Appendicitis
Appendicitis is the commonest surgical emergency of the abdomen. Roughly one person in fifteen develops it during their lifetime. It is generally straightforward to treat and the outcome is excellent, but two things about it are less simple than they appear: the diagnosis is genuinely difficult in a significant minority of patients, particularly the very young, the elderly and women of reproductive age; and the question of whether every appendicitis actually requires an operation has been reopened by good evidence in the past decade.
How it develops
The appendix is a blind-ending tube arising from the caecum, with a narrow lumen and a rich lining of lymphoid tissue. That combination is what makes it vulnerable.
The sequence is one of obstruction followed by a closed-loop infection:
- The lumen becomes obstructed. In children and young adults this is usually lymphoid hyperplasia — the lymphoid tissue in the wall swelling in response to an infection elsewhere, often a viral illness. In adults it is more often a faecolith, a hardened pellet of stool. Less commonly, a tumour, a parasite or a foreign body.
- Secretion continues behind the obstruction. The mucosa goes on producing mucus into a closed space, and pressure rises.
- Venous and lymphatic drainage is compromised before arterial supply, because veins collapse at lower pressures. The wall becomes congested and oedematous, worsening the obstruction.
- Bacteria proliferate in the stagnant contents and invade the wall — suppurative appendicitis.
- Arterial supply fails, the wall becomes ischaemic and then gangrenous.
- Perforation follows, which may be contained by omentum and adjacent loops into a localised abscess or phlegmon, or may spread as generalised peritonitis.
This progression explains the characteristic evolution of the pain, which is the single most useful feature in the history. Early distension of the appendix stimulates visceral afferent nerves, which enter the spinal cord at T10 and are poorly localised — producing vague, central, periumbilical pain. As inflammation reaches the serosa and irritates the overlying parietal peritoneum, which has somatic innervation, the pain becomes sharp, constant and precisely localised to the right iliac fossa. Migration of pain from the centre of the abdomen to the right lower quadrant is more valuable diagnostically than any single test.
Position varies and alters the presentation: a retrocaecal appendix (the commonest variant) may cause flank pain with few abdominal signs; a pelvic appendix may cause diarrhoea and urinary symptoms and tenderness only on rectal examination; a long appendix reaching across the midline may cause left-sided pain.
Symptoms
- Pain beginning centrally and shifting to the right iliac fossa over some hours
- Anorexia — so consistent that a genuinely hungry patient makes the diagnosis less likely
- nausea and vomiting, characteristically after the pain begins — vomiting first suggests gastroenteritis instead
- low-grade fever; a high fever suggests perforation
- pain worse on movement, coughing or going over bumps in the road
- tenderness and guarding at McBurney's point, with rebound tenderness and percussion tenderness
- Rovsing's sign (pain in the right iliac fossa on palpating the left), psoas sign and obturator sign, all of variable usefulness
Atypical presentations are where mistakes are made:
- Young children — non-specific symptoms, and a higher rate of perforation at diagnosis
- Elderly patients — muted pain and fever, delayed presentation, and a higher rate of perforation and of underlying tumour
- Pregnancy — the appendix is displaced upward by the gravid uterus, so pain may be in the right upper quadrant; nausea is attributed to pregnancy; and delay risks both mother and fetus
- Women of reproductive age — ovarian and tubal conditions mimic appendicitis closely, and this group has historically had the highest rate of normal appendix removal
How the diagnosis is made
It remains a clinical diagnosis supported by investigation, not a radiological one.
- Blood tests — raised white cell count and C-reactive protein. Normal inflammatory markers in a patient with a convincing history do not exclude it early, but normal markers with a normal examination make it unlikely.
- Urinalysis and a pregnancy test in all women of childbearing age — non-negotiable, since ectopic pregnancy is the diagnosis that must not be missed.
- Scoring systems — Alvarado, AIR and Adult Appendicitis Score — stratify risk and reduce both unnecessary imaging in low-risk patients and unnecessary delay in high-risk ones.
- Ultrasound — first-line in children and pregnant women, with no radiation. It is operator-dependent, and a non-visualised appendix does not exclude the diagnosis.
- CT — highly accurate, and the investigation of choice in adults where the diagnosis is uncertain, particularly in the elderly, where it also detects the alternative diagnoses that are common in that group.
- MRI — in pregnancy where ultrasound is inconclusive.
- Diagnostic laparoscopy — both diagnostic and therapeutic, and particularly valuable in young women where gynaecological causes are a real possibility.
Increased use of imaging has reduced negative appendicectomy rates considerably, and the old view that a certain rate of removing normal appendices is acceptable no longer holds.
Treatment
Surgery
Laparoscopic appendicectomy is the standard treatment. Compared with open surgery it causes less pain, fewer wound infections, a shorter stay and a faster return to work, and it allows inspection of the pelvis and the rest of the abdomen when the appendix looks normal. Open surgery through a small right iliac fossa incision remains entirely appropriate in some circumstances.
Antibiotics are given at induction. Where the appendix has perforated, a longer postoperative course is given and the abdomen is irrigated.
Antibiotics alone
This is the genuine change of recent years, and it deserves an honest account rather than dismissal.
