ACUTE APPENDICITIS Anatomy
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ACUTE APPENDICITIS Anatomy • Embryologically, the appendix is a continuation of the cecum, first delineated during the fifth month of gestation • The appendix averages 10 cm in length (range 2‐20 cm). • The wall of the appendix consists of both an inner circular and an outer longitudinal layer of muscle. The longitudinal layer is a continuation of the taeniae coli. • The appendix is lined by colonic epithelium • Few submucosal lymphoid follicles are noted at birth. These follicles enlarge, peak between age 12 and 20 years, then decrease. Anatomy Anatomy • Blood supply from the appendicular artery, a branch of the ileocolic artery. This artery courses through the mesoappendix posterior to the terminal ileum. • An accessory appendicular artery can branch from the posterior cecal artery. • The appendix runs into a serosal sheet of the peritoneum called the mesoappendix Anatomy Anatomy • While the appendiceal base is in a constant location, the position of the tip of the appendix varies widely. • 65% of patients, the tip is located in a retrocecal position • 30%, it is located at the brim or in the true pelvis • 5%, it is extraperitoneal, situated behind the cecum, ascending colon, or distal ileum. Anatomy ETIOLOGY Appendicitis results from obstruction of the lumen of the appendix. o lymphoid hyperplasia (60%) o fecalith or fecal stasis (35%) o foreign body (4%) o tumors (1%) • Rarely non‐obstructive; vasculitis, Yersinia Obstructive causes Fecaliths form when calcium salts and fecal debris become layered around a nidus of inspissated fecal material located within the appendix. Lymphoid hyperplasia is associated with various inflammatory and infectious disorders including Crohn disease, gastroenteritis, amebiasis, respiratory infections, measles, and mononucleosis. Non‐obstructive acute appendicitis • Inflammation commences either in mucous membrane or in lymph follicles and terminates either as resolution, ulceration, suppuration, fibrosis or gangrene. • Infection progresses rapidly once it reaches submucous tissue. • The vascularity of the distal part of appendix is often in jeopardy as the artery is intramural and liable to occlusion by inflammation/ thrombosis thereby, leading to gangrene of the tip. • The non‐obstructive appendicitis progress slowly allowing protective barrier to develop and at times inflammation does not progress beyond the mucosal lining (Catarrhal appendicitis) and attack goes off without sequel incidence • The annual incidence of acute appendicitis has gradually declined by nearly 50% from its peak incidence in the early 20th century to its current levels of 1 case per 1000 population in the United States and 86 cases for every 100,000 persons worldwide • Acute appendicitis is less common in Africa and in parts of Asia because of the high‐residue diets of the inhabitants. incidence • There is a slight male preponderance of 3:2 in teenagers and young adults • In adults, the incidence of appendicitis is approximately 1.4 times greater in men than in women. • The incidence of primary appendectomy is approximately equal in both sexes. incidence • The incidence of appendicitis gradually rises from birth, peaks in the late teen years, and gradually declines in the geriatric years. • The mean age when appendicitis occurs in the pediatric population is 6‐10 years. • Younger children have a higher rate of perforation, with reported rates of 50‐85%. • The median age at appendectomy is 22 years • Rare neonatal and even prenatal appendicitis have been reported Pathophysiology • Obstruction leads to increased intraluminal pressure with increase mucus secretion and this leads to distention of the appendix and visceral pain • Stasis leads to bacterial overgrowth. • The mucus then turns into pus that causes a further increase in luminal pressure causing invasion of the wall by pathogenic bacteria. • the overlying parietal peritoneum becomes inflammed, causing the pain to localize to the right lower quadrant (RLQ) Pathophysiology • Further increase in pressure leads to venous obstruction, causing edema and ischemia of the appendix. • The ensuing bacterial invasion of the wall of the appendix is known as acute suppurative appendicitis. • Finally, with continued pressure increases, venous thrombosis and arterial compromise occur, leading to gangrene and perforation. Presentation • Clinical presentation of appendicitis notoriously inconsistent o Variations in the position of the appendix, o age of the patient o degree of inflammation. • Statistics report that 1 of 5 cases of appendicitis is misdiagnosed; however, a normal appendix is found in 15‐40% of patients who have an emergency appendectomy. history 55% of patients with appendicitis present with classic history and