What laboratory test is essential in all women presenting with abnormal uterine bleeding?

• A. Complete blood count
• B. Pregnancy test
• C. TSH level
• D. Serum ferritin

Answer: (B)

Determining pregnancy status upfront is essential when evaluating abnormal uterine bleeding. In any woman of reproductive potential, pregnancy must be ruled in or out before proceeding with treatments or further testing because pregnancy drastically changes management and carries specific risks. A positive pregnancy test guides urgent assessment of location and viability and avoids inappropriate therapies that could harm a developing pregnancy. If the test is negative, you can safely pursue other evaluations for causes of AUB and for anemia. Tests like a complete blood count, TSH, or ferritin provide useful information about bleeding impact and contributing factors, but they do not determine the initial approach as reliably as confirming whether pregnancy is present. Thus, a pregnancy test is the essential first step in all cases.