Psoas Sign in Bedridden Patients: An Underappreciated Clue

Dr Neeraj Manikath, claude.ai

Abstract

Background: The psoas sign, characterized by pain on hip extension or passive hip flexion, represents a crucial but often overlooked clinical finding in critically ill and bedridden patients. Despite its diagnostic significance, this sign is frequently missed or misattributed to positioning discomfort in the intensive care unit (ICU) setting.

Objective: To provide a comprehensive review of the psoas sign's pathophysiology, clinical presentation, and diagnostic utility in bedridden patients, with emphasis on retroperitoneal abscess, iliopsoas hematoma, and femoral nerve palsy.

Methods: Literature review of peer-reviewed articles from 1980-2024 focusing on psoas-related pathology in critically ill patients, supplemented by clinical pearls from critical care practice.

Results: The psoas sign demonstrates variable sensitivity (30-95%) depending on the underlying pathology and patient population. Early recognition through systematic examination and bedside ultrasound can significantly impact patient outcomes, particularly in retroperitoneal infections and hemorrhage.

Conclusions: A systematic approach to evaluating the psoas sign, combined with targeted imaging and bedside ultrasound, should be standard practice in the evaluation of abdominal pain and unexplained clinical deterioration in bedridden patients.

Keywords: Psoas sign, retroperitoneal abscess, iliopsoas hematoma, femoral nerve palsy, critical care, bedside ultrasound

Introduction

The psoas sign, first described by Cope in 1921, remains one of the most clinically relevant yet underutilized physical examination findings in modern critical care medicine.¹ In the contemporary ICU environment, where patients are often sedated, mechanically ventilated, or neurologically impaired, subtle clinical signs become paramount for early diagnosis and intervention.

The iliopsoas muscle complex, comprising the psoas major, psoas minor, and iliacus muscles, serves as a crucial anatomical landmark in the retroperitoneum. Its intimate relationship with vital structures including the lumbar plexus, common iliac vessels, and posterior peritoneum makes it susceptible to various pathological processes that can significantly impact patient morbidity and mortality.²

This review aims to provide critical care practitioners with a comprehensive understanding of the psoas sign's clinical significance, diagnostic approach, and management implications in the bedridden patient population.

Anatomy and Pathophysiology

Anatomical Considerations

The psoas major muscle originates from the lateral aspects of T12-L5 vertebrae and their intervertebral discs, coursing anteriorly and inferiorly to insert on the lesser trochanter of the femur. The psoas minor, present in approximately 60% of individuals, lies anterior to the psoas major. The iliacus muscle originates from the iliac fossa and joins the psoas major to form the iliopsoas complex.³

Clinical Pearl: The psoas muscle's retroperitoneal location makes it particularly vulnerable to inflammatory processes originating from adjacent structures, including the appendix, colon, pancreas, and genitourinary tract.

Pathophysiological Mechanisms

The psoas sign results from irritation or inflammation of the psoas muscle or surrounding structures. Three primary mechanisms contribute to its manifestation:

Direct muscle involvement: Abscess formation, hematoma, or inflammatory infiltration within the muscle fibers
Nerve compression: Involvement of the lumbar plexus, particularly the femoral nerve (L2-L4)
Referred pain: Irritation of adjacent retroperitoneal structures

Clinical Presentation and Examination Techniques

Traditional Psoas Sign Assessment

The classic psoas sign is elicited through two primary maneuvers:

Active psoas sign: Patient actively lifts the affected leg against resistance while lying supine
Passive psoas sign: Examiner extends the hip while the patient lies in the lateral decubitus position with the affected side up

Hack for Sedated Patients: In mechanically ventilated patients, observe for grimacing, increased heart rate, or blood pressure elevation during passive hip extension. Consider temporary lightening of sedation if clinically appropriate.

