Surgical Emergencies
A 23 year old man presents to the Emergency Department with a 3 day history of abdominal pain. He describes a gradual onset of pain near the umbilicus which has now migrated to the right iliac fossa. You suspect appendicitis. On examination you note that passive extension of the right thigh with the patient in the left lateral position elicits pain in the right lower quadrant. What is the most likely position of the appendix?
Answer:
The psoas sign, is a sign that indicates irritation to the iliopsoas group of hip flexors in the abdomen, and consequently indicates that the inflamed appendix is retrocaecal in orientation (as the iliopsoas muscle is retroperitoneal). Muscular rigidity and tenderness to deep palpation are often absent because of protection from the overlying caecum.Appendicitis
Surgical Emergencies
Last Updated: 5th January 2022
Pathophysiology
Appendicitis describes an acute inflammation of the appendix. The aetiology and pathogenesis of acute appendicitis remain largely unknown, but it is thought to be caused by luminal obstruction in about 50% of cases. The main causes of luminal obstruction are thought to be faecolith (hard mass of faecal matter), lymphoid hyperplasia during an infection, impacted stool, foreign body, or rarely appendiceal or caecal tumour. Luminal obstruction leads to distension of the appendix owing to increased mucus production, bacterial overgrowth, and suppurative inflammation. This results in impaired lymphatic and venous drainage from the appendix, with eventual ischaemia and necrosis, and potential perforation.
Clinical features
Suspect a diagnosis of acute appendicitis if there are suggestive clinical features on history and examination. Establishing a diagnosis may be challenging, as it may present atypically and vary in severity.
- Typical symptoms
- Abdominal pain (common).
- Periumbilical or epigastric pain that worsens, and migrates to the right lower quadrant over 24–48 hours.
- Often worsened by movement (such as coughing and driving over uneven roads).
- Note: a history of sudden relief of pain may indicate appendiceal perforation.
- Fever (often low grade), general malaise, and anorexia.
- Nausea and vomiting.
- Constipation (or sometimes diarrhoea).
- Abdominal pain (common).
- Typical signs
- Facial flushing, dry tongue, halitosis, low-grade fever (less than 38°C), and/or tachycardia.
- Tenderness in the right lower quadrant on abdominal examination.
- The site of maximal tenderness is typically over 'McBurney’s point', which lies two-thirds of the way along a line drawn from the umbilicus to the anterior superior iliac spine.
- Abdominal distension, guarding (muscular rigidity), and rebound tenderness or percussion tenderness may suggest peritonitis. Absent bowel sounds may indicate ileus or peritonitis associated with perforation.
- A palpable abdominal mass may suggest an appendix mass or abscess.
- Consider testing for peritoneal signs specific for acute appendicitis:
- Rovsing's sign — palpation of the left lower quadrant increases the pain felt in the right lower quadrant.
- Psoas sign — passive extension of the right thigh with the person in the left lateral position elicits pain in the right lower quadrant.
- Obturator sign — passive internal rotation of the flexed right thigh elicits pain in the right lower quadrant.
Atypical presentations may occur in:
- Children - infants and young children may present with non-specific abdominal pain and anorexia, and may appear withdrawn.
- Older patients – there may be minimal pain or fever; may present with acute confusion or shock.
- Pregnancy – there may be displacement of the appendix by the gravid uterus. In the later stages of pregnancy, may present with right upper quadrant or right flank pain. Nausea and vomiting may be mistaken for pregnancy-related symptoms.
- Variant anatomical positions of the appendix:
- A retrocaecal/retrocolic appendix may present with right loin pain and tenderness, and a positive psoas test. Muscular rigidity and tenderness to deep palpation are often absent because of protection from the overlying caecum.
- A pre-ileal and post-ileal appendix may present with vomiting and diarrhoea (due to irritation of the distal ileum).
- A subcaecal and pelvic appendix may present with suprapubic pain and urinary frequency; diarrhoea and tenesmus may be present owing to rectal irritation; abdominal tenderness may be lacking, but rectal or vaginal tenderness may be present on the right side; microscopic haematuria and leucocytes may be present on urine dipstick testing.
