Ultrasound for Diagnosis of Ectopic Pregnancy
Author: Christine B. Irish, MD, Director of Emergency Ultrasound, Department of Emergency Medicine, Maine Medical Center, Portland, Maine.
Peer Reviewer: Roytesa R. Savage, MD, Assistant Professor of Pediatrics, Brody School of Medicine at East Carolina University, Greenville, NC.
Introduction
Ectopic pregnancy continues to be a leading cause of maternal morbidity and mortality during the first trimester. Ectopic pregnancy occurs in 2% of all pregnancies, but the incidence can be as high as 6-16% in patients presenting to the emergency department (ED) with vaginal bleeding or abdominal pain.1,2 Between 1976 and 1993, the incidence of ectopic pregnancy rose from 11.2 to 18.8 per 1000 pregnancies in Northern Europe and continues to rise in patients older than age 35 due to advanced reproductive techniques.3 As many as one in five patients may experience vaginal bleeding and abdominal pain during pregnancy.
The use of diagnostic ultrasound, first transabdominal and now transvaginal, has revolutionized the care of first trimester patients. Ultrasound may help clarify pregnancy dating, establish the number of intrauterine pregnancies, or determine pregnancy loss. In the ED setting, the most critical role of transvaginal ultrasound is to rule out ectopic pregnancy. The current standard of care includes a transvaginal ultrasound and beta-hCG level in any patient who is at risk for ectopic pregnancy. Ultrasound may be diagnostic in as many as 60-70% of patients during their initial ED presentation.4 The remainder of patients are in an indeterminate group, which can challenge the most experienced physician.
Many considerations exist regarding the appropriate management of first trimester patients with vaginal bleeding and abdominal pain. Clinicians should understand the value of the history and physical exam in ruling out ectopic pregnancy, as well as the indications for transvaginal ultrasound in patients with low beta-hCG levels. This article will explore these concepts and the various challenges that emergency providers face when evaluating first trimester patients with abdominal pain and vaginal bleeding.
Are History and Physical Exam Predictive of Ectopic Pregnancy?
Source: Dart RG, Kaplan B, Varaklis K. Predictive value of history and physical examination in patients with suspected ectopic pregnancy. Ann Emerg Med 1999;33:283-290.
Dart and colleagues examined various components of the history and physical exam in pregnant patients with vaginal bleeding or abdominal pain to determine which findings were predictive of ectopic pregnancy. The authors proposed that by identifying high-risk history or physical exam findings, patients with indeterminate ultrasounds might be further risk stratified and that inpatient admissions for observation and serial testing could be avoided in low-risk patients. This was a prospective, observational study of consecutive patients who presented to an urban ED over a 12-month period. Patients were age 18 years or older, had positive beta-hCG testing, and had abdominal pain or vaginal bleeding.
A total of 441 patients were enrolled and 57 patients (13%) had a final diagnosis of ectopic pregnancy. All patients were classified with a final diagnosis from one of three predefined categories, normal intrauterine pregnancy (IUP), abnormal IUP, or ectopic pregnancy. Variables such as peritoneal signs or cervical motion tenderness were categorized as either present or absent and appropriate statistical analysis was performed using chi-squared and Fischer's exact testing. Combination and regression analysis testing was used to determine combinations of variables that could be high or low risk for ectopic pregnancy.
Historical factors that increased the risk of ectopic pregnancy included lateral, sharp, or moderate to severe pain, as well as a previous history of IUD (intrauterine device) use, infertility, pelvic surgery, or tubal ligation. Physical exam findings such as cervical motion tenderness, peritoneal findings, and lateral or bilateral abdominal pain were associated with increased risk of ectopic pregnancy. The authors concluded that although certain combinations of predictive variables were associated with increased risk of ectopic pregnancy, no combination could rule in or rule out ectopic pregnancy with a high degree of certainty.