Modified Examination in Bedridden Patients

Bedside Technique - "The ICU Psoas Assessment":

Position: Patient supine with head of bed elevated 30-45 degrees
Passive flexion test: Gently flex the hip to 90 degrees while observing for facial grimacing or physiological responses
Extension test: Slowly extend the hip while monitoring for signs of discomfort
Palpation: Deep palpation of the lower quadrants, particularly the iliac fossa

Oyster: A positive psoas sign in a bedridden patient should never be dismissed as "positioning discomfort" - it warrants immediate investigation.

Specific Clinical Conditions

Retroperitoneal Abscess

Retroperitoneal abscesses represent a life-threatening condition with mortality rates ranging from 13-50%.⁴ The psoas muscle serves as a common site for abscess formation due to its rich vascular supply and proximity to potential infectious sources.

Etiology and Risk Factors

Primary Sources:

Crohn's disease with fistula formation
Diverticulitis with perforation
Appendicitis with retroperitoneal extension
Pyelonephritis with perinephric extension
Spinal osteomyelitis

Secondary Factors in ICU Patients:

Immunosuppression
Prolonged antibiotic therapy
Invasive procedures
Prolonged immobilization

Clinical Presentation

Classic Triad (Present in <50% of cases):

Fever
Groin/back pain
Limitation of hip movement

Atypical Presentations in ICU:

Unexplained sepsis
Failure to wean from mechanical ventilation
Persistent leukocytosis despite appropriate antibiotic therapy
Unexplained delirium or altered mental status

Pearl: The absence of fever does not exclude retroperitoneal abscess, particularly in immunocompromised or elderly patients.

Diagnostic Approach

Laboratory Investigations:

Complete blood count with differential
C-reactive protein (CRP) and procalcitonin
Blood cultures (positive in 60-70% of cases)
Lactate dehydrogenase (often elevated)

Imaging Studies:

CT with contrast: Gold standard (sensitivity 90-100%)
MRI: Superior soft tissue contrast, particularly useful in renal impairment
Bedside ultrasound: Emerging role in initial assessment

Iliopsoas Hematoma

Iliopsoas hematoma represents a potentially devastating complication, particularly in anticoagulated patients. The incidence has increased significantly with the widespread use of anticoagulants and antiplatelet agents in critical care.⁵

Risk Factors

High-Risk Scenarios:

Anticoagulation therapy (warfarin, direct oral anticoagulants)
Dual antiplatelet therapy
Thrombolytic therapy
Coagulopathy (liver disease, disseminated intravascular coagulation)
Invasive procedures (cardiac catheterization, arterial puncture)

Mechanical Factors:

Prolonged immobilization
Aggressive physiotherapy
Patient positioning during procedures

Clinical Presentation

Acute Presentation:

Sudden onset of severe groin/thigh pain
Hip flexion contracture
Hemodynamic instability
Rapidly declining hemoglobin

Subacute Presentation:

Gradual onset of hip pain
Progressive weakness
Palpable mass in the iliac fossa
Femoral nerve compression symptoms

Hack: The "40-40-20 rule" - 40% of patients present with acute symptoms, 40% with subacute symptoms, and 20% remain asymptomatic until complications arise.

Diagnostic Workup

Laboratory Assessment:

Serial hemoglobin levels
Coagulation studies (PT/INR, aPTT)
Type and crossmatch
Comprehensive metabolic panel

Imaging:

CT angiography: Preferred initial imaging to identify active bleeding
Ultrasound: Useful for monitoring hematoma evolution
MRI: Superior for chronic hematomas and nerve involvement assessment

Femoral Nerve Palsy

Femoral nerve palsy in the ICU setting often results from compression by retroperitoneal hematomas, abscesses, or positioning-related injuries.⁶

Pathophysiology

The femoral nerve (L2-L4) travels through the psoas muscle before emerging at the lateral border and passing beneath the inguinal ligament. Compression anywhere along this pathway can result in motor and sensory deficits.

