Psoas abscess

Features of iliopsoas abscess or psoas abscess, or retroperitoneal abscess, approach to psoas abscess,

1. P soas Abscess & Its management Sushil Gyawali MS Resident General surgery

2. Introduction: IPA or PA Psoas (or iliopsoas) abscess is a collection of pus in the iliopsoas muscle compartment The incidence is rare, but the frequency of this diagnosis has increased with the use of computed tomography, prior to which most cases were diagnosed at postmortem.

3. Anatomy: Psoas muscle Fusiform shaped muscle, cover anterio -lateral surface of lumbar vertebral bodies . ORIGIN- Lateral surface, intervertebral disc and transverse process of T12 -L5 • COURSE - passing inferiorly along pelvic brim and iliacus muscle beneath inguinal ligament towards anterior thigh. INSERTION- lesser trochanter of femur Innervation :L1-L3 P rimary flexor of the hip joint .

4. I liopsoas compartment The iliopsoas compartment is an extraperitoneal compartment, contains the iliacus and the iliopsoas muscle. The iliopsoas muscle : rich blood supply from the lumbar, iliolumbar, obturator, external iliac, and common femoral arteries. predisposes the iliopsoas to heamatogenous spread of infection

5. Relation to hip joint The tendon is separated from the hip capsule by the iliopsoas bursa ( communication joint space in up to 15 %) which may facilitate spread of infection between these sites . Infection readily spreads to the muscle from contiguous vertebrae . The psoas muscle runs under the inguinal ligament and attaches to the lesser trochanter of the femur - a psoas abscess often presents as a mass  below  the inguinal ligament.

6. Pathogenesis A ccording to the pathogenesis divided as: Primary abscess —result of hematogenous or lymphatic seeding from a distant site (which may be occult ) Risk factors : D iabetes , IVDU, HIV infection, renal failure, and immunosuppression. Trauma and hematoma formation can predispose to development of psoas abscess. Mostly in children and young adults More common in tropical and developing countries. In Asia and Africa, 99 % are primary; in Europe and North America, 17-61%are primary . L r

7. Pathogenesis… 2. Secondary abscess —occurs as a result of direct spread of infection to the psoas muscle from an adjacent structure . ( contiguous extension) It may be uncertain whether involvement of a contiguous structure is a cause or a consequence of the psoas muscle abscess. Risk factors for secondary abscess include trauma and instrumentation in the inguinal region, lumbar spine, or hip region. Adjacent structures —vertebral bodies and discs, the hip joint, the gastrointestinal tract, the genitourinary tract, vascular structures, etc

8. Secondary… Spread of infection from gastrointestina l disease is the most common source Renal disease :second most common source . Extension from the psoas muscle into the  iliacus muscle  is a common  sequela . Tubercular-from potts spine Pyogenic

9. SECONDARY CAUSES OF PSOAS ABSCESS 1 Gastrointestinal Crohn’s disease , diverticulitis, appendicitis, colorectal cancer 2 Genitourinary Urinary tract infection, Malignancy, ESWL 3 Musculoskeletal spondylitis or spondylodiscitis, Vertebral osteomyelitis, TB spine , septic arthritis, infectious sacroiliitis 4 Vascular Infected AAA, femoral vessel catheterisation 5 Miscellaneous Endocarditis, intrauterine contraceptive device, suppurative lymphadenitis, epidural anesthesia Shields et al.Iliopsoas abscess – A review and update on the literature, International Journal of Surgery, 2012

10. MICROBIOLOGY V aries with geography and pathogenesis of infection Primary psoas abscesses: mostly single organism Most common bacterial cause is Staphylococcus aureus, including MRSA; followed by streptococci and E coli Mycobacterium tuberculosis where TB is common. A s a complication of Brucella spondylodiscitis, in endemic area. Secondary psoas abscess may be monomicrobial or polymicrobial ; enteric organisms (particularly in the setting of abscesses with gastrointestinal tract origin). Anaerobes too Klebsiella pneumoniae especially in patients with diabetes . Other: Streptococcus pneumoniae , Streptobacillus moniliformis , Staphylococcus lugdunensis , Actinomyces israelii , and disseminated nocardiosis . N on- typhi Salmonella, Candida albicans are rare

11. Rodrigues J et al . Clinical presentation, etiology, management, and outcomes of iliopsoas abscess from a tertiary care center in South India . J Family Med Prim Care. 2017 Oct-Dec

