Iliopsoas abscesses

Iliopsoas abscess is a relatively uncommon condition that can present with vague clinical features. Its insidious onset and occult characteristics can cause diagnostic delays, resulting in high mortality and morbidity. The epidemiology, aetiology, clinical features, and management of iliopsoas abscess are discussed.

Psoas abscess: case report and review of the literature

Psoas muscle abscess is rare and presents a diagnostic challenge requiring a high index of suspicion. We report an unusual case of primary psoas abscess caused by Proteus mirabilis. Primary psoas abscess is most commonly present in children and is usually caused by Staphylococcus aureus. A total of 434 cases of psoas abscess has been reported. The subject is discussed noting the differences between primary and secondary cases, and emphasizing the importance of ultrasound and computerized tomography guided drainage of psoas abscess. A flow chart for the evaluation and management of primary and secondary abscess is presented, taking into consideration the success rate of the various methods of treatment described in the literature.

Microbiology and outcome of iliopsoas abscess in 124 patients

To describe the microbiology and outcome of iliopsoas abscess (IPA) in a large case series, we analyzed 124 cases of IPA collected from 1990 through 2004 in 11 hospitals in Spain. Twenty-seven (21.8%) patients had primary and 97 (78.2%) had secondary IPA. The main sources of infection were bone (50.5%), gastrointestinal tract (24.7%), and urinary tract (17.5%). A definitive microbial diagnosis was achieved in 93 (75%) cases. Abscess culture was the most frequent procedure leading to microbial diagnosis, followed by blood cultures. Staphylococcus aureus, Escherichia coli, and Bacteroides species were the most frequent microbial causes: S. aureus was the most common organism in patients with primary abscesses (42.9%) and with abscesses of skeletal origin (35.2%), whereas E. coli was the leading organism in those with abscesses of urinary (61.5%) and gastrointestinal (42.1%) tracts. Mycobacterium tuberculosis was found in 15 patients, 4 of them associated with human immunodeficiency virus (HIV) infection. Twenty (21.5%) cases had polymicrobial infections; these were more common among patients with abscesses of gastrointestinal origin. Information on clinical outcome was available for 120 patients; 19 (15.8%) had a relapse and 6 (5%) died due to complications related to the IPA. Patients who died were older and more likely to have bacteremia and E. coli isolated from cultures. In conclusion, secondary IPA is more prevalent than primary IPA. Among those with secondary IPA, most abscesses are secondary to a skeletal source. A bacterial etiology can be identified in most cases. The overall prognosis of patients with this condition is good.

Primary vs secondary iliopsoas abscess. Presentation, microbiology, and treatment

OBJECTIVE

To review the characteristics of patient presentation, microbiology, and treatment of primary iliopsoas abscess.

DESIGN

A case series of patients with iliopsoas abscess diagnosed on computed tomographic scans from 1987 to 1994.

SETTING

Tertiary care inner-city university hospital.

PATIENTS

Eleven patients with secondary iliopsoas abscess, defined as being secondary to gastrointestinal or genitourinary causes or trauma, and seven patients with primary abscess, defined as the absence of the above causes.

MAIN OUTCOME MEASURES

Patient characteristics, presenting symptoms and signs, microbiologic characteristics, treatment, and clinical course of patients with primary iliopsoas abscesses compared with those in patients with secondary abscesses.

RESULTS

In the primary group, six patients (86%) were intravenous drug users and four (57%) were positive for human immunodeficiency virus. Staphylococcus aureus grew from cultures from five of seven patients with primary abscesses, whereas secondary abscesses had enteric flora. The typical patient presentation included fever, with complaints of pain in the flank, hip, or abdomen. Comparison of abscess drainage options showed shorter hospitalizations for surgical drainage than for percutaneous drainage (15.9 vs 28.5 days; P < or = .01).

CONCLUSIONS

A patient who presents with pain in the flank, hip, or abdomen may have a primary iliopsoas abscess. Computed tomography is the standard method of diagnosis. Antibiotic regimens for patients with primary iliopsoas abscess should include coverage for S aureus, and patients with secondary abscesses should have antibiotic regimens tailored for enteric bacteria. Drainage of abscess is essential for appropriate treatment, and surgical drainage is superior to percutaneous drainage in achieving prompt recovery.

