A 26 y.o. G1P0 female presented to the Emergency Department for abdominal pain and near-syncope. Notably, four days ago she was seen at an outside hospital and treated with Methotrexate for likely ectopic pregnancy. Today, she reports worsening lower abdomen and pelvis pain without any vaginal bleeding or discharge. Earlier today, she had an episode of near syncope upon standing which prompted her to present to the ED. No significant PMHx or PSHx.
Upon arrival, she is placed in a high acuity bed. Initial vitals: BP- 109/75, HR – 109 O2 – 100% on RA, RR – 18, Temp – 98.9. Given her recent history you contact the OB team and begin your bedside ultrasound examination.
In addition to stabilizing the patient, which ultrasound study should you perform at this time?
FAST Exam: Given this patient’s recent medical history there is high suspicion for a ruptured ectopic pregnancy. In the setting of recent near-syncope and worsening abdominal pain performing the FAST will allow you to quickly gauge if there is free fluid present in the abdomen. This information will quickly help the OB team decide if this patient needs to go to the OR immediately. This also may be the first sign of severe pathology before her vitals begin to deteriorate.
What do you see in the images below? What is your next step in management?
Free fluid is visualized throughout the FAST exam. When performing a FAST, ensure you are thoroughly inspecting Morison’s pouch as well as completely visualizing the inferior pole of the liver and kidney. In the LUQ view, fluid is present between the spleen and diaphragm. The suprapubic view is notable for fluid between the bladder and uterus. A FAST exam can be positive with as little as 100cc of fluid in the abdominal cavity. In this case, there appears to be much more than that and you are thankful that the OB team is already on their way.
Case Conclusion: Prior to evaluating the patient, the OB team ordered a formal ultrasound study. At bedside, OB reviews your bedside ultrasound images and makes the decision to take the patient immediately to the operating room. In the OR, she undergoes a diagnostic laparoscopy and left salpingectomy with removal of a mid-fallopian ruptured ectopic pregnancy. Additionally 600 cc of blood is evacuated from the pelvis. The patient recovers quickly and is discharged home later that day in stable condition. In this case, bedside US performed by the ED providers expedited care allowing the patient to make it to definitive management in the operating room before she became clinically unstable.
Additional Learning Topic: Possible Ultrasound Findings when Evaluating for Ectopic Pregnancy
- Empty uterine cavity
- In a female patient, positive BhCG, lower abdominal pain and no gestational sac visualized in the uterus on ultrasound, ectopic must be suspected. By 5 weeks, a gestational sac with yolk sac should be visualized. If only the gestational sac is present without a yolk sac at 5 weeks,, this does not confirm an IUP and the patient may need to return in 24-48 hours for a repeat scan.
- Pseduo-gestational Sac
- A gestational sac should appear with a double echogenic rim, however it is possible that a pseudo-gestational sac forms with just a single echogenic rim. This should not be mistaken for an intrauterine pregnancy as it may lead to prematurely ruling out a possible ectopic pregnancy.
- ‘Ring of Fire’ sign
- If a cyst-like structure is located outside of the uterus, placing color flow on the image may help further identify the structure. First, it will ensure this is not a vessel but also the edges should brightly enhance giving it a ‘ring of fire’ appearance. When examining the adnexa, this can be seen in a corpus luteal cyst or an ectopic pregnancy.
- Extra-uterine fetal cardiac activity
- While rare, seeing extra-uterine fetal cardiac activity is 100% specific for the diagnosis of ectopic pregnancy. M-mode or pulse wave can be used to help improve visualization of possible cardiac activity.
- Free fluid in the Pouch of Douglas
- Also known as the rectouterine pouch, it is a space located between the uterus and rectum. This is a common potential space for fluid to accumulate. While fluid may be present due to physiologic reasons such as a ruptured cyst its presence should increase suspicion for an ectopic pregnancy. Free fluid in the setting of a positive B-hCG is 70% specific and 63% sensitive for ectopic pregnancy.