Can a linear collection in the right posterior rectus sheath develop after a Cesarean section, presenting on postoperative day 4 with fever, chills, marked leukocytosis and supra‑ and periumbilical tenderness?

Can Linear Collection in Posterior Rectus Sheath Develop After Cesarean Section?

Yes, a linear collection along the right posterior rectus sheath can absolutely develop after cesarean section, and in this clinical context with fever, chills, and dramatically rising leukocytosis (12,000 to 35,000), this represents a surgical site infection with subfascial/rectus sheath abscess formation that requires urgent intervention.

Understanding the Pathophysiology

• Subfascial hematomas and fluid collections are well-documented complications following cesarean delivery, particularly when they occur beneath the rectus sheath 1.
• The posterior rectus sheath is a recognized location for post-cesarean complications, including hematomas that can become secondarily infected 2, 3.
• Postoperative day 4 is a typical timeframe for infected collections to manifest with systemic signs 4.

Clinical Significance of This Presentation

• The combination of fever with chills, rising WBC count from 12,000 to 35,000, and supraumbilical/periumbilical tenderness indicates an infected collection requiring drainage 4, 1.
• This dramatic leukocytosis (35,000) far exceeds typical post-cesarean elevations and signals significant infection 1.
• Linear collections along the posterior rectus sheath can represent subfascial abscesses or infected hematomas, both of which are recognized post-cesarean complications 1.

Mechanism of Development

• Cesarean sections create potential spaces beneath the rectus sheath where fluid can accumulate, particularly when the rectus sheath is incised and closed 3, 5.
• Blood or seroma can collect in the subfascial space and become secondarily infected with skin flora or vaginal flora (cesarean sections are classified as clean-contaminated procedures) 1.
• The posterior rectus sheath location is anatomically vulnerable because it represents the plane between the rectus muscle and the peritoneum 6.

Critical Imaging Findings

• MRI showing a linear collection along the posterior rectus sheath in this clinical context strongly suggests an infected subfascial collection 1.
• The ACR guidelines note that subfascial hematomas >4 cm or those with clinical signs of infection warrant intervention 1.
• CT with IV contrast would better characterize whether there is rim enhancement (suggesting abscess) or active extravasation, though MRI can also demonstrate these features 1.

Immediate Management Algorithm

For this patient with systemic infection signs and rising leukocytosis:

• Obtain CT abdomen/pelvis with IV contrast immediately to better define the collection, assess for rim enhancement, and evaluate for other complications like uterine dehiscence or rupture 1.
• Initiate broad-spectrum antibiotics covering mixed gram-positive, gram-negative, and anaerobic flora (ampicillin-sulbactam, cefoxitin, or ertapenem) 7.
• Arrange urgent CT-guided percutaneous catheter drainage (PCD) for any collection ≥3 cm with infection signs 1, 8.
• Use either Seldinger (wire-guided) or trocar (direct puncture) technique for drainage 1.

Critical Pitfalls to Avoid

• Do not delay drainage based on collection size alone—the dramatic leukocytosis and systemic signs mandate intervention regardless of exact dimensions 1, 4.
• Do not misinterpret this as simple postoperative edema—the rising WBC count from 12,000 to 35,000 over 4 days indicates progressive infection, not normal healing 1, 4.
• Evaluate for necrotizing fasciitis, which has been reported in post-cesarean rectus sheath collections and requires immediate surgical debridement 2.
• Assess for uterine dehiscence or rupture, as subfascial hematomas >5 cm should raise suspicion for these complications 1.

Additional Diagnostic Considerations

• Check for gas within the collection on imaging—gas in the myometrial defect extending to parametrial tissue suggests uterine rupture rather than isolated rectus sheath abscess 1.
• Evaluate for ovarian vein thrombosis, a recognized complication of postpartum endometritis that can present with similar symptoms 1.
• The supraumbilical and periumbilical location is consistent with subfascial infection extending along the rectus sheath planes 2, 6.

Evidence Supporting Post-Cesarean Rectus Sheath Collections

• A 2021 case report documented a 15-cm rectus sheath hematoma one month post-cesarean that became infected and progressed to necrotizing fasciitis 2.
• Historical data from 1988 showed that placing drains beneath the rectus sheath significantly reduced wound infection rates, confirming this space as vulnerable to fluid accumulation and infection 3.
• Recent studies demonstrate that surgical site infection rates after cesarean range from 3-15%, with subfascial collections being a recognized manifestation 5.

Surgical Consultation

• Obtain immediate surgical consultation given the severity of systemic signs and potential for necrotizing infection 2.
• If PCD fails or if there are signs of necrotizing fasciitis (crepitus, rapidly progressive erythema, systemic toxicity), exploratory laparotomy with debridement is mandatory 2.