What initial investigations should be conducted for a patient presenting with chronic pelvic pain to rule out serious underlying conditions?

Initial investigations for a patient presenting with chronic pelvic pain should aim to exclude serious underlying conditions such as ectopic pregnancy, ovarian cancer, colorectal cancer, and other significant pathologies.

1. Pregnancy test: Always offer a pregnancy test to women of reproductive age presenting with pelvic pain to exclude ectopic pregnancy, even if symptoms are non-specific, as ectopic pregnancy can present atypically and without risk factors ³.

2. Physical examination: Conduct an abdominal and pelvic examination to identify any masses or organ enlargement. If an abdominal or pelvic mass is found (not obviously uterine fibroids), refer urgently via a suspected cancer pathway to exclude ovarian or colorectal cancer ¹.

3. Blood tests: Measure serum CA125 in women, especially if aged 50 or over, presenting with persistent or frequent pelvic pain to help exclude ovarian cancer ¹. Consider a full blood count urgently if hepatosplenomegaly is suspected to exclude haematological malignancies ¹.

4. Faecal immunochemical testing (FIT): Offer quantitative FIT in patients with unexplained abdominal or pelvic pain, particularly if aged 40 and over, or with rectal bleeding, to exclude colorectal cancer ¹.

5. Imaging: If an upper abdominal mass or organ enlargement is suspected, consider urgent direct access ultrasound within 2 weeks to assess for gall bladder or liver pathology ¹. For pelvic pain with suspected endometriosis, specialist imaging may be required but initial assessment is clinical ².