Surgery chapters
Appendix: appendicitis and appendiceal tumours
Anatomy of the appendix, causes and stages of acute appendicitis, symptoms and signs, special groups, differential diagnosis, Alvarado score, imaging, open and laparoscopic appendicectomy, appendix mass and abscess, complications, carcinoid and mucinous tumours with pseudomyxoma peritonei.
- Acute appendicitis usually starts with luminal obstruction (lymphoid hyperplasia in the young, faecolith in adults): periumbilical visceral pain shifts to the right iliac fossa with anorexia, low fever and McBurney point tenderness.
- Diagnosis is clinical, helped by the Alvarado score (7 or more strongly suggests it), ultrasound (children, young women, pregnancy) or CT. Treatment is appendicectomy (laparoscopic or open).
- An appendix mass is treated conservatively (Ochsner–Sherren); an abscess is drained. Carcinoid is the commonest appendix tumour: appendicectomy unless 2 cm or more, base involved or nodes positive → right hemicolectomy.
On this page
Overview
Acute appendicitis is the commonest surgical cause of an acute abdomen in young people and the commonest urgent abdominal operation. Peak age is the teens and twenties; it is rare under 2 years.
The diagnosis is mainly clinical. Missing it risks perforation and peritonitis; over-diagnosing it removes normal appendices. Imaging and scoring systems help. Tumours of the appendix are uncommon but MCQ favourites.
Applied anatomy
- A blind muscular tube, usually about 7.5–10 cm long, arising from the posteromedial caecum.
- The base is constant: where the three taeniae coli converge. Following the anterior taenia leads to it at operation.
- Surface marking of the base: McBurney point, one-third of the distance along a line from the ASIS to the navel.
- Blood supply: appendicular artery, from the lower (ileal) branch of the ileocolic artery, running along the edge of the mesoappendix. It is an end artery → thrombosis causes gangrene.
- Mucosa contains much lymphoid tissue (prominent in the young) and Kulchitsky (argentaffin) cells, the source of carcinoid.
- Visceral pain fibres enter at T10 → pain referred to the umbilicus.
| Position | Approximate frequency |
|---|---|
| Retrocaecal | About 74% (commonest) |
| Pelvic | About 21% |
| Paracaecal, subcaecal, pre-ileal, post-ileal | The rest (each small) |
Causes and pathology
- Luminal obstruction is the key step:
- Lymphoid hyperplasia (children, young adults; often after viral illness). - Faecolith (appendicolith): inspissated stool, calcium salts and debris. - Others: carcinoma of the caecum or carcinoid (older patients), stricture, worms (pinworm), foreign body.
- Low-fibre, refined diet is linked with higher rates.
- Sequence: obstruction → mucus and pus build up → raised pressure → lymphatic then venous obstruction → ischaemia → bacterial invasion (mixed aerobes and anaerobes, e.g. E. coli, Bacteroides) → gangrene → perforation.
- Outcome: resolution, appendix mass (omentum and bowel wall it off), abscess, or generalised peritonitis.
Factors that increase the risk of perforation: extremes of age, immunosuppression, diabetes, faecolith obstruction, a loose pelvic appendix hanging in the pelvis, and previous surgery (the omentum cannot wall it off).
In young children the omentum is short and underdeveloped, so perforation spreads quickly to diffuse peritonitis.
Clinical features
Symptoms
- Periumbilical colicky pain (visceral, midgut).
- Anorexia, nausea and one or two vomits after the pain begins.
- Pain shifts to the right iliac fossa (RIF) and becomes constant and sharp (parietal peritoneum irritated); worse on coughing or moving.
In appendicitis the pain comes before the vomiting. Vomiting before pain points to gastroenteritis.
The classic shift happens in only about half of patients.
Signs
- Low-grade fever (around 37.5°C) and mild tachycardia. A temperature over 38.5°C in a child suggests another cause (e.g. mesenteric adenitis).
