I have undifferentiated connective tissue disease.  I am experiencing a good bit of lower back and flank pain.  I was treated for UTI and kidney infection that have since cleared but the pain is continuing.  My urologist said it is difficult to determine what is from arthritis and what is from my kidney area.  Is lower back and flank pain common with UCTD?
Welcome to Chat Doctor. People with undifferentiated connective tissue disease are often misdiagnosed or are diagnosed late. I will try to help you as much as possible here. There is a chance that this pain is related to ECTD, but it is pertinent that we rule our other causes of back/flank pain. If the back pain is because of kidney infection, it would present with fever. If the flank pain is severe and episodic, it could be because of a stone in the ureter. The first investigations that we do are urinalysis and ultrasound. If they show nothing, then CT scan is done as ultrasound can miss about 40% of ureteric stones, even when done by a very competent professional. If there are no findings on the CT scan, then we can begin to entertain the idea that it is because of ECTD. I would recommend that you visit your physician regarding this problem and schedule an appointment with a urologist and a rheumatologist. Thank you for giving us the opportunity to help you. Please feel free to ask if you have any other questions. Have a nice day. Sincerely,