Ultrasound first for many questions
For ovarian cysts, early pregnancy and a first look at pelvic pain, ultrasound is faster and does not need a tunnel. MRI is added when ultrasound is unclear, when a mass needs staging, or when endometriosis is suspected beyond what a scan probe can map.
What pelvic MRI is good at
Fibroids and adenomyosis, and how they sit relative to the uterine wall.
Endometriosis deep in the pelvis, when a specialist is planning treatment.
An ovarian mass that ultrasound cannot classify.
Prostate anatomy, which is covered in more detail in the prostate MRI guide.
Preparation
Some protocols ask you to fast or to arrive with a partly filled bladder. A few use a medication to slow bowel movement, or gel in the rectum or vagina. The clinic’s instructions matter more than a general article. Contrast is used for some masses and not for others.
MRI does not replace a smear test, an HPV test or a gynaecological examination.