Real-Time Readings
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You are working a 48-hour shift in a remote hospital with limited ancillary services. It’s been busier than usual, but as things stand now, you may actually be able to clear the board before your colleague arrives to relieve you. All of the admits have gone upstairs and there are just two patients remaining in the ED, both of which you will need to see. You pick up the first chart and read the triage chief complaint: “Baby not moving”. 

You walk into the room and smile and introduce yourself to a 19-year-old G1P0 female who states that she is 26 weeks pregnant. She says she is scared because she hasn’t felt her baby move in the past six hours. She’s asks if it could be due to the tuna she ate yesterday, because today a friend told her that the mercury in tuna could be dangerous to her baby. She denies pain or cramping and when she arrived there had not been any vaginal bleeding, but when she just went to the bathroom to provide the urine sample she noticed that she was spotting. Otherwise she is healthy with an uneventful pregnancy until now.
On exam she is definitely on the nervous side. Vital signs show that she is afebrile with a heart rate of 104, a blood pressure of 135/85 and a respiratory rate of 20. The patient’s head and neck are normal to inspection. Her lungs are clear, and her heart is regular. Her abdomen is gravid, but non-tender. A pelvic exam is deferred. Her legs are unremarkable except for trace symmetric bipedal edema, which the patient herself had not even noticed. There is not erythema or tenderness and Homan’s sign is negative. You notice that her wedding band does not look tight.

(Image 1)
altSince it is 5am and there is no ultrasound tech on call currently, you decide that your first course of action will be to do your best to reassure this mother-to-be by using your bedside ultrasound skills with the ED machine. From experience you know that most of the time in similar situations you are able to see the fetal heart beat as well as gross fetal movement, and you can also demonstrate this to the mom. More importantly, to you at least, you can altmake sure nothing else is going on such as free fluid in the abdomen or an empty uterus. If you can accomplish this, everybody usually ends up happy and the patient can go home to see her obstetrician later the same day or tomorrow in the office. If she insists on a formal ultrasound you can always offer to let her wait until 8am. This approach is particularly helpful when fetal heart tones are challenging to detect with a Doppler.
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Left is an image from your patient (Image 1) along with a few other images of the uterus in a pregnancy.  (Images 2 & 3) What does each image show? Is there any other evaluation your patient requires at this time?

 
 
 
 
For the diagnosis and discussion, see NEXT
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In most cases, once the fetus reaches a gestational age of 26 weeks, a transvaginal scan is not necessary. The images were all taken via the trans-abdominal approach with a curvilinear probe. Image 1 is a transverse view of the pelvis with a good view of the fetal spine. Note that dark acoustic shadowing that projects farfield off each dense vertebral body. The absence of fully developed intervertebral discs at this stage allows propagation of some sound waves farfield and produces the serrated acoustic pattern noted behind the spine. Image 2 shows a more complete image of the fetus in transverse plane with the placenta seen anteriorly. The fetal skull is hyperechoic, but allows penetrations of some sound waves so the brain can be visualized as well. The intra-abdominal organs and the placenta are both of mixed echogenicity and will appear as a heterogeneous mix of white and gray on ultrasound. The amniotic fluid is anechoic and appears black on the screen.  Image 3 shows a rare image of an early pregnancy in a bicornuate uterus. There is an empty sac in the left horn and a fetal pole within another sac in the right horn. The amniotic fluid in the sacs is anechoic. The pole and double ring of the sac border are both hyperechoic. The uterine body is of mixed echogenicity.

When you review the trans-abdominal images you are able to see the fetal heart beating and show it to mom. In addition, the child is noted to be moving quite actively. Your patient seems quite happy and thanks you for the reassurance. But you are not quite done yet. She needs her vital signs repeated. Blood pressure should usually be less than 125/75 in pregnancy. If her blood pressure remains elevated, you’ll need to consider additional testing for pre-eclampsia, and possible admission.

Continue next for Ultrasound Tips
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Pearls & Pitfalls for Pregnancy Ultrasound

// Know your limitations: Ultrasound (US) may help clarify findings elicited by a thorough H & P. When used correctly, it can greatly improve diagnostic accuracy and help guide patient management, especially for time-critical diagnosis and treatment of unstable patients. If you use US in your ED, your department should have a quality improvement program set up that is approved by both ED administration and radiology.
 
// Start with a trans-abdominal approach: If the patient’s gestational age is greater than 6-8 weeks by dates, you should be able to visualize changes suggestive of an intrauterine pregnancy. Obtain both transverse and sagittal views of the uterus and pelvis. If you do not see an IUP at this stage, scan through the abdomen and pelvis and assess for free fluid. A small amount of physiological free fluid can be normal, but in the absence of a double-decidual sign around a gestational sac, this free fluid may mean your pregnant patient has an ectopic pregnancy.
 
// Know what to look for: A normal uterus is approximately 6 cm long and 3 cm wide. It enlarges during pregnancy and the first clear sonographic sign of pregnancy is usually the gestational sac seen at approximately 5 weeks. Beware of pseudosacs. After the gestational sac forms, you will see a yolk sac develop, and soon afterwards you should be able to see a fetal pole on US. Cardiac activity should be noted within the embryo between 6 to 8 weeks of gestational age.
 
// Ensure comprehensive follow-up studies: Always inform your patient that you are performing a focused and limited beside ultrasound scan to ensure that there is nothing emergent that needs to be cared for immediately. Your patient should be advised that a comprehensive follow-up scan should be performed to fully evaluate the pregnancy as soon as possible. If a subtle abnormality is noted, a full, comprehensive scan should be performed within 24-48 hours.
 
// Don’t be a photographer: Avoid the temptation to print out a thermal copy or give the patient a copy of their ultrasound scan. Detecting subtle sonographic changes of development are outside of our realm of expertise and you don’t want patients to accept your scan as their final and comprehensive fetal evaluation.
 
// Practice Makes Perfect: With bedside ultrasound there is no substitute for experience. The more ultrasounds you do, the better you will be able to differentiate abnormal from normal, even when you may not be sure exactly what the abnormality is. A free image library of normal and abnormal ultrasounds is available through www.epmonthly.com, in the Real-Time Readings department. 

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