A 29-year-old patient presents to your office with abdominal pain and a fever. The patient was well until 1 day ago and had never experienced abdominal pain. A vague periumbilical pain awoke him from sleep 12 hours previously, and he soon developed anorexia, nausea, and vomiting. His wife consulted their family medical reference guide and then brought him to the office, concerned that his symptoms matched a description of appendicitis. The pain then migrated to the right lower quadrant (RLQ) and was much worse while he was riding in the car to the physician's office.
The patient's oral temperature is 37.8°C; the pulse rate and blood pressure are normal. He has RLQ tenderness, guarding but not rigidity, and rebound tenderness in the RLQ. A rectal examination reveals no tenderness, and he does not exhibit the psoas or obturator signs. Rovsing sign is positive.
Why Is This an Important Question to Answer With a Clinical Examination?
In western countries, appendicitis represents a common cause of acute abdominal pain. According to National Center for Health Statistics data, approximately 500 000 patients underwent appendectomies from 1979 to 1984. Individuals carry a 7% lifetime risk of developing appendicitis.1 The incidence of appendicitis causing abdominal pain depends on the clinical setting. In series from emergency departments or surgical services, 25% of patients younger than 60 years and evaluated for acute abdominal pain have acute appendicitis, whereas the incidence in those older than 60 years is approximately 4%.1-5 Only 0.7% to 1.6% of all ambulatory patients with abdominal pain have appendicitis.6, 7 Among children treated in the ambulatory care setting, appendicitis causes 2.3% of all abdominal pain episodes.8 In children admitted for acute abdominal pain, appendicitis is the etiology for approximately 32%.9-11
The morbidity and mortality of appendicitis remain significant, even with the advent of antibiotics and effective surgical management. Although the overall mortality rate with appropriate treatment is less than 1%, in the elderly it remains approximately 5% to 15%.2, 4 There is a significant amount of morbidity caused by appendiceal rupture.12-15 The incidence of perforation in patients with appendicitis ranges from 17% to 40%, with a median of 20%.16, 17 The perforation rate is significantly higher in the elderly, with rates as high as 60% to 70%. Several factors contribute to the increased incidence of perforation in the elderly, including significant delay in seeking care, nonspecificity of the presenting symptoms and signs, diminished febrile response, and fewer abnormalities in important laboratory characteristics such as the white blood cell count (WBC).2, 3, 5, 14, 18, 19 Children also have an increased incidence of perforation because of delays in consulting a physician for abdominal pain.8 The negative laparotomy result rate in most series ranges from 15% to 35% and creates morbidity.16, 17, 20-22 In younger women, the negative laparotomy result rate is significantly higher (up to 45%) because of the prevalence of pelvic inflammatory disease and other common obstetric and gynecologic disorders.16, 17, 23, 24
The Accuracy of Other Diagnostic Modalities
Routine medical history and physical examination remain the most effective and practical diagnostic modalities.25, 26 Several other clinical methods for diagnosing appendicitis have been studied. Computer or algorithm-driven analyses of patients with abdominal pain have been evaluated,27-35 although most studies have incomplete controls and yield inconsistent results. Thus, the utility of computer-guided diagnosis compared with unassisted clinical diagnosis needs further evaluation. The authors of most of these studies believe that the improved utility they demonstrated was primarily because clinicians were forced to focus on specific clinical data that were readily available to be entered into the analysis tree. Finally, these authors observed that all of these modalities completely depend on the accuracy of the data gathered and interpreted by clinicians before the data are entered into the computer or algorithm analysis. The concept of an extended period of observation of patients with questionable appendicitis has been shown by some authors to be helpful.8, 27, 28 Its utility, like that of computer and algorithm analyses, depends on routine medical history and physical examination skills of clinicians.
