US Probe: Ultrasound for Ectopic Pregnancy
- Apr 26th, 2017
- Mark Gonzales
Author: Mark Gonzales DO, MPH, FAAEM (Attending Physician and Ultrasound Director, Carolinas HealthCare System – University Hospital, Charlotte, NC) // Edited by: Stephen Alerhand, MD and Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital)
You are just wrapping up your resuscitation of a patient with acute respiratory failure. As you are about to leave the room, a concerned RN interrupts you. He is concerned about a 23-year-old female patient who presents with acute-onset lower abdominal pain. She is G3P0030 and had received Methotrexate for a presumed ectopic pregnancy 24 days earlier. She has had no significant vaginal bleeding or discharge today, but reports having had moderate vaginal bleeding after her Methotrexate treatment. Her two prior pregnancies terminated due to spontaneous abortion. The patient is afebrile with a blood pressure of 104/66, heart rate of 60, respiratory rate 18, and oxygen saturation of 100% on room air. She appears moderately distressed and has significant bilateral lower abdominal tenderness on exam.
You place her in a supine position, grab your ultrasound machine and perform a transabdominal assessment of the pelvis with the curvilinear probe:
You note the presence of free fluid in both the sagittal and transverse views. You also note an abnormality in the right pelvis that catches your eye, so you zoom in on this structure:
Given the patient’s history, the mass in the image concerns you for an ectopic pregnancy, and with the previously noted free fluid in her pelvis, you slide the probe to the right upper quadrant for a view of Morison’s pouch:
With evidence of free fluid in Morison’s pouch, you put down the probe, ask the nurse to start two large bore IV’s, and head to your desk, this time uninterrupted. You place a STAT page for the on-call OB/Gyn as well as orders for STAT blood products. You also have the secretary notify the Operating Room. The patient’s preliminary labs show a positive urine pregnancy test and a Hb/Hct of 12.7/40. Her blood pressure and heart rate remain stable. The OB/Gyn consultant comes downstairs, reviews your images, and agrees with your assessment. The patient is taken to the OR for an emergent laparoscopy, where 750 cc of hemoperitoneum is evacuated. The patient also undergoes a right salpingectomy due to ruptured ectopic pregnancy. The OB/Gyn later tells you that the patient’s Hb/Hct dropped to 7.6/24 intra-operatively, but she expects the patient to do well. You write your ED nurse a compliment card to commend him for the heads-up and continue your shift.
Six take-away points for this case:
1) In one study, the presence of non-traumatic free fluid in Morison’s pouch in a female with suspected ectopic pregnancy was 99.5% specific for ruptured ectopic pregnancy requiring operative intervention, having a positive likelihood ratio of 112.1
2) Failure of methotrexate treatment for ectopic pregnancy is uncommon. In a systematic review that included 26 observational studies of 1,300 women with ectopic pregnancy, the success rate of methotrexate was 88% for single dose therapy and 93% for multiple dose therapy.2
3) Obstetric and abdominal US are must-know applications for all emergency physicians. This is a classic example demonstrating the power of bedside ultrasound in its ability to meaningfully affect patient care for a time-sensitive diagnosis in the Emergency Department.
4) Remember that young patients may be able to compensate and maintain an adequate heart rate and blood pressure in the setting of ruptured ectopic pregnancy and intravascular volume depletion. Do not let normal vital signs fool you.
5) For further interest, ACEP recently released a new iBook in 2016 titled “Point-of-Care OB Ultrasound.”3
6) Don’t forget to thank your nurses.
References / Further Reading
1) Moore C, Todd WM, O’Brien E, Lin H. Free fluid in Morison’s pouch on bedside ultrasound predicts need for operative intervention in suspected ectopic pregnancy. Acad Emerg Med. 2007 Aug;14(8):755-8.
2) Tulandi T. Ectopic pregnancy: Choosing a treatment and methotrexate therapy. UpToDate. 27 Mar 2017.
3) Jones R and Goldstein J. “Point-of-Care OB Ultrasound.” First Edition. American College of Emergency Physicians, 2016. iBooks. https://itun.es/us/o1C4eb.l