What are the causes of rectus sheath hematoma?

Causes of Rectus Sheath Hematoma

Rectus sheath hematoma results from bleeding into the rectus abdominis muscle sheath, most commonly due to rupture of the superior or inferior epigastric arteries. 1

Primary Etiologic Mechanisms

Anticoagulation-Related Bleeding

• Anticoagulant therapy is the most common predisposing factor for rectus sheath hematoma, accounting for the majority of cases in contemporary practice. 2 As anticoagulant use has increased in the population, the incidence of RSH has correspondingly risen. 1
• Direct oral anticoagulants, warfarin, and low-molecular-weight heparins (LMWH) all increase bleeding risk into the rectus sheath. 1, 2
• Antiplatelet agents also contribute to RSH development, though less commonly than anticoagulants. 3

Iatrogenic Trauma

• Abdominal injections of LMWH can cause severe RSH, particularly when administered without careful attention to technique. 2 One case series documented a patient requiring surgery after developing severe RSH following LMWH injection. 2
• Improper technique during abdominal paracentesis can injure the inferior epigastric arteries, leading to RSH. 4
• Trocar insertion during laparoscopic surgery without direct visualization poses risk for epigastric vessel injury. 2
• Vascular access procedures and catheterization can result in vascular complications including hematoma formation, though this typically affects femoral access sites rather than the rectus sheath. 5

Direct Trauma

• Blunt abdominal trauma can cause bleeding from epigastric vessels or direct rectus muscle tears. 1, 2
• Penetrating trauma including gunshot wounds can directly contaminate or injure blood vessels. 5

Muscle Strain and Increased Intra-abdominal Pressure

• Excessive coughing, particularly in patients with chronic obstructive pulmonary disease, can precipitate RSH. 3
• Pregnancy-related muscle strain increases risk due to stretching and increased vascularity of the abdominal wall. 1
• Severe straining during defecation or heavy lifting can trigger bleeding. 1

Spontaneous RSH in the Elderly

• Atheromatous changes in epigastric vessels are identified as contributing factors for spontaneous RSH in elderly patients, even without anticoagulation or trauma. 3 This represents a distinct entity where vessel wall disease leads to spontaneous rupture.
• A case report documented a 100-year-old woman developing spontaneous RSH without anticoagulation, trauma, or excessive strain, attributed to age-related vascular changes. 3

Anatomic Considerations Affecting Hematoma Development

• Hematomas occurring below the arcuate line (typically below the umbilicus) tend to be larger because the posterior rectus sheath is absent at this level, allowing unrestricted spread of blood into the preperitoneal space. 1
• Above the arcuate line, the posterior rectus sheath provides containment, limiting hematoma size. 1
• The inferior epigastric artery is the most commonly injured vessel, as it courses through the rectus sheath and is vulnerable to both direct trauma and spontaneous rupture. 1

Risk Factors for Development

Patient Demographics

• Elderly patients represent the highest-risk population, particularly those over 60 years of age. 2 The mean age in one series was 57.1 years, with a range extending to 86 years. 2
• Female gender is associated with increased risk of vascular complications in general, though RSH affects both sexes. 5
• Obesity increases risk through multiple mechanisms including difficult vascular access and increased abdominal wall vascularity. 1

Coexisting Medical Conditions

• Coagulopathy from any cause (inherited or acquired) predisposes to RSH. 1, 6
• Chronic kidney disease and end-stage renal failure increase bleeding risk through platelet dysfunction. 7
• Peripheral vascular disease increases overall vascular complication rates. 5

Critical Clinical Pitfall

The most important pitfall is failing to consider RSH in elderly patients on anticoagulation who present with acute abdominal pain and a palpable mass. 2 This condition frequently mimics intra-abdominal pathology and can lead to unnecessary surgery if not recognized. CT imaging establishes the diagnosis in 100% of cases and should be obtained promptly when RSH is suspected. 2

Clinicians must also recognize that spontaneous RSH can occur without any identifiable trauma or anticoagulation, particularly in very elderly patients with atherosclerotic vessel disease. 3 A history negative for these typical risk factors should not exclude the diagnosis.