CT image of the Pelvis showing an
enlarged appendix and
a fluid filled abscess
Tubo-ovarian abscess in Pelvic
What is an abscess?
An abscess is a localised collection of pus surrounded by a fibrous capsule or case and contained in a cavity. Pus itself is a fluid containing bacteria (germs or bugs), dead and dying inflammatory cells called neutrophils and proteins secreted by cells to try and kill the bacteria. The most usual and likely cause of an abscess is a bacterial infection. Certain bacteria such as Staphylococcus aureus and Streptococcus pyogenes are more likely to form pus because the chemicals (toxins) that they make can damage the body’s tissues. The infection causes the immune system to activate white blood cells and chemicals in order to fight the bacteria, inevitably some of the tissue dies and a cavity forms and fills with pus. The cavity will increase in size if the infection continues. The formation of an abscess is actually part of the body’s immune system as it serves to trap and contain the invading bacteria ensuring that it does not spread to other parts of the body.
What is a Pelvic abscess?
Pelvic abscesses most commonly occur after an acute bacterial infection such as appendicitis or gynaecological infections, for example, Pelvic Inflammatory Disease (PID). PID is an infection of the uterus, fallopian tubes with possible ovarian involvement as well. Common causes of PID are sexually transmitted infections such as Chlamydia or gonorrhoea. However, some cases of PID result from the usually harmless bacteria found in the vagina increasing in number and causing infection following childbirth, abortion, insertion of a contraceptive coil or some other invasive procedure.
Pelvic abscesses can also form secondary to generalized peritonitis, such as that caused by a perforated ulcer or bowel if the pus and fluid from the intra-peritoneal abscess track downwards into the pelvis.
Pelvic CT Image (Non Contrast Enhanced)
White arrow indicating insertion of two pigtail drains
for percutaneous drainage of the abscesses
(30 cc of fluid drained).
A pelvic abscess can be drained by an Interventional radiologist using Imaging Guidance (CT, Ultrasound or fluoroscopy). A thin needle is placed in the abscess to drain or remove the infected fluid. If this is not possible or successful then surgical drainage of the abscess in an operating theatre may be necessary. Drainage of the abscess combined with antibiotic therapy is the treatment of choice.