What are the key indications for requesting an ultrasound scan in primary care?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 22 August 2025Updated: 22 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Key indications for requesting an ultrasound scan in primary care include:

  • Suspected early pregnancy complications such as pain, bleeding, pregnancy of 6 weeks' gestation or more, or uncertain gestation to assess viability and location of pregnancy (e.g., to exclude ectopic pregnancy) .
  • Women with bleeding but less than 6 weeks' gestation without pain or risk factors may initially be managed expectantly, with ultrasound considered if symptoms worsen or persist .
  • Women with symptoms or signs suggestive of ectopic pregnancy (e.g., pain, bleeding, or worsening symptoms) should be referred for ultrasound assessment .
  • Serum CA125 of 35 IU/ml or greater in women aged 18 and over to investigate possible ovarian pathology, prompting an abdominal and pelvic ultrasound scan .
  • Unexplained vaginal discharge or visible haematuria in women aged 55 and over may warrant a direct access ultrasound scan to assess for endometrial pathology .
  • Ultrasound is indicated when clinical suspicion of malignancy arises, such as ovarian cancer suggested by raised CA125 or abnormal clinical findings, to guide urgent referral .

Additional considerations: Transvaginal ultrasound is preferred for early pregnancy assessment, but transabdominal ultrasound may be used if transvaginal is unacceptable or if pelvic pathology such as fibroids or ovarian cysts is suspected .

Educational content only. Always verify information and use clinical judgement.