Psoas abscess: making an early diagnosis in the ED

The variable and nonspecific presentations of psoas abscess, as well as its infrequent incidence in the emergency department (ED), can result in delayed diagnosis or misdiagnosis. Previous reports have not discussed the diagnostic difficulties of psoas abscess from the viewpoint of emergency physicians (EPs), especially in light of the widespread use of ED ultrasonography. This report describes a 1-year experience between November 1993 and October 1994, during which 10 ED patients were diagnosed to have psoas abscess; in 7 cases, diagnoses were established in the ED. Patients' mean age was 64.6 years (range, 46 to 76). Pain was the most frequently encountered symptom (80%), with 5 patients (50%) complaining of flank pain. The triad of fever, flank pain, and limitation of hip movement, which is specific for psoas abscess, was present only in 3 patients (30%). The mean duration of symptoms was 10.6 days (range, 1 to 30 days). The mean time spent to establish the diagnosis was 1.7 days (range, 0 to 7 days). The diagnosis of psoas abscess was established by ultrasound in 6 patients, by computed tomography (CT) in 3 patients, and by surgery in 1 patient. Four patients who presented with either sepsis and nonspecific abdominal/flank pain or sepsis and thigh swelling were diagnosed to have psoas abscess by ultrasound performed by EPs. Only 3 patients were admitted to the ED with an initial diagnosis of psoas abscess. The remaining 7 had the following initial ED diagnoses: 2, fever of unknown origin; 2, septic shock; 1, shock; 1, sepsis; and 1, peritonitis. All but one had manifestations of sepsis. Two patients died of septic shock; these two patients had failed to be drained well. This report also includes a discussion of the role of EPs and ultrasonography in the diagnosis of psoas abscess. With their alertness and their expertise in ultrasonographic techniques, EPs can make an immediate diagnosis and arrange an early drainage procedure. For patients with sepsis of unknown origin, prolonged fever of unknown origin, and some specific manifestations suggestive of psoas abscess, the screening ultrasound should scan not only abdominal solid organs but also peritoneal cavity and retroperitoneal space. In addition, a flow chart is presented for facilitating the diagnosis of psoas abscess in the ED.

Changing etiology of iliopsoas abscess

Over a 5-year period, iliopsoas abscesses were found in 11 patients. Although the most common underlying condition was Crohn's disease (3 of 11 patients), 5 abscesses resulted from hematogenous spread from a distant site. Each of these five patients was elderly, severely malnourished, or had an underlying chronic disease. Fever was a presenting sign in 8 of 11 patients, whereas all 4 patients who presented with back pain had nontuberculous lumbar osteomyelitis or disk space infections. No patient presented with the classic triad of fever, back pain, and anterior thigh or groin pain. Computed tomographic (CT) scans accurately established the clinical diagnosis in 10 of 11 patients. Two of the patients died. One patient was an intravenous drug abuser, whereas the other patient was being treated with steroids for systemic lupus erythematosus. Elderly patients, diabetics, and patients with chronic disease are susceptible to this kind of occult infection and may present with minimal clinical findings. Aggressive diagnosis using CT scanning and treatment with resection of involved bowel, complete drainage of the abscess, and prolonged antibiotics are required to salvage these patients.

Psoas abscess: the spine as a primary source of infection

STUDY DESIGN

Case report, literature review, discussion.

OBJECTIVES

To emphasize the role of the spine as primary source of infection for psoas abscess.

SUMMARY OF BACKGROUND DATA

Spine-associated psoas abscesses increase with more frequent invasive procedures of the spine and recurring tuberculosis in industrialized countries. Diagnosis is often delayed by misinterpretation as arthritis, joint infection, or urologic or abdominal disorders.

METHODS

We present six cases of psoas abscesses associated with spinal infections that were treated in our hospital from January to December 2001. Diagnostic and treatment concepts are discussed.

RESULTS

Our data emphasize the importance of the spine as primary source of infection and suggest an increase in the incidence of secondary psoas abscess. Treatment includes open surgical drainage and antibiotic therapy. In patients with high operative risk and uniloculated abscess, a CT-guided percutaneous abscess drainage can be sufficient. It is essential to combine abscess drainage with causative treatment of the primary infectious focus. Related to the spine, this includes treatment of spondylodiscitis or implant infection after spinal surgery. Usually, several operations are necessary to eradicate bone and soft-tissue infection and restore spinal stability. Continuous antibiotic therapy over a period of 2-3 weeks after normalization of infectious parameters is recommended.