- Tenderness at McBurney point, guarding, rebound (or pain on coughing or gentle percussion).
- Foetor oris and furred tongue.
| Sign | How elicited | What it suggests |
|---|---|---|
| Rovsing | Pressure in the left iliac fossa causes pain in the RIF | Peritoneal irritation in RIF |
| Psoas | Pain on extending the right hip; patient may lie with hip flexed | Retrocaecal appendix on psoas |
| Obturator | Pain on flexing and internally rotating the right hip | Pelvic appendix on obturator internus |
| Pointing sign | Patient points to where pain began and moved | Shift of pain |
| Rectal tenderness | On the right side of the pelvis | Pelvic appendix or pelvic abscess |
Variations by position and patient
| Situation | Features |
|---|---|
| Retrocaecal | "Silent" abdomen anteriorly; tenderness in the flank or loin; psoas spasm |
| Pelvic | Suprapubic pain, diarrhoea and tenesmus (rectum irritated), urinary frequency (bladder); tenderness only on rectal examination |
| Post-ileal | Pain may not shift; diarrhoea, retching; vague tenderness near the umbilicus |
| Infants and young children | Late diagnosis, high perforation rate; vomiting nearly always present |
| Elderly | Vague pain, few signs, may mimic obstruction; gangrene and perforation more common; higher mortality |
| Obese | Signs blunted; imaging and laparoscopy helpful |
| Pregnancy | Commonest non-obstetric surgical emergency; the appendix is pushed upwards as the uterus grows, but RIF pain stays the key feature; fetal loss rises sharply after perforation |
Differential diagnosis
| Group | Main mimics |
|---|---|
| Children | Mesenteric adenitis (recent sore throat, higher fever, shifting tenderness, cervical nodes), gastroenteritis, Meckel diverticulitis, intussusception, constipation, UTI, right lower lobe pneumonia, Henoch–Schönlein purpura |
| Adults | Terminal ileitis (Crohn, Yersinia, TB), ureteric colic, pyelonephritis, perforated duodenal ulcer, testicular torsion, pancreatitis, rectus sheath haematoma |
| Women of childbearing age | Ectopic pregnancy, PID, mittelschmerz (mid-cycle), torsion or bleeding of an ovarian cyst, endometriosis |
| Elderly | Caecal carcinoma, diverticulitis (long sigmoid loop on the right), obstruction, mesenteric ischaemia, leaking aneurysm |
In every woman of childbearing age with RIF pain, do a pregnancy test. In every man, examine the testes.
Investigations
- Full blood count: raised white cells with neutrophilia.
- Urinalysis: a few cells can occur with an inflamed appendix near the ureter or bladder; heavy pyuria or haematuria suggests a urinary cause.
- Pregnancy test in women.
- Ultrasound: first choice in children, thin adults, pregnant women and when gynaecological disease is suspected (non-compressible tubular structure, about 6 mm or more).
- CT abdomen and pelvis: most accurate (about 95%); valuable in older adults (excludes cancer and diverticulitis). Low-dose protocols suit younger adults.
- MRI is an option in pregnancy if ultrasound is not conclusive.
Alvarado (MANTRELS) score
| Item | Points |
|---|---|
| Migration of pain to RIF | 1 |
| Anorexia | 1 |
| Nausea or vomiting | 1 |
| Tenderness in RIF | 2 |
| Rebound tenderness | 1 |
| Elevated temperature | 1 |
| Leucocytosis | 2 |
| Shift to the left (neutrophilia) | 1 |
| Total | 10 |
Score 7 or more: appendicitis likely. 5–6: equivocal, image (ultrasound or CT). Low scores: appendicitis unlikely.
A 20-year-old man: pain moved to the RIF (1), anorexia (1), vomited once (1), RIF tenderness (2), no rebound (0), temperature 37.9°C (1), WBC 14 × 10⁹/L (2), neutrophilia (1).
Total = 1 + 1 + 1 + 2 + 0 + 1 + 2 + 1 = 9 → appendicitis likely; proceed to appendicectomy.