The utility of radiographic techniques has also been evaluated. Plain abdominal radiographs and barium enemas are neither specific nor sensitive for appendicitis.36 Ultrasonography is more effective in detecting a distended appendix than appendiceal perforation.10, 15, 36-44 No study has demonstrated ultrasonography to be clearly superior to the clinical examination, and many authors believe that its primary utility is to supplement the medical history and physical examination in patients with equivocal findings. The accuracy of computed tomography in diagnosing appendicitis has also been inconsistent.36, 42, 43
Laparoscopy has been shown by some authors to be useful, particularly in young women in whom it can be difficult to differentiate between pelvic inflammatory disease, ectopic pregnancy, and appendicitis.27 However, other series have not been as supportive, with negative appendectomy result rates from 20% to 30%.44, 45 Studies of outcomes comparing laparoscopy with laparotomy have yielded conflicting results.46, 47 Even though ultrasonography, computed tomography, and laparoscopy can be helpful, none are ideal techniques, and the clinician must depend on patient medical history and physical examination results.
Appendiceal Anatomy and Pathophysiology of Appendicitis
The adult's appendix averages 10 cm in length, arising from the posteromedial wall of the cecum, about 3 cm below the ileocecal valve.48 Its position in the abdominal cavity is variable, being described as retrocecal, retroileal, preileal, subcecal, or pelvic, and this variability in location may influence the clinical signs and symptoms associated with appendicitis. Although the physiologic role of the appendix is unproved, an immunologic function is suggested by its content of lymphoid tissue.49
Appendiceal obstruction, followed by secondary bacterial invasion, causes the majority of appendicitis. Continued fluid secretion by the mucosa of the obstructed appendix distends the lumen, eventually exceeding venous pressure and leading to tissue ischemia and, ultimately, necrosis. Causes of obstruction include fecaliths, calculi, tumors, parasites, foreign bodies, or, rarely, barium. In the one-third of patients without apparent obstruction, infection by viruses, parasites, or bacteria, or either trauma or postoperative fecal stasis may be involved.50-55
Normally, appendicitis presents with a highly characteristic sequence of symptoms and signs.56 Initially, appendicitis causes visceral pain poorly localized to the epigastrium or periumbilical region, presumably because of distention of the appendix. Anorexia, nausea, and vomiting soon follow as this pathophysiology worsens. More advanced inflammation causes irritation of adjacent structures or the peritoneum, low-grade fever, and peritoneal pain localized to the RLQ. The pathophysiology explains the classic migration of pain caused by appendicitis. The point of maximal tenderness may be distinct from McBurney point, 5 cm from the anterior superior iliac spine on a line running from the umbilicus.
Atypical locations of the appendix may lead to unusual clinical findings. In the case of retrocecal or retroiliac appendices,57, 58 the pain may be poorly localized and may not undergo the transition from epigastric to RLQ locations. Pelvic appendicitis frequently causes pain in the left lower quadrant, with an absence of tenderness, and is reflected by increased pain during a rectal examination. Unusual symptoms of urinary and defecation urgency, caused by irritation of the ureter and rectum, respectively, plus dysuria and diarrhea may also occur.
Although often a diagnostic dilemma in the first trimester of pregnancy because of confusion with other diagnoses, appendicitis in later stages of gestation may present a challenge for the clinician because of displacement of the appendix by the enlarging uterus. In such cases, periumbilical or right subcostal tenderness may be found.
How to Elicit the Relevant Symptoms and Signs
Pain is commonly the first symptom of appendicitis.9, 59 Classically, the vague, midepigastric or periumbilical pain awakens the patient from sleep but is not initially severe. After reaching its peak in around 4 hours, it diminishes and then migrates to the RLQ. Most patients will seek medical attention within 12 to 48 hours. Pain usually occurs before vomiting, and the patient has usually not experienced similar symptoms before the present episode.
According to Cope's Early Diagnosis of the Acute Abdomen,60 many patients feel constipated and anticipate that defecation will relieve discomfort, leading them to use cathartic agents. However, pain persists after a bowel movement.
