A 42-year-old nulliparous woman with known uterine fibroids presents with infertility of 3 years. Hysterosalpingography shows a normal cavity and patent tubes. She desires fertility preservation. Which investigation is most appropriate to determine if the fibroid is responsible for infertility and to guide treatment?

## Investigation for Fibroid-Related Infertility **Key Point:** In infertile women with fibroids, the critical question is whether the fibroid distorts the endometrial cavity. Transvaginal ultrasound with 3D reconstruction combined with hysteroscopy is the gold standard for this assessment. ### Rationale for Combined Approach **High-Yield:** Only **submucosal fibroids** (protruding into the cavity) are definitively associated with infertility. The degree of cavity distortion determines treatment: | Fibroid Type | Cavity Distortion | Infertility Risk | Investigation | |--------------|-------------------|------------------|----------------| | **Subserosal** | None | Minimal | Ultrasound sufficient | | **Intramural (non-cavity distorting)** | <50% | Debated | Ultrasound + MRI | | **Intramural (cavity distorting)** | >50% | Moderate | 3D ultrasound + hysteroscopy | | **Submucosal** | Yes (protrudes) | High | 3D ultrasound + hysteroscopy | ### Why This Combination Works 1. **Transvaginal ultrasound with 3D reconstruction:** - Accurately measures cavity distortion percentage - Assesses fibroid location and depth (myometrial involvement) - Non-invasive, repeatable 2. **Hysteroscopy:** - Direct visualization of cavity and fibroid - Allows simultaneous myomectomy if indicated - Assesses endometrial health and other cavity pathology (polyps, septum) **Clinical Pearl:** The **FIGO classification** (2018) grades submucosal fibroids (0–4) based on cavity involvement. Grade 0–2 fibroids may be amenable to hysteroscopic resection; Grade 3–4 require open/laparoscopic approach. **Mnemonic: CAVITY** — **C**avity distortion, **A**ssess with 3D ultrasound, **V**isualize with hysteroscopy, **I**ntramural depth, **T**reatment planning, **Y**ield of combined approach. ### Why Other Options Are Suboptimal **Diagnostic Laparoscopy with Chromopertubation:** - Excellent for assessing tubal patency (already done via HSG) - Cannot adequately visualize or assess cavity distortion - Invasive; does not guide fibroid treatment **Pelvic MRI with DWI:** - Provides excellent fibroid characterization - Does NOT assess cavity distortion as precisely as 3D ultrasound - Expensive and time-consuming for infertility workup - Does not allow simultaneous therapeutic intervention **Hysteroscopic Myomectomy as Investigation:** - This is a **treatment**, not an investigation - Premature if cavity distortion has not been quantified - Risks uterine perforation and adhesions if not indicated [cite:FIGO Classification of Submucosal Fibroids (2018); Park 26e Ch 12]