The Prevalence of Interstitial Cystitis in Gynecologic Patients with Pelvic Pain, as Detected by Intravesical Potassium Sensitivity
Abstract & Commentary
The potassium sensitivity test (PST) was administered to 244 patients with pelvic pain and 47 control patients by enrolling gynecologists at 4 separate facilities. Previous work by these physicians had shown that the test appears to identify the presence of interstitial cystitis (IC) by detecting abnormal permeability of the bladder epithelium. The patients were enrolled consecutively at each site, with no exclusion criteria applied. Pelvic pain patients as well as age-matched control patients, completed a survey addressing both pelvic pain and urinary issues. The PST consisted of: 1) instillation of 40 cc of water into the bladder for 5 minutes; 2) grading of pain/urgency on 0-5 scale; 3) drainage of water; 4)instillation of 40 cc KCl solution (40 mEq KCl in 100 cc water); and 5) grading of pain/urgency. Of note, the patients were blinded to the solution contents, and they were also asked afterward which solution caused more symptoms.
The PST was positive in 81% of patients with pelvic pain with similar rates across centers. None of the control patients had a positive test. Eighty-four percent of the patients with pain had urologic symptoms, but only 1.6% had originally been assigned a diagnosis of IC. Parsons and colleagues conclude that IC appears to be a common, unrecognized cause of pelvic pain in gynecologic practice. They wonder whether IC shouldn’t be given greater, or even primary, consideration in our differential diagnosis (Parsons CL, et al. Am J Obstet Gynecol. 2002;187:1395-1400).
Comment by Frank W. Ling, MD
Whoa! Time out! Isn’t the primary author of this study, who is also the primary author of other articles on the PST, a urologist? Where does he get off telling gynecologists how to diagnose the cause of pelvic pain? Aren’t ob/gyn physicians the specialists that patients and other physicians turn to for answers in these tough cases? Aren’t gynecologic surgeons the ones who "when in doubt, cut it out?"
I’m confident that the reader clearly sees my tongue firmly planted in my cheek. Yes, we are the surgeons, but we are also the physicians who see the whole patient, who review all organ systems, looking for clues to the often-difficult cases. Since our relationship with our patients often encompasses far more than the surgical experience, this article is even more timely. One albeit simplistic approach to patients with pelvic pain is to remember "GUMP." This helps keep the gynecologist focused on non-gynecologic causes of pelvic pain, sometimes avoiding unnecessary surgery or, at least, identifying concurrent conditions that may also be causing pain.
G: gastrointestinal causes. Primarily this leads to a diagnosis of irritable bowel. Patients who have pain associated with intermittent constipation, diarrhea, bloating, etc should be evaluated and treated before a commitment is made to gynecologic surgery.
U: urologic causes. In contemporary parlance, I suppose this should read urogynecologic causes. The point is that IC should certainly be considered, particularly when patients present with urologic symptoms. Even though urogynecology as a subspecialty is gaining broader recognition and acceptance, urologists are often the primary resources for many gynecologists. Regardless of what resources are available, the astute clinician can greatly enhance his/her ability to diagnose IC knowing that patients with IC void frequently (in this study, patients could not be included in the control group if they voided more than 8 times in a 24 period), have urge, often void small amounts, have dyspareunia, and even can feel better after voiding. Bladder tenderness on vaginal examination that recreates the chief complaint increases the index of suspicion.
M: musculoskeletal causes. Both abdominal wall and pelvic floor muscles can potentially cause pain that is mistakenly assumed to originate from pelvic organs. A history of trauma (eg, a fall or motor vehicle accident) or positional impact on pain is helpful in making this diagnosis. A physical therapist may be of some benefit if the pain can be recreated with light palpation of the abdominal wall or direct pressure of the pelvic floor.
P: psychiatric causes. Most commonly, considerations of depression, somatization disorder, and history of sexual abuse should be explored. Because depression has been found to be an inherent part of the chronic pain process, trying to figure out "which came first, the chicken or the egg," is often fruitless. Pain and depression both need attention when both are present. As the experienced clinician has discovered, often the hard way, the patient with somatization (multiple somatic complaints without identifiable organic cause) cannot be cured, merely managed over time. To address sexual abuse, whether child or adult, the question must be posed at some time. Patients need to sense the safety of a provider who is sensitive and willing to listen and help. The question "Have you ever been touched against your will, either as a child or as an adult?" is a nonthreatening way to convey to the patient your willingness to help address this concern.
The bottom line: Causes of pelvic pain in any particular patient are potentially multiple. An organized approach to what otherwise may seem a complex problem can often lead to findings that might have been missed. Perhaps this article can serve as an aid to help some more of our patients get care for pelvic pain that looks outside the pelvis.
Dr. Ling is UT Medical Group Professor and Chair, Department of Obstetrics and Gynecology at the University of Tennessee Health Science Center, Memphis, TN.
The potassium sensitivity test (PST) was administered to 244 patients with pelvic pain and 47 control patients by enrolling gynecologists at 4 separate facilities. Previous work by these physicians had shown that the test appears to identify the presence of interstitial cystitis (IC) by detecting abnormal permeability of the bladder epithelium.
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