The labs have all come back on a 38-year-old female who you suspected had pyelonephritis. She had presented with 24 hours of flank pain and fever but no vomiting, abdominal pain or dysuria. Her last menstrual period was 2 weeks ago and she denies any possibility of pregnancy. Her past medical history was only significant for hypertension treated with hydrochlorothiazide. Her physical exam showed no surprises: She was afebrile despite the history of fever at home, and she was slightly hypertensive with a BP of 157/93 mmHg. Other than right costo-vertebral angle tenderness, the rest of her exam was normal.
Her labs unfortunately are giving you a few uncomfortable surprises. Her CBC shows an expected leukocytosis with a WBC count of 14.9, but the rest of the values are normal. The unexpected twists are her abnormal renal function and the amount of blood in her urine. Her creatinine is 2.4. She is unaware of any prior kidney damage, but doesn’t know when she last had blood tests. The rest of her chemistry panel is normal except for a potassium of 3.2 and a bicarb or 34, both of which you attribute to her hydrochlorothiazide. She does have old labs on file, which are normal, but they are from 2001. She states that she has been on blood pressure medication for about 5 years. You wonder if it is the hypertension alone that has started to cook her beans.
Her UA has some remarkable abnormalities, as well. There are only 5-10 WBC’s per high powered field (hpf) and 2+ bacteria, but >200 RBC’s per hpf. You’ve diagnosed many cases of pyelonephritis with only 5-10 WBC’s per hpf, some with even fewer, especially when there is bacteruria. Despite unimpressive pyuria, when you’ve checked the urine cultures a few days later, they often came back positive when your clinical suspicion was otherwise high, and even some times when it wasn’t. And, since bacteruria is 90-95% specific for a UTI, you feel pretty confident that your patient today does indeed have pyelonephritis with only 5-10 WBC’s to show for it. What is bothering you about the UA is actually the number of RBC’s. In hemorrhagic cystitis you can certainly get lots of RBC’s and even have more RBC’s than WBC’s, but this patient does not have dysuria. She’s mid-cycle and denies any vaginal bleeding, so that’s not the explanation. You are worried that she may have a concomitant kidney stone and so some type of imaging will be necessary.
Since she is relatively young, you especially want to avoid unnecessary radiation so you would prefer to get an ultrasound. However, you know that CT is more sensitive and this is one of the few cases where you really wouldn’t want to miss a kidney stone, because concomitant infection is one of the few exceptions to the rule, “No one ever died from a kidney stone”. You decide that you will use the ED portable ultrasound machine to take a quick look. If you see hydronephrosis, so will the radiologist, and so you’ll order the ultrasound and spare your patient the radiation. If the kidneys look normal, however, you’ll order the more definitive CT-urogram.
You wheel over one of your department’s machines and get the image above. Is there hydronephrosis? See next page for conclusion