12. Epidemiology   First described by Mynter in 1881 who referred it as ‘ psoitis ’ M>F M edian age : 44-58 years in developed countries . In <20 years in developing countries Rt = Lft side; Bilateral psoas abscesses are uncommon.(5 %) In western data: hematogenous spread from the gastrointestinal tract is most common In Our: Mycobacterium tuberculosis is commonest Mortality rate varies from 5% to 11%  D. Shields et al “Iliopsoas abscess—a review and update on the literature,”  International Journal of Surgery , 2012

13. Delay in diagnosis Hamano et al . reported that prediagnosis symptom duration of patients could vary from 1 day to 63 days , and Wong et al. reported that it could vary from 1 day to 3 months . S. Hamano et al , “Pyogenic psoas abscess: difficulty in early diagnosis,”  Urologia Internationalis , 2003 O. F. Wong et al , “Retrospective review of clinical presentations, microbiology, and outcomes of patients with psoas abscess,”  Hong Kong Medical Journal , 2013 .

14. The classical triad of fever, limp, and back pain is present in <30% of patients. NON SPECIFIC Pain (up to 91% ) with localization to the back, flank, or lower abdomen rarely mimic inguinal lymphadenopathy or a femoral hernia . Abdominal pain radiating to hip, flank Fever (75%) , and can manifest as a fever of unknown origin I nguinal mass, limp , anorexia, and weight loss Position of comfort- supine with knee flexed and hip mildly externally rotated . Psoas abscesses occasionally extend distally and present as a painful or painless mass below the inguinal ligament. Symptoms and signs

15. Other symptoms Various nerves of lumbar plexus also pass through the psoas muscle and cause muscle weakness and sensory deficit the abscess may drain  inferiorly  into the upper  medial  thigh and present as a swelling in the region. The disc is more susceptible to infection, from tuberculosis and  Salmonella discitis . The infection can spread into the psoas muscle sheath.

16. Signs Pain with thigh flexion ( esp against resistance) Lower abdominal pain is often exacerbated when psoas muscle is stretched or extended; the " psoas sign" is pain brought on by extension of the hip. Limitation of hip movement is common, prefer to be in a position of less discomfort that includes supine with hip flexion and lumbar lordosis . Unlike septic arthritis, hip pain in patients with psoas abscesses is usually diminished with hip flexion . When painless ( ie , a cold abscess), tuberculosis is a more likely cause than another bacterial infection.

17. Complications Septic shock (up to 20%) DVT due to extrinsic compression of the iliac and femoral vein Hydronephrosis due to ureteric compression Bowel ileus Hip septic arthritis including prosthetic joint infection Intraperitoneal rupture

18. Diagnosis Of Psoas abscess The diagnosis is suspected on clinical grounds and confirmed on imaging studies . I nsidious onset and occult characteristics can cause diagnostic delays Identification of the etiological organism requires culture of blood or aspirated pus or, rarely, surgically obtained tissue.

19. Lab tests Leukocytosis (>10,000/mL) up to 83%; A nemia <11 g/L is frequent (up to 42%) Thrombocytosis less frequently (up to 27 %) An elevated ESR (>50 in 73%) CRP :often elevated Elevated AST frequently associated with gram-negative rod etiology. Screening for Diabetes, HIV , Renal disorder Urine RE, Urine c/s

20. Imaging Computed tomography (CT) is the optimal radiographic modality to evaluate for psoas abscess though sensitivity may be limited early in the course of disease. In most cases, an abscess is obvious; other findings may include a focal hypodense lesion, infiltration of surrounding fat, and gas or an air fluid level within the muscle . Low density mass in retroperitoneum   Is the modality of choice/ Gold standard  

21. MRI Magnetic resonance imaging (MRI) may allow improved definition of soft tissues and adjacent structures, especially visualization of the vertebral bodies. Evidence of bony spinal infection : suspicion for tuberculosis in the appropriate epidemiologic circumstances. Advantage : better discrimination of soft tissues and the ability to visualise the abscess wall and the surrounding structures without the need of a intravenous contrast medium

22. A) Axial T2 MRI image showing the psoas muscle (red arrow) and facet joint lesion spreading to multifidus muscle (blue arrow). (B) Coronal T1 MRI post gadolinium showing extensive psoas muscle abscess (red arrow). MR is more sensitive than CT in diagnosis of intra-abdominal abscesses.

