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Acute Appendicitis

From Mediwikis

Appendicitis, post appendectomy

Inflammation of the appendix, mostly occuring when lumen of the appendix becomes obstructed with a faecolith (however in some cases there is only generalised acute inflammation). If the appendix is not removed at this stage, gangrene occurs with perforation, leading to a localised abscess or to generalised peritonitis. Affects all age groups. Most common surgical emergency.


  • Abdominal pain - intiallly vaguely central then moving to right iliac fossa
  • Nausea
  • Vomiting
  • Diarrhoea
  • Anorexia

The anatomical location of the appendix can influence the presentation of appendicitis:

  • Retrocaecal (70%) - poorly localised abdominal pain or even RUQ in a long appendix. A positive psoas sign can indicate a retroceacal appendix.
    Psoas Sign, courtesy of AllAccessMedicine
  • Pelvic (21%) - diarrhoea due to proximity to the rectum
  • Close to bladder - frequency and dysuria
  • The anatomical location of the appendix is commonly referred to as McBurney's point and is located 1/3 of the distance from the umbilicus to the anterior superior iliac spine (ASIS).
  • Anatomical Location of the appendix, courtesy of All Access Medicine.


Perform a full abdominal examination in patients with appendicitis

  • Patients will often lie down and flex their hips and knees to try and relieve the pain
  • Tenderness in right iliac fossa
  • Guarding (localised peritonitis)
  • Tender mass in right iliac fossa
  • Rebound tenderness (pain worsening on release of pressure)

Differential Diagnoses

  • Ectopic Pregnancy – Abnormal implantation of embryo mainly in fallopian tubes causing abdo pain
  • Mesenteric adenitis – Inflamed lymph nodes secondary to infection. Can cause RLQ pain and fever.
  • Urinary tract infection. Frequency, dysuria, abdo pain and fever.
  • Cholecystitis – Inflammed gallbladder. Poorly localised abdo pain
  • Diverticulitis – Inflammed outpouchings of colon. Abdo pain, fever, nausea
  • Salpingitis – Infection and inflammation of fallopian tubes. Abdo pain, fever, nausea and vomiting (PID)
  • Dysmenorrhoea – Pain during menstruation. Lower abdo pain, fever, nausea and vomiting
  • Pelvic Inflammatory Disease (PID)
  • Ovarian cyst or torsion of ovarian cyst (when the cyst twists around and cuts off its own blood supply leading to infarction and severe pain)
  • Crohn's Disease – IBD. Abdo pain, fever
  • Perforated ulcer – Perforated peptic ulcer. Abdo pain, fever, nausea and vomiting.
  • Gastroenteritis – An inflamed appendix next to rectum can cause diarrhoea symptoms.
  • Meckel’s Divertivulum – Congenital diverticulum in distal ileum can become inflammed. Abdo pain, fever, nausea and vomiting
  • Intussusception - mostly seen in paediatrics (an area of bowel telescopes in on itself and compromises its blood supply leading to pain and blood in stool)


  • Bloods
    • WBC and ↑CRP
    • U+Es for surgery and dehydration
    • LFTs and Amylase
  • Urinalysis – Dipstick to exclude UTI
  • Pregnancy test – beta HCG to exclude ectopic pregnancy
  • Chest X Ray– pneumoperitoneum showing perforated bowel
  • Ultrasound - detection of inflamed appendix, and reveals abscesses

If further conformation is required in unusual cases:

  • MRI scan
  • PR and PV exam to exclude IBD, gynaecological causes
  • Exploratory laproscopy


Primarily clinical from the history and examination of the patient. The Alvarado score can be used to crudely assess the probablity of appendicitis in a patient although research has shown it is sensitive it is not specific enough to be validated.

Symptoms Migration of pain 1
Anorexia 1
Nausea/vomiting 1
Signs RIF pain 2
Rebound tenderness 1
Temperature > 37.3 °C 1
Laboratory Leukocytosis 2
Neutrophils > 75% WCC 1
Total score 10


<= 4 Appendicitis unlikely
5-6 Observe patient
>= 7 Operation required


  • IV access
    • Give IV fluids and antibiotics
    • Give analgesia and antiemetics as required
  • Appendectomy - either laparotomy/laparoscopy