An appendicular abscess (abscess in the appendix) is a complication of acute appendicitis – invasion of the appendix of the large intestine by bacteria usually due to an obstruction. The appendix exists at the junction of the small and large intestine and is exposed to the movement of digested food, waste matter and is teeming with bacteria. It is therefore prone to becoming blocked and coupled with an infection, acute appendicitis can even be life threatening. An abscess is not the only possible complication. Other complications include gangrene, appendicular masses, rupture and general peritoneal infections. These complications associated with appendicitis is more likely to occur in a patient who delays in seeking medical attention.
What is an appendicular abscess?
An appendicular abscess is a collection of pus resulting from perforation or rupture of acutely inflamed appendix. The pus remains localized close to the appendix, because it is walled off by adhesions formed by the surrounding abdominal structures. This prevents the pus from leaking and the infection spreading throughout the peritoneal cavity.
How doe an appendicular abscess forms?
When the appendix become inflamed (appendicitis), complications arise if the infection is not treated promptly. In some patients, appendicitis can lead to gangrene of appendix. In most of these patients the intestinal coils and omentum in the abdominal cavity tend to cover the inflamed gangrenous appendix. This forms an appendicular mass. The continuing suppurative process inside the appendicular mass can lead to the formation of an abscess. The development of abscess usually follows rupture of a gangrenous appendix within the appendicular mass. The abscess remains limited by the walls of cavity formed by the inflamed coils of intestine, caecum and omentum and usually forms in the right lower abdomen. Other sites of an appendicular abscess are in the pelvis and behind the caecum.
Some patients with acute appendicitis who are medically managed with antibiotics can also occasionally progress into an appendicular abscess.
Signs and Symptoms of an Abscess in the Appendix
Patients with appendicular abscess usually have a history of severe colicky pain in the right lower abdomen (right iliac fossa) with a tender boggy swelling in the right lower abdomen. Read more on appendix pain location. A high grade fever with chills and rigors is also present. Other symptoms may include vomiting, constipation or less frequently, diarrhea. On examination the abdomen may be rigid and the swelling can be felt.
There are other types of abscesses in the abdomen which may give rise to similar symptoms in the given location.
Diagnosing an Abscess in the Appendix
The diagnosis of appendicular abscess is based on the clinical history, clinical features and investigations. Blood investigations show an increase in the white blood cell count. X-ray can sometimes show the presence of an abscess although ultrasound and CT scan are more commonly used radiological investigations to confirm presence of abscess and to assess the size.
Treatment of an Abscess in the Appendix
Patients with abscess larger than 4 cm size and a high fever are usually managed with drainage of abscess. The abscess is drained after localizing it radiologically. Drainage can be done through the rectum (transrectal), through vagina (transvaginal) or through the skin (percutaneous) depending on the location. An appendicular abscess in pelvis is drained transrectally or transvaginally. Retrocaecal appendicular abscess is drained retroperitoneally. Some patients may require open surgical drainage (laparotomy). The abscess drainage is supported with antibiotic therapy.
Patients with smaller abscesses who are in good condition may be managed initially with antibiotics alone. Patients showing no response may then require drainage of the abscess. The removal of appendix is usually done after the patient has fully recovered from the condition (interval appendicectomy). This avoids risks of complications related to suturing of the inflamed caecum.
Poor management or rupture of an appendicular abscess can lead to more dangerous generalized peritoneal infection (peritonitis).