Okay, let's tackle this question. The patient is a 68-year-old woman with abdominal distension and pain. The physical exam shows an abdominal mass, no shifting dullness, induration in the rectal pouch, and bilateral adnexal masses. Breast exam and mammogram are normal. So, I need to figure out the most likely diagnosis here.

First, the key symptoms: abdominal mass, rectal induration, and adnexal masses. The absence of shifting dullness suggests there's not a lot of free fluid in the abdomen, which might point away from something like ascites. But the rectal pouch induration could indicate a mass in the pelvis pressing on that area.

Bilateral adnexal masses are often associated with gynecological issues. Since the breast is normal, maybe it's not a primary breast cancer that's metastasized. Ovarian cancer comes to mind because the adnexal masses are there, and the rectal induration could be due to a mass pressing on the rectum. Ovarian cancer can present with a palpable abdominal mass, and the absence of shifting dullness might be because the mass is solid rather than causing ascites. Also, the rectal induration could be from the tumor extending into the rectovaginal septum.

Other possibilities? Maybe a gynecological malignancy like endometrial cancer, but that might present with other symptoms like abnormal bleeding. Or maybe a primary rectal tumor, but the adnexal masses would be less likely. Uterine fibroids can cause masses, but they're usually not associated with rectal induration. The age is a risk factor for ovarian cancer, which is more common in postmenopausal women. The fact that the breast is normal makes primary breast cancer less likely as a source of metastasis.

So, the most likely diagnosis here is ovarian cancer. The key points are the adnexal masses, rectal induration suggesting local spread, and absence of ascites (no shifting dullness). The absence of shifting dullness is important because in ovarian cancer, especially early stages, there might not be significant ascites yet. The rectal induration is a sign of direct extension into the rectum, known as a rectovaginal fistula or infiltration. This presentation is classic for advanced ovarian cancer, which can present with a palpable mass and pelvic involvement.

**Core Concept**
This question assesses the clinical presentation of advanced **ovarian cancer**, emphasizing pelvic and abdominal signs. Key features include **bilateral adnexal masses**, **rectal induration** (indicating tumor extension into the rectovaginal septum), and an **abdominal mass**. The absence of shifting dullness suggests minimal ascites, consistent with early or non-ascitic presentation.

**Why the Correct Answer is Right**
Ovarian cancer is the most likely diagnosis. The **bilateral adnexal masses** indicate primary gynecological malignancy. **Rectal induration** on rectal examination suggests direct tumor spread into the **rectovaginal septum**, a classic sign of advanced ovarian cancer. The **abdominal mass** could represent a solid ovarian tumor or omental metastasis. The absence of shifting dullness implies no significant ascites, which may occur in earlier stages or in non-serous subtypes (e.g., mucinous or low

✓ Correct Answer: A. Serous cystadenocarcinomas of both ovaries