There is a large variation in fibroid growth such that fibroids may grow at vastly different rates or, conversely, may spontaneously regress. The ability to predict the growth of fibroids could help clinicians decide, with their patients, the need for treatment. For example, asymptomatic women with fibroids detected incidentally may require follow up if these fibroids are predicted to have a high growth rate. In women of reproductive age, fast-growing fibroids located in a submucous or intramural position may subsequently impair fertility and so early surgical removal should be considered. Medical treatments, such as ulipristal acetate, can prevent growth of fibroids and so may be indicated in women with fast-growing fibroids. Angiogenic growth factors play an important role in the complex, not fully understood mechanisms of fibroid growth (Tal et al. Hum Reprod Update 2014;20:194). Vascularisation of fibroids is known to be important in clinical practice through observations that the effect of embolisation is more limited in avascular fibroids (Tang et al. Eur Radiol 2016;10:3571) and that persistent perfusion of fibroids after embolisation or ablation is related to fibroid growth following these procedures (Dueholm et al. Eur J Obstet Gynecol Reprod Biol 2014;178:100). The standard procedure for evaluation of fibroid vascularisation has been magnetic resonance imaging (MRI) with contrast. However, the vasculature of fibroids and their pseudo-capsule can be visualised using colour Doppler or power Doppler ultrasound. Volume and Vascular Indices (VI) can be calculated by 3D ultrasonography using the manual contour mode in VOCAL (Virtual Organ Computer-aided AnaLysis). VI is a measure of the proportion of blood vessels within the tissue (number of colour voxels divided by the total number of both colour and grey voxels). Nieuwenhuis et al. in the current issue of BJOG (Nieuwenhuis et al. BJOG 2018;125:577–84) measured baseline fibroid volume and VI of fibroids and their capsule using 3D ultrasound and related the VI to fibroid volume after 12 months. They found that the growth rate of fibroids was related to the initial VI of the fibroid, but not the VI within the capsule. Although the findings derived from 3D power Doppler ultrasound are dependent upon the image settings and so may not be consistently reproducible, the technology is increasingly available and accessible. Moreover, 3D ultrasound assessment of fibroid size and vascularity is cheaper than MRI. Thus, the findings from this study are potentially important for clinical practice and also for the design of further studies evaluating the future growth of fibroids and response to medical and surgical treatments based upon 3D ultrasound technologies. None declared. Completed disclosure of interests form available to view online as supporting information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.