**Core Concept**
Urinary bladder stones, also known as vesical stones, are hardened mineral deposits that form inside the bladder. They can cause severe pain, bleeding, and obstructive urinary symptoms. The formation of bladder stones is often related to urinary stasis, infection, or metabolic disorders.

**Why the Correct Answer is Right**
Bladder stones typically form in the setting of urinary stasis, which can be due to a variety of factors such as bladder outlet obstruction, neurogenic bladder, or catheter use. The most common types of bladder stones are struvite stones (magnesium ammonium phosphate) and uric acid stones. Struvite stones often form in the setting of urinary tract infections (UTIs), particularly those caused by urease-producing bacteria like Proteus, Klebsiella, or Pseudomonas. These bacteria split urea into ammonia and carbon dioxide, which increases the pH of the urine and promotes the precipitation of struvite crystals.

**Why Each Wrong Option is Incorrect**
**Option A:** Bladder stones are most commonly associated with urinary tract infections caused by Escherichia coli.
* This is incorrect because while E. coli is a common cause of UTIs, it is not typically associated with the formation of struvite stones. Urease-producing bacteria like Proteus, Klebsiella, or Pseudomonas are more commonly implicated.

**Option B:** The primary risk factor for bladder stone formation is a high-sodium diet.
* This is incorrect because while dietary factors can contribute to stone formation, a high-sodium diet is not the primary risk factor for bladder stones. Urinary stasis, infection, and metabolic disorders are more significant risk factors.

**Option C:** Bladder stones are always painful and require surgical intervention for removal.
* This is incorrect because while bladder stones can cause severe pain, they may not always be painful. Additionally, not all bladder stones require surgical intervention for removal. Small stones may pass spontaneously with medical management.

**Option D:** Bladder stones are more common in females than in males.
* This is incorrect because bladder stones are actually more common in males than in females. This is due to a combination of factors, including anatomical differences, urinary stasis, and the presence of urethral strictures.

**Clinical Pearl / High-Yield Fact**
One important clinical pearl to remember is that bladder stones can cause urinary frequency, urgency, and dysuria, but they may not always cause severe pain. A high index of suspicion should be maintained in patients with urinary symptoms and a history of urinary tract infections or urinary stasis.

**Correct Answer:** D.