Commentary
Recent literature4,5 has shown that the incidence of ectopic pregnancy in patients presenting to an ED with vaginal bleeding or abdominal pain is between 9% and 13%. Physicians typically use a combination of transvaginal ultrasound, quantitative beta-hCG levels, and less often progesterone levels to diagnose ectopic pregnancy in patients presenting to the ED with vaginal bleeding or abdominal pain during the first trimester of pregnancy. Unfortunately, each of these diagnostic strategies has various considerations that limit their utility, including time, expense, and availability. Twenty-four hour ultrasound access is not available at many institutions. At some institutions, guidelines exist that prohibit the use of ultrasound if the quantitative beta-hCG level is below a predetermined threshold, often 1000-1500 mIU/mL.6 These authors evaluated whether any history or physical exam findings could be used to diagnose ectopic pregnancy with a high degree of certainty. While there were several findings such as cervical motion tenderness or peritoneal signs that were associated with increased risk of ectopic pregnancy, no combination of factors was diagnostic of ectopic pregnancy. This study reinforces the importance of adjunctive testing in all first trimester patients who are at risk for ectopic pregnancy. Physicians can not rely solely on history and physical exam findings to exclude this dangerous condition.
Can Absolute Beta-hCG Value be Used to Rule Out Ectopic Pregnancy?
Source: Kohn M, Kerr K, Malkevich D, et al. Beta-human chorionic gonadotropin levels and the likelihood of ectopic pregnancy in emergency department patients with abdominal pain or vaginal bleeding. Acad Emerg Med 2003;10:119-126.
The quantitative beta-hCG value and transvaginal ultrasound findings often are used as complimentary parts of the evaluation of pregnant patients with vaginal bleeding and abdominal pain. However, some guidelines call for deferring the transvaginal ultrasound in cases of beta-hCG levels of less than 1500 mIU/mL. This study compared the beta-hCG levels of patients with ectopic pregnancy, IUP, and abnormal IUP.
The authors performed a retrospective chart review of 730 ED patients over a 34-month period. Ninety-six (13%) patients had ectopic pregnancies, 253 (35%) had abnormal intrauterine pregnancies, and 381 (52%) had normal intrauterine pregnancies. The absolute value of the beta-hCG levels of the ectopic and abnormal intrauterine pregnancies was much lower than the beta-hCG level of patients with normal IUPs. In this patient population, a beta-hCG level of less than 1,500 mIU/mL doubled the odds of ectopic pregnancy. One hundred fifty-eight patients had a beta-hCG level of less than 1500 mIU/mL; of these, 40 (25%) were ectopic pregnancies and only 25 (16%) were normal IUPs. The authors concluded that in this study of pregnant patients with vaginal bleeding and abdominal pain, the risk of ectopic pregnancy was substantially increased with beta-hCG levels below 1500 mIU/mL.
Commentary
This research by Kohn et al identifies that the risk of ectopic pregnancy was significantly increased in patients with a beta-hCG level of less than 1500 mIU/mL. Physicians should not be falsely reassured in pregnant patients with low beta-hCG levels who present with vaginal bleeding or abdominal pain. Ectopic pregnancy is still a significant concern and diagnostic testing including transvaginal ultrasound should be pursued. If the initial transvaginal ultrasound is non-diagnostic, physicians must ensure that reliable follow-up plans are in place prior to discharge.
This paper was limited by the high number (66) of patients who could not be classified at their initial visit and were subsequently lost to follow-up. The authors did note that most normal IUPs were classified at the initial ED visit; therefore, many of the patients lost to follow up may have been abnormal IUPs or ectopic pregnancies, which were reinforced by the low beta-hCG levels in this group. If these patients were included in the analysis, they would have increased the incidence of ectopics, not adversely impacted the study's results or conclusions.
How Precise is Transvaginal Ultrasound When the Beta-hCG Value is Below the Discriminatory Zone?
Source: Dart RG, Kaplan B, Cox C. Transvaginal ultrasound in patients with low beta-human chorionic gonadotropin values: how often is the study diagnostic? Ann Emerg Med 1997;30:135-140.
This study examined the diagnostic accuracy of transvaginal ultrasound in pregnant patients with abdominal pain or vaginal bleeding and with beta-hCG levels below 1000 mIU/mL. The authors performed a retrospective chart review of all patients who presented to the ED during a 4-year period with abdominal pain or vaginal bleeding, including patients who had beta-hCG levels below 1000 mIU/mL and who received a transvaginal ultrasound within 24 hours of initial presentation.