Many signs have been associated with appendicitis or peritonitis. Some of obvious value, such as the pelvic examination, have not been adequately evaluated to merit mention in this systematic review or they lack an adequate description or standardization of the elicitation of the sign to ensure accurate reproduction. A common reference for definitions in the best studies is a text by De Dombal.61 What follows is the most consistent and useful description of the signs:
Guarding: Guarding is a state of voluntary contraction of the abdominal muscles. The muscles are held tense by the patient because he or she knows (or fears) that further examination is likely to be painful. Fear can be partially, or fully, overcome by tact and persuasion.61
Rigidity: Rigidity is also known as involuntary guarding. The best studies of abdominal pain have described rigidity as an involuntary reflex spasm of the muscles of the abdominal wall. It can never be overcome by tact and reassurance.61
Rebound tenderness: (1) Press on the area of question with the flat of your hand, sufficient to depress the peritoneum. The patient should be experiencing pain. (2) Keep pressing with a constant intensity. As the patient adjusts to this pressure during 30 to 60 seconds, the pain diminishes. It may go away completely, although usually it does not. (3) Without warning, and preferably while the patient's attention is distracted, remove the hand suddenly to just above skin level. Watching the patient grimace is more indicative than a complaint of pain.61
Rovsing sign: A sign related to the rebound tenderness test. Press deeply and evenly in the left lower quadrant and then release pressure suddenly. The presence of tenderness in the RLQ during palpation or referred rebound tenderness in the RLQ during release is considered a positive Rovsing sign.
Psoas sign: With the patient in the supine position, ask the patient to lift the thigh against your hand, placed just above the knee. Alternatively, with the patient in the left lateral decubitus position (Figure 5-1), extend the patient's right leg at the hip. Increased pain with either maneuver is a positive sign and indicates irritation of the psoas muscle by an inflamed appendix.
Obturator sign: This sign is similar mechanically to the psoas sign. It is elicited by passively flexing the right hip and knee and internally rotating the leg at the hip, stretching the obturator muscle (Figure 5-2). Resultant right-sided abdominal pain is a positive sign, indicating irritation of the obturator muscle. The obturator sign has not been studied independent of the psoas sign, but most clinicians would attribute the same significance.
Rectal examination: Classically, tenderness and fullness perceived on the right but not the left side on rectal examination are indicative of a pelvic appendicitis.60 This sign is subjective and poorly described in most major physical examination texts. No studies that assess rectal tenderness describe the examination technique.
The Psoas Sign in Examination for Appendicitis
The sign can be elicited with 2 different patient positions. First, with the patient in the supine position, ask the patient to lift the right thigh against your hand placed just above the knee. With the patient in the left lateral decubitus position (as shown), extend the right leg at the hip. Increased pain with either maneuver is a positive sign and indicates irritation of the psoas muscle by an inflamed appendix.
The Obturator Sign in Examination for Appendicitis
Elicit this sign by passively flexing the patient's right hip and knee and internally rotating the leg at the hip, stretching the obturator muscle. Resultant right-sided abdominal pain is a positive sign, indicating irritation of the obturator muscle.
Precision of These Symptoms and Signs
There have been no studies published evaluating the precision of the clinical examination for appendicitis. A standardized clinical examination might produce strong interrater reliability.
Accuracy of These Symptoms and Signs
A handful of studies published during the past few decades have evaluated the accuracy of the clinical presentation of appendicitis. The studies are of various quality and design. Most are best described as cross-sectional in design because a clinical judgment is made, with outcomes measured in terms of pathologic confirmation of appendicitis vs a negative laparotomy result or no requirement for surgery. Eleven of the highest-quality studies, based on number of patients studied, the study design, and completeness of reported data, are summarized in Table 5-1.9, 24, 33, 35, 62-67 The search strategy for identifying these articles is available from the authors on request. This strategy yielded about 300 articles since 1966. Further limiting sets to adult age groups yielded 200 studies. The titles and abstracts were reviewed and chosen if adequate detail of the outcomes and aspects of the clinical examination allowed construction of 2 × 2 tables and subsequent calculation of likelihood ratios [LRs].
