My husband and I are in our 60s. We have undergone tests of occult blood in the stool, and these came out negative. But we wonder whether we should undergo a colonoscopy just to make sure we have no polyps in the colon. We have heard of "virtual colonoscopy" and would like to know if it is as accurate as a real colonoscopy. Do the health funds cover virtual scans as well? I have heard it is noninvasive and certainly sounds easier to have. And why don't Israeli doctors recommend it as they do in North America to people over the age of 50? - N.S., Jerusalem Prof. Shimon Bar-Meir, director of the gastroenterology department at Sheba Medical Center at Tel Hashomer, comments: The health funds don't cover the cost of virtual colonoscopy, except that some may offer partial coverage to members with supplementary insurance policies. They also don't cover virtual scans of the heart. Doctors are reluctant to send patients for a virtual scan not only because of the cost to the patient but also because if a pre-cancerous polyp is discovered in the virtual scan, the patient has then to undergo a regular colonoscopy, as it cannot be removed during the virtual scan. In addition, the preparation for a virtual colonoscopy is the same as the real one - fasting and then drinking an unpleasant liquid to evacuate the stools from the colon. In any case, patients who undergo a real colonoscopy are given sedation so they don't feel much anyway. Patients should know that with virtual colonoscopy, the accuracy for detecting cancerous lesions less than 6 mm. in size is low. There are false-positive findings (meaning that a lesion appears but is not really there). In this case, the patient will have to undergo conventional colonoscopy to investigate the finding. In addition, virtual colonoscopy - performed without sedation - is painful due to air pressure, while conventional colonoscopy involves almost no pain because it is done under sedation. I am a 61-year-old woman who suffers from pain after having a bout of shingles. The sores have dried up and disappeared, but the pain lingers. What is the way to alleviate the pain, which I am told can last for a year?- E.N., Givat Shmuel Prof. Avinoam Reches, senior neurologist at Hadassah University Medical Center in Jerusalem's Ein Kerem, comments: There are a number of medications that can help. I suggest that you go to a qualified neurologist in your area. I don't have all your medical details, and I don't want to name specific drugs, but a specialist can assist you. I am a 35-year-old woman who suffers from an itchy rash on my wrists. My dermatologist is not sure what the cause is. What could it be? - S.V., Ashkelon Dr. Lisa Garner, a dermatologist at Baylor Medical Center in Texas, says: Unexplained skin irritations and itchy rashes are very widespread. It is more common in women and in those people - women and men - who have their ears pierced. Some patients who seek help actually realize what's going on, and others don't have any idea what's causing their rash. In many cases, nickel or other shiny, silver-colored metals are the problem. Getting diagnosed is the first step to stopping the breakouts, but treating them is not so simple. The only real treatment for an allergy like this is to avoid contact with jewelry and other items made from such metal. It sounds easy, but nickel can be found in practically anything made of metal. Dermatologists say a big help are test kits that can be used to detect nickel in items you're considering wearing. You should test the fasteners on your jeans, the metal buckles on your belts and so on. Determining whether or not your rashes or irritations are the result of an allergy to nickel is quite simple. If it is something you're wearing that's causing you to break out, simply not wearing it should cause it to go away quickly and not return. In addition, your dermatologist can give you a patch test to double check. Readers welcomes queries from readers about medical problems. Experts will answer those we find most interesting. Write Rx for Readers, The Jerusalem Post, POB 81, Jerusalem 91000, fax your question to Judy Siegel-Itzkovich at (02) 538-9527, or e-mail it to firstname.lastname@example.org, giving your initials, age and residence.