We describe the case of a 23-year-old nulligravid woman who complained of increasing post-menstrual lower abdominal pain. She used contraceptives permanently for three months and was referred with a sub-mucosal lesion suspicious for a type 2 fibroid to be resected. During hysteroscopy, no fibroid mass could be confirmed. A post-operatively performed ultrasound including hydrosonography demonstrated a lesion highly suspicious for a uterus unicollis with a non-communicating uterine horn and a haematometra. Laparoscopy confirmed a normal outer lining of the uterus with hypoplastic tube on the right side. Referring to pre-operative findings, a broadly based uterine horn including a large haematometra was diagnosed. We performed a laparoscopic resection of the rudimentary horn and a right salpingectomy. The patient could be discharged without any complications three days later.