Table 5-1Studies of the Operating Characteristic of the Clinical Examination for Appendicitis |Favorite Table|Download (.pdf) Table 5-1 Studies of the Operating Characteristic of the Clinical Examination for Appendicitis
|Authors ||Year ||Inclusion Criteria ||Design ||No. of Patients Studied (% Women) ||Country ||Age Range, y |
|Staniland et al62 ||1972 ||Admitted for acute abdomen ||Retrospective ||600 (49) ||United Kingdom ||<9 to >70 |
|Brewer et al63 ||1976 ||ED evaluation for acute abdomen ||Retrospective ||1000 (0) ||United States ||15 to >65 |
|Berry and Malt24 ||1984 ||Operation for suspected appendicitis ||Retrospective ||300 (40) ||United States ||10 to >50 |
|Nauta and Magnant64 ||1986 ||Operation for suspected appendicitis ||Prospective ||97 (40) ||United States ||2 to 91 |
|Alvarado33 ||1986 ||Admitted for suspected appendicitis ||Retrospective ||305 (42) ||United States ||4 to 80 |
|Fenyo35 ||1987 ||Admitted for suspected appendicitis ||Prospective ||830 (57) ||Sweden ||15 to 86 |
|Liddington and Thomson65 ||1991 ||Admitted for abdominal pain ||Prospective ||150 (58) ||United Kingdom ||7 to 84 |
|Dixon et al9 ||1991 ||Admitted for suspected appendicitis ||Prospective ||1204 (39) ||Scotland ||7 to 87 |
|Izbicki et al66 ||1992 ||ED evaluation for suspected appendicitis ||Prospective ||150 (56) ||Germany ||11 to 88 |
|Eskelinen et al67 ||1994 ||Admitted for abdominal pain ||Prospective ||222 (58) ||Finland ||65 to 90 |
|Eskelinen et al68 ||1995 ||Admitted for abdominal pain ||Prospective ||417 (54) ||Finland ||>50 |
|Total || || || ||5275 (41) || || |
The 11 studies were divided into 2 groups by the patients on whom they focused. Approximately half of the studies focused on patients in whom appendicitis was suspected, and half, on those who were examined for acute abdomen. In the studies of suspected appendicitis, the inclusion criteria were not further defined. In the studies of acute abdomen, inclusion criteria usually involved pain for less than 1 week. Taken together, the studies report on the findings of more than 4000 patients and provide the best available evidence supporting the most valuable aspects of the clinical examination for appendicitis (Table 5-2).
Table 5-2Aspects of the Clinical Examination Studieda |Favorite Table|Download (.pdf) Table 5-2 Aspects of the Clinical Examination Studieda
|Author ||Pain Migr ||Anorexia ||Nausea ||Vomiting ||Pain ||Similar ||Rectal ||Psoas ||RLQ Pain ||Rebound ||Rigid ||Guard ||Fever |
|Staniland et al62 || ||× ||× ||× || ||× || || ||× ||× ||× ||× || |
|Brewer et al63 ||× ||× || ||× ||× ||× || || || ||× || || ||× |
|Berry and Malt24 || ||× ||× || || || ||× ||× ||× ||× ||× || || |
|Nauta and Magnant64 ||× ||× ||× ||× || || ||× ||× ||× ||× || || || |
|Alvarado33 ||× ||× ||× || || || ||× || ||× ||× || || ||× |
|Fenyo35 ||× || || || || || || || || ||× ||× || || |
|Liddington and Thomson65 || || || || || || || || || ||× || || || |
|Dixon et al9 || || || || || || ||× || ||× ||× ||× || || |
|Izbicki et al66 ||× || || || || ||× || ||× ||× ||× ||× || || |
|Eskelinen et al67 || || || || || ||× ||× || ||× ||× ||× ||× || |
|Eskelinen et al68 || ||× ||× ||× ||× || ||× || ||× ||× ||× ||× ||× |
|No. of cases studied ||1354 ||2161 ||1691 ||1684 ||651 ||1542 ||2349 ||450 ||3979 ||4688 ||3555 ||2267 ||1264 |
Each study reports on a varying constellation of clinical findings. Many aspects of the clinical examination are not evaluated in all of these studies. Unfortunately, some of the aspects evaluated are poorly defined in the text of the studies, so specific recommendations for these aspects are difficult to derive for medical education or the everyday practice of medicine.
