Department of Emergency Medicine, Stanford University School of Medicine, Palo Alto, CA, USAUnited States
Associate Director, Emergency Ultrasound Program; Department of Emergency Medicine, Stanford University School of Medicine, Palo Alto, CA, USAUnited States
Department of Emergency Medicine, Kaiser Permanente Medical Group, Santa Clara, CA, USAUnited States
Clinical Instructor, Department of Emergency Medicine, Stanford University School of Medi- cine, Palo Alto, CA, USAUnited States
Director of the Ultrasound Program and Assistant Medical Director, Adult Emergency Medi- cine and Imaging, Department of Emergency Medicine, Stanford University School of Medi- cine, Palo Alto, CA, USAUnited States
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We present a case of a female patient who presented to the emergency department (ED) with lower abdominal pain and was found to have a ruptured ectopic pregnancy with hemorrhagic uterine contents mimicking a fetal pole on bedside transabdominal point-of-care ultrasound (POCUS). The case reinforces the importance of accurately interpreting the transabdominal pelvic POCUS for potential mimics of an intrauterine pregnancy. In addition, the case also emphasizes the performance of an abdominal ultrasound for free fluid assessment in the right and left upper quadrants to evaluate for free fluid in patients with concerns for a ruptured ectopic pregnancy.
Keywords: Point-of-care; Ultrasound; Ectopic; Pregnancy; Emergency medicine
The importance of timely diagnosis of ectopic pregnancy cannot be understated. The incidence
of ectopic pregnancy in the general population is approximately 2%.1 The prevalence of ectopic
pregnancy in the emergency department (ED) patient population is estimated around 8%.2
Ruptured ectopic pregnancy comprises a significant proportion of these cases. Risk factors
for ectopic pregnancy include previous ectopic pregnancy, pelvic inflammatory disease,
Chlamydia trachomatis infection, prior intrauterine surgeries, tubal surgery, fertility treatment,
endometriosis and smoking.3 Ruptured ectopic pregnancy also comprise a significant proportion
of maternal death.1 Fortunately, with appropriate utilization of ultrasound (US) and lab analysis,
evaluated by the Emergency Physician (EP) at the bedside. The presence of an intrauterine
for an ectopic pregnancy, but a proportion of these patients will 4,5 go on to have a normal IUP.4,5 However, if there is also evidence
of an adnexal mass then there is a higher likelihood for being an 5,6 ectopic pregnancy.5,6
When an ectopic pregnancy is a consideration, a
transabdominal ultrasound should be followed by a transvaginal
study to adequately evaluate the adnexa.2,5 When echogenic
material, such as clotted blood, is seen within an anechoic uterine
sac, the POCUS evaluation can be challenging and must be
differentiated from a true yolk sac and fetal pole. Furthermore, in
patients with abdominal pain and a possible ectopic pregnancy,
a ruptured ectopic pregnancy must be considered. This timely
diagnosis is facilitated with the addition of an abdominal
ultrasound for free fluid assessment in the right and left upper
quadrants, as the presence of free fluid significantly increases the
likelihood of a ruptured ectopic pregnancy requiring operative
management.7
A young female patient presented to the ED complaining of
abdominal pain for three days. The pain started in both upper
quadrants with migration to the right lower quadrant six hours
prior to presentation. The pain initially was intermittent, but had
become more constant over several hours with associated nausea
without vomiting. She had one episode of vaginal bleeding with
clots during the day. She denied fevers, chills, diarrhea, melena,
dysuria, vaginal discharge, chest pain or shortness of breath. On
gynecological history, she reported her Last Menstrual Period
(LMP) was over a month prior and denied the possibility of
being pregnant despite having one current sexual partner without
contraception use. She had one previous spontaneous abortion
three years prior and denied previous sexually transmitted
infections. She had no other past medical or surgical history.
Her social history was positive for daily tobacco and occasional
alcohol use.
Image 1: Transabdominal Pelvic Ultrasound – Linear echogenic material within an anechoic intrauterine sac.
On physical examination, she was noted to be in
moderate distress secondary to pain. Her vital signs included a
heart rate of 68 bpm, blood pressure of 117/64 mmHg, respiratory
rate of 18 per minute, temperature of 37 degrees Celsius and
oxygen saturation of 98% on room air. Her abdomen was soft,
but tender to palpation diffusely, especially in the right lower
quadrant. She exhibited voluntary guarding without rebound 2,5 tenderness. Pelvic exam was notable for a closed os, tenderness
to palpation over the right adnexa, and no cervical motion
tenderness. There was a small amount of blood in the vaginal
vault. All other physical exam components were unremarkable.
Initial ED interventions included insertion of an
intravenous catheter and obtaining the following tests: a
urinalysis, urine pregnancy test, complete blood count and
comprehensive chemistry panel. Pain control, antiemetics and a
normal saline bolus were also ordered. The point-of-care (POC)
urine pregnancy test resulted as positive and a quantitative
pregnancy test was added.
