Interstitial cystitis: 'Evil Twin' of endometriosis; a 70%-90% concordance between the two. (Gynecology).

NEW YORK -- Think about interstitial cystitis before you start planning invasive procedures for a woman with endometriosis or chronic pelvic pain, Dr. Maurice Chung advised at an international congress sponsored by the Society of Laparoendoscopic Surgeons.

"Why do so many endometriosis patients come back with pain, but then you open them up or look inside and see no pathology?" asked Dr. Chung, director of the Regional Center for Chronic Pelvic Pain, Lima, Ohio. "A lot of chronic pelvic pain (CPP) patients just don't have very much endometriosis, while a lot of patients with very big endometriomas don't hurt very much."

He believes that the key to this seeming paradox is interstitial cystitis, a condition he considers the "evil twin" of endometriosis. There is a 70%-90% concordance between the two conditions, leading Dr. Chung to recommend that physicians ask about urinary symptoms very early in the diagnostic work-up of a patient with CPP. It could end up avoiding a lot of unnecessary surgery.

Dr. Chung described his experience treating 60 women, aged 19-62 years, presenting with CPP from May 1999 to October 2000. All had intractable pain, dysmenorrhea, or dyspareunia. The patients had negative cervical cultures but positive cervical motion tenderness and positive bladder tenderness.

Endometriosis was assessed via laparoscopy, and if found, was excised at the time of surgery. Of the 60 patients, 56 had endometriosis, with 48 having "active" disease (presence of a biopsy-confirmed lesion) and 8 having "inactive" disease (prior biopsy-confirmed lesions but current biopsy negative).

But 58 of the 60 patients had interstitial cystitis, which was diagnosed by history (bladder pain, dysuria, increased voiding frequency, and increased urgency in the absence of urinary tract infection) and by hydrodistention and cystoscopy. In many cases, the cytoscopy revealed significant bladder wall glomerulation.

Overall, 54 of the 56 patients with endometriosis also had cystitis. Dr. Chung said that the overlap in his cohort was somewhat higher than the 40%-70% reported by other investigators. But even at 70%, the co-occurence warrants serious attention.