Nonetheless, several points can be drawn from a systematic literature review. In evaluation of patients presenting with emergency and acute abdominal pain, usually defined as less than 1 week in duration before presenting to an emergency department or surgical ward, the prevalence (pretest probability) of acute appendicitis ranges from 12% to 26%.12, 30, 32, 69 The clinical examination will influence this probability further. If various aspects of the clinical examination are viewed as diagnostic tests, LRs 70, 71 and posttest probability can be calculated.
From the medical history, 6 aspects have been evaluated. Seven physical examination items have also been studied well. These aspects are examined further in Table 5-3.72 The large number of patients studied and the similarities across studies make the data suitable for being combined into summary measures.
Table 5-3Summary of Clinical Examination Operating Characteristics for Appendicitisa |Favorite Table|Download (.pdf) Table 5-3 Summary of Clinical Examination Operating Characteristics for Appendicitisa
|Procedure ||Sensitivity ||Specificity ||LR+ (95% CI) ||LR– (95% CI) |
|Right lower quadrant pain ||0.84 ||0.90 ||7.3-8.5b ||0-0.28b |
|Rigidity ||0.20 ||0.89 ||3.8 (3.0-4.8) ||0.82 (0.79-0.85) |
|Migration of pain ||0.64 ||0.82 ||3.2 (2.4-4.2) ||0.50 (0.42-0.59) |
|Pain before vomitingc ||1.0 ||0.64 ||2.8 (1.9-3.9) ||NA |
|Psoas sign ||0.16 ||0.95 ||2.4 (1.2-4.7) ||0.90 (0.83-0.98) |
|Fever ||0.67 ||0.79 ||1.9 (1.6-2.3) ||0.58 (0.51-0.67) |
|Rebound tenderness test ||0.63 ||0.69 ||1.1-6.3b ||0-0.86b |
|Guarding ||0.73 ||0.52 ||1.7-1.8b ||0-0.54b |
|No similar pain previously ||0.86 ||0.40 ||1.50 (1.46-1.7) ||0.32 (0.25-0.42) |
|Rectal tenderness ||0.41 ||0.77 ||0.83-5.3b ||0.36-1.1b |
|Anorexia ||0.68 ||0.36 ||1.3 (1.2-1.4) ||0.64 (0.54-0.75) |
|Nausea ||0.58 ||0.37 ||0.69-1.2b ||0.70-0.84b |
|Vomiting ||0.51 ||0.45 ||0.92 (0.82-1.0) ||1.1 (0.95-1.3) |
Three findings show a high positive LR (LR+) across all studies and, when present, are most useful for identifying patients at increased likelihood for appendicitis: RLQ pain (LR+, 8.0), rigidity (LR+, 4.0), and migration of initial periumbilical pain to the RLQ (LR+, 3.2). Rebound tenderness was studied in most patients, but its positive likelihood varied too much to allow a statistical point estimate of its effect (LR+, 1.1-6.3). Although the obturator sign has not been studied independently, the authors suspect that this sign has operating characteristics similar to those of the psoas sign.
