient without IC experiences no pain during the procedure.
False positive results are seen in patients with urinary tract infections and radiation
cystitis.
A positive PST has a correlation with high PUF scores. 2-5
Urodynamic Tests
Urodynamic studies are not routinely recommended for evaluation of IC.
There are no specific and consistent urodynamic findings in patients with IC.
Patients with IC show symptoms of pain with bladder filling and a small volume void
sensation during cystometrogram (CMG). However, a reduction in bladder capacity
is only noted in advanced cases of IC.
Bladder compliance, volitional bladder contractions, pressure flow studies and uroflow
studies are normal in patients with IC.
Increased activity is seen with pain caused by bladder filling during sphincter
electromyography testing.
Urodynamic studies help in distinguishing cases of painful voiding or overactive
bladder from IC. 1,3,4
Cystoscopy
Cystoscopy is the most important tool in the assessment of patients with IC.
It is usually done under anaesthesia as there is a tendency for bladder hypersensitivity
in patients with IC.
While majority of the patients experience a temporary relief of symptoms after the
procedure, it gets aggravated in the remaining few. Some of the diagnostic findings
are diminished bladder capacity under anaesthesia and evidence of Hunner ulcer.
1,2,6
Cystoscopy with Hydrodistention
Cystoscopy with hydrodistention of the bladder is no longer used to diagnose IC,
owing to the presence of classic Hunner ulcers in less than 10% of IC patients.
Major indications for this test are haematuria and abnormal cytology reports.
Findings in patients with classic or ulcerative IC are glomerulations, submucosal
haemorrhages and fissures with bleeding. Scarring of the bladder wall is seen in
cases with reduced bladder capacity.
There is no evidence of ulcers or scars in the nonulcerative IC patients and the
bladder capacity is noted to be more than 400 mL.
History of pregnancy, UTI and prior rupture during distension are contraindications
for this procedure. 1-3, 6
Intravesical Anaesthetic Challenge Test
This relatively new diagnostic test may help in identifying bladder as the source
of pain in patients presenting with symptoms of IC. It is based on the principle
that the instillation of an anaesthetic lidocaine/bicarbonate solution in the bladder
of a patient with IC would result in reduction of pain. 1,2
Bladder Biopsy
This procedure is primarily based on the proposition that there is an increased
density of mast cells in patients with IC.
It is a nonmandatory test in the clinical work-up in patients with IC.
Biopsies are primarily performed when there is a suspicion for malignancy, premalignant
lesions and other varieties of cystitis.
In patients with IC, pancystitis with heavy mast cell infiltration of the bladder
wall is seen.
The histological features show an increased numbers of mast cells in the detrusor
muscle or submucosa.
Chronic inflammatory infiltration of the lamina propria is seen with fibrosis of
the detrusor or lamina propria. 1,2