Randomised trials, including the large CODA trial, have shown that for uncomplicated appendicitis — no perforation, no abscess, and importantly no faecolith — antibiotics alone succeed in the majority of patients. The trade-offs are clear:
- Roughly one in four to one in three patients treated with antibiotics come to appendicectomy within a year.
- The presence of a faecolith substantially increases the failure rate, and most units exclude those patients.
- Antibiotic treatment avoids an operation and its risks for those in whom it works, and for a patient who strongly wishes to avoid surgery, or in whom surgery carries particular risk, it is a reasonable first choice.
- Surgery is definitive, removes the diagnostic uncertainty, and prevents recurrence.
Both are defensible. The right approach is to present the choice honestly to suitable patients rather than to present surgery as the only option or antibiotics as a universal alternative.
Appendix mass and abscess
Where presentation is delayed and a phlegmon or abscess has formed, immediate surgery into an inflamed mass is difficult and risks damaging the caecum or small bowel. Standard management is antibiotics, with percutaneous drainage of a sizeable abscess, allowing the inflammation to settle.
Interval appendicectomy afterwards is no longer routine, as many patients never have further trouble. However, investigation of the colon after recovery is important in patients over about forty, by colonoscopy or CT colonography, since an underlying caecal or appendiceal tumour is found in a meaningful minority presenting this way.
Incidental findings
All removed appendices are examined histologically. Findings that require action include neuroendocrine tumour (the commonest appendiceal tumour, usually cured by appendicectomy alone if small and at the tip; right hemicolectomy considered for larger or base-involving lesions), appendiceal adenocarcinoma, and mucinous neoplasm, which carries a risk of pseudomyxoma peritonei and requires specialist referral.
Recovery
After laparoscopic appendicectomy for uncomplicated appendicitis, most patients go home within a day, eat normally straight away, and return to work or school within one to two weeks. Heavy lifting is avoided for a few weeks. After perforated appendicitis, hospital stay is longer, intravenous antibiotics are continued, and a collection may develop in the following week or two — persistent fever, pain or feeling unwell after discharge should be reported rather than waited out.
When to seek help urgently
Abdominal pain that has moved to the right lower abdomen, is worse on movement, and is accompanied by loss of appetite, requires same-day assessment. Severe generalised pain with a rigid abdomen and fever requires immediate emergency attention. Pain of this kind in pregnancy should always be assessed promptly.
Common questions
What does the appendix do?
It is not useless, though it can be removed without consequence. It contains lymphoid tissue involved in immune function and appears to act as a reservoir of beneficial gut bacteria that can repopulate the bowel after a severe infection. Its removal has no measurable effect on health.
Can appendicitis be treated with antibiotics instead of surgery?
For uncomplicated appendicitis, often yes. Good trials show most people treated with antibiotics avoid an operation, though roughly one in three needs one within a year. It is less likely to work if a hardened pellet of stool is blocking the appendix, which shows on a scan. It is a genuine choice, and worth discussing if you would prefer to avoid surgery.
What happens if I wait?
The appendix may burst, usually within a day or two of symptoms starting. That turns a straightforward day-case operation into a more complicated illness with a longer stay, antibiotics, and the possibility of an abscess forming afterwards. Delay is the main thing that makes appendicitis serious.
How long will I be off work?
After keyhole surgery for an uncomplicated appendix, usually one to two weeks, and most people go home the same or the next day. Heavy manual work needs a few weeks. Recovery after a burst appendix takes longer.
They operated and the appendix was normal. Was the operation unnecessary?
Not necessarily. Appendicitis is genuinely difficult to diagnose with certainty, and the consequences of waiting too long are worse than the consequences of an operation that finds a healthy appendix. During a keyhole operation the rest of the abdomen and pelvis can be inspected, which frequently identifies the real cause. Scanning before surgery has made this much less common than it used to be.
Can it happen again if the appendix is left in?
Yes. If you are treated with antibiotics alone, the appendix remains and appendicitis can recur — most commonly within the first year. After removal, it cannot recur.
Why do I need a colonoscopy after this?
If you are over forty and presented with an appendix mass or abscess rather than straightforward appendicitis, there is a small but real chance that a tumour of the bowel near the appendix caused the blockage. A colonoscopy after you recover excludes that. It is a precaution, not an expectation.
I am pregnant. Is the operation safe?
Yes, and it is safer than leaving appendicitis untreated, which poses a greater risk to both mother and baby. Keyhole surgery is performed safely in pregnancy. Diagnosis is harder because the appendix is pushed upward as the uterus grows, so the pain may be higher than expected, and ultrasound or MRI is used rather than CT.
Related conditions
Other conditions of the colon & rectum covered on this site:
- Colon cancer
- Rectal cancer
- Bowel polyps (colorectal polyps)
- Diverticular disease and diverticulitis
- Crohn's disease — the surgical perspective
- Ulcerative colitis — the surgical perspective
- Large bowel obstruction and volvulus
- Hereditary bowel cancer syndromes (Lynch syndrome and FAP)
This page provides general information and does not replace an individual medical consultation. Suspected appendicitis requires same-day medical assessment.