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How is Appendicitis Diagnosed?

Personal History and Physical Examination
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Appendicitis DiagnosisThe diagnosis begins with a thorough history and physical examination.

Before beginning a physical examination, a nurse or doctor will usually measure vital signs: temperature, pulse rate, breathing rate, and blood pressure. Usually the physical examination proceeds from head to toe. Many conditions such as pneumonia or heart disease, can cause abdominal pain. Generalized symptoms such as fever, rash, or swelling of the lymph nodes may point to diseases that wouldn't require surgery.

Patients often have an elevated temperature, and there usually will be moderate to severe tenderness in the right lower abdomen (right lower quadrant or RLQ)when the doctor pushes there. If inflammation has spread to the peritoneum, there frequently is rebound tenderness. This means that when the doctor pushes on the abdomen and then quickly releases his hand, the pain becomes suddenly, but temporarily, worse.

Abdominal X-Ray
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An abdominal x-ray may detect the fecalith (the hardened and calcified, pea-sized piece of stool that blocks the appendiceal opening) that may be the cause of appendicitis. This is especially true in children.

Barium Enema
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A barium enema is an x-ray imaging test where the colon is filled through the anus with liquid barium, a substance readily seen under x-ray imaging. Barium enema can also exclude other intestinal problems that mimic appendicitis, such as Crohn's disease. Advantages of barium enema are its wide availability, use of simple equipment, and potential for diagnosis of other diseases (eg, Crohn’s disease, colon cancer, ischemic colitis) that may mimic appendicitis. Disadvantages include its high incidence of non-diagnostic examination, radiation exposure, insufficient sensitivity, and invasiveness. These disadvantages make barium enema a poor screening examination for use by emergency physicians. Barium enema essentially has no role in the diagnosis of acute appendicitis in the era of ultrasonography and CT.

Clinical Diagnostic Scores
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Several investigators have created diagnostic scoring systems in which finite numbers of clinical variables are elicited from the patient, and each is given a numerical value. The sum of these values is used to predict the likelihood of acute appendicitis.

The best known system is the MANTRELS score, which tabulates presence or absence of migration of pain, anorexia, nausea/vomiting, tenderness in the RLQ, rebound tenderness, elevated temperature, leukocytosis, and shift to the left.

Clinical scoring systems are attractive because of their simplicity; however, none has been prospectively shown to improve upon physician judgment in the subset of patients evaluated in the ED for abdominal pain that may be suggestive of appendicitis. The MANTRELS score, in fact, was based on a population of patients hospitalized for suspected appendicitis, which markedly differs from the population seen in the ED.

CT Scan
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CT ScanComputed Tomography (CT) is a series of detailed pictures of areas inside the body, taken from different angles. The pictures are created by a computer linked to an x-ray machine. It may also be called a Computerized Axial Tomography (CAT) scan.  In patients who are not pregnant, a CT scan of the appendix area is useful in diagnosing appendicitis and peri-appendiceal abscesses as well as in excluding other diseases inside the abdomen and pelvis that can mimic appendicitis. Advantages of CT scanning include superior sensitivity and accuracy compared with some other imaging techniques, ready availability, noninvasiveness, and potential to reveal alternative diagnoses. Disadvantages include radiation exposure, depiction of anatomy only, which may lead to inconclusive diagnosis, potential for allergic reaction if intravenous (IV) contrast is used, lengthy acquisition time if oral contrast is used, and patient discomfort, if rectal contrast is used. CT with IV contrast is contraindicated for renally impaired patients.

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Laparoscopy is a surgical procedure wherein a small fiberoptic tube with a camera is inserted into the abdomen through a small puncture made on the abdominal wall. Laparoscopy allows a direct view of the appendix as well as other abdominal and pelvic organs. If appendicitis is found, the inflamed appendix can be removed at the same time. The disadvantage of laparoscopy, compared to ultrasound and CT scanning, is that it requires a general anesthetic.

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UltrasoundAn ultrasound is a procedure that examines internal organs using high frequency sound waves. Ultrasound can identify an enlarged appendix or an abscess.  However, the appendix is seen in a wide range of values from 71% - 97%.  Success is highly dependent on operator skill, ultrasound’s primary disadvantage.  Therefore, not seeing the appendix during an ultrasound does not exclude appendicitis. Ultrasound is helpful in women because it can exclude the presence of conditions involving the ovaries, fallopian tubes, and uterus that can mimic appendicitis. Advantages include noninvasiveness, short acquisition time, lack of radiation exposure, and potential for diagnosis of other causes of abdominal pain, particularly in the subset of females of childbearing age. Many authorities feel that ultrasonography should be the initial imaging test in pregnant women, and in pediatric patients, because radiation exposure is particularly undesirable in those groups.

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Urinalysis is a microscopic examination of the urine that detects red blood cells, white blood cells, and bacteria in the urine. Urinalysis usually is abnormal when there is inflammation or stones in the kidneys or bladder, which sometimes can be confused with appendicitis. Therefore, an abnormal urinalysis suggests that there is a kidney or bladder problem, while a normal urinalysis is more characteristic of appendicitis.

White Blood Cell Count
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The white blood cell (WBC) count usually becomes elevated with infection. In early appendicitis, before infection sets in, white blood cell count can be normal but, most often, there is at least a mild elevation even early.  Studies consistently show that 80-85% of adults with appendicitis have a WBC count greater than 10,000. Neutrophilia greater than 75% occurs in 78% of patients. Fewer than 4% of patients with appendicitis have a WBC count less than 10,000 and neutrophilia less than 75%. Unfortunately, appendicitis is not the only condition that causes elevated WBC counts. Almost any infection or inflammation can cause this count to be abnormally high. Therefore, an elevated WBC count, alone, cannot be used as a definitive sign of appendicitis.