- A long appendix with tip inflammation in the left lower quadrant may cause pain in that region.
| Visceral pain | Parietal pain |
|---|---|
| Caused by stretching of hollow viscus or capsule of solid viscus or chemical irritation | Caused by irritation of the parietal peritoneum |
| Locality of pain dependent on embryologic origin of viscera | Pain is localised to the region of abdominal wall that the parietal peritoneum lines |
| Less severe | More severe |
| Poorly localised | Easily localised |
| Dull or aching pain | Sharp, stabbing pain |
| May be intermittent or constant | Constant pain |
Differential diagnosis
- Gastrointestinal
- Gastroenteritis, intestinal obstruction, incarcerated inguinal hernia, intussusception, volvulus, Meckel diverticulum, biliary colic and acute cholecystitis, perforated peptic ulcer, diverticulitis, pancreatitis, inflammatory bowel disease, irritable bowel syndrome, constipation, mesenteric adenitis
- Urological
- Ureteric colic, pyelonephritis, UTI, urinary retention, testicular torsion
- Gynaecological
- Ectopic pregnancy, ruptured ovarian cyst, ovarian torsion, Mittelschmerz, pelvic inflammatory disease, endometriosis or adenomyosis, fibroids, dysmenorrhoea
- Other
- Basal pneumonia, back pain, abdominal wall abscess or haematoma, DKA, shingles
Investigations
Consider the need for additional investigations to exclude an alternative cause, depending on clinical judgement.
- Full blood count — neutrophil-predominant leucocytosis is present in 80–90% of people with appendicitis.
- C-reactive protein (CRP) — raised levels may be present, but normal levels do not exclude a diagnosis of appendicitis.
- Urine dipstick test — to help exclude a urinary tract infection (UTI).
- Pregnancy test — to exclude ectopic pregnancy and other pregnancy-related conditions.
Clinical Scoring System
The Alvarado score predicts the likelihood of appendicitis diagnosis in patients presenting with suspected acute appendicitis.
Score (out of 10):
- Signs
- Right lower quadrant tenderness +2
- Elevated temperature (>37.3°C) +1
- Rebound tenderness +1
- Symptoms
- Migration of pain to right lower quadrant +1
- Anorexia +1
- Nausea or vomiting +1
- Laboratory values
- Leukocytosis >10,000 +2
- Leukocyte left shift (>75% neutrophils) +1
Results:
- ≤4 = Unlikely appendicitis
- 5 - 6 = Possible appendicitis
- ≥7 = Likely appendicitis
Management
Specialist management of suspected acute appendicitis may include:
- Imaging investigations
- Imaging studies in people with a clinical suspicion of acute appendicitis can reduce the negative appendectomy rate, which has been reported to be as high as 15%. Ultrasonography, abdominal computed tomography (CT) and magnetic resonance imaging (MRI) are most commonly used.
- Non-operative management
- After imaging, a non-operative management strategy with intravenous fluids and antibiotics can be a safe and effective approach in selected patients with uncomplicated acute appendicitis.
- Operative management
- Removal of the appendix is the gold standard treatment for appendicitis. In people with progressive or persistent pain, exploratory laparoscopy is recommended to establish/exclude the diagnosis of acute appendicitis or alternative diagnoses. Laparoscopic appendicectomy offers significant advantages over open appendicectomy in terms of less pain, lower incidence of surgical site infection, decreased length of hospital stay, earlier return to work, overall costs, and better quality of life scores.
Complications
Appendicitis may be uncomplicated (non-perforating) or complicated (perforating).
A delay or misdiagnosis of appendicitis can result in additional severe complications from perforation such as:
- Appendix mass ( the inflamed appendix becomes walled off by omentum and surrounding viscera to form an inflammatory mass)
- Appendix abscess
- Generalised peritonitis
- Sepsis
- Intra-abdominal adhesions
Possible postoperative complications include:
- Small bowel obstruction
- Superficial wound infection
- Intra-abdominal abscess
- Stump leakage
- Stump appendicitis
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
