Application of Etiology List in Differential Diagnosis of Acute Abdominal Pain *

Objective: To use the etiology list of abdominal pain to help identify acute abdominal pain. Methods: to design a list of causes of acute abdominal pain as per the concept of system thinking, determine the five differential diagnosis directions of “local organ disease, adjacent organ disease, systemic disease, psychogenic disease, and female reproductive system disease”, and elaborate the application effect of the checklist in the diagnosis of acute abdominal pain by virtue of the analysis of one case of acute abdominal pain. Results: according to the list of causes of abdominal pain, the causes of acute abdominal pain were screened, and patients suffering from acute renal infarction (ARI) who presented with simple abdominal pain were diagnosed and treated timely. Conclusion: the etiology list is helpful to guide the diagnosis direction of acute abdominal pain, and make a rapid clinical diagnosis, so as to form a systematic thinking mode.


Introduction
Abdominal pain, one of the common symptoms in the Emergency Department, has complex etiological factors, usually involving internal medicine, surgical, pediatric, and gynecological diseases [1], with sudden onset and rapid changes. The complexity of the etiology of abdominal pain makes emergency physicians really confused, and it is a very heavy task for any of them to remember and master the differential diagnosis of abdominal pain, thereby falling into a wrong

Method
An application of an etiology list of abdominal pain: based on the concept of system thinking and anatomical location, and following the principle of integrity of clinical thinking [4], an etiology list of abdominal pain in five key directions of "local organ disease, adjacent organ disease, systemic disease, psychogenic disease, and female reproductive system disease" was designed [5] (see Table 1), as the top layer of the modular differential diagnosis program. In the second and third layers, the anatomical location and lesions natures were used to define subcategories. The secondary classification of local organ diseases includes abdominal and abdominal wall diseases; the adjacent organ diseases include respiratory, mediastinal, and spinal diseases; By analogy, the systemic diseases include blood diseases, endocrine metabolism, immunity, poisoning diseases, etc. In the fourth layer of the program, the common and frequently occurring diseases of diagnostics are embraced to rank the types of diseases that cause abdominal pain. Then in the light of the step-down thinking for screening [4], Then according to the list of causes of abdominal pain, the direction of diagnostic thinking was guided, the differential diagnosis of abdominal pain is improved.

Clinical Application
Abdominal pain is easy to be misdiagnosed and omitted in the early stage, leading to improper treatment which may endanger the life of patients. In particular, for abdominal vascular diseases, such as acute renal infarction, some patients may have no symptoms or signs, lacking specific clinical manifestations and laboratory examinations [6]. The following describes the application ideas and effects of the etiology list in acute renal infarction.

Case Report
Female, 77 years old. Chief complaint: abdominal pain for 2 days. Two days ago, the patient suffered from the persistent dull pain in the left lower abdomen, which was mainly in lower abdomen, and had nothing to do with the activity or Open Journal of Emergency Medicine

Case Analysis
Among the causes of abdominal pain, the patient, female, 77 years old, has been menopausal for 20 years. Therefore, the fertility-related diseases of the