CONCLUSION

The spine as primary source of infection for secondary psoas abscess should always be included in differential diagnosis. Because the prognosis of psoas abscess can be improved by early diagnosis and prompt onset of therapy, it needs to be considered in patients with infection and back or hip pain or history of spinal surgery.

Acute pyogenic iliopsoas abscess in Taiwan: clinical features, diagnosis, treatments and outcome

OBJECTIVES

To study the variations of aetiology in the patients with acute pyogenic iliopsoas abscess and identify the appropriate diagnostic modalities as well as therapeutic alternatives (e.g. extraperitoneal or retrofascial percutaneous catheter drainage, PCD) other than surgery.

METHODS

We carried out a retrospective review and analysis of 25 patients with acute pyogenic iliopsoas abscess in our institution from August 1988 to July 1998. Blood and urine cultures, imaging studies of the plain films of the abdomen (KUB), ultrasonography (echo) and computed tomography (CT scan) were performed in all patients. The therapeutic regimens included antibiotics only, PCD or aspiration, and surgery.

RESULTS

The male to female ratio was 7: 18. The mean age was 64 years old. Diabetes mellitus (64%) was the dominant predisposing or associated factor. The most common aetiological source was urinary tract infection (52%) with enteric micro-organisms (Escherichia coli: 44% and Klebsiella spp.: 24%). Nineteen patients (76%) had pain in the abdomen, flank or back. Six cases (24%) were classified as 'primary' abscess, and only two patients survived. Nine cases were treated with antibiotics alone, only four responded and the others expired. Of the 15 cases receiving PCD or aspiration, five cases received subsequent surgical drainage or nephrectomy and survived. Another one case of Clostridia gas gangrene received emergency fasciotomy and expired. The total mortality was extremely high (11/25, 44%).

CONCLUSIONS

We concluded that: (i) the aetiology of iliopsoas abscess may vary with the country of origin, with a preponderance of urinary tract infection in our Taiwanese series; (ii) a high index of suspicion is mandatory to enable early diagnosis of acute pyogenic iliopsoas abscess, particularly for older diabetic patients with fever, pain in the abdomen or flank, limp or flexion of the ipsilateral hip; (iii) CT scan can confirm the diagnosis and define the extent of the abscess; (iv) effective management should include appropriate antibiotic therapy and drainage of the abscess; (v) image-guided PCD should be tried first because of its low morbidity. However, should it fail, subsequent surgical drainage should be performed.

Psoas abscess: difficulties encountered

From 1961 to 1989, 67 patients underwent various surgical procedures for psoas abscess. Retrospective analysis was undertaken in an effort to determine optimal surgical therapy. Forty patients were cured with one operation. Twenty-one patients required two operations, four patients required three operations, and two patients required more than three operations. The reason for failure of treatment was failure to resect the diseased bowel or to drain the psoas abscess adequately. A technique to recognize and treat the abscess definitively will be illustrated. The most common etiologies were Crohn's disease in 49 patients, postoperative sepsis in eight patients, and complications of renal disease in four patients. The length of hospital stay ranged from 5 to 392 days (mean, 26 days). There were two deaths. Failure to recognize and treat psoas abscess results in considerable morbidity.

Pyomyositis in children

Bacterial infections of muscle, also known as pyomyositis or tropical pyomyositis, occur more commonly in tropical regions. This article reviews five cases of pyomyositis diagnosed in children over a 1-year period. Pyomyositis should be considered in the differential diagnosis of septic-appearing children as well as children complaining of joint pain or muscle aches. The diagnosis can be aided with either a computed tomography (CT) or magnetic resonance imaging (MRI) scan. The MRI is preferable because multiple processes can be evaluated, such as joint effusion suggesting septic arthritis. If the patient does not respond quickly to antibiotics and surgical intervention, either there is a recurrence of the previously debrided abscess, or there is an unrecognized secondary abscess. Multiple abscess sites should be entertained prior to initial debridement.

Psoas abscess - not as rare as we think?

OBJECTIVE

Iliopsoas abscess (IPA) is a rare condition with a reported worldwide incidence of 12 new cases per year with primary abscesses now predominating. The presentation is often vague and the diagnosis not considered.

METHOD

The medical records of 15 consecutive patients presenting to our hospital in a 3-year period with IPA were reviewed. Demographic data, presenting features, predisposing factors and the investigations performed were recorded. Abscesses were classified as primary or secondary and the treatment provided and eventual outcomes were analysed.