Common Causes in ICU:

Retroperitoneal hematoma
Psoas abscess
Prolonged hip flexion positioning
Inguinal procedures
Lithotomy position complications

Clinical Assessment

Motor Examination:

Quadriceps weakness (knee extension)
Hip flexion weakness
Inability to perform straight leg raise

Sensory Examination:

Numbness over the anteromedial thigh
Diminished sensation in the saphenous nerve distribution

Reflex Testing:

Diminished or absent patellar reflex

Pearl: In sedated patients, observe for asymmetric leg movement during routine care or suctioning.

Bedside Ultrasound in Psoas Evaluation

Technical Approach

Equipment:

Low-frequency curvilinear probe (2-5 MHz)
High-frequency linear probe (5-12 MHz) for superficial structures

Patient Positioning:

Supine with hip slightly flexed
Lateral decubitus for posterior approach

Scanning Technique:

Transverse Approach:
- Probe placement: Just lateral to the umbilicus
- Identify psoas muscle lateral to the spine
- Assess for asymmetry, fluid collections, or mass effect
Longitudinal Approach:
- Trace the psoas muscle from the lumbar spine to the inguinal ligament
- Evaluate muscle echotexture and surrounding structures

Ultrasonographic Findings

Normal Psoas:

Homogeneous, hypoechoic muscle tissue
Smooth, well-defined borders
Symmetric appearance bilaterally

Pathological Findings:

Abscess: Hypoechoic or mixed echogenicity collection with possible gas shadows
Hematoma: Variable echogenicity depending on age (hyperechoic when acute, hypoechoic when chronic)
Inflammatory changes: Muscle enlargement with altered echogenicity

Hack: Use color Doppler to differentiate between abscess (minimal flow) and hematoma (no internal flow, possible peripheral hyperemia).

Limitations and Considerations

Technical Limitations:

Bowel gas interference
Obesity
Patient positioning restrictions
Operator experience

Clinical Limitations:

Cannot definitively differentiate between abscess and hematoma
Limited assessment of deeper structures
Requires correlation with clinical findings

Differential Diagnosis

Mimickers of Psoas Sign

Musculoskeletal Conditions:

Hip joint pathology
Lumbar spine disorders
Sacroiliitis
Piriformis syndrome

Intra-abdominal Conditions:

Appendicitis
Diverticulitis
Inflammatory bowel disease
Urinary tract infection

Neurological Conditions:

Lumbar plexopathy
Radiculopathy
Diabetic amyotrophy

Oyster: Consider multiple conditions can coexist - a positive psoas sign doesn't exclude other pathology.

Management Strategies

Retroperitoneal Abscess Management

Medical Management:

Broad-spectrum antibiotics based on culture results
Anaerobic coverage essential
Duration: 4-6 weeks for uncomplicated cases

Interventional Approaches:

Percutaneous drainage: First-line for accessible collections >3 cm
Surgical drainage: Reserved for complex cases or failed percutaneous drainage
Laparoscopic approach: Emerging technique for selected cases

Monitoring Parameters:

Serial inflammatory markers
Imaging follow-up at 48-72 hours
Clinical response assessment

Iliopsoas Hematoma Management

Conservative Management:

Anticoagulation reversal (if possible)
Blood product transfusion as needed
Pain management
Physical therapy consultation

Interventional Management:

Embolization: For active bleeding on CT angiography
Surgical evacuation: Reserved for compartment syndrome or failed conservative management

Complications Management:

Femoral nerve palsy: Rehabilitation and supportive care
Compartment syndrome: Emergent surgical decompression
Infection: Antibiotic therapy and possible drainage

Femoral Nerve Palsy Management

Acute Management:

Address underlying cause
Pain control
Prevent contractures

Rehabilitation:

Physical therapy
Occupational therapy
Orthotic devices as needed

Prognosis:

Variable recovery depending on cause
Compression-related: Often good recovery
Ischemic injury: Poor prognosis

Clinical Decision-Making Algorithm

Initial Assessment

History and Physical Examination
- Systematic psoas sign evaluation
- Risk factor assessment
- Associated symptoms
Laboratory Investigation
- Complete blood count
- Inflammatory markers
- Coagulation studies
Imaging Decision
- Bedside ultrasound (if available)
- CT with contrast (definitive)
- MRI (if contrast contraindicated)

