Obs (abdo) Flashcards
Sonde utilisée?
curvilinéaire
Préparation de la sonde pré scan?
Dive the depth to centre all relevant anatomy.
Recommended starting depth for beginners: 15 cm in adults. Initial depth for pediatric patients varies with age.
Beginners should always set the initial depth deep enough to avoid missing relevant anatomy. With experience, initial depth should be adjusted to account for patient body habitus.
Gain = mid-range.
System preset(s) = abdominal / OB
Préparation du pt? position et orientation de la sonde?
Patient positioning
Supine.
Patient draping
Abdomen exposed from umbilicus down, towel covering waist.
Probe orientation
Longitudinal – Probe held perpendicular to the floor / stretcher with the beam directed towards the patient’s back and the probe marker oriented towards the patient’s head.
Transverse – Probe held perpendicular to the floor / stretcher with the beam directed towards the patient’s back and the probe marker oriented towards patient right.
Probe grip
Longitudinal – Probe held softly between thumb and 2-3 fingers close to the probe face, one to two fingers on patient to enhance proprioception.
Transverse – same as Aortic scan.
repère externe?
Midline just cephalad to symphysis pubis.
repère interne?
vessie
Anatomie pertinente de la région?
Bladder, uterus, endometrial stripe, vagina, cervix, rectum, recto-uterine space, vesico-uterine space.
Zone(s) d’intérêt?
Pregnancy: Uterus / endometrial stripe.
Free fluid: Recto-uterine and vesico-uterine spaces.
Technique –> Que faut-il identifier?
Recognize and accurately outline uterine tissue.
Demonstrate bladder-uterine juxtaposition.
Demonstrate continuity of the uterus with the vagina (via the cervix) in the longitudinal plane.
Differentiate the uterus from the vagina in the transverse plane.
Identify a decidual reaction (if visible).
Identify a gestational sac (if visible).
Identify a yolk sac (if visible).
Identify a fetal pole (if visible).
Identify a fetal heart within a fetal pole (if visible).
Accurately determine if a visible fetal heart rate is greater or less than 100 beats per minutes, using either the eyeball method (i.e., counting) or with M-mode (this is a more advanced technique and is not required for certification).
Accurately measure myometrial mantle (if required) by comparing it to the centimeter marks on the ultrasound screen or using calipers.
Recognize that in the longitudinal plane, the endometrial stripe, when visible, should be located centrally along the long axis of the uterus.
Recognize that in the transverse plane, the endometrial stripe, when visible, should be circular and located centrally within the uterus.
Recognize that the vesico-uterine space is between the uterus and the bladder (i.e., anterior to the uterus), that the recto-uterine space is between the uterus and the rectum (i.e., posterior to the uterus). Free pelvic fluid can appear in both locations.
Technique longitudinale?
Longitudinal approach:
Place the probe just above the symphysis pubis with the beam directed towards the patient’s back and the marker oriented towards the patient’s head. Identify the bladder. Heel the probe as needed to place the bladder on screen right. Slide the probe from side to side to find/center the uterus at the point where its image is largest and clearest.
The longitudinal scan is completed by sweeping slowly from left to right until the uterus disappears in both directions, looking for:
ALL criteria of an intrauterine pregnancy OR an endometrial stripe, located centrally along the long axis of the uterus. AND
Pelvic free fluid anterior or posterior to the uterus (i.e., in the vesico-uterine and recto-uterine spaces).
Technique transverse?
Transverse approach:
Place the probe just above the symphysis pubis. Identify the bladder. Sweep the probe caudad to the level of the vagina. This is the starting point for this scan.
The transverse scan is completed by sweeping slowly cephalad from the vagina until the uterus disappears, looking for:
ALL criteria of an intrauterine pregnancy OR an endometrial stripe, located centrally within the uterus.
AND
Pelvic free fluid anterior or posterior to the uterus (i.e., in the vesico-uterine and recto-uterine spaces).
Truc si l’utérus n’est pas visible?
If entire uterus is not visible:
1. Ensure probe placed right against symphysis pubis.
- Press and hold to displace bowel gas.
- Slide the probe off centre and heel / toe back, in transverse view, or sweep back, in longitudinal view. In situations where the uterus is not midline AND is obscured by overlying bowel, the probe is moved AWAY from the uterus and angled back through the bladder. This movement optimizes the use of the bladder as an acoustic window and effectively looks around the bowel gas.
- Fill the bladder. Intravenous fluids are recommended if filling the patient’s bladder is required. Oral fluids are contraindicated as this takes more time and should be avoided in patients who have potential surgical conditions (i.e., ectopic pregnancy). The use of catheters for installation of fluids followed by clamping is not recommended. Depending on the clinical context, patient stability and local resources, it is often preferable to move directly to transvaginal scanning when an empty bladder is preventing adequate views of the uterus.
- Move to transvaginal scanning.
Trucs si utérus et sac gestationnel visible mais pas l’oeuf?
If uterus with gestational sac is visible but yolk sac is not visible:
1. Change view from longitudinal to transverse or vice versa.
- Increase probe frequency. The higher frequency and resultant improved axial resolution will potentially allow visualization of a small yolk sac.
- Move to transvaginal scanning. This higher frequency probe placed closer to the uterus will often allow visualization of a small yolk sac.
piège d’interprétation d’image?
Mistaking a pseudo-gestational sac for an intrauterine pregnancy.
Failure to ensure bladder-uterine juxtaposition. A pregnancy is only considered to be safe if the surrounding tissue is confirmed to be uterine using bladder-uterine juxtaposition and continuity with the vagina (in the longitudinal view).
Mistaking maternal blood flow in the decidual reaction as fetal cardiac activity.
Pièges de génération d’image?
Sweeping too quickly.
Starting the scan in the transverse plane. All First TM scans should start in the longitudinal plane as pelvic anatomy is easy to recognize, even when the bladder is not optimally filled.
Placing the probe too far cephalad. The probe must always be placed initially right against the symphysis pubis to use the bladder as an acoustic window and avoid gas scatter.
Inadequate sweeping (i.e. not sweeping until the uterus disappears).
Sweeping too far caudad in the transverse view (i.e. past the level of the vagina).
Not moving far enough from side to side to find the uterus.
Piège d’intégration clinique?
Assuming that a scan that does not have ALL criteria for a safe intrauterine pregnancy (i.e. not strictly applying the 3-2-1 rule) cannot be an ectopic pregnancy.
Assuming that free fluid in the pelvis is physiologic. Even though physiologic free pelvic fluid is quite common, its presence is not always benign. Scans should always be repeated; the upper quadrants should be interrogated and elective imaging in radiology should be performed based on the clinical context of the patient. Any free pelvic fluid should be considered acute blood until proven otherwise if it is suspected to be increasing in volume, if it fills both the recto-uterine and vesico-uterine spaces (i.e. the fluid surrounds the uterus) or if it is also present in the upper quadrants.
Mistaking physiologic fluid for blood. A small amount of fluid in the pelvis can be normal, provided that it is not increasing in size or extends into the upper quadrants.
Declaring a safe IUP when no yolk sac is visible and a presumed fetal pole does not have an obvious fetal heart. This structure could just be debris within the uterus.