Discussion
Diagnosis is a complex cognitive process covering a number of links [7]. Currently, the thinking mode commonly used in emergency treatment is hypothetical deduction [8], that is, based on the patient's symptoms, and in combination with medical history, detailed physical examination and necessary laboratory examination, first, a certain disease is assumed, and then further deterministic inspections are performed, to compare the results obtained with the hypothetical disease characteristics, and judge whether the hypothesis is true, so as to obtain a preliminary diagnosis, which belongs to the model-controlled diagnosis mode [7]. The decision-making process relies on personal experience. It is more advantaged over rapid diagnosis for common diseases, but it is very difficult to diagnose complex or rare diseases. Since people are concerned about common and frequently-occurring diseases, or often ignore rare diseases due to lack of experience, misdiagnosis and missed diagnosis are easily caused since they can't think of or don't think about it [2].
This study reorganizes the causes of acute abdominal pain, reclassifies the causes of abdominal pain, and designs five key diagnostic directions of "local organ disease, adjacent organ disease, systemic disease, psychogenic disease, and female reproductive system disease", which covers all common causes of abdominal pain, grasps the differential diagnosis of abdominal pain as a whole, and forms a systematic thinking mode.
This study reorganizes the causes of acute abdominal pain, reclassifies the causes of abdominal pain, and designs five key diagnostic directions of "local organ disease, adjacent organ disease, systemic disease, psychogenic disease, and female reproductive system disease", which covers all common causes of abdominal pain, grasps the differential diagnosis of abdominal pain as a whole, and forms a systematic thinking mode.
The cause of abdominal pain is complex, and it is difficult to fully grasp the differential diagnosis of abdominal pain. As a result, the misdiagnosis rate is fairly high [2] [9], especially among the elderly. It has been shown that: the misdiagnosis rate in the emergency room for patients ≥ 65 years old is 52% [10].
Acute renal infarction is mainly manifested by abdominal pain, and it has been reported that flank pain in patients with acute renal infarction accounts for C. Lv et al. Open Journal of Emergency Medicine 71.2% [11]. It is a rare disease with an incidence of 0.004% of emergency patients [12]. Hematuria is of suggestive significance for the diagnosis of ARI, but it is not common. It is neither a sensitive diagnostic clue, nor a specific clinical manifestation, and it makes the diagnosis of acute renal infarction more difficult [10]. Not every acute renal infarction will develop the symptoms described in the textbook. Even if these symptoms are developed, because the symptoms overlap with other diseases, the symptoms of different diseases are the same. As a result, it's not easy to make a diagnosis because it can't be associated with acute renal infarction by only one or several symptoms developed. In the meantime, the understanding of symptoms requires the accumulation of experience. Any expe-  [14]. It quickly builds a thinking mode of experts, which not only gives directions of medical history, physical examination, and laboratory examination, but also collects the clinical data of the patient, and screens the diseases in the list one by one, without missing key diseases. As for the case of this study, the patient presented with abdominal pain and suffered from persistent dull pain in the left lower abdomen. In this case, it is difficult for physicians to think of acute renal infarction, and the next step of examination and diagnosis is blind. According to the list, the four aspects of "adjacent organ disease, systemic disease, psychogenic disease, and female reproductive system disease" are excluded via medical history, symptom physical examination, and general laboratory examination. In local organ diseases, the patient did not suffer from "fever, obvious tenderness and rebound tenderness", and viscera rupture, torsion, and obstruction of hollow viscera are not supported. Although the symptoms and signs of the elderly can be atypical, except for observation and further examination, the list suggests: "Vascular abdominal pain" is a life-threatening disease that needs to be ruled out. Therefore, we directly performed angiography and did not carry out CT abdominal plain scan, thus saving the diagnosis time and finally clarifying the diagnosis.  [3]. The "list of thinking" is in conformity with the principle of mind mapping, but it is more concise, helping us forese rare diseases, and gives the rapid diagnosis, thus avoiding misdiagnosis and missed diagnosis caused by atypical clinical manifestations and rare diseases.
The list is not under a blind screening but based on the prompts of the list to screen for suspicious diseases, which is also well-targeted. If no possible diseases are found, a second screening will be conducted as per the list from 5 directions, without missing key diseases just as the first screening, which conforms to the principle of critical thinking.
The shortcomings of this study are as follows: due to the simple operation of the diagnosis process, the physician may develop menu-based thinking and the possibility of excessive medical care for inexperienced physicians. Therefore, the long-term effect of this program needs to be further observed.

Authors' Contributions
Chang Lv wrote this paper; Xurui Li, Zhangshun Shen, and Cuiya Wang consulted data and wrote revisions; Jianguo Li carried out the conception of this paper. This paper has no conflict of interest.