Collagen Plug Identification and Absorption Timeline After Femoral Catheterization
Yes, the 1 cm hard nodule at your femoral puncture site 21 days post-catheterization is almost certainly the collagen-based vascular closure device, and it typically resolves completely within 2–6 weeks, though small palpable masses may persist for up to 90 days. 1
What You Are Feeling
The hard lump is the collagen plug component of the hemostatic puncture closure device (such as VasoSeal or Angio-Seal), which consists of purified bovine absorbable collagen deployed in the supra-arterial space directly over the arterial puncture site. 2, 3
All patients who receive collagen-based closure devices develop a small, pain-free palpable swelling over the puncture site that persists for 2–6 weeks—this is the expected normal finding, not a complication. 1
Serial duplex ultrasound studies performed at 1,7,30, and 90 days after collagen plug placement demonstrate that the collagen material gradually resorbs, with normalization of femoral artery flow patterns in nearly all patients by 90 days. 2
Expected Absorption Timeline
Hemostasis is achieved within 1–4 minutes of collagen plug deployment, allowing early mobilization (typically 6–19 hours post-procedure). 2, 1
The palpable collagen mass remains detectable for 2–6 weeks in the vast majority of patients, gradually softening and shrinking during this period. 1
Complete resorption occurs by 90 days in nearly all cases, with ultrasound confirmation showing restoration of normal arterial anatomy and flow. 2
When the Lump Is NOT Normal
Immediate Imaging Is Required If:
The mass is rapidly enlarging, pulsatile, or refills after compression—these features indicate a pseudoaneurysm, not a simple collagen plug. 4
You develop new pain, expanding swelling, skin discoloration, or warmth over the lump, which may signal infection or hematoma rather than normal collagen resorption. 1
Physical examination alone misses more than 60% of pseudoaneurysms; therefore, duplex ultrasound should be performed immediately whenever a femoral mass is enlarging or symptomatic, even if you assume it is "just the collagen plug." 4
Distinguishing Collagen Plug from Pseudoaneurysm
A collagen plug is firm, non-pulsatile, non-compressible, and stable in size over days to weeks, gradually softening as it resorbs. 1
A pseudoaneurysm is compressible, pulsatile, refills after pressure, and demonstrates characteristic "to-and-fro" Doppler flow on ultrasound—it will enlarge if untreated. 4
At 21 days post-procedure, a stable 1 cm firm nodule without pulsation or expansion is consistent with normal collagen plug resorption, but any change in size or character warrants immediate ultrasound evaluation. 2, 1
Common Pitfalls to Avoid
Do not assume all femoral lumps are benign collagen plugs—small subcutaneous hematomas (detected in 