The appendicitis is the most common cause of 'surgical abdomen' in schoolchildren.

1. The diagnosis of appendicitis can be difficult in children.
2. Therefore, the percentage of complicated types of appendicitis is high: Perityphlitic abscess and generalized peritonitis, abdominal wall and intraabdominal abscess, postoperative obstructive ileus due to adhesions, and imminent primary sterility in girls.

Unknown. In some families there is a frequent occurrence.

Depending on the stage of the disease, different pathoanatomical types are encountered: Acute focal, acute suppurative, gangrenous, and perforated appendicitis. A gangrenous appendicitis also leads to peritonitis as a perforated appendicitis. In case of perforated appendicitis there may be a communication with the abdominal cavity leading to a generalized peritonitis, or there is a localized peritonitis with a perityphlitic abscess due to adhesions of the adjacent intestinal loops.
The mean course of appendicitis lasts 2-3 days; 24 to 36 hours after the onset, a perforation is already possible.
In addition, some special types of appendicitis may be observed, such as chronic recurrent appendicitis with self-subsiding single episodes, and neuroimmunological appendicitis.

The obstruction of the cavity of the appendix by stercoliths, foreign bodies, and hyperplasia of the lymphatic structures caused by germs seems to play an important role. Following an increase in pressure within the lumen situated distally of the obstruction, the venous and lymphatic outflow is hindered, and simultaneously, there is an increased germinal growth and invasion in the appendical wall.
Ischemia, infarction and gangrene of the appendical wall lead to perforation or passage of germs, and to a generalized or localized peritonitis. The increase in pressure within the appendix leads to the dull, periumbilical visceral pain, and the involvement of the peritoneal serosa to somatic pain localized in the lower right abdomen.

History: Within 1 to 2 days, dull abdominal pain (not colics) followed by anorexia, nausea, vomiting, and constipation.
Findings: First, attention should be directed to pains in the lower right abdomen on movements, cough, palpation, and to localized tenderness. Rectal examination only makes sense if performed with a special technique in schoolchildren, or if a pelvic abscess or gross constipation is to be expected. In childhood in general, there is a large variability of signs and symptoms (e. g. diarrhea instead of constipation and dysuria); in infants and in complicated forms of appendicitis, the clinical presentation may be blurred. Therefore, the differential diagnosis of abdominal emergencies must always include the possibility of appendicitis.

It is unknown why some episodes of appendicitis subside spontaneously, whereas probably most of them progress through all stages of the disease up to the perforation.

The differential diagnosis includes all diseases producing peritoneal irritation, of which gastroenteritis is the most frequent and most frequently suspected one. In addition, pathologies of the gonads must be considered, such as torsion of the testis in boys and of the ovary in girls, in the latter also disorders following puberty. Finally, all causes of abdominal and retroperitoneal emergencies such as obstructive ileus or complications of abdominal tumors, a pseudo-appendicitis in cystic fibrosis, or pneumonia.
Beside the age, the stage of appendicitis or its type of clinical presentation is important in the consideration of pathologies for specific differential diagnoses.

A careful history and clinical examination is the most important factor for a prompt diagnosis because none of the available additional examinations has a 100-percent sensivity and specifity in the single case.
Measurement of temperature, total leucocyte count and hemogram, C-reactive protein and erythrocyte sedimention rate and urinalysis belong to the commonly used examinations and may have a differential diagnostic value.
With the aim to avoid unnecessary surgery, and due to an increasing lack of clinical experience, and because of time constraints, ultrasound, CT and MRI are used as additional examinations, adding little additional safety, but much more time-consuming examinations that may frighten the children, while increasing health care costs.
Nevertheless, ultrasound is useful in case of a suspected ovarian pathology, and CT in case of a suspected complicated appendicitis with intraabdominal abscesses.

A prompt open or laparoscopic operation belongs to the golden standard of pediatric surgery. There are many publications about these two types of appendectomy without obvious advantages of one method over the other. Nevertheless, laparoscopic surgery is superior in girls with acute or obscure lower abdominal pain during puberty.

Depending on the stage of appendicitis at which surgery is performed: Abscesses in 1 % in acute appendicitis vs. 5 % in perforated appendicitis; and obstructive ileus due to adhesions in 1 % vs. more than 5 %.