physical findings. • Periumbilical pain • Classic history of anorexia, nausea and vomiting • Right lower quadrant (RLQ) pain (shifting) • Diarrhea or constipation is noted in as many as 18% of patients and should not be used to discard the possibility of appendicitis. history • The duration of symptoms is less than 48 hours in approximately 80% of adults • Longer in elderly persons and in those with perforation. • Approximately 2% of patients report duration of pain in excess of 2 weeks. • A history of similar pain is reported in as many as 23% of cases Presentation • When the appendix is located anteriorly, the classic migratory pain is expected. However, a dull ache is often described in patients with a retrocecal appendix. • Atypical pain is commonly encountered when the tip of the appendix is located in the pelvis. Patients may report dysuria and urinary frequency due to the inflamed appendix irritating the bladder. • Patients may also have diarrhea or tenesmus if the inflamed appendix is adjacent to the rectum. • In early appendicitis, the patient is initially afebrile or has a low‐ grade fever. Higher fevers are associated with a perforated appendix Physical examination • Ulying still, as movement worsens the pain. • Having the patient cough elicits localized pain in the RLQ. • Local tenderness to palpation is usually observed. • Percussion tenderness is also noted in this area. • Children often have localized pain with walking and jumping. Physical examination • When the tip of the appendix is retrocecal, tenderness may be manifested by passive extension of the hip (psoas sign). • When it is located in the pelvis, tenderness may be detected during rectal examination or pelvic examination. • If the appendix is lying adjacent to the obturator internus muscle, pain may be manifested with flexion of the right hip and internal rotation Physical examination • Obturator sign (RLQ pain with internal and external rotation of the flexed right hip): Suggests the inflamed appendix is located deep in the right hemipelvis • Psoas sign (RLQ pain with extension of the right hip or with flexion of the right hip against resistance): Suggests that an inflamed appendix is located along the course of the right psoas muscle • Dunphy sign (sharp pain in the RLQ elicited by a voluntary cough): Suggests localized peritonitis • RLQ pain in response to percussion of a remote quadrant of the abdomen or to firm percussion of the patient's heel: Suggests peritoneal inflammation • Markle sign (pain elicited in a certain area of the abdomen when the standing patient drops from standing on toes to the heels with a jarring landing pregnancy • During pregnancy, the appendix migrates in a counterclockwise direction toward the right kidney, rising above the iliac crest at about 4.5 months' gestation. • RLQ pain and tenderness dominate in the first trimester • in the latter half of pregnancy, right upper quadrant (RUQ) or right flank pain must be considered a possible sign of appendiceal inflammation. • Nausea, vomiting, and anorexia are common in uncomplicated first trimester pregnancies, but their reappearance later in gestation should be viewed with suspicion. Diagnostic Scoring Alvarado Characteristic Score M = Migration of pain to the RLQ 1 A = Anorexia 1 N = Nausea and vomiting 1 T = Tenderness in RLQ 2 R = Rebound pain 1 E = Elevated temperature 1 L = Leukocytosis 2 S = Shift of WBCs to the left 1 Total 10 Stages of Appendicitis • Early stage appendicitis • Suppurative appendicitis • gangrenous appendicitis. • Perforated appendicitis Other forms of Appendicitis • Recurrent appendicitis: The incidence of recurrent appendicitis is 10%. The diagnosis is accepted as such if the patient underwent similar occurrences of RLQ pain at different times that, after appendectomy, were histopathologically proven to be the result of an inflamed appendix. • Chronic appendicitis: Chronic appendicitis occurs with an incidence of 1% and is defined by the following: 1. the patient has a history of RLQ pain of at least 3 weeks’ duration without an alternative diagnosis; 2. after appendectomy, the patient experiences complete relief of symptoms 3. histopathologically, the symptoms were proven to be the result of chronic active inflammation of the appendiceal wall or fibrosis of the appendix. Differential diagnosis • Ovarian cyst and torsion • Degenerating uterine leiomyoma • Midcycle pain • Ectopic pregnancy • Pelvic inflammatory disease (PID) or tubo‐ovarian abscess • Endometriosis Differential diagnosis • Diverticulitis • Crohns disease • Colonic carcinoma • Bacterial enteritis • Mesenteric adenitis and ischemia • Gastroenteritis • Enterocolitis • Perforated duodenal ulcer • Meckel’s diverticulitis Differential diagnosis • Pancreatitis • Cholecystitis • Omental torsion Differential diagnosis •