Fig. 1

Development of the UPA over 2 weeks by ultrasound. Visit 1 with a. Ultrasound image of the ill-defined solid mass in the adnex at the initial presentation at 23 + 2 gestational weeks. The arrows mark the outer margins of the lesion. An endometrioma is not clearly visible. b. Corresponding Doppler image of the left adnexa showing moderate blood flow (Color Score 3) in the lesion. Visit 2 with c

Ultrasound Image of the same lesion on the follow up at 25 + 2 gestational weeks. On the lower right there is an unilocular mass suggestive of endometrioma. In the center there is a pulsating vessel (UPA) of about 2 cm with most likely haematoma surrounding the UPA and d. corresponding Doppler image confirming blood flow in the vessel.