I care for a lot of women.  Many present with pelvic pain.  This is a challenging diagnosis because symptoms and signs are vague and hard to tease out.  I was taught to always rule out the urgent life-threatening conditions first.

• Ectopic pregnancy (a pregnancy outside of the uterus)
• Appendicitis
• Ruptured ovarian cyst

 Certainly, with pelvic pain, fertility-threatening conditions would be a close second to rule out and treat.

• Pelvic inflammatory disease (complication of an STD)
• Ovarian torsion (twisting of the ovary on its blood-supply stalk)

 A careful history (focusing on pain characteristics, gynecologic, sexual and social history) will be paired with a physical exam and lab work to help narrow the list.

Imaging is sometimes helpful.  A transvaginal ultrasound is frequently the best modality to use: good pictures of female internal anatomy  without  radiation exposure. 

Multiple studies have shown that 20-50% of women presenting with pelvic pain have pelvic inflammatory disease.  This means that these women in the past may have had a sexually transmitted disease which festered long enough to cause scarring in the fallopian tubes.  The CDC suggests testing adolescents for sexually transmitted infections every year or anyone with risk factors by a vaginal exam.  STD screening is for the pelvic health and future fertility of that patient.

I hope this helps.