Clinicians also collect evidence to help prove normality. Unfortunately, no single component consistently provided a low negative LR (LR–) that would rule out appendicitis. There were, however, many signs that proved to be helpful in ruling out appendicitis. The absence of RLQ pain and the presence of similar previous pain demonstrated powerful LR– (0.28 and 0.25, respectively). The absence of the classic migration of pain also diminished the likelihood of appendicitis significantly (LR–, 0.5). The absence of RLQ guarding or rebound pain has excellent properties for ruling out appendicitis in some studies, but not others. The presence of pain before vomiting needs further study to identify its diagnostic efficiency because, in its only evaluation, it was highly efficient in ruling out appendicitis. Astute clinicians will recognize that the absence of anorexia, nausea, or vomiting has little effect on the likelihood of appendicitis.
The Role of Combined Findings
Clinicians rarely rely on a single sign or symptom for diagnosis but instead rely on a combination of findings. Unfortunately, the precision and accuracy of combinations of findings have not been reported in these studies. Several studies do assess, however, various decision rules that do combine these findings.6, 33-35, 66, 73-77 Four of the most powerful rules were validated on an independent set of 1254 patients older than 50 years and presenting with abdominal pain. No single score was found to be superior; however, it was observed that the decision rules reported in the original work to be most powerful incorporated at least 2 of 5 common variables: site and duration of pain, site of tenderness, rebound tenderness, and leukocytosis.78
Returning to the beginning clinical scenario, the historical components of the presentation are highly suggestive of appendicitis. Our patient demonstrates the classic sequence of abdominal pain before vomiting, culminating with the migration of the initial midepigastric pain to the RLQ. The combination of these LR+s alone makes appendicitis more likely.
The findings of guarding but not rigidity tend to neutralize each other's effect. The rectal examination results and the psoas and related signs are helpful if present but are not helpful when absent, as in this case. In sum, we suspect appendicitis in this man, so further evaluation is warranted.
A surgical doctrine suggests that a decrease in the perforation rate will be achieved only by an increase in the negative laparotomy result rate in suspected acute appendicitis. The truth of this doctrine has been called into question, given the results of large- and small-area variation studies.29 Improved clinical evaluation is suggested as a remedy for a high rate of negative laparotomy results without increasing the perforation rate. Evidence suggests the essential nature of clinical details.79, 80 Clinicians often do not collect enough clinical details for accurate and precise diagnosis.81-83 Correction of this deficit, therefore, may well increase diagnostic accuracy without increasing the perforation rate.
In summary, there are several conclusions that can be made concerning the clinical presentation, pathophysiology, and diagnosis of appendicitis:
Appendicitis is a common clinical entity, with significant morbidity and mortality, particularly at the extremes of age.
The pathophysiology of appendicitis consists of initial dilatation of the appendix, followed by appendiceal ischemia, necrosis, and parietal peritoneal irritation. Clinical findings are predictable, predicated on knowledge of this pathophysiology.
The characteristic sequence of symptoms and signs includes the following: (1) vague pain initially located in the epigastric or periumbilical region; (2) anorexia, nausea, or unsustained vomiting; (3) migration of the initial pain to the RLQ; and (4) low-grade fever.
Migration of pain in the characteristic manner, RLQ pain, and the presence of pain before vomiting are historical findings that suggest appendicitis. The presence of rigidity, a positive psoas sign, fever, or rebound tenderness is a sign on physical examination indicating an increased likelihood of appendicitis.
Conversely, the absence of RLQ pain, the absence of the classic migration of pain, and the presence of similar pain previously are powerful symptoms in the medical history that make appendicitis less likely. In the physical examination, the lack of RLQ pain, rigidity, or guarding makes appendicitis less likely.
Because no finding on the clinical examination can effectively rule out appendicitis, prudence dictates close follow-up of patients with abdominal pain who do not receive further diagnostic testing.
Author Affiliations at the Time of the Original Publication
Department of Internal Medicine, University of Texas, Southwestern Medical Center, Dallas, Texas (Drs Wagner, McKinney, and Carpenter).