One hundred eleven patients were included. Transvaginal ultrasound was diagnostic for IUP or ectopic pregnancy in 19 patients (17%); 10 patients had intrauterine pregnancies and 9 patients had ectopic pregnancies. The beta-hCG levels of patients with diagnostic ultrasounds ranged from 47-995 mIU/mL. Ultimately, 23 patients were diagnosed with ectopic pregnancies from the study population. Transvaginal ultrasound correctly diagnosed more than one-third of these patients at the initial presentation, when the beta-hCG levels were less than 1000 mIU/mL. The authors conclude that physicians should strongly consider transvaginal ultrasound in patients with suspected ectopic pregnancy, regardless of the beta-hCG quantitative level.
Commentary
This study further supports the routine use of transvaginal ultrasound in all pregnant patients presenting with vaginal bleeding or abdominal pain. While Barnhart and colleagues questioned the routine use of ultrasound in patients with low beta-hCG levels, Dart et al found that ultrasound was diagnostic in nearly one-fifth of patients (17%) with levels below 1000 mIU/mL. In fact, the beta-hCG levels in patients with diagnostic ultrasounds ranged from 47 to 995 mIU/mL. While the sample size was small, it should be noted that more than one-third of patients with an ultimate diagnosis of ectopic pregnancy were diagnosed correctly on the initial ultrasound.
The authors noted that making the diagnosis of ectopic pregnancy at the initial ED visit is important because any delay in diagnosis exposes the patient to the risk of ectopic rupture, hemorrhage, and increased morbidity and mortality. Institutions that limit the use of transvaginal ultrasound with low beta-hCG levels have had an average delay in diagnosis of 5.2 days.6
What is the Accuracy of Transvaginal Ultrasound Above and Below Beta-hCG Discriminatory Zone?
Source: Barnhart KT, Simhan H, Kamelle SA. Diagnostic accuracy of ultrasound above and below the beta-hCG discriminatory zone. Obstet Gynecol 1999;94:583-587.
The discriminatory zone is the beta-hCG level above which clear evidence of an intrauterine pregnancy (IUP) should be seen with transvaginal ultrasound. The exact level has been debated in the literature, with reference ranges between 1000-2000 mIU/mL. These authors evaluated the use and accuracy of transvaginal ultrasound in diagnosing IUP, ectopic pregnancy, and spontaneous abortions in patients who presented to an ED with vaginal bleeding or abdominal pain. The initial ultrasound findings and final diagnosis were compared in 333 consecutive patients. The authors used a beta-hCG level of 1500 mIU/mL as the discriminatory zone in this paper. Two hundred sixty-nine (81%) of patients had beta-hCG levels of greater than 1500 mIU/mL, while sixty-four (19%) had levels below 1500 mIU/mL.
Overall, 200 patients (60.1%) were diagnosed with IUP, 82 patients (24.6%) were diagnosed with spontaneous abortion, and 27 patients (8.1%) were diagnosed with ectopic pregnancy. Of the 200 patients with IUP, 94% had beta-hCG levels above the discriminatory zone while 6% had levels below the zone. The distribution of patients with miscarriage showed 52% of patients presented with initial beta-hCG levels above the discriminatory zone and patients with ectopic pregnancies had 56% with levels above and 44% with a beta-hCG below 1500 mIU/mL.
Transvaginal ultrasound was non-diagnostic in 59 patients (17.7%). In the sub-group of 64 patients with beta-hCG levels of less than 1500 mIU/mL, the initial ultrasound was non-diagnostic in 43 cases (67.2%). The accuracy of initial ultrasound was highest (91.5%) in patients with beta-hCG levels greater than 1500 mIU/mL. In patients with beta-hCG levels of less than 1500 mIU/mL, the ability of ultrasound to accurately distinguish normal early IUP from abnormal IUP, spontaneous abortions, and ectopics is limited. The authors advocate for the importance of follow-up studies in patients with beta-hCG levels below the discriminatory zone, including follow-up ultrasound imaging and repeat quantitative beta-hCG levels.
