Ultrasound - Pregnancy (abdominal)
To confirm the presence of:
Consider in the following presentations in the first trimester:
Contraindications (absolute in bold)
Airway management or resuscitation required
Formal ultrasound scan
Consent is not required if the patient lacks capacity or is unable to consent
Brief verbal discussion is recommended if the situation allows
Less complex non-emergency procedure with low risk of complications
Failure to visualise structures (bowel gas, excess tissue, pain)
Failure of image interpretation (false negative or positive)
PPE: Non-sterile gloves
Ultrasound machine and gel
Curvilinear ultrasound probe (abdominal pre-set or adjust depth to centre uterus and adnexa)
Supine with hips flexed to relax the abdominal muscles (full bladder preferred)
Transducer placed on the lower abdomen over bladder just above the symphysis pubis
Place transducer in the longitudinal plan (marker to head)
Identify bladder and uterus posteriorly with vaginal stripe (hyperechoic line from cervix to uterus)
Scan uterus from fundus to cervix
Fanning right and left obtaining complete view of the uterus
Locate pouch of Douglas behind uterus and examine for free fluid
Rotate into the transverse plane (marker to the right)
Scan through the uterus again from cervix to fundus
If a gestational sac is identified, assess for a yolk sac or foetal heartbeat
Scan laterally from the uterus, locate ovaries and assess for adnexal masses
Consider performing a FAST scan looking for free fluid
Clean ultrasound gel from patient
Complete clinical assessment combining results with clinical history, exam and β-hCG
Consider further assessment (gynae assessment, formal ultrasound)
Always discuss scan limit with patient (early pregnancy may not be seen even if it is present and viable)
Visualising an intrauterine pregnancy with heartbeat is often reassuring to the patient
Patients with a positive pregnancy test and symptoms suggestive of an ectopic pregnancy can be evaluated in the emergency department by point-of-care ultrasound. This is especially useful when intrauterine pregnancy has not been previously confirmed.
Transabdominal ultrasound provides a wide field of view of the pelvis and provides good visualisation of the uterus and superior adnexa and free fluid. A transvaginal examination is out of the scope of practice for most emergency physicians, but allows a more detailed evaluation of the endometrial cavity ovaries and other adnexal structures.
The sonographic visualisation of an intrauterine gestational sac containing a yolk sac or embryo confirms intrauterine pregnancy and essentially excludes ectopic (heterotopic pregnancy is rare outside of in vitro fertilisation). If intrauterine pregnancy is not identified, this may represent normal early pregnancy below the detection threshold for transabdominal ultrasound (β-hCG <6000 mIU/ml), or an ectopic pregnancy.
Scanning the adnexa is also recommended looking for free fluid or for signs of ectopic such as extraovarian heterogeneous mass, usually representative of a haematoma at the site of ectopic implantation or echogenic ring in the adnexa surrounding an unruptured ectopic pregnancy (tubal ring sign).
This guideline has been reviewed and approved by the following expert groups:
Emergency Care Institute
Please direct feedback for this procedure to ACI-ECIs@health.nsw.gov.au.
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