This image is brought to us by Drs. Anna Yaffe and Sean Lowe. They used transvaginal ultrasound to evaluate a 28-year-old G2P0 with multiple obstetric complaints and a positive urine pregnancy test. Vaginal bleeding and pelvic pain are common complaints in first-trimester pregnancy. When formulating a differential, always have ectopic pregnancy at the front of your mind.
Remember our job as emergency physicians is to rule out ectopic pregnancy by finding an intrauterine pregnancy (IUP). In the simplest terms: if the patient has a + ß-hCG and you cannot find an IUP, it is an ectopic pregnancy until proven otherwise. Intrauterine pregnancy is defined as a gestational sac that contains either a yolk sac or a fetal pole.
This image shows the uterus in the longitudinal plane using an intracavitary probe with a clear yolk sac, making this a definitive IUP.
Image 1
Looking at the above image:
What gestational age do you estimate for this fetus by looking at this image alone?
- Probably around 6, as transvaginal ultrasonography should pick up a yolk sac at 6 weeks and begin seeing a fetal pole by 7 weeks. At 8 weeks you should be able to see cardiac activity using transvaginal imaging.
What quantitative serum ß-hCG would you expect to see in this mother’s lab work based on this ultrasonographic image?
- Probably a little bit more than 2500 (mIU/ml), as this is the value at which you begin to see a yolk sac by transvaginal ultrasonography, though these numbers can be highly variable.
Here is a simple breakdown from Rosen’s:
Reference: Debra E. Houry Jean T. Abbott Chapter 177. Acute Complications of Pregnancy. Marx: Rosen's Emergency Medicine: Concepts and Clinical Practice, 6th ed. 2006 5031-66.
Date: September 2012