Dear editor,

Emergency physicians are often the first providers to encounter patients with complications in early pregnancy. Point-of-care (POC) pelvic ultrasound is being increasingly used in the evaluation of emergency department (ED) patients with first trimester symptoms.[1]While the initial aim of POC ultrasound in this setting is to confirm an intrauterine pregnancy, a secondary goal is to differentiate between a normal and abnormal pregnancy. There exist a number of sonographic features to suggest a pregnancy is non-viable.[2-4] One of which is the entity known as the yolk stalk sign. During early embryonic development, the embryo is routinely detected immediately adjacent to the yolk sac, as the yolk stalk has yet to develop (Figure 1). Later in pregnancy, as the yolk stalk develops, the embryo will then be noted to separate from the yolk sac. “Yolk stalk sign” is abnormal separation of the embryo from the yolk sac in early embryonic development, specifically where crown-rump length (CRL) is 5 mm or less with no visible heartbeat.[5]At this point, any separation of the embryo from the yolk sac with development of yolk stalk is abnormal as the yolk stalk should be non-existent. Thus, an unexpected separation of the embryo from the yolk sac in embryos with a CRL of 5 mm or less and lacking a heartbeat could be indicative of a threatened abortion.[5]

We present this case of a patient who had a yolk stalk sign on a POC ultrasound performed to evaluate a pregnancy that inevitably ended in fetal demise. This case emphasizes the importance of identification of the yolk-stalk sign in the assessment of an early pregnancy.

CASE

A 17- year old female G1P0 presented to the ED with a chief complaint of vaginal bleeding. The patient states she had a confirmed intrauterine pregnancy, estimated at 8 weeks gestation by ultrasound a week prior at her obstetrician’s office. On the day of her initial visit, she endorsed painless vaginal bleeding. Overall, the patient was well appearing and hemodynamically stable on presentation. Physical examination demonstrated some minimal suprapubic tenderness to palpation without guarding or rebound. A vaginal speculum examination was significant for scant blood in the vaginal vault and a closed cervical os. Bimanual examination revealed no abnormalities. At this visit, the patient’s beta human chorionic gonadotropin (hCG) was 29,559 mIU/mL.As the results of the patient’s previous ultrasound were not available, the decision was made to perform a POC ultrasound in the ED to confirm an intrauterine pregnancy. The ultrasound examination was performed using Zonare Ultra system (Zonare Medical Systems,Mountain View, California) with a 9-4 MHz endocavity transducer. The embryo was noted to have a CRL of ＜5 mm and no detectable heart rate was found. Additionally,a long yolk stalk sign was identified, with a yolk sac seen significantly displaced from the embryo (Figure 2 and Figure 3). Given these findings, the patient was counseled that this was likely a non-viable pregnancy.She was discharged home with instructions to follow up with her obstetrician.

The patient returned to the ED 2 days later for worsening of her vaginal bleeding and pelvic cramping.Her beta hCG was repeated and was significantly lower at 18,000 mIU/mL. A repeat ultrasound during this visit demonstrated gestational sac without fetal pole. Obstetric consultation was obtained during this visit based on these findings. On their pelvic examination, they removed products of conception from cervix. The patient was eventually discharged with a diagnosis of abortion in progress.

Figure 1. Transvaginal ultrasound of intrauterine pregnancy with small embryo (E) seen adjacent to the yolk sac (YS) suggesting yolk stalk has yet to develop.

Figure 2. Transvaginal ultrasound images showing a small embryo(E) with no cardiac activity, yolk sac (YS) and amnion (A). significant separation of the embryo from yolk sac seen in this image suggests the presence of a long yolk stalk.

Figure 3. Transvaginal ultrasound image demonstrating yolk stalk(YSt), embryo (E), yolk sac (YS) and amnion (A). The yolk stalk allows marked separation between the small embryo and yolk sac.

DISCUSSION

The utilization of a POC ultrasound in the ED helps to promptly and accurately evaluate early pregnancies.POC pelvic ultrasound can assist in distinguishing a viable pregnancy from an abnormal intrauterine pregnancy or miscarriage or an ectopic pregnancy. It helps avoid inappropriate reassurance about the viability of an intra-uterine pregnancy in the ED. The predictive value of ultrasound findings for early embryonic demise has been well described.[2] Sonographic identification of failed first trimester pregnancy in the ED allows for selection of appropriate case-specific management strategies (expectant, medical, and surgical).[6]

The utility of pelvic ultrasound in the evaluation of a first trimester pregnancy has long been demonstrated in the Obstetric setting. A number of specific sonographic findings[2] in early pregnancy have demonstrated predictive value for identifying an abnormal intrauterine pregnancy. Ultrasound is often used in Obstetric practice to identify high-risk pregnancies and determine the need for appropriate antepartum interventions.[7] Doppler assessments are increasingly being used for the detection and surveillance of intrauterine growth restriction and prediction of preeclampsia.[8-10] Additionally, ultrasound is utilized to screen for fetal anomalies in the Obstetric settings. A well-established example is the practice of measuring fetal nuchal translucency; one of the best screening tests for fetal Down syndrome. The detection rate of Down syndrome using this test alone can reach 60%-70%, with a low false-positive rate.[11] In addition,an increased fetal nuchal translucency with a normal karyotype signifies greater risk for fetal cardiac defects and other syndromes.[12]

然而，在其后的近二十年间，法律虚无主义思潮肆意蔓延，法治受到彻底地批判和否定，民主制度受到摧残，广大行政执法工作人员深受轻视法律、否认法制思想的影响，普遍有法不依，直到最后无法可依，刚刚萌芽的法治政府荡涤无存。

Funding: None.