Risk Stratification

High Risk:

Immunocompromised patients
Recent invasive procedures
Anticoagulation therapy
Unexplained sepsis

Moderate Risk:

Inflammatory bowel disease
Diabetes mellitus
Chronic kidney disease
Prolonged ICU stay

Low Risk:

Young, healthy patients
No predisposing factors
Isolated finding

Prevention Strategies

General Measures

Positioning:

Avoid prolonged hip flexion
Regular position changes
Proper support during procedures

Infection Prevention:

Strict aseptic technique
Appropriate antibiotic prophylaxis
Early recognition and treatment of primary infections

Anticoagulation Management:

Regular monitoring
Dose adjustment based on bleeding risk
Consideration of reversal agents when appropriate

Quality Improvement Initiatives

Education Programs:

Nursing staff training on psoas sign assessment
Physician education on bedside ultrasound
Multidisciplinary team approach

Protocol Development:

Standardized assessment tools
Clinical decision pathways
Quality metrics tracking

Pearls and Oysters

Pearls

The "ICU Psoas Paradox": The sickest patients who most need psoas sign assessment are often the least able to cooperate with traditional examination techniques.
Bilateral psoas signs: Almost always indicates systemic disease (sepsis, coagulopathy) rather than localized pathology.
The "Silent Psoas": Absence of the psoas sign doesn't exclude retroperitoneal pathology, especially in immunocompromised patients.
Timing matters: Early recognition and intervention significantly improve outcomes in both retroperitoneal abscess and iliopsoas hematoma.
Bedside ultrasound: An invaluable tool for initial assessment but should not delay definitive imaging in unstable patients.

Oysters

Anticoagulation reversal: Always consider the thrombotic risk when reversing anticoagulation for iliopsoas hematoma.
Femoral nerve palsy: May be the presenting sign of retroperitoneal pathology before other symptoms become apparent.
Imaging pitfalls: Small retroperitoneal collections may be missed on ultrasound but visible on CT.
Drug interactions: Antibiotics for retroperitoneal abscess may interact with anticoagulants, requiring dose adjustments.
Recovery expectations: Femoral nerve palsy recovery can take months to years, requiring long-term rehabilitation planning.

Future Directions

Emerging Technologies

Artificial Intelligence:

Computer-aided diagnosis from imaging
Predictive modeling for high-risk patients
Automated monitoring systems

Advanced Imaging:

Contrast-enhanced ultrasound
Elastography for tissue characterization
Real-time imaging guidance for interventions

Biomarkers:

Novel inflammatory markers
Genetic susceptibility testing
Personalized medicine approaches

Research Priorities

Validation of bedside ultrasound protocols
Development of clinical prediction rules
Optimal antibiotic duration for retroperitoneal abscess
Prevention strategies for high-risk patients
Long-term outcomes of femoral nerve palsy

Conclusion

The psoas sign represents a crucial clinical finding that demands systematic attention in the critical care setting. Its significance extends beyond traditional appendicitis evaluation to encompass life-threatening conditions including retroperitoneal abscess and iliopsoas hematoma. The combination of careful physical examination, risk factor assessment, and appropriate imaging - particularly bedside ultrasound - can significantly improve diagnostic accuracy and patient outcomes.

Critical care practitioners must maintain a high index of suspicion for psoas-related pathology, particularly in bedridden patients with unexplained clinical deterioration. The integration of traditional clinical skills with modern imaging techniques provides the foundation for optimal patient care in this challenging clinical scenario.

Early recognition, prompt intervention, and multidisciplinary management remain the cornerstones of successful outcomes in patients with psoas sign-related pathology. As our understanding of these conditions evolves, continued research and quality improvement initiatives will undoubtedly enhance our ability to care for these complex patients.

References

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Conflict of Interest Statement: The authors declare no conflicts of interest.

Funding: No external funding was received for this work.

Ethical Approval: Not applicable for this review article.

Wednesday, July 16, 2025