Commentary
All physicians who care for first trimester pregnant patients should be aware of this important paper, which includes two significant concepts. First, patients that present with vaginal bleeding or abdominal pain and low beta-hCG levels often do not have normal intrauterine pregnancies. The authors found that of the 19% of patients presenting with beta-hCG levels below the discriminatory zone, 48% had miscarriage, 44% had ectopic pregnancy, and 6% had ongoing IUP. This highlights the importance of reliable follow-up in patients with indeterminate initial ultrasounds and low beta-hCG levels.
The second substantial finding of this study is that the sensitivity of ultrasound for diagnosing ongoing pregnancy is high, while the sensitivity for diagnosing ectopic pregnancy is low. The ability of ultrasound to visualize an ectopic sac is inherently low; therefore, it is the absence of an IUP that should alert the physician to consider ectopic pregnancy. Safe clinical algorithms to diagnose ectopic pregnancy do not rely on finding the ectopic sac by transvaginal ultrasound. Instead, it is the absence of an IUP, significant free fluid in the cul-de-sac or adnexal abnormalities, combined with appropriate clinical concerns that mandate further investigation.
There are several limitations to this study. The sample size is small at 333 patients with wide confidence intervals. However, the data trends are supported by other literature, including the study by Kohn et al discussed earlier.
While the results of this study are compelling, the conclusions of the authors are debatable. Barnhart et al conclude that the routine use of transvaginal ultrasound in patients with beta-hCG levels below the discriminatory zone should be reconsidered since its accuracy is low. The limited accuracy in this group could have been improved with a modification to the definition of IUP. While transvaginal ultrasound was indeterminate in 67% of the patients with low beta-hCG levels, it was diagnostic in 33% of cases. Given that the incidence of ectopic pregnancy in patients presenting to the ED is between 8% and 13% and a considerable percentage of these present with low beta-hCG levels, it would be a risky clinical algorithm that prohibited transvaginal ultrasound in all patients with low beta-hCG values.5,7
What Sonographic Findings Suggest Ectopic Pregnancy in the Absence of a Well Defined Mass or Ectopic Sac?
Source: Dart R, Dart L, Mitchell P. Normal intrauterine pregnancy is unlikely in patients who have echogenic material identified within the endometrial cavity at transvaginal ultrasonography. Acad Emerg Med 1999;6:116-120.
Transvaginal sonography is the test of choice in pregnant patients who present to the ED with vaginal bleeding or abdominal pain. However, in patients with documented ectopic pregnancy, transvaginal sonography only identifies the ectopic sac or adnexal mass in up to one-third of cases. This paper examines another sonographic finding, echogenic material within the endometrial canal in the absence of a gestational sac. The authors examined whether the finding of echogenic material within the endometrial canal can reliably exclude normal IUP. A retrospective chart review was performed over a period of 6 years in an urban ED. The authors identified and enrolled pregnant patients with echogenic material on ultrasound. Five patients were excluded; three had a dilatation and evacuation procedure prior to the exclusion of a normal IUP by other means (falling beta-hCG, open cervical os, beta-hCG greater than 3000, or low progesterone levels) and in two patients the final diagnosis was not available. A total of 78 patients were enrolled. None of the enrolled patients had a normal IUP, and 9 patients (11.5%) had an ectopic pregnancy. The authors concluded that the sonographic finding of echogenic material within the endometrial canal virtually excludes a normal IUP and should prompt continued evaluation for potential ectopic pregnancy.
Commentary
As we have previously noted elsewhere in this paper, there is a significant minority of patients who will have an indeterminate pelvic ultrasound. Further classification of these pregnancies often is challenging to the emergency provider. Given that it is undesirable to discharge a patient with eventual ectopic pregnancy, many authors have attempted to highlight sonographic findings that could be suggestive of or associated with ectopic pregnancy. Dart and colleagues evaluated the importance of echogenic material within the endometrial cavity and concluded that it is very suggestive of abnormal pregnancy, including spontaneous miscarriage and ectopic pregnancy. Although the incidence of ectopic pregnancy was low in this group (7%), echogenic material within the endometrial cavity should be considered a marker of abnormal pregnancy with appropriate follow-up and disposition based on the individual clinical scenario.
