The Ability of Microscopic Hematuria to Predict the Presence of Urolithiasis in Patients with Acute Flank Pain: An Iraqi Experience


Background: Iraq is a country with high prevalence of urinary stones since the dawn of civilization. Flank pain is a common complaint encountered in emergency rooms and outpatients clinics in which diagnosis can overlap due to the poor localization of pain by the patient. There is an anecdotal belief that anyone with flank pain must have a 'kidney stone'. General urine examination (GUE) is the primary screening test done for almost all patients presenting with acute loin pain. The interpretation of the results of urinalysis is usually done by the requesting doctor, hence building a decision whether a urinary stone is present or not. The finding of microscopic hematuria largely contributes to this decision and may or may not preclude the need for further investigations to confirm or exclude the presence of urinary stones as a cause of pain.Purpose: To test the ability of the microscopic hematuria in predicting the presence or absence of urolithiasis in patients presenting with acute flank pain using ultrasound, KUB, intravenous urogram (IVU) and to a less extent computerized tomography (CT) scan as gold standards.Materials and Methods: A randomized prospective study was performed in the Urology Consult Clinic of Al-Karama Teaching Hospital on 64 patients presenting with acute loin pain between January 2008 and December 2009. Each patient had a urinalysis within few hours of onset of pain as primary screening test, to look for microscopic hematuria. To confirm or exclude presence of stones, all patients were subjected to ultrasonic examination in the radiology department; some patients have KUB in addition. In cases of uninformative results, IVU or CT scan study were done in the hospital or requested in an outside radiological unit of another hospital or a private clinic. The results were recorded and interpreted to test for a correlation of microscopic hematuria and presence of urinary stones. Each patient was managed according to his individual condition. Results: Sensitivity and specificity of microscopic hematuria were 51.61% and 54.55% respectively. The positive predictive value and negative predictive value for hematuria as a predictor for stone disease was 63.64% and 38.71% respectively. Overall accuracy of microscopic hematuria was 51.56%.Conclusion: Hematuria is not found to be a sensitive or a specific marker in predicting urinary stones for patients with acute flank pain in current urological practice. Initial diagnosis of renal or ureteric stones should be made by an accurate history and by the results of urinalysis for hematuria. IVU is still a key-role player in establishment of diagnosis especially, ureteric stones. CT scan is now being introduced as an accurate tool with unrivalled superiority.Keywords: Urolithiasis, microscopic hematuria, acute loin pain, Iraq.