There is no conclusive diagnostic testing for IC/PBS. This is highly problematic. Currently, a diagnosis of IC/PBS takes a somewhat reductionist approach. It is a diagnosis of exclusion where the patient generally undergoes a series of invasive and non-invasive tests to exclude other possible causes which may be responsible for their ongoing lower urinary tract symptoms (LUTS). When these other possible causes are ruled out, yet LUTS remain, the patient receives a diagnosis of IC/PBS.
For the typical person undergoing IC/PBS investigations, the process often involves some, or all, of the following—UTI testing, urodynamic testing, transvaginal and pelvic ultrasound, CT and MRI scans, cystoscopy with or without bladder hydrodistension (stretching), urethral stretching and/or bladder biopsy. It has been reported that, on average, it takes three to seven years and three to five different practitioners before an IC/PBS diagnosis is reached.
Sometimes investigative tests for IC/PBS look to determine that symptoms do in fact originate from the bladder and not from another pelvic organ. A range of agents may be used to determine the origin of symptoms. One such test is the ethically dubious, invasive and painful potassium chloride bladder instillation, known as the potassium sensitivity test. If the patient feels pain during its administration into the urinary bladder, and an increase in symptoms, they may receive a diagnosis of IC/PBS. This test rests on an understanding that a bladder without damage to its urothelium will not experience any increase in pain with the introduction of an irritating agent, (Jiang, 2016). Yet, we now know that infection, particularly chronic UTI, may invade and damage the bladder lining (urothelium), and any substance which is not relatively pH neutral will cause pain if introduced to an inflamed bladder.
Another testing agent utilised more recently as a gentler alternative is intravesical lidocaine, an anaesthetic often used to numb sensations of pain. Lidocaine is instilled into the urinary bladder. If this reduces patient pain levels, then pain may be determined, quite reliably, as originating from the bladder, (Henry, 2016).
A cystoscopy with or without hydrodistension is commonly performed to look inside the bladder during the IC/PBS diagnostic process. Sometimes, a biopsy may be performed to rule out more serious conditions, such as cancer. Neither potassium sensitivity testing or hydrodistension have been found to be accurate for effectively diagnosing IC/PBS, (Jiang, 2016). Not surprisingly, while these tests may confirm a ‘painful bladder’, they fail to identify the cause of the pain.
Reaching a diagnosis of IC/PBS does not follow the same pathway for all. Some people will endure a full battery of tests before a diagnosis of ICPBS is made—some are diagnosed following a cystoscopy and hydrodistension procedure—others are given the diagnosis based solely on having UTI symptoms without the presence of one or more positive urine cultures.
Nonetheless, after all other causes have been excluded, either through a series of tests or by assumption, an IC/PBS diagnosis is made based upon the patient’s clinical symptoms, medical history and, most importantly, one or more negative, ‘normal’ urine culture tests to rule out urinary tract infection (UTI).
It is this reliance on cultures to rule out UTI in favour of a diagnosis of IC/PBS that patients find most challenging. Urine is not sterile, as was previously assumed. As we explain in detail on our UTI Testing page, urine culture tests were originally developed based upon a significantly defective understanding and we now know it is impossible to rule out UTI based on negative urine cultures. This is explained succinctly in ‘Cystitis Unmasked’: “All definitions of IC/PBS/BPS stipulate a crucial step—the absence of UTI. Unfortunately, the tests used to rule out UTI cannot rule out UTI and the risk of a missed infection is substantial” (Malone-Lee, 2020, p.73).
As explained by Professor Curtis Nickel, urine culture is an inferior diagnostic tool: “The microbiologic diagnosis of infection in the bladder has traditionally been based on cultivation techniques in which bacteria are grown from voided urine spread on culture plates, which does not have the nutritive and environmental conditions required to support the growth of many microorganisms. We now understand that these traditional tools used to study bacteria, not only in IC/BPS patients but also in patients with presumed bacterial cystitis, are inadequate as a means to survey the microorganisms present in patient samples” (Nickel, 2019).