There have been other attempts to identify sonographic signs highly associated with ectopic pregnancy; sonographic signs included extrauterine gestational sac (31%), adnexal mass (21%), echogenic fluid (31%), and viable extrauterine embryo (15%).8 Rodgerson et al and Moore et al evaluated the presence of fluid in Morison's pouch and an empty uterus. Both studies concluded that these findings are highly suggestive of ruptured ectopic pregnancy.9,10 It is crucial that emergency providers understand the implications of these additional ultrasound findings since the majority of patients diagnosed with ectopic pregnancy do not have an ectopic sac visualized by ultrasound. There is one major limitation of this study. Since it relied on dictated ultrasound reports, the authors did not determine the ability of sonographers to distinguish a thickened endometrial stripe (normal in early pregnancy) from echogenic endometrial material (highly abnormal in early pregnancy). These two sonographic signs can appear quite similar and it is possible that this may have been a confounding factor in this study. Further investigation would be needed to prospectively evaluate this critical distinction.
What is the Expected Outcome of Patients with Indeterminate Pelvic Ultrasound?
Source: Tayal VS, Cohen H, Norton HJ. Outcome of patients with an indeterminate emergency department first-trimester pelvic ultrasound to rule out ectopic pregnancy. Acad Emerg Med 2004;11:912-917.
While transvaginal ultrasound often is diagnostic at the initial visit, there is a significant minority of patients who will have an indeterminate initial ultrasound. These authors followed patients with indeterminate diagnoses on their initial ED transvaginal ultrasound to determine final outcomes. This was an observational prospective cohort study performed at an urban ED with high volume (>100,000 visits per year) over a 13-month period. Transvaginal ultrasound was performed by emergency providers and gynecologic consultation was obtained in the absence of identifiable IUP.
There were 1,490 ultrasounds performed over 13 months, with initial diagnoses as follows: 1037 IUP (70%), 127 embryonic demise (8%), 24 ectopic (2%), 2 molar (<1%), and 300 indeterminate (20%). Of the 3 indeterminate scans, final diagnostic categories included 158 embryonic demise (53%), 88 IUP (29%), 44 ectopic pregnancy (15%), and 10 had unknown outcome (3%). Tayal and colleagues also examined the treatment course of all patients classified with ectopic pregnancy. Patients classified with ectopic pregnancy at the initial ED visit had surgical treatment in 20 of 24 cases (83%). In contrast, the indeterminate group of patients with ectopic pregnancy received medical management with methotrexate in 57% of cases. The authors concluded that the outcome of patients with an indeterminate transvaginal ultrasound is poor, with almost 70% of patients having either embryonic demise or ectopic pregnancy.
Commentary
This study by Tayal and colleagues has several important implications. It was an observational prospective evaluation of bedside transvaginal ultrasound performed at a large urban academic ED, supported by a large sample size. The authors clearly defined their sonographic findings with strict definitions of IUP (gestational sac + yolk sac) and ectopic pregnancy (gestational sac + yolk sac outside uterine rim). Their results reinforce previous literature that suggests transvaginal ultrasound can establish a diagnosis in 60-70% of patients at initial presentation.4 However, a significant minority will have an initially indeterminate ultrasound, as did 20% of the patients in this study. It is critical to note that patients with an indeterminate ultrasound are automatically at increased risk for abnormal pregnancy, including spontaneous abortion and ectopic pregnancy. Seventy percent of the patients with indeterminate ultrasound had abnormal pregnancies and there was no significant difference in the initial beta-hCG level that could help distinguish these final outcomes. Therefore, while some institutions support guidelines that restrict the routine use of transvaginal ultrasound in patients with beta-hCG levels below the discriminatory zone, this study provides more evidence why this may be a harmful practice.6
In addition, the difference in treatment among patients diagnosed with ectopic pregnancy was remarkable. Most patients diagnosed with ectopic pregnancy at the initial ED visit were managed surgically, presumably due to rupture or advanced pregnancy. In contrast, more than half of the patients diagnosed with ectopic pregnancy after an indeterminate ultrasound were given methotrexate as initial management and no patient in this group required laparotomy. Tayal et al's findings support the use of transvaginal ultrasound in all patients who are at risk for ectopic pregnancy, regardless of the quantitative beta-hCG level. This study also raises an important question for future research, whether patients with indeterminate initial ultrasounds are inherently more stable and amenable to conservative therapeutic options.
