What is Psoas Muscle Abscess?
The Psoas Muscle is located in the pelvic area of the body and is surrounded by various vital organs of the body and hence is prone to infections. This muscle connects the lower back to the upper thigh. Psoas muscle performs various vital functions like facilitating movement of the knee to the chest.
Psoas Muscle Abscess is a collection of pus in Psoas Muscle compartment. This is normally caused due to various types of bacteria which may have infiltrated the surrounding organs.1 It may also develop due to infection spreading from a distant organ in the body.
Psoas Muscle Abscess is an extremely rare condition and is often missed by physicians as a diagnosis due to its rarity and the nonspecific clinical presenting features, although diagnosis of Psoas Muscle Abscess is on the rise with the introduction of CT scans done in the pelvic region. The most common bacteria that may cause Psoas Muscle Abscess are Staphylococcus Aureus and Pseudomonas Aeruginosa.
What are the Classifications of Psoas Muscle Abscess?
Psoas Muscle Abscess has been classified into two categories which are primary and secondary.2 The type of Psoas Muscle Abscess depends on the presence or absence of an underlying disease.
Primary Psoas Muscle Abscess: This type of Psoas Muscle Abscess occurs due to spread of an infectious process from a known source in the body. Psoas Muscle Abscess is seen mostly in people who have diabetes, who abuse recreational drugs intravenously, people who are suffering from AIDS, people who have a known history of kidney failure, and people who have a compromised immune system making them prone to frequent infections.2
Secondary Psoas Muscle Abscess: This type of Psoas Muscle Abscess develops due to spreading of an infectious process from any gastrointestinal infection like appendicitis or diverticulitis. It may also develop due to abnormal renal condition.2
What are the Causes of Psoas Muscle Abscess?
As stated, bacteria are the most common cause of Psoas Muscle Abscess. The types of bacteria which can result in Psoas Muscle Abscess are Staphylococcus Aureus in majority of the cases of Psoas Muscle Abscess with other bacteria like Pseudomonas Aeruginosa, Haemophilus Aphrophilus, and Proteus Mirabilis also contributing to development of Primary Psoas Muscle Abscess. Secondary Psoas Muscle Abscess is normally caused by Escherichia coli and Salmonella Enteritidis. It may also be caused by Methicillin Resistant Staphylococcus Aureus.
What are the Symptoms of Psoas Muscle Abscess?
The symptoms of Psoas Muscle Abscess are rather nonspecific. Individuals with Psoas Muscle Abscess may complain of fever, flank pain, pain in the abdomen, and difficulty walking. The difficulty walking is due to the Psoas Muscle being innervated by L2, L3, and L4 and when these get inflamed the individual experiences pain in the thigh and hip making it tough for the individual to walk. Some of the other symptoms of Psoas Muscle Abscess are:
- Unintentional weight loss.
How is Psoas Muscle Abscess Diagnosed?
A definitive diagnosis of Psoas Muscle Abscess is difficult due to the rarity of the condition and the clinical features which resemble other more common diseases which leads a physician to miss Psoas Muscle Abscess as a diagnosis. For diagnosis, the physician needs to examine the pelvic and abdominal area very carefully. Psoas Muscle Abscess may be suspected if the patient favors a certain position of comfort. Laboratory investigations are also very helpful in diagnosis of Psoas Muscle Abscess as they can identify any bacteria which might be at play here and may be causing infection but by far the clinching evidence to diagnose Psoas Muscle Abscess can be provided by a CT scan of the pelvis CT which will clearly show the pus filled area and confirm the diagnosis of Psoas Muscle Abscess.
How is Psoas Muscle Abscess Treated?
The treatment for Psoas Muscle Abscess is started with broad spectrum antibiotics. The use of antibiotics depends on the type of bacteria responsible for the condition. Drainage of the psoas muscle abscess is also done for treatment. The antibiotics dosages need to be adjusted depending on what the laboratory studies show and what the culture and sensitivity reports are. Medications like clindamycin and penicillin may be given for treatment of Psoas Muscle Abscess. The drainage of the abscess can be done through two ways which are either CT guided percutaneous drainage or a surgical drainage. The CT guided percutaneous drainage is minimally invasive and is the preferred choice of draining a Psoas Muscle Abscess. Surgical Drainage is recommended for those people with underlying medical conditions like Crohn’s disease or other gastrointestinal disorders. For such patients in a single procedure the abscess is drained and the diseased segment is resected. In some cases, multiple drainage procedures may need to be done before Psoas Muscle Abscess resolves completely. Drainage of the psoas muscle abscess needs to be continued until there is substantial improvement in the symptoms. Repeat laboratory studies and CT scans can detect exactly how much resolution has taken place of the Psoas Muscle Abscess. Even after complete drainage of the Psoas Muscle Abscess, antibiotics need to be continued for at least a couple of weeks for complete resolution of Psoas Muscle Abscess.