We appreciate the expert advice offered by gynecologist Joanne Piscitelli, MD, and general surgeon Ted Pappas, MD, both of Duke University, Durham, North Carolina, during the preparation of the manuscript.
TT. Abdominal pain: a surgical audit of 1190 emergency admissions. Br J Surg.
CG. Surgical emergencies of the abdomen. Emerg Med Clin North Am.
LF. Acute abdominal pain in the elderly. Ann Emerg Med.
G. Acute abdominal disease in the elderly. Am J Surg.
G. Diagnostic problems of acute abdominal diseases in the aged. Acta Chir Scand.
CH. The diagnosis of abdominal pain in ambulatory male patients. Med Decis Making. 1981(3);2151:–224.
J. The diagnostic difficulties of abdominal pain. Aust Fam Physician.
JA. Intensive in-hospital observation: a safe way to decrease unnecessary appendectomy. Am Surg.
DA. Rectal examination in patients with pain in the right lower quadrant of the abdomen. BMJ.
TC. Appendicitis in children aged 13 years and younger. Am J Surg.
RW. Appendicitis in children. Surg Gynecol Obstet.
J. Acute appendicitis: prospective trial concerning diagnostic accuracy and complications. Am J Surg.
PF. Current features in the treatment of acute appendicitis: an analysis of 100 consecutive cases. Surgery.
PJ. Increased morbidity of appendicitis with advancing age. Am Surg.
WB. Accuracy of ultrasound in the diagnosis of acute appendicitis compared with the surgeon's clinical impression. Arch Surg.[Archives of Surgery Full Text]
RV. The epidemiology of appendicitis and appendectomy in the United States. Am J Epidemiol.
HF. Appendicitis in the elderly. Ann Surg.
RP. Removal of the normal appendix: the cause of serious complications. Br J Clin Pract.
DR. The fate of the negative appendix. Am J Surg.
JGR. Death from appendicitis and appendicectomy. Lancet.
RA. Appendicitis near its centenary. Ann Surg.
LV. Contributions of the history, physical examination, and laboratory investigation in making medical diagnoses. West J Med.
C. Relative contributions of history-taking, physical examination, and laboratory investigation to diagnosis and management of medical outpatients. BMJ.
PF. Practicalities in the management of the acute abdomen. Br J Surg.
SI. Tempering the technological diagnosis of appendicitis. N Engl J Med.
RR. Appendicitis: decreasing normal removals without increasing perforations. Med Care.
et al.. Computer aided diagnosis of acute abdominal pain: a multicentre study. BMJ. 1986;293:800–804.
ET. Educational assessment of clinical diagnostic skills: studies across Europe on acute abdominal pain. Postgrad Med J. 1993;69(suppl 2):S94–S96.
AP. Human and computer-aided diagnosis of abdominal pain: further report with emphasis on performance of clinicians. BMJ. 1974;1(5904):376–380.
A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med.
G. Routine use of a scoring system for decision-making in suspected acute appendicitis in adults. Acta Chir Scand.
AH. The radiologic evaluation of acute abdominal pain of intestinal origin. Med Clin North Am.
M. Appendicitis diagnosis today: clinical and ultrasonic deductions. World J Surg.
in the acute abdomen. Br J Surg.
WZ. The value of laparoscopy in acute pelvic pain. Ann Surg. 1974;118(4):484–486.
et al.. A clinical evaluation of ultrasonography
in the diagnosis of acute appendicitis. Surgery.
1989;105(2 pt 1):154–159.
JM. Acute abdomen of unknown origin: impact of CT on diagnosis and management. Gastrointest Radiol.
GS. Diagnosis of acute appendicitis in pregnant women: value of sonography. AJR Am J Roentgenol.
et al.. Impact of adjunctive testing on the diagnosis and clinical course of patients with acute appendicitis. Am J Surg. 1993;166(6):664–665.
HCJ. Value of diagnostic laparoscopy in young women with possible appendicitis. Surg Gynecol Obstet.