What is the Absolute Diagnostic Beta-hCG Level for Ectopic Pregnancy in the Absence of IUP?
Source: Mol BW, Hajenius PJ, Engelsbel S, et al. Serum human chorionic gonadotropin measurement in the diagnosis of ectopic pregnancy when transvaginal sonography is inconclusive. Fertil Steril 1998;70:972-981.
Mol and colleagues prospectively reviewed 354 pregnant patients with inconclusive transvaginal sonography to determine how accurate the beta-hCG levels could be in the diagnosis of ectopic pregnancy. All study subjects had transvaginal sonography and were classified into one of three groups; IUP, ectopic pregnancy, or indeterminate. Patients with clinical evidence suggestive of spontaneous abortion were excluded from the study. All patients had a quantitative beta-hCG level drawn at presentation, day 2, and day 4. Final diagnostic categories were IUP, ectopic, and nonviable pregnancy. These diagnoses were confirmed by several methods, including laparoscopy, repeat ultrasounds, and following the beta-hCG levels until undetectable.
The authors found that in patients with an indeterminate initial ultrasound, beta-hCG levels greater than 1500 mIU/mL were most predictive of ectopic pregnancy when there were additional sonographic findings such as adnexal mass or fluid in the cul-de-sac. In cases without additional sonographic abnormalities, the course of the beta-hCG was more important than the absolute beta-hCG level. Any rise in the beta-hCG level by day four made the diagnosis of ectopic pregnancy much more likely than the alternative diagnoses. The authors concluded that a beta-hCG level of 1500 mIU/mL or greater could be used as definitive evidence of ectopic pregnancy in cases in which ultrasound showed an empty uterus with free fluid in the cul-de-sac or adnexal mass. In cases with an empty uterus and no additional sonographic findings, a beta-hCG level of greater than 2000 mIU/mL should be used to diagnose ectopic pregnancy.
Commentary
The absence of a definitive IUP by transvaginal ultrasound raises many diagnostic possibilities, including early normal pregnancy, completed miscarriage, and most importantly ectopic pregnancy. Emergency practitioners often need to formulate a diagnostic impression with limited information based on a single patient encounter. In these cases, the beta-hCG level may be used as additional evidence of an ectopic pregnancy but the appropriate absolute cut-off value has been debated.
Mol and colleagues found three important trends that should be noted by all physicians caring for patients at risk for ectopic pregnancy. First, a beta-hCG level of 1500 mIU/mL or greater is virtually diagnostic of ectopic among patients with an empty uterus by ultrasound and free fluid in the cul-de-sac or an adnexal mass. Next, among patients with an empty uterus but no additional ultrasound findings, a beta-hCG level greater than 2000 mIU/mL was highly predictive of ectopic. Finally, among patients with non-diagnostic initial ultrasounds and low beta-hCG levels, the course of the beta-hCG levels was more predictive of ectopic than the absolute value. Any rise in the beta-hCG levels by four days was suggestive of ectopic pregnancy. Over a four-day follow-up, a decline in the beta-hCG levels by greater than 50% essentially ruled out ectopic pregnancy in this study. The risk of ectopic was increased with less than 50% decline or any rise in the beta-hCG levels. However, neither option was diagnostic of ectopic pregnancy and these patients require continued close evaluation.
Is Focused Bedside Ultrasound Precise in the Diagnosis of Ectopic Pregnancy?
Source: Adhikari S, Blaivas M, Lyon M. Diagnosis and management of ectopic pregnancy using bedside transvaginal ultrasonography in the ED: a 2-year experience. Am J Emerg Med 2007;25:591-596.
