Brief Answer: Not really unless there are other symptoms Detailed Answer: Hi and thank you so much for this query. From the information you have provided, i don't think you should be very concerned about this. I will advise that you maintain your regular 10yearly colonoscopy for screening of colon cancer. So long as they have not shown any lesions to be concerned about, ignore the shape of these stools. if the last one dates to more than 10years back, please consider scheduling one at your earliest convenience. If for real this were caused by a disease, the change in size from a pencil to the direct opposite wold not be possible. Thy are more likely to be explained by other not permanent factors like bowel movements and diets consistency which are non pathological. I hope this addresses your query fully. Thank you for using our services and please do feel comfortable to ask for clarifications if need be. I wish you the best of health. Dr. Ditah, MD

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