The presence of significant hemoperitoneum managed conservatively in some women precedes the development of deep endometriosis (DE), depicted in 'Ultrasound in Obstetrics and Gynecology'.

E. Bean et al. and his colleagues conducted a prospective cohort study to determine whether significant hemoperitoneum could act as a precursor for the development of endometriosis in non-pregnant women with lower abdominal pain. This prospective observational cohort study was executed in a dedicated gynaecological diagnostic unit for 18 months.

Non-pregnant premenopausal women who presented with acute lower abdominal pain and underwent a pelvic ultrasound examination were enrolled in the study. The participants were screened for surgical and conservative treatment based on pain intensity and symptom severity. Women selected for conservative treatment were asked for the follow-up ultrasound scans. Newly developed deep endometriosis at follow-up was regarded as the evidence for the primary outcome measure.

Out of 118 participants, 20 women selected for emergency surgery and 17 women with a history or evidence of endometriosis on the initial scan were excluded from the study. The conservative management was used in 81 women, eight of whom depicted evidence of significant hemoperitoneum at presentation. A total of 35 women attended follow up ultrasound scans. After follow up, 4 out of 6 women who presented with significant intra-abdominal bleeding initially had shown new evidence of DE as compared to one of 29 women without hemoperitoneum.

The number of participants in this study was relatively small. So, the study authors suggest, "Further larger prospective studies are important to confirm the findings before any interventional studies could be planned."