23. Imaging…. Ultrasound has low sensitivity and specificity (operator dependent) ;  The retroperitoneal space can be difficult to visualize , obscured by bowel gas, pelvic bone. It is diagnostic in only 60% of cases of psoas abscess, compared with 80% to 100% for CT.  Abdominal Xray : may suggest loss of psoas muscle definition, abnormal soft tissue shadows, bulge in psoas shadow and the presence of gas, But a poor diagnostic tool Chest radiograph may demonstrate elevation of the diaphragm or a pleural effusion .

24. Imaging… However, the sensitivity of CT and MRI was less in the early stages, i.e., only 33% and 50%, respectively, and hence CT and MRI can miss psoas abscess in the early stages (<5 days ). A recent case study from Japan has shown that  18 F-fluorodeoxyglucose positron emission tomography-CT (PET-CT) can be used in the diagnosis and follow-up of a patient with tuberculous psoas abscess. PET-CT was also used for assessing the therapeutic response to ATT and resolution of the disease in this case report

25. Culture Culture — Both blood cultures and abscess materials: Gram stain AFB smear and mycobacterial culture :when TB suspected These specimens should be obtained when a diagnosis of psoas abscess is confirmed and before initiation of antimicrobial therapy, if feasible, to optimize the culture yield. Blood cultures are positive in (41 to 68%) : the most frequent S . aureus Psoas abscess with or without vertebral osteomyelitis can be a presentation of endocarditis . Echocardiography to be done.

26. D/D Psoas muscle hematoma –in the setting of anticoagulation or a bleeding disorder . Retrocecal appendicitis –"psoas sign“ Iliopsoas bursitis – Iliopsoas bursitis can occur in the setting of rheumatoid arthritis, trauma, or overuse injuries . Infection generally occurs as a result of hematogenous or contiguous spread of infection or, in rare cases, direct inoculation in the setting of corticosteroid injection. In a minority of patients, the iliopsoas bursa is in direct communication with the hip joint. Deep septic bursitis is confirmed by bursa aspiration. Septic hip arthritis Metastatic disease –mimicking a psoas abscess, including a poorly differentiated carcinoma and a mucinous adenocarcinoma . In both, the diagnosis was confirmed by tissue biopsy .

27. TREATMENT Management of psoas abscess : prompt antibiotic therapy and drainage. Secondary abscess also requires management of the adjacent infected focus (such as ruptured viscus, fistula, or infected aortic aneurysm ). Drainage — percutaneous or surgical intervention.

28. Antibiotic therapy In general, directed antimicrobial therapy (based on the results of cultures and smears) is preferable to empiric therapy. S hould include activity against S. aureus (including MRSA )and enteric organisms (both aerobic and anaerobic enteric flora ): broad spectrum antibiotics like clindamycin, antistaphylococcal penicillin, and an aminoglycoside Antimicrobial therapy tailored to culture and susceptibility results. Evidence of mycobacterial infection should prompt management(ATT) Parenteral antibiotics in conjunction with psoas abscess drainage.

29. Antibiotics: duration Antibiotics alone are unlikely to be curative, although some success with antibiotic therapy alone has been reported in a small number of patients with abscesses <3 cm. The optimal duration uncertain ; three to six weeks of therapy following adequate drainage is likely appropriate; the decision on duration of therapy may be impacted by the presence of osteomyelitis, Follow-up imaging should be performed near the end of the planned course of antimicrobial therapy to ensure satisfactory response to therapy. Most, if not all, cases of tuberculous psoas abscesses have associated vertebral osteomyelitis.

30. Percutanous Drainage (PCD) Mueller  et al  reported first application of PCD in iliopsoas abscesses in 1984. Percutaneous drainage (by ultrasound or CT guided) is an appropriate initial approach ; (up to 90%) PCD is much less invasive and has been proposed as the draining method of choice The Percuteanous Catheter may be removed when drainage has ceased, the patient's condition has improved, and repeat imaging demonstrates that the drainage has been satisfactory . Sometimes PCD can be a useful initial treatment to improve the patient’s condition before surgery.

