## **Core Concept**
Postcoital bleeding, also known as postcoital hemorrhage, refers to vaginal bleeding that occurs after sexual intercourse. This symptom can be indicative of various gynecological conditions, ranging from benign to malignant. The primary concern with postcoital bleeding is to rule out cervical cancer or other serious cervical lesions.

## **Why the Correct Answer is Right**
The correct approach to a patient presenting with postcoital bleeding involves a thorough evaluation to determine the cause of the bleeding. Given that cervical cancer is a significant concern, the next step should aim at assessing the cervix for any abnormalities. A **Pap smear** is a screening test used to detect potentially precancerous and cancerous processes in the cervix. However, in the context of postcoital bleeding, a more immediate and direct assessment of the cervix is often preferred. **Colposcopy** allows for a detailed examination of the cervix, vagina, and vulva for signs of disease. It is particularly useful in evaluating postcoital bleeding because it can help identify lesions that may be bleeding.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While a **Pap smear** can be useful for screening, it might not provide an immediate diagnosis for the cause of postcoital bleeding and does not allow for a direct visualization of the cervix.
- **Option B:** **Ultrasound** might be helpful in evaluating other causes of vaginal bleeding, such as uterine or ovarian pathology, but it is not the best next step for evaluating postcoital bleeding specifically.
- **Option C:** **Endometrial biopsy** could be considered if the suspicion is high for endometrial cancer or if there's a strong indication of an endometrial cause for the bleeding, but it's not the immediate next step for postcoital bleeding evaluation.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that postcoital bleeding is a symptom that warrants a thorough gynecological examination, including a **colposcopy**, to rule out cervical pathology. Early detection of cervical cancer significantly improves outcomes. Therefore, any woman presenting with postcoital bleeding should be evaluated promptly.

## **Correct Answer:** D. Colposcopy.