RESULTS

Fifteen patients (eight males) were included. Nine patients were pyrexial on admission, 14 were anaemic and all had raised inflammatory markers. Only five patients presented with the classical triad of pain, fever and limp. The median time to diagnosis was 3 days with a median hospital stay of 27 days (range 7-243 days). Fourteen patients were diagnosed by computed tomographic scan. Three patients were treated with antibiotics alone whilst 11 received percutaneous drainage (PCD) as well. Of these, five had recurrence following initial drainage, needing further PCD procedures but none needed open drainage. Only one patient underwent open drainage initially. The mortality rate was 20%.

CONCLUSION

The incidence of IPA is probably under-reported. The vague presentation leads to delays in diagnosis and increases morbidity and a high index of suspicion is the key to early diagnosis. Percutaneous drainage with antibiotics is the first line of treatment although recurrence rate is high. Open drainage allows simultaneous treatment of underlying pathology in secondary abscesses.

Percutaneous drainage and continuous irrigation in patients with severe pyogenic spondylitis, abscess formation, and marked bone destruction

Object

The use of percutaneous suction aspiration has recently become viewed as an effective management strategy for pyogenic spondylitis unresponsive to conservative treatment. What remains unclear is whether it can be effective for severe pyogenic spondylitis in which abscess formation or marked bone destruction is present. The authors undertook a study to clarify answers to this question.

Methods

The authors evaluated clinical and radiographic/neuroimaging data obtained in five patients with severe pyogenic spondylitis, extensive abscesses, and marked bone destruction. These patients had undergone percutaneous drainage and continuous irrigation because open surgery was considered contraindicated in light of their poor general health. The mean period during which continuous irrigation was applied was 9 days (range 7–11 days), and the mean period during which the drainage tube was in place was 19 days (range 13–38 days). All patients suffered from back pain, which was relieved by the percutaneous technique in four patients after a mean of 8 days. The abscesses and inflammation resolved in all patients. Progressive osseous destruction was not observed, and open surgery was performed in only one patient in whom back pain persisted as a result of spinal instability.

Conclusions

After an unsuccessful course of conservative treatment, severe pyogenic spondylitis with abscess formation or marked bone destruction was successfully treated using percutaneous drainage and continuous irrigation. Based on their results, the authors believe that this procedure can be used in patients with severe pyogenic spondylitis that was unresponsive to conservative treatment, particularly in those whose general health is poor.

Psoas abscess and cellulitis of the right gluteal region resulting from carcinoma of the cecum

Although retroperitoneal or psoas abscess is an unusual clinical problem, the insidious and occult characteristics of this abscess sometimes cause diagnostic delays, resulting in considerably high morbidity and mortality. In particular, psoas abscess caused by perforated colon carcinoma is uncommon. We report a case of psoas abscess caused by a carcinoma of the cecum. A 72-year-old Japanese woman was admitted to our hospital, with pain in the right groin and buttock. The pain had appeared 6 months before admission, and the symptoms had then been relieved by oral antibiotics. On March 25, 1999, inflammatory signs in the right buttock indicated localized cellulitis, and incision and drainage was performed at a local hospital. The patient was referred to our hospital on the same day. On admission to our hospital, computed tomography (CT) scan revealed a thick right-sided colonic wall and enlargement of the right ileopsoas muscle. Barium enema and colonofiberscopy revealed an ulcerated tumor occupying the entire circumference of the cecum. A retroperitoneal abscess and fistula had been formed by the retroperitoneal perforation of cecum carcinoma: surgical resection was performed after remission of the local inflammatory signs. Operative findings indicated that the cancerous lesion and its surrounding tissues were firmly attached to the right iliopsoas and major psoas muscle, and en-bloc resection, including adjacent muscular tissue, was performed. The fact that carcinoma of the colon could be a cause of psoas abscess and cellulitis in the gluteal region should be considered when an unexplained psoas abscess is diagnosed.

Primary psoas abscess

Psoas abscess is an uncommon condition with varied etiology. Diagnosis is based on symptoms, signs, and CT scan of the abdomen. Treatment consists of adequate drainage either percutaneously or surgically with antibiotic coverage. Serious complications such as sepsis and mortality may result if there is a delay in treatment.

Paraplegia caused by spinal infection after acupuncture

STUDY DESIGN

Case report of a 64-year-old man with psoas abscesses, epidural abscess and spondylitis after acupuncture.

OBJECTIVE

To report a case of paraplegia caused by spinal infection after acupuncture.

