On transvaginal ultrasound, a 30-year-old woman with dysmenorrhoea shows a uterus with a junctional zone thickness >12 mm and a honeycomb pattern with irregular myometrial heterogeneity. What is the most likely diagnosis?
- A Uterine fibroid (intramural leiomyoma)
- B Endometrial carcinoma
- C Adenomyosis ✓
- D Subacute endometritis
Correct answer: C. Adenomyosis
Explanation
Adenomyosis on transvaginal ultrasound (TVUS) is characterised by a thickened junctional zone (>12 mm on MRI; ultrasound equivalent is heterogeneous, globular uterus), myometrial cysts (the honeycomb pattern), asymmetric myometrial thickening, and fan-shaped acoustic shadowing. MRI is the gold standard with junctional zone thickness >12 mm being diagnostic. Intramural fibroids are well-defined hypoechoic masses with edge shadowing. Endometrial carcinoma shows endometrial thickening and disruption of junctional zone. Endometritis shows echogenic endometrium with fluid.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.