**Question:** For evaluating a case of recurrent spontaneous abortion, which of the following investigations is unwanted?

**Core Concept:** Recurrent spontaneous abortion (RSA) is defined as the loss of three or more consecutive pregnancies before the gestational age of 20 weeks or fetal birth weight of 500 grams. Investigations are essential to identify underlying causes and guide management. However, some investigations may be less relevant or unnecessary in a specific case.

**Why the Correct Answer is Right:** The correct answer is **D. Complete Blood Count (CBC)**. In most cases, a routine CBC is not specifically indicated for the evaluation of RSA. While certain anemias or infections can cause miscarriages, it is usually not the primary etiology in RSA cases. Instead, other tests should be prioritized, such as thyroid function tests (TFT), anti-phospholipid antibody screening, and thrombophilia panel.

**Why Each Wrong Option is Incorrect:**

A. **Liver function tests (LFTs)**: These tests focus on liver function and are not specifically related to pregnancy-related complications like RSA.

B. **HIV test**: Human Immunodeficiency Virus (HIV) infection is a cause of RSA, but a negative result does not exclude its presence. It is essential to perform the appropriate test for HIV (HIV ELISA) rather than a general blood test.

C. **Venereal Disease Research Laboratory (VDRL) test**: This test is used for syphilis diagnosis, which is not a common cause of RSA. A more appropriate test for syphilis is Treponema pallidum particle assay (TPPA) or rapid plasma reagin (RPR) test.

**Clinical Pearl:** In cases of recurrent miscarriages, it is crucial to conduct a thorough evaluation targeting the most common causes, such as anti-phospholipid antibodies, thrombophilia panel, and TFTs. Performing unnecessary tests like CBC, LFTs, VDRL, and HIV tests can lead to misguided conclusions and unnecessary expenses. Instead, a focused approach with the right tests helps identify the underlying cause and guide appropriate management.