In conclusion, this case highlights the value of recognizing the yolk stalk sign on POC ultrasound.Emergency physicians frequently evaluate patients in the first trimester of pregnancy. As POC ultrasound becomes more widely utilized in the ED, it is imperative that providers familiarize themselves with these less common sonographic findings, whose presence can confirm a suspected diagnosis of an abnormal pregnancy. Failure to recognize an indicator of fetal demise can result in number of adverse consequences, such as misdiagnosis and providing false reassurance to the patient. Whether a yolk stalk sign is used independently or in conjunction with other abnormal sonographic findings, its presence can help guide physicians in further counseling their patients and establishing appropriate care and timely follow up.

从技术角度出发，尽管当前部分自动驾驶汽车产品已经达到L3（有条件自动化）、L4（高度自动化）的技术水平，但由于某些特定关键技术发展的不充分性，导致自动驾驶技术要实现L5阶段的完全无人驾驶目标仍需要很长的时间。专利作为技术知识的载体，是集经济、法律、技术为一体的信息体，90%以上的技术信息都可以从专利信息反映出来。对专利信息进行挖掘研究，不仅能够准确揭示各国家（地区）、组织机构、技术研发的侧重点，而且能为技术发展提供数据支持和决策参考。目前关于揭示自动驾驶技术发展全貌的定量性研究较少，因此本文采用专利分析方法研究了自动驾驶技术的全球市场态势。

CONCLUSION

There are a number of sonographic findings that support the diagnosis of a failed pregnancy; one of which is the yolk stalk sign. A recent study undertook the exploration of this sonographic finding. Filly et al[5]performed a retrospective study, which reviewed first trimester sonograms where there was a CRL ＜5 mm and no fetal cardiac activity. These cases were reviewed to look for separation between the embryo and yolk sac, a “yolk stalk sign”. It was found that patients who demonstrated this sonographic sign subsequently proved to have failed pregnancies. In this cohort, the positive predictive value of the yolk stalk sign for predicting early pregnancy failure was 100%; indicating that the yolk stalk sign could serve as a predictor of early embryonic death on ultrasound.

This case highlights an instance in which the utilization of a POC pelvic ultrasound in the ED can help promptly and accurately evaluate early pregnancies.An ultrasound that suggests an abnormal pregnancy can drastically change the patient interaction and management in the ED. In cases of suspected fetal demise found on POC ultrasound, physicians are able to properly counsel patients on the prognosis of their pregnancy and help them to obtain timely follow up with Obstetrics consultant, whether in the ED or as an outpatient. Aside from the direct benefits of patient care,there is also a positive economical aspect of POC pelvic ultrasound to consider. With many hospitals experiencing a rise in their ED census over the recent years there are growing demands to decrease throughput time.Studies have shown that pelvic ultrasound performed by emergency physicians can actually decrease ED length of stay and improve throughput.[13,14]

To our knowledge, this is the first case report of a yolk stalk sign found on a POC ultrasound. In the case presented, the yolk stalk sign served as an indicator of early fetal demise. The treating physician suspected an abnormal pregnancy after noting an abnormal separation between the embryo and yolk sac. At this point, the patient was counseled that the findings on her ultrasound likely depicted fetal demise and was diagnosed with a threatened abortion. This was confirmed on repeat ultrasound performed two-days later and the patient eventually went on to have a completed abortion.

Ethical approval: Not needed.

9月15日，2018京津冀汽修行业环保形势及污染防治政策技术研讨会暨“汽环联环保管家”汽修行业治理服务供需会在北京成功举办。来自行业内的科研院所权威专家、环保公司相关领导等作为嘉宾参加了此次研讨会，他们一起在会上充分探讨京津冀范围内汽车维修业的环保政策、法规、现状及发展趋势，交流和总结与VOCs排放相关的环保问题及控制技术需求。活动主办方也希望通过此次会议能够帮助汽修行业宣传VOCs政策，推动行业标准的建立，推动建立汽修行业全方位一站式解决方案，推动汽修行业绿色发展，让汽修企业专心经营生产，杜绝环保“红线”，进一步提升汽修行业绿色发展和环保治理水平。

荧屏不能充斥着阴柔之气，更不能只有阴柔之气，但这又不能只是对荧屏提出要求，因为这同时也与更广大的社会环境有关。在一些地方和领域，家庭教育和学校教育的问题都比较突出，如果家庭和学校都能够按照未成年人成长的科学规律来教育孩子，就应当能够在相当程度上抵御荧屏的影响。在现代社会，体育锻炼是培养“阳刚之气”的一个重要渠道，我们能不能把更多孩子带进体育场，让他们在挥汗如雨中享受阳刚之美，培养他们的阳刚之气？

Conflicts of interest: Each author of this manuscript does not have any conflict of interest.

Contributors: JA proposed the study and wrote the first draft. All authors read and approved the final version of the paper.

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