Bedside transvaginal ultrasound (ED-US) is a skill increasingly used by emergency physicians. This study described the diagnosis and management of ectopic pregnancy using ED-US. This was a retrospective study over a two-year period at a level 1 academic emergency medicine program. Patients were included in the study if they presented in the first trimester of pregnancy and had a ED-US performed.
Seventy-four patients were included in the study with ages ranging from 16-39 years. ED-US findings were defined as follows: definite ectopic pregnancy with extrauterine GS (gestational sac) with YS (yolk sac) and fetal pole (6/74), probable ectopic pregnancy with tubal ring, adnexal mass or large amounts of free fluid (28/74), and possible ectopic pregnancy if adnexal mass was identified (40/74). Of these 74 patients, 47 had a final diagnosis of ectopic pregnancy by the consulting obstetrics provider. All 6 patients with ED-US definite ectopic had ectopic at final diagnosis. Twenty-four of 28 patients with ED-US probable ectopic had ectopic pregnancy at final diagnosis. Bedside transvaginal ultrasound findings included tubal ring (19%), complex adnexal mass (61%), and fluid in the cul-de-sac (21%). A formal radiology ultrasound was ordered in 10 cases but did not change the diagnosis or management. No ectopic pregnancies were missed by ED-US. In patients with a final diagnosis of ectopic pregnancy, the beta-hCG levels ranged from 41 to 59,846 and 36% of patients had a beta-hCG of less than 1000. Of the 47 ectopic pregnancies, 29 were managed surgically, 17 received methotrexate, and 1 patient left against medical advice. The authors concluded that with sufficient experience, emergency providers can perform and accurately interpret ED-US, including identifying important adnexal findings associated with ectopic pregnancy.
Commentary
Focused bedside ultrasound is performed in many academic EDs and a growing number of community EDs. Burgher and colleagues demonstrated a reduction in LOS of at least 60 minutes and reduced need for consultation by 85%. No ectopic pregnancies were missed.11 Traditionally, the role of focused ultrasound has been to exclude ectopic by ruling in IUP. The current study by Blaivas et al suggests that with appropriate training, emergency sonographers can gain sufficient skill and sophistication in transvaginal ultrasound to identify adnexal findings associated with ectopic pregnancy. This study has several limitations, including the small number of patients with pathologic ectopic pregnancy diagnosis. In all other patients, the obstetrics diagnosis was considered the gold standard. It also is limited by the exclusion of patients who received obstetrics or radiology ultrasound initially due to lack of trained EM physicians available at the study site. It is possible that the inclusion of these patients may have altered the study results. Despite the limitations, this study still provides further evidence that ED-US is highly accurate at identifying IUP and may likely identify other important sonographic findings as emergency physicians gain skill and training in transvaginal ultrasound.
Conclusions
Ectopic pregnancy remains a troublesome diagnostic possibility among patients with vaginal bleeding or abdominal pain in the first trimester of pregnancy. Despite a low overall incidence, it occurs with increased frequency among patients who present to the ED. Traditional risk factors include a history of previous ectopic, tubal surgery, tubal pathology, known intrauterine device, or infertility treatment. Pelvic inflammatory disease can increase the incidence of ectopic pregnancy by seven times.3 Despite these known factors, many patients with ectopic pregnancy have no identifiable risks at the time of diagnosis. In the absence of a well defined IUP by ultrasound, ectopic pregnancy should remain a vigilant concern in pregnant patients.
Diagnostic algorithms for ectopic pregnancy should center on the concept of ruling out an IUP by transvaginal ultrasound and the identification of high-risk sonographic features, including significant amounts of free fluid, complex adnexal masses, or, less commonly, visualization of the ectopic sac. The addition of serial beta-hCG values to this diagnostic pathway is helpful to the practitioner with a firm grasp of the discriminatory zone and its application to each individual scenario. History and physical exam alone are never sensitive enough to exclude ectopic pregnancy. While a beta-hCG level and transvaginal ultrasound remain the standard of care, a single beta-hCG value often is not diagnostic and up to 30% of patients may have an indeterminate transvaginal ultrasound at initial presentation. Physicians must evaluate each clinical scenario carefully, combined with adjunctive testing and a solid understanding of the current literature to develop a safe management plan for each patient.
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