## Investigation of Choice for PID Confirmation and Complication Assessment **Key Point:** Transvaginal ultrasonography is the first-line imaging modality for confirming PID and detecting complications such as tubo-ovarian abscess, pyosalpinx, and free fluid in the pelvis. ### Why Transvaginal Ultrasound? 1. **Superior sensitivity and specificity** for adnexal pathology compared to transabdominal ultrasound 2. **Non-invasive** with no radiation exposure 3. **Real-time assessment** of: - Thickened, fluid-filled fallopian tubes (pyosalpinx) - Tubo-ovarian complex or abscess - Free pelvic fluid - Ovarian enlargement 4. **Cost-effective** and readily available in most centers 5. **Guides management** — helps differentiate uncomplicated PID from complicated PID requiring intervention ### Imaging Findings in PID on Ultrasound | Finding | Significance | |---------|-------------| | Thickened, fluid-filled tubes | Pyosalpinx; indicates salpingitis | | Tubo-ovarian complex (TOC) | Inflammatory adhesions; may resolve with antibiotics | | Tubo-ovarian abscess (TOA) | Loculated collection; may require drainage | | Free pelvic fluid | Peritonitis; non-specific but supportive | | Ovarian enlargement | Oophoritis | **High-Yield:** Transvaginal ultrasound has ~90% sensitivity for detecting PID-related adnexal pathology when clinical suspicion is high. ### Clinical Pearl In resource-limited settings, clinical diagnosis based on **Pelvic Inflammatory Disease Diagnostic Criteria** (empirical treatment threshold) is often sufficient. However, imaging confirmation is essential when: - Diagnosis is uncertain - Complications are suspected - Response to antibiotics is inadequate after 48–72 hours - Surgical intervention is being considered [cite:Park 26e Ch 12] 
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