13-011 · EVIDENCE B · SOURCE-SENSITIVE
A leg suddenly swells, feels tight, and is tender to the touch — seek medical care promptly; if shortness of breath or chest pain develops suddenly, call 120 immediately.
一条腿突然肿起来、发紧、按着疼，尽快就医；再加上突然喘不上气或者胸痛，立刻打 120
An ultrasound of the leg veins (lower extremity venous ultrasound) costs around 100–200 yuan.
If one leg suddenly swells, becomes noticeably thicker than the other, and is painful to press, get a leg vein ultrasound done as soon as possible. Should shortness of breath, chest pain when taking a deep breath, a rapid heartbeat, or dizziness appear, a blood clot may have traveled to the lungs — call 120 right away. Among people diagnosed with pulmonary embolism, 17.4% die within three months. Sitting still for more than four hours roughly doubles the risk, though the actual chance for any one person remains very low.
B
Move “A leg suddenly swells, feels tight, and is tender to the touch — seek medical care promptly; if shortness of breath or chest pain develops suddenly, call 120 immediately.” to Future Me's calendar
The excuse
One more exception feels free because the bill arrives outside the current scene.
What feels good now
Today I keep a little money, a few minutes and avoid interrupting my default routine.
What the source says
The source summarizes the return this way: “If one leg suddenly swells, becomes noticeably thicker than the other, and is painful to press, get a leg vein ultrasound done as soon as possible. Should shortness of breath, chest pain when taking a deep breath, a rapid heartbeat, or dizziness appear, a blood clot may have traveled to the lungs — call 120 right away. Among people diagnosed with pulmonary embolism, 17.4% die within three months. Sitting still for more than four hours roughly doubles the risk, though the actual chance for any one person remains very low.” Evidence grade B. The original states the population, caveats, and sources; this is not a personal forecast.
Use the original facts and limits. For an urgent medical, safety, financial, or legal issue, contact a qualified local professional or service.
THE ENGLISH EDITION
Original recommendation and evidence
11. A leg suddenly swells, feels tight, and is tender to the touch — seek medical care promptly; if shortness of breath or chest pain develops suddenly, call 120 immediately.
Cost: An ultrasound of the leg veins (lower extremity venous ultrasound) costs around 100–200 yuan.
In plain terms: If one leg suddenly swells, becomes noticeably thicker than the other, and is painful to press, get a leg vein ultrasound done as soon as possible. Should shortness of breath, chest pain when taking a deep breath, a rapid heartbeat, or dizziness appear, a blood clot may have traveled to the lungs — call 120 right away. Among people diagnosed with pulmonary embolism, 17.4% die within three months. Sitting still for more than four hours roughly doubles the risk, though the actual chance for any one person remains very low.
Benefit: The International Cooperative Registry on Pulmonary Embolism (ICOPER) gathered data from 2,454 patients with confirmed acute pulmonary embolism treated at 52 hospitals across seven countries. Pulmonary embolism occurs when a blood clot blocks a pulmonary artery. Within three months, the overall mortality rate for these patients — regardless of cause — was 17.4% (426 out of 2,454). The WHO WRIGHT project found that travel lasting four or more continuous hours “roughly doubles” the risk of blood clots forming in veins and traveling to the lungs (venous thromboembolism). Even so, the actual probability for any individual remains low; prolonged inactivity exceeding four hours translates to roughly one in 6,000 people facing this risk.
Evidence grade: B
Sources: Goldhaber SZ, Visani L, De Rosa M (1999). Acute pulmonary embolism: clinical outcomes in the International Cooperative Pulmonary Embolism Registry (ICOPER). Lancet, 353(9162), 1386-1389. <https://doi.org/10.1016/S0140-6736(98)07534-5>; WHO (2007). Study results released on travel and blood clots. <https://www.who.int/news/item/29-06-2007-study-results-released-on-travel-and-blood-clots>
Notes: Swelling in both legs is usually linked to issues involving the heart, liver, kidneys, or venous function. Sudden swelling of just one leg, noticeably larger than the other, is a classic sign of deep vein thrombosis. High-risk situations include long car or plane trips, bed rest after surgery or a fracture, wearing a cast, pregnancy and the postpartum period, cancer, and oral contraceptive use. When a clot breaks loose and blocks a pulmonary artery, pulmonary embolism results — marked by sudden shortness of breath, worsening chest pain with deep breaths, rapid heartbeat, dizziness, and sometimes coughing up blood. In such cases, call 120 immediately. The 17.4% figure reflects mortality among confirmed pulmonary embolism cases, not the overall risk associated with leg swelling alone; don’t let this number cause undue alarm.
Read the complete Chinese source and notes
11. 一条腿突然肿起来、发紧、按着疼，尽快就医；再加上突然喘不上气或者胸痛，立刻打 120
成本: 腿部血管做一次超声（下肢静脉超声），一两百元。
说人话: 一条腿突然肿起来、比另一条粗一圈、按着疼，尽快去做腿部静脉超声。再出现突然喘不上气、深吸气时胸痛、心跳快、发晕，血块可能已经跑到肺里，直接打 120。确诊肺栓塞的人 3 个月内死亡 17.4%。久坐超过 4 小时风险大约翻倍，但摊到一个人头上仍然很低。
收益: 国际肺栓塞协作登记（ICOPER）收了 7 个国家 52 家医院的 2454 例确诊急性肺栓塞病人。肺栓塞就是血块堵住肺动脉。这批人 3 个月内不分原因的死亡率是 17.4%（426/2454）。世界卫生组织 WRIGHT 项目：连续 4 小时以上的旅行，让静脉里长血块、血块跑到肺里（静脉血栓栓塞）的风险「大约翻倍」。但摊到一个人头上的概率仍然很低，久坐不动超过 4 小时「约为六千分之一」
证据等级: B
来源: Goldhaber SZ, Visani L, De Rosa M (1999). Acute pulmonary embolism: clinical outcomes in the International Cooperative Pulmonary Embolism Registry (ICOPER). Lancet, 353(9162), 1386-1389. <https://doi.org/10.1016/S0140-6736(98)07534-5> ; WHO (2007). Study results released on travel and blood clots. <https://www.who.int/news/item/29-06-2007-study-results-released-on-travel-and-blood-clots>
备注: 两条腿一起肿，多半是心、肝、肾或者静脉功能的问题。一条腿突然肿、比另一条粗一圈，才是深静脉血栓的典型样子。容易出事的是长途坐车坐飞机、手术或骨折后卧床、打石膏、怀孕生产前后、肿瘤、吃口服避孕药。血块脱落、堵住肺动脉就是肺栓塞：突然喘不上气、深吸一口气胸口更疼、心跳快、发晕、咳出血（咯血）。到这一步直接打 120。17.4% 是确诊肺栓塞病例的死亡率，不是「腿肿了就有这么大风险」，别对着这个数字吓自己。
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