**Question:** A 55-year-old male with history of repeated attacks of UTI, x-ray KUB showing radio opaque shadow:

A. Ureteric calculus
B. Kidney calculus
C. Bladder calculus
D. Urinary catheter

**Correct Answer:** A. Ureteric calculus

**Core Concept:**
The correct answer is a ureteric calculus because it is the most common cause of radio opaque shadow on x-ray KUB (Kubert's KUB is an abbreviation for a radiographic examination of the kidney, ureters, and bladder) in a patient with a history of recurrent UTIs (Urinary Tract Infections). X-ray KUB is a diagnostic tool used to visualize the upper urinary tract, and the radio-opaque shadow suggests the presence of a calculus.

**Why the Correct Answer is Right:**
Ureteric calculus is a type of urinary stone formed in the ureter due to the deposition of salts and crystals from the urine, typically calcium oxalate or calcium phosphate. These stones can obstruct the ureter, leading to symptoms like recurrent UTIs, flank pain, and hematuria. In this case, the radio-opaque shadow indicates the presence of a calculus, which is usually composed of calcium salts or uric acid.

**Why Each Wrong Option is Incorrect:**

B. Kidney calculus: Although kidney stones can occur, they are less common and typically larger, causing symptoms like flank pain and fever, which the patient does not exhibit in this case.

C. Bladder calculus: Bladder calculi are relatively rare and cause symptoms like hematuria, urgency, and frequency, which are not present in this scenario.

D. Urinary catheter: A urinary catheter would typically be visible on imaging studies and is not associated with UTIs.

**Clinical Pearl:**
It is essential to differentiate between the different types of calculi and their clinical presentations to make an accurate diagnosis and initiate appropriate management for the patient. In the setting of a history of recurrent UTIs and no other symptoms, a ureteric calculus is the most likely cause of the radio-opaque shadow on the x-ray KUB. Consultation with a urologist and further imaging studies (e.g., ultrasound or CT scan) are necessary for definitive diagnosis and treatment planning.