SETTING

Seoul, Korea.

CASE REPORT

A 64-year-old man came to an emergency room because of severe back pain. At 3 days prior to visit, the patient received acupuncture therapy to the low back with a needle about 10 cm in length because of back pain. Pain was aggravated gradually for 3 days. Escherichia coli sepsis developed with altered mentality during admission. At hospital day 9, he regained his consciousness and was found to have paraplegia. Abdominal computerized tomography (CT) and lumbar spine magnetic resonance imaging (MRI) revealed abscesses of bilateral psoas muscles and spondylitis with epidural abscess. After conservative management with intravenous administration of antibiotics, infection was controlled but the patient remained paraplegic (ASIA scale C L1 level) without neurological recovery.

CONCLUSION

Paraplegia might result from complications of an acupuncture therapy.

Psoas abscess following intravesical bacillus Calmette-Guerin for bladder cancer: a case report

An 87-year-old man with an abdominal aortic aneurysm received intravesical bacillus Calmette-Guerin therapy for transitional cell carcinoma of the bladder. He presented 9 months later with a psoas abscess that mimicked a contained retroperitoneal abdominal aortic aneurysm rupture. The abscess cultures yielded Mycobacterium bovis. Recent transurethral resection and high voiding pressures after instillations of bacillus Calmette-Guerin may have led to distant dissemination of the drug.

MRI of retroperitoneal collections: a comparison with CT

Retroperitoneal collections in the absence of pancreatitis are rare. Imaging plays an important role in determining the aetiology of these collections and in allowing percutaneous drainage to be performed safely. A review of the imaging characteristics on both CT and MRI is presented, highlighting the advantages and disadvantages of these two modalities and their complimentary roles.

Tumeurs rétropéritonéales primitives de l’adulte

Primary retroperitoneal tumors are rare and most of the time malignant. Because of the large space in which they grow, they are often discovered lately as they are large. CT and MR are the imaging techniques of choice for the primary diagnosis and the follow up of these tumors. Multiplanar reconstructions , signal and density resolution help for the nature diagnosis. The examinations allowed to find associated signs that helps also for the right diagnosis. The purpose of this paper is to answer a serie of questions: Is the mass in the retroperitoneal space? Are they imaging signs that helps for the diagnosis of nature? Are they associated signs that helps for the diagnosis of nature? What are the most common diagnosis? Is there any place for percutaneous biopsies? What is the role of imaging in the follow up? Are there any other processes that can mimic retroperitoneal tumors?

Retroperitoneal schwannoma misdiagnosed as a psoas abscess: report of a case

A retroperitoneal cystic mass compressing the right psoas muscle was found incidentally by ultrasonography in a 67-year-old woman. The radiological findings and a history of costal caries led us to suspect a psoas cold abscess. Ultrasound-guided needle aspiration was done to establish the diagnosis and to drain the content, but only a small amount of sterile fluid was obtained. The patient complained of neuralgia in her right leg at the time of puncture. Under the preoperative diagnosis of a neurogenic tumor, the mass was surgically resected, and found to be filled with old blood. The solid region consisted of a proliferation of fusiform cells, leading to a diagnosis of benign schwannoma. Retroperitoneal schwannoma is often misdiagnosed as an adjacent anatomical structure. Thus, we conclude that both microbiological and cytological examination of an aspiration specimen is important when psoas abscess is considered in a differential diagnosis.

[Abscess of the psoas muscle. Description of a series of 23 cases]

BACKGROUND

Abscess of the psoas muscle (PA) is an infrequent disease of difficult diagnosis. During the last decade, the number of cases has increased because of the raising use of radiology tecniques: ecography, computerized tomography and magnetic resonance nuclear.

METHODS

The presentation and management of psoas abscess was studied retrospectively in 23 patients from 1992 2000.

RESULTS

Sixteen of 23 abscesses were regarded as secundary: spondylodiscitis and pyelonefritis were most frequent pathologic processes. Homolateral pain in the flank area and hip were the usual manifestations. The duration of symptoms prior to the diagnosis was superior than 7 days. Staphylococcus aureus was the most common pathogen, followed by Escherichia coli and Mycobacterium tuberculosis. All abscesses were diagnosed by computerized tomography images. Seven patients underwent percutaneous drainage, while nine received surgical debridement. Four of the patients with psoas abscess died and only three relapsed.

