You really hope today’s shift is better than yesterday’s. You had to tell a really nice homeless man that internal medicine refused to admit him for his femoral DVT because he doesn’t meet “admission criteria” and that he would have to find the means to pay for his outpatient Lovenox on his own. Then a patient came into the ED with chronic pack pain, and you ended up diagnosing him with metastatic prostate cancer with spinal metastases.
Your next patient seems nice enough. She’s 29 years old and is accompanied by her husband at the bedside. She starts by saying, “Please just tell me my baby is OK. We’ve been trying to conceive all year!” She is a G1P0 who is otherwise healthy and without any co-existing conditions. She came into the ED because she’s been having some mild cramping and some intermittent spotting. Her OB appointment is next week, and she has not had any prenatal care. She is taking over-the-counter prenatal vitamins regularly, and Tylenol to help with her pain. She appears anxious and worried and is hanging on every word, gesture, and movement you make in the room.
Her vital signs are normal and her physical exam is only remarkable for some mild suprapubic tenderness on palpation, and a scant amount of blood near her closed cervix in her vaginal vault. You send off a serum quantitative hCG level given the fact that she doesn’t know exactly when her last menstrual period was. You also order a peripheral IV so you can send off a basic CBC with diff, BMP, pT/pTT, type & Rh, and provide her with IVFs to get her prepared for her pelvic ultrasound and UA. You give her some Tylenol for her abdominal cramping and keep her NPO otherwise.
She questions you with her eyes intently and says, “What do you think could be going on with my baby? My pregnancy test at home was positive. I just don’t know why I’m having all of this bleeding and pain.”
You gently coax her into the lithotomy position so that you can perform a good transabdominal pelvis scan followed immediately by a transvaginal evaluation of her uterus and adnexa. You insert the intracavitary probe with the indicator pointing anterior towards the patient’s pubic symphysis. You carefully sweep through the patient’s uterus and this is what you see (above).
What do you see on your ultrasound?
What do you need to do now? Conclusion on next page
Dx: Blighted Ovum
Within the uterus, you see a clear view of a gestational sac that measures almost 30 mm in its widest diameter. As you fan through, you do not see any evidence of a yolk sac or a fetal pole (above image).
The patient’s labs start to return and she has a quantitative hCG level of 3500 mIu/mL. With a quantitative hCG level that high, you would expect to see a yolk sac already.
Because the mean gestation sac measures >14 mm, and there is no visible yolk sac on the scan, it is likely that your patient has an anembryonic gestation or blighted ovum at this time.
You walk back into your patient’s room and pull up a chair so that you can have an uninterrupted conversation with her and her husband about her ultrasound findings. You hold her hand and explain to them that the ultrasound images obtained today suggest that she is having a blighted ovum in her uterus and that it doesn’t look promising for a viable pregnancy. You take your time to explain to her and her husband that it wasn’t anything they did wrong, and that it doesn’t mean they can’t try again in the near future. You reinforce that many couples have had miscarriages or a blighted ovum, and are still able to conceive and have beautiful, healthy babies in the future. Your nurse provides them with multiple pamphlets and references that they can read and refer to with any questions they may think of after they leave the ED. You recommend subsequent imaging in the next week or two to ensure that nothing else has progressed unexpectedly. The patient and her husband thank you for your time and empathy, and schedule their outpatient radiology and OB appointments as they walk out of your ED. It doesn’t appear as if your clinical black cloud is going to clear up anytime soon. You prepare for your next case with hopes of sunshine and silver linings.
Continue NEXT for tips and tricks
Tips & Tricks for Ultrasound Evaluation of a Blighted Ovum
01. Always begin your pelvic ultrasound with a full bladder and a transabdominal scan to map out the important organs and structures. A full bladder provides an excellent acoustic window. Remember that everyone’s anatomy is different and once you start performing the intracavitary portion of the exam, your view is more limited because of the confined space.
02. On your transabdominal scan, determine how the uterus is lying and determine if there is any obvious free fluid or intrauterine findings.
03. To perform the endovaginal portion of the pelvic ultrasound, start by covering the intracavitary transducer with a gel filled sheath and apply a copious amount of clean gel to the outside of the sheath.
04. Insert and advance the transducer with the indicator marker pointing anteriorly towards the patient’s pubic symphysis. Alternatively, you may let the patient insert the probe herself as this method is often less uncomfortable.
05. Scan through the uterus in this sagittal plane, noting the presence or absence of a gestational sac, yolk sac, fetal pole, fetal heartbeat, etc. If the patient has a positive urine or pregnancy test, and the uterus appears empty, an ectopic pregnancy should be suspected.
06. If you see a gestational sac, carefully evaluate the size and shape of the sac, and correlate the size of the sac to the quantitative hCG level and date of the patient’s LMP.
07. When the gestational sac is larger than 10 mm and no yolk sac is identified, it is likely that the patient has a blighted ovum or anembyonic pregnancy.
08. If you see a yolk sac that is larger then 7 mm but you do not see a developing fetal pole, this also suggests a nonviable intrauterine pregnancy.
09. Remember that the fetal pole is typically seen on transvaginal ultrasound at approximately 5-6 weeks gestation. You should see a fetal pole when the gestational sac is >18 mm on transvaginal ultrasound or >25 mm on transabdominal ultrasound.
10. At times, it is difficult to determine if the sac you are seeing is a true gestational sac, or a pseudogestational sac associated with an ectopic pregnancy. To determine the difference, look at the location of the sac. A gestational sac will be seen within the decidua, whereas pseudogestational sacs are usually in the endometrial canal. When color Doppler is applied over a gestational sac, it will be “warm” and highlight with color. A pseudogestational sac is usually “cold” and no color is visualized on color Doppler.
11. Rememeber, the mean diameter of the gestational sac +42 should = the gestational age of the fetus in days. Use that number to help determine if you see the expected fetal structures for that size of the gestational sac.
12. Patients with a suspected blighted ovum warrant an OB/Gyn consultation in the ED or very close outpatient OB/Gyn follow-up. It is important that patients undergo a follow-up ultrasound with a high-resolution ultrasound machine to ensure that a small yolk sac or fetal pole is not overlooked.
Brady Pregerson manages a free on-line EM Ultrasound Image Library and is the editor of the Emergency Medicine Pocketbook series. For more information visit EMresource.ORG.
Teresa S. Wu is the Associate Residency Director, and Director of Ultrasound and Simulation Programs and Fellowships, for the Maricopa Emergency Medicine Program in Phoenix, Arizona.