**Core Concept**
An ectopic ureter is a congenital anomaly where the ureter fails to connect to the bladder, resulting in its opening at an abnormal location. This condition is often associated with an ectopic or duplicated renal pelvis, which can affect the normal development of the ureter.

**Why the Correct Answer is Right**
In females with an ectopic pelvis, the ureter may open into a vaginal or urethral diverticulum, leading to symptoms such as urinary incontinence, recurrent urinary tract infections, or difficulty urinating. The ectopic ureter may also open into the bladder neck or urethra, causing similar symptoms. This condition is often diagnosed on imaging studies such as intravenous pyelography (IVP), ultrasonography, or voiding cystourethrogram (VCUG).

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because an ectopic ureter typically does not open into the urethra in females with an ectopic pelvis. This would be more characteristic of a urethral diverticulum.

**Option B:** Incorrect because while an ectopic ureter may open into a vaginal diverticulum, this is not the most common location in females with an ectopic pelvis.

**Option C:** Incorrect because an ectopic ureter typically does not open into the perineum in females with an ectopic pelvis. This would be more characteristic of a urethral or vaginal fistula.

**Option D:** Incorrect because an ectopic ureter typically does not open into the skin in females with an ectopic pelvis. This would be more characteristic of a urethral or vaginal fistula.

**Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that females with an ectopic ureter may present with urinary incontinence or difficulty urinating due to the abnormal ureteric opening, which can be challenging to diagnose on physical examination alone.

**Correct Answer: B. Vaginal diverticulum.**