In MANTRELS, only T (tenderness) and L (leucocytosis) score double: "Two Lots".
Management
Preparation
- IV fluids, analgesia (do not withhold it; it does not hide the diagnosis), antiemetic.
- Antibiotics: a single dose at induction for simple appendicitis; a full course covering Gram-negatives and anaerobes (e.g. cefuroxime or a third-generation cephalosporin plus metronidazole) if perforated or gangrenous.
Appendicectomy
- Laparoscopic: preferred where available. It is diagnostic as well (valuable in women and the obese), with less wound infection and faster recovery. Ports: umbilicus (camera), suprapubic and left lower quadrant.
- Open:
- Gridiron incision: at right angles to the line from the ASIS to the umbilicus, centred on McBurney point. - Lanz incision: transverse skin-crease cut a little below and to the right of the navel, over the line running down from the mid-clavicle to the mid-inguinal point; better cosmesis. - Rutherford Morison: muscle-cutting extension for a fixed retrocaecal appendix. - Lower midline if the diagnosis is uncertain or there is generalised peritonitis.
- Gridiron layers: skin, Camper and Scarpa fascia, external oblique aponeurosis, internal oblique and transversus (split along their fibres), transversalis fascia, extraperitoneal fat, peritoneum. The ilioinguinal and iliohypogastric nerves can be injured.
- Steps: deliver the caecum, find the base via the taeniae, divide and ligate the mesoappendix, crush and ligate the base, remove, with or without burying the stump.
- Retrograde appendicectomy (base first) for a fixed retrocaecal appendix.
- If the appendix is normal: look for Meckel diverticulum, terminal ileitis, mesenteric nodes, and inspect the pelvic organs.
Non-operative treatment with antibiotics alone can work for uncomplicated, CT-confirmed appendicitis without a faecolith, but about a quarter recur within a year. It suits selected or high-risk patients.
Appendix mass
A tender RIF mass of inflamed appendix wrapped in omentum and bowel, usually after a few days of symptoms.
- Ochsner–Sherren regime (conservative): nil or limited oral intake, IV fluids, antibiotics, analgesia, 4-hourly pulse and temperature, mark the edges of the mass on the skin, CT to look for abscess.
- About 90% settle.
After an appendix mass settles in a patient over 40, the colon must be examined: a caecal carcinoma can present exactly like an appendix mass.
- Stop conservative treatment and operate if: pulse rises, pain increases or spreads, or the mass grows.
- Afterwards: interval appendicectomy (some weeks later) or observation. In patients over 40, colonoscopy or CT to exclude caecal carcinoma or Crohn disease.
Appendix abscess
- Spiking fever, enlarging mass. Percutaneous (ultrasound or CT-guided) drainage plus antibiotics; open drainage if this fails.
- Pelvic abscess: swinging fever, diarrhoea with mucus, tenesmus, a tender boggy mass anterior to the rectum on PR. Drain radiologically or through the rectum.
Early surgery on an established appendix mass is dangerous (friable bowel, risk of faecal fistula). Treat it conservatively unless it worsens.
Complications after appendicectomy
| Complication | Points |
|---|---|
| Wound infection | Commonest; about day 4–5; mixed Gram-negatives and anaerobes (Bacteroides) |
| Intra-abdominal or pelvic abscess | Fever and malaise about 5–7 days after surgery; CT; drain |
| Paralytic ileus | Especially after peritonitis |
| Portal pyaemia (pylephlebitis) | Septic thrombophlebitis of the portal vein after gangrenous appendicitis; rigors, high fever, jaundice; multiple liver abscesses |
| Faecal fistula | Stump leak, oedematous caecum, or hidden Crohn, TB, carcinoma or foreign body |
| Adhesive obstruction | Commonest late complication; often a single band |
| Stump appendicitis | Long stump left behind |
| Right inguinal hernia | After a gridiron incision damaging the ilioinguinal nerve |
Tumours of the appendix
Found in about 1% of appendicectomy specimens, most as a surprise to the pathologist.