31. Surgical drainage In setting of percutaneous drainage failure; Indications for surgical drainage include multiloculated abscesses and significant involvement of an adjacent structure requiring surgical management, the presence of an another intra-abdominal pathology which requires surgery. Open Vs laparoscopic If there are strong indications for primary operation, such as ruptured infected aortic aneurysm, ruptured appendicitis, or epidural abscess with spinal cord compression, surgical intervention should not be delayed . Furthermore, surgical intervention was preferred when gas-forming IPA was observed because of the higher failure rate of PCD . Hsieh , MS   et al.  Features and treatment modality of iliopsoas abscess and its outcome: a 6-year hospital-based study.  BMC Infect Dis   13,  578 (2013 )

32. Large series , 61 patients P atients with bacteremia and small abscesses (<3.5 cm) responded well to antibiotic treatment alone . However, we did not find any statistical correlation between abscess size and treatment success . As a safe and minimally invasive alternative to open drainage, PCD is usually considered a first-line treatment option . Most patients with an underlying gastrointestinal tract cause such as Crohn disease ultimately required operative management mortality was 5%  Literature:

33. Literature says: Hsieh, MS  et al.  Features and treatment modality of iliopsoas abscess and its outcome: a 6-year hospital-based study.  BMC Infect Dis   13,  578 (2013) In the case of primary psoas abscess, PCD is indicated for a small, and single abscess if technically possible ; however , for large, extensive, or multiple abscesses , percutaneous drainage may result in recurrence or simply be insufficient. In this situation, open surgical drainage is more appropriate Baier Pket al . The iliopsoas abscess: aetiology , therapy, and outcome. Langenbecks Arch Surg. 2006 , 88 pts klebsiella

34. Surgical … L aparoscopic: Advantage include the extraperitoneal nature of the procedure, the capability to break down loculations , and rapid postoperative recovery . Open drainage . Open surgical drainage may be warranted in the setting of a multiloculated psoas abscess, an abscess secondary to bowel disease ( eg , Crohn's disease) in which bowel resection may be necessary, or a psoas abscess with a gas-forming organism via an extraperitoneal approach was previously the surgical intervention of choice; in one series, successful outcomes were described in 97 percent of patients

35. Laparoscopic approach

36. Surgical approach: Open Open Drainage of abscess : Through lateral loin incision- via Petit’s triangle: retro peritoneal Through anterior incision Ludloffs /Medial approach: When abscess points subcutaneously at adductor region of thigh . Although open surgery via the extraperitoneal approach combined with drug treatment has traditionally been the mainstay of therapy, retroperitoneal or laparoscopic drainage has recently been used

37. Open extraperitoneal drainage Through lateral loin incision Psoas region reached extraperitoneally .Pus drained – drainage tube kept

38. Anterior approach 5-7 cm long vertical incision from ASIS to anterior thigh. Identify Sartorius-dissect medially to it upto AIIS. Care of femoral nerve Insert an artery along medial side of wing of ilium under poupart’s ligament Drain abscess and close

39. Ludolf’s : Medial approach

40. Tropical doctor Study from NEPAL 72 pts for surgical drainage BPKIHS Approach: Lower abdominal, extraperitoneal , muscle splitting incision Staph aureus: most common Mean duration of drainage: 3.2 +/- 1.4 days (range 1-7 days) Mean hospital stay: 9 days (range 3-40) 2 pt had recurrence, 10 months and 1 year after operation 1 had incisional hernia Average cost of treatment : Rs 2800 (US $ 40)

41. Outcome Has significant morbidity and mortality. In one series, mortality due to primary and secondary abscess was 2.4 and 19 % , respectively; in untreated cases, mortality may approach 100 percent. Risk factors for mortality include delayed or inadequate treatment, advanced age, the presence of bacteremia , cardiovascular disease, and infection due to E. coli . Mortality is low with early diagnosis and appropriate treatment. Relapse can occur up to one year after initial presentation; 15-36% . Recurrence may be associated with inadequate drainage or inadequate antimicrobial therapy. In addition, presence of hip flexion deformity at clinical presentation may not completely resolve as a result to fibrosis within the iliopsoas sheath.

42. Take home message Psoas abscess : Non specific symptoms/features Insiduous onset and occult nature – diagnostic delays High morbidity High index of suspicion required CT : choice of image Iliopsoas abscess remains a therapeutic challenge Timely Drainage: PCS/surgical Multidisciplinary

43. R eferences Sabistons 2020 Management of Psoas abscess , Up To Date, 2021 Iliopsoas abscess – A review and update on the literature, international Journal of surgery, 2012 Review on Iliopsoas abscesses, BMJ, 2004