CONCLUSIONS

Not specific symptoms and signs and subacute presentation difficult diagnosis of AP. High range antibiotics and drainage (percutaneous or surgical) should be considered as the election treatment.

Imaging of iliopsoas metastasis

The imaging features of four patients with metastasis to the iliopsoas are presented with emphasis on the ultrasound, CT and MRI appearances. In patients with a known primary tumour, the possibility of iliopsoas metastasis, although uncommon should be considered.

Psoas muscle abscess caused by Mycobacterium tuberculosis and Staphylococcus aureus: case report and review

Tuberculosis psoas muscle abscess is currently an uncommon clinical entity in industrialized countries. It was considered the predominant cause of these abscesses in the early part of the 20th century as a result of complicated Potts disease. We describe the case of a psoas abscess caused by the combination of Mycobacterium tuberculosis and Staphylococcus aureus. In this patient, the abscess was not associated with Potts disease but with osteomyelitis of the iliac crest, in which the evaluation with magnetic resonance imaging was very specific in determining the extent and regional spread.

[A technic of MRT-guided abdominal drainage with an open low-field magnet. Its feasibility and the initial results]

PURPOSE

To test the practicality of MRT-aided drainage using an open low-field magnet and to report on the early clinical results.

METHODS

So far seven patients have been treated (four subphrenic abscesses, two psoas abscesses and one pancreatic pseudocyst). The planning of the approach and catheter insertion were carried out under MRT control (Magnetom Open, 0.2 T). Subsequent treatment was controlled by CT and fluoroscopy. Initial puncture was carried out with a non-magnetic 18 gauge Chiba needle. The drainage catheter was introduced by Seldinger's technique in six cases and with a trocar in one patient.

RESULTS

In all seven patients drainage could be started successfully. The design of the magnet and coils permitted adequate accessibility of the patient. There were no problems in visualising the puncture needle. Controlling the position of the catheter by MRT was, however, difficult.

CONCLUSION

The first two steps in abscess drainage (planning the approach and inserting the catheter) can be carried out under MRT control. For further catheter control and observing the course of the disease we presently prefer CT or fluoroscopy.

Diagnosis and treatment of pyogenic psoas abscess in diabetic patients: usefulness of computed tomography and gallium-67 scanning

OBJECTIVES

To examine retrospectively the clinical presentations, microbiologic characteristics, and treatment outcomes of psoas abscess in patients with diabetes mellitus (DM) and to assess the usefulness of computed tomography and gallium-67 scanning in its early diagnosis.

METHODS

During a 9-year period, psoas abscesses in patients with DM were collected at a medical center. The clinical history and associated etiologic factors, microbiologic results, clinical outcomes, and hospitalization days were recorded. The use of imaging in the diagnosis of psoas abscess and other concomitant infectious lesions was also studied.

RESULTS

Fifteen patients with DM and psoas abscess (13 women and 2 men; mean age 58.7 +/- 9.0 years) were found. The most frequent symptom was fever (12 of 15). Of the six different microorganisms that grew in the blood and/or abscess cultures, Staphylococcus aureus was the most frequent (7 of 15). The most commonly associated pathologic finding was vertebral osteomyelitis (5 of 15). Computed tomography and/or magnetic resonance imaging confirmed the diagnosis of psoas abscesses in all 15 patients. The gallium-67 scan especially aided in the diagnosis of the patients who had initially been diagnosed as having fever of unknown origin (4 of 5) and in the diagnosis of concomitant lesions (9 of 12). Debridement or surgical drainage of the abscess was done in 12 patients. All the patients received adequate antibiotic treatment. However, the mortality rate was 20%. The average hospitalization stay was 42.7 +/- 20.7 days.

CONCLUSIONS

Psoas abscess in patients with DM is a disease with both diagnostic and therapeutic challenges. We found the infecting microorganisms to be variable and the mortality rate high.

Primary pyogenic abscess of the psoas muscle

During a six-year period, eleven persons with primary pyogenic abscess of the psoas muscle were treated at the Mackay Memorial Hospital. Five were males and six were females and their average age was 47.2 years (range 6-83 years). The abscess was identified by CT in 7 patients, MRI in 2 and ultrasonography in 1. One abscess was found during laparotomy. Treatment included extraperitoneal drainage of the abscess in 7 patients and CT guided aspiration in 3. One patient improved after antibiotic therapy and they all recovered after treatment. The diagnosis of primary pyogenic abscess requires a high index of suspicion and the best treatment is early operative drainage and administration of systemic antibiotics.