The initial POCUS exam included the transabdominal
pelvic view (Image 1 and Video 1) which shows an intrauterine
fluid-filled sac with hyperechoic linear contents. The ovaries were
poorly visualized. A definitive intrauterine pregnancy (IUP) was
initially considered, as the linear echogenic material was similar
in appearance to a fetal pole. However, there was irregularity in
the structure of the intrauterine contents, significant free fluid in
the pelvis and no evidence of fetal heart activity. Then, the right
upper quadrant abdominal ultrasound was performed (Image 2
and Video 2). This was positive for free fluid around the inferior
liver edge within the superior paracolic gutter. These findings
increased the suspicion for a ruptured ectopic pregnancy. Ob/Gyn
was immediately consulted and requested a transvaginal US by
the radiologist per institution protocol for image archiving while
they evaluated the patient and prepared for potential operative
intervention. The radiologist was able to identify the ectopic
pregnancy with fetal heartbeat on transabdominal US due to the Video 1: Transabdominal Pelvic Ultrasound – Linear echogenic material within an anechoic intrauterine sac.
Image 2: Right Upper Quadrant of FAST scan – Anechoic free fluid seen around the caudal tip of the liver.
Image 3: Transabdominal Pelvic Ultrasound of Right Adnexa (zoomed) – Gestational sac adjacent to right ovary.
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full bladder and thus sent the patient back to the ED without
performing the transvaginal scan (Image 3 and Video 3).
The patient was taken emergently to the operating room
(OR) for a laparoscopic right salpingectomy and a dilatation
and curettage. The operative report described “approximately
200 cc of blood and clot in the pelvis” with a “1-2 cm mass
within the right fallopian tube.” Pathology was not completed
on the uterine products. The patient had an unremarkable post-
operative course and was discharged the following morning,
only twelve hours after presentation to the ED.
Diagnosis of ectopic pregnancy requires careful interpretation
of lab and POCUS examinations. Stein et al performed a meta-
analysis that confirmed that EPs are competent in diagnosing
ectopic pregnancy by POCUS with a sensitivity of 99.3% and a
Video 2: Right Upper Quadrant of FAST scan – Anechoic free fluid seen around the caudal tip of the liver.
Video 3: Transabdominal Pelvic Ultrasound of Right Adnexa (zoomed) – Gestational sac adjacent to right ovary.
negative predictive value of 99.9%. With this increasing accuracy
of US, reliance on one-time serum beta-hCG levels have proven
unreliable as a diagnostic tool due to poor correlation of a single 8,9 measurement with ectopic pregnancy.8,9 Wang et al evaluated
pregnant patients with varying beta-hCG levels and concluded
that a beta-hCG discriminatory zone cannot reflect ectopic
pregnancy risk.9 Some patients with high beta-hCG levels and no
definitive IUP on US can develop a normal IUP on subsequent 4,5,9 scans. Thus, administering medication to terminate the
pregnancy, or performing surgery, is not advisable based solely
on a lab value. Rather, the beta-hCG level should be interpreted
in conjunction with the US results and not independent of them.4
Transvaginal US is the single best diagnostic test
for ectopic pregnancy.2 Careful interpretation of the pelvic
ultrasound is paramount to prevent in advertent harm to normal
early pregnancies.10 When the transvaginal ultrasound shows an
adnexal mass and absence of an intrauterine pregnancy, it carries
the highest likelihood ratio of being an ectopic pregnancy.4,5
However, the pelvic US can be indeterminate in diagnosing an
ectopic pregnancy. One indeterminate finding, as illustrated in
our case, includes echogenic material within the gestational sac
that is ill-defined and inconsistent with a normal intrauterine 2,10 pregnancy.2,10 A retrospective study by Benson et al showed that
16.6% of patients with ectopic pregnancies have intrauterine fluid
on transvaginal ultrasound, proving that important interpretation
of that fluid is imperative in correctly diagnosing an ectopic
pregnancy.11 According to the authors, type A fluid, or fluid with
pointy shaped edges, echoes and/or debris is more common in
ectopic pregnancies than type B, or anechoic, intrauterine fluid.11
The obvious challenge in our case was the presence of
intrauterine echogenic linear contents that, on initial evaluation,
seemed to mimic a gestational sac with fetal pole. However, with
the absence of cardiac activity and with a high clinical suspicion
and careful interpretation of the POCUS findings, the ill-defined
contents were differentiated from an actual IUP. The presence
of free fluid near the caudal tip of the liver on an abdominal
ultrasound for free fluid increased the likelihood of a ruptured
ectopic pregnancy requiring surgery.
Ultimately, this case report emphasizes the importance
of careful interpretation of the pelvic POCUS and the
additional performances of an abdominal ultrasound for free
fluid assessment in the right and left upper quadrants when
evaluating for a ruptured ectopic pregnancy. The physician must
differentiate ill-defined echogenic uterine sac contents from an
IUP, as these findings can be seen in cases of ectopic pregnancy
and, when shaped in a way similar to our images, can mimic a 10,11 fetal pole. Contents within an intrauterine sac without cardiac
activity require transvaginal US to analyze the adnexa and an
abdominal ultrasound for free fluid assessment in the right and
left upper quadrants to evaluate for free fluid to assess for ectopic 8,12 pregnancy rupture.8,12