Carcinoid (neuroendocrine) tumour
- The appendix is the commonest site of gut carcinoid; about 1 in 300–400 appendices examined.
- Arises from Kulchitsky cells, often at the tip (distal third); yellow on cut section.
- Rarely metastasises; carcinoid syndrome is very rare.
| Finding | Treatment |
|---|---|
| Under 2 cm, at the tip, margins clear | Appendicectomy alone |
| 2 cm or more, base or caecal wall involved, or lymph nodes positive | Right hemicolectomy |
Epithelial (mucinous) tumours and pseudomyxoma peritonei
- LAMN (low-grade mucinous neoplasm), HAMN (high-grade) and mucinous adenocarcinoma; non-mucinous adenocarcinoma behaves like colon cancer (right hemicolectomy).
- Mucocele: appendix distended with mucus (from a mucinous neoplasm or obstruction). Remove intact; rupture spills mucin.
- Pseudomyxoma peritonei: a ruptured mucinous appendiceal tumour seeds the peritoneum → jelly-like mucinous ascites, "omental cake", ovarian deposits in women, progressive abdominal swelling.
- Treatment: cytoreductive surgery with heated intraperitoneal chemotherapy (HIPEC) in specialist centres.
In a woman with pseudomyxoma and an ovarian mass, the appendix is usually the true primary, not the ovary.
Expect: the commonest position (retrocaecal) and its silent signs; the end artery from the ileocolic artery; McBurney point and Rovsing, psoas and obturator signs; pain before vomiting, anorexia as a constant feature; pelvic appendix with diarrhoea and rectal tenderness; differentials in children (mesenteric adenitis) and women (ectopic, PID); Alvarado score items and cut-offs; incisions and layers; management of appendix mass (Ochsner–Sherren) and when to abandon it; pelvic abscess; wound infection as the commonest complication and pylephlebitis; appendiceal carcinoid size rule and pseudomyxoma peritonei.
Quick revision
- Retrocaecal commonest; base where taeniae meet; appendicular artery is an end artery.
- Periumbilical pain → RIF; anorexia; pain before vomiting; low fever.
- Rovsing (LIF press → RIF pain), psoas (retrocaecal), obturator (pelvic).
- Alvarado: 10 points, 7 or more likely; ultrasound in children and pregnancy, CT in adults.
- Appendicectomy, laparoscopic preferred; look for Meckel if the appendix is normal.
- Appendix mass: conservative; abscess: drain; over 40: colonoscopy afterwards.
- Wound infection commonest; pylephlebitis rare and serious.
- Carcinoid: 2 cm or more, base or nodes → right hemicolectomy. Mucinous tumour → pseudomyxoma.
Written by The House Job from standard references (Bailey & Love).
FAQ
Why does appendicitis pain start around the umbilicus?
Early inflammation stimulates visceral afferents from the midgut that enter the cord at about T10, so pain is felt centrally. Once the parietal peritoneum is irritated, it localises to the right iliac fossa.
What is the Ochsner–Sherren regime?
Conservative treatment of an appendix mass with fluids, antibiotics and close observation. Surgery is needed if the pulse rises, pain spreads or the mass grows.
Why can a retrocaecal appendicitis have few abdominal signs?
The gas-filled caecum lies in front of it and shields it from the examining hand. Tenderness is found in the flank or loin, often with a positive psoas sign.
When does an appendiceal carcinoid need a right hemicolectomy?
When it is 2 cm or larger, involves the base or caecal wall, or has spread to lymph nodes. Smaller tumours at the tip are cured by appendicectomy.
What is pseudomyxoma peritonei?
Spread of mucin-producing tumour cells around the peritoneum, usually from a ruptured mucinous appendiceal tumour. It is treated by cytoreductive surgery with heated intraperitoneal chemotherapy.