A 32-year-old multiparous woman with a 5-year-old levonorgestrel-releasing IUCD (LNG-IUS) reports amenorrhea for the past 8 months and denies pregnancy symptoms. She is concerned about the absence of menses. Which investigation is most appropriate to assess the structural integrity and position of the device and rule out complications?

Explanation

## Clinical Context: LNG-IUS and Amenorrhea The patient has an **LNG-IUS (levonorgestrel-releasing intrauterine system)** with **amenorrhea** — a common and expected side effect due to endometrial atrophy from chronic progestin exposure. However, the clinical question asks for the **investigation of choice to assess device integrity and position**, not to diagnose the cause of amenorrhea. ## Investigation of Choice: Transvaginal Ultrasound **Key Point:** Transvaginal ultrasound (TVS) is the **gold standard** to confirm correct IUCD positioning, assess endometrial thickness, and detect complications (perforation, malposition, expulsion). ### Why TVS is Indicated in LNG-IUS Users | Clinical Question | TVS Finding | Significance | |-------------------|-------------|---------------| | **Is the device in situ?** | IUCD echo in uterine cavity | Confirms correct position | | **Is there perforation?** | IUCD outside uterus ± free fluid | Surgical emergency | | **Is there malposition?** | IUCD in lower segment or tilted | May ↓ efficacy; consider replacement | | **Endometrial status** | Thin endometrium (2–3 mm) | Expected with LNG-IUS; reassuring | | **Is there expulsion?** | Absence of IUCD | Device failure; needs reinsertion | **High-Yield:** Amenorrhea with an LNG-IUS is **expected and reassuring** (indicates good progestin effect and endometrial suppression). TVS confirms the device is **functioning correctly** and not causing harm. ## Clinical Pearl **Amenorrhea ≠ pathology with LNG-IUS.** Up to 20% of users achieve amenorrhea by 1 year; by 5 years, 40–50% are amenorrheic. This is a **feature, not a bug** — it indicates excellent contraceptive efficacy and reduced menstrual blood loss. However, **device position must always be confirmed** by TVS to rule out silent perforation or expulsion. ## Why Other Investigations Are Not Appropriate See **whyEachDistractorIsWrong** section below. [cite:Park 26e Ch 18]