Case #11: Oh Baby
Jennifer Marshalla, M.D.

HPI: 24 yo female presents to the ER with vaginal bleeding. G3 P2. LMP a few months ago. Reports mild spotting started yesterday. She has not taken a home pregnancy test. She reports "I think I might be pregnant."

Physical Exam:

Mild bleeding from closed os. No CMT. No adnexal tenderness. Abdomen: benign, soft, nontender.

Bedside Ultrasound:

What are the landmarks in this image?

What view is this image? Transabdominal or transvaginal? Longitudinal or transverse?

Transabdominal Longitudinal View: 

M-mode:

Ultrasound Education:

How to obtain fetal heart tone using M-mode:

-First make sure the ultrasound is on OB mode, using either the transabdominal or transvaginal probe.

-Find uterus with fetus, looking for moving heart.

-Hit m-mode. The cursor line from top of screen will appear and place it over the heart.

-Hit freeze.

-Measure peak to peak, or valley to valley

-Calculated fetal heart rate will appear on the screen for you!

Why is doppler not ideal?

Although ultrasound is considered relatively safe, we can take efforts to try and reduce harm while using ultrasound. Spectral Doppler violates the ALARA (as low as reasonably achievable) principle in imaging. The ALARA principle is to minimize harm (i.e. using the lowest amount of energy possible).

Spectral doppler uses higher energy than the M-mode to detect fetal heartbeat. This higher energy has been shown to have adverse effects on the unborn fetus in animal studies. As the ultrasound travels through tissues, the tissues can absorb that energy emitted by the ultrasound waves. This energy can be converted into heat depending on the frequency and intensity of the energy. It is thought that the higher energy can cause increases in temperature which can damage biological tissues.

Conclusion:

Obtaining fetal heart tones (FHT) by using m-mode is safer for the unborn fetus and should be used whenever possible to prevent potential harm.

Additional resources:

https://www.acep.org/sonoguide/obgyn.html

http://jeffsono.org/spectral-doppler-for-fetal-heart-rate-a-sono-no-no/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4547707/

July Tape Review for CME

Thursday 7/5 at 9:00am, Dr. Hart

Thursday 7/12 at 9:00am, Dr. Burns

Thursday 7/19 at 9:00am, Dr. Chan

Thursday 7/26 at 9:00am, Dr. Lambert