What are the indications for ultrasound in the assessment of abdominal

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

In adult patients presenting with abdominal pain, ultrasound is indicated for several specific conditions:

Suspected Renal or Ureteric Colic: Ultrasound should be offered as the initial imaging modality for suspected acute renal and ureteric colic ,. A low-dose non-contrast CT should only be considered if the diagnosis remains uncertain after ultrasound ,.
Suspected Ectopic Pregnancy: For women in early pregnancy presenting with abdominal pain, transvaginal or transabdominal ultrasound is used to identify signs of a tubal ectopic pregnancy . These signs include an adnexal mass (which may contain a gestational sac, yolk sac, or fetal pole), an empty gestational sac (tubal ring/bagel sign), a complex inhomogeneous adnexal mass, an empty uterus, or a collection of fluid within the uterine cavity (pseudo-sac) . The scan also looks for moderate to large amounts of free fluid in the peritoneal cavity, which may indicate haemoperitoneum .
Evaluation of Abdominal Masses: An urgent direct access ultrasound scan (to be done within 2 weeks) should be considered for an upper abdominal mass consistent with an enlarged gall bladder or an enlarged liver .
Suspected Appendicitis: Ultrasound is the preferred imaging modality for pregnant women with suspected appendicitis . It may also be used in other adults when the diagnosis is uncertain to help reduce the negative appendectomy rate .

What are the indications for ultrasound in the assessment of abdominal pain in adults?