39yo F no significant pmh p/w R pelvic pain and vaginal bleeding x2wks, getting progressively worse. LMP 7/24. No f/c/n/v/d, CP, SOB, urinary sx. VSS. On exam, pt has R pelvic ttp and blood in vaginal vault with a closed os. Her urine pregnancy test is positive. You perform a bedside ultrasound which is seen below.
What do you see?
What are your next steps in management of this patient?
What are abnormal pregnancies you can see on ultrasound and how do they appear?
What is the first definitive marker of an intrauterine pregnancy (IUP) on ultrasound?
When performing trans-abdominal (TAUS) and trans-vaginal ultrasounds (TVUS), should the bladder be full or empty?
At how many weeks and what beta hCG would you expect to see a gestational sac on TAUS and TVUS?
What is a normal fetal heart rate (FHR)?
What should you avoid while doing an ultrasound evaluating for pregnancy?
- First image shows free fluid surrounding the right ovary which contains a complex adnexal mass. The second image shows no gestational sac within the uterus
- Her ultrasound is concerning for a right ovarian ectopic pregnancy with possible rupture. Her beta hCG comes back at 777. You place another IV, check to make sure her vitals remain stable, and call OB immediately.
- Other abnormal pregnancies you can visualize on ultrasound include
- Threatened Abortion: Normal IUP with vaginal bleeding
- Incomplete Abortion: Retained products with no FHR
- Intrauterine Fetal Demise: Normal IUP with no FHR
- Subchorionic Hemorrhage: area of hemorrhage noted just outside of the gestational sac by ultrasound
- Blighted Ovum: Large gestational sac >2cm with no fetal pole which is evidence of a failed IUP
- Pseudogestational Sac: Can be seen in some ectopic pregnancies from high beta. Typically small and <1cm.
- Molar Pregnancy: Snowstorm appearance with high bHCG
- The first definitive marker of IUP on ultrasound is the yolk sac.
- Trans-abdominal ultrasounds should be performed with the bladder full and transvaginal US should be performed after the trans-abdominal US and post-void.
- Classically, on TAUS, a gestational sac should be visible at 6-7wks or with a beta of ~6000. On TVUS, gestational sacs can be visible at 5-6wks or with a beta of ~2000. However, remember that an ectopic pregnancy is an abnormal pregnancy and does not have to follow the classic rules.
- Normal FHR in pregnancy is between 110-170bpm, depending on gestational age.
- You should avoid using pulse wave doppler in OB ultrasound because of the higher mechanical index (MI) and possible damage to developing fetal tissues.