A. Laparoscopic appendectomy for acute appendicitis: is there really any benefit? Am Surg.
1993;59(8):541–547; discussion 547-548.
RM. Laparoscopic versus open appendectomy for suspected appendicitis: a prospective study
. Aust N Z J Surg.
A. Investigation and analysis of the position, fixation, length, and embryology of the vermiform appendix. Acta Chir Scand.
TO. Distribution of immunoglobulin producing cells is different in normal human appendix and colon mucosa [abstract]. Gut.
MH. Cytomegalovirus-associated appendicitis in a patient with the acquired immunodeficiency syndrome
. Am J Med.
J. Acute appendicitis complicating infectious mononucleosis
: case report and review. Rev Infect Dis.
B. Appendiceal infection by Entamoeba histolytica
and Strongyloides stercoralis
presenting like acute appendicitis. Dig Dis Sci.
HJ. Acute appendicitis following blunt abdominal trauma: incidence
or coincidence? Am Surg.
N. Appendicitis complicating colonoscopy. Gastrointest Endosc.
D, van Heerden
PJ. The diagnostic challenge of postoperative acute appendicitis. World J Surg.
TR. Acute appendicitis. In: Sleisinger
JS, eds. Gastrointestinal Disease: Pathophysiology, Diagnosis, Management. Philadelphia, PA: WB Saunders Co; 1996:1339–1347.
GV. Anatomic basis for delayed diagnosis of appendicitis [abstract]. South Med J.
et al.. Does the retrocecal position of the vermiform appendix alter the clinical course of acute appendicitis? a prospective analysis [abstract]. Arch Surg.[Archives of Surgery Full Text]
JJ. Appendicitis: improvements in diagnosis and treatment. Am Surg.
W. Cope's Early Diagnosis of the Acute Abdomen. New York, NY: Oxford University Press Inc; 1987:1–290.
FT. Diagnosis of Acute Abdominal Pain. New York, NY: Churchill Livingstone Inc; 1991:1–259.
J, De Dombal
ET. Clinical presentation of acute abdomen: study of 600 patients. BMJ.
SL. Abdominal pain: an analysis of 1000 consecutive cases in a university hospital emergency room. Am J Surg. 1976;131:219–223.
C. Observation versus operation for abdominal pain in the right lower quadrant: roles of the clinical examination and the leukocyte count
. Am J Surg.
WHF. Rebound tenderness test. Br J Surg.
et al.. Accurate diagnosis of acute appendicitis: a retrospective and prospective analysis of 686 patients. Eur J Surg.
P. Acute appendicitis in patients over the age of 65 years: comparison of clinical and computer based decision making. Int J Biomed Comput. 1994;36:239–249.
P. The value of history-taking, physical examination, and computer assistance in the diagnosis of acute appendicitis in patients more than 50 years old. Scand J Gastroenterol.
JC, De Dombal
FT. Diagnosis of acute abdominal pain in the accident and emergency department. Br J Surg.
DM. Physical examination: a revered skill under scrutiny. South Med J.
P. Clinical Epidemiology: A Basic Science for Clinical Medicine. Boston, MA: Little Brown & Co; 1991:173–186.
DB. Likelihood ratios with confidence: sample size estimation for diagnostic test studies. J Clin Epidemiol.
GP. A simple scoring system to reduce the negative appendicectomy rate. Ann R Coll Surg Engl.
J. A test of a linear discriminant for identifying low-risk abdominal pain. Med Decis Making.
J. Practical score to aid decision making in doubtful cases of appendicitis. Br J Surg.
L. Scoring system to aid in the diagnosis of appendicitis. Ann Surg.
N. Predicting which abdominal pain patients can be appropriately discharged home [abstract]. Ann Emerg Med. 1995;25:140.
C. Diagnostic scores for acute appendicitis. Eur J Surg.
B. The information value of clinical data. Int J Biomed Comput.
R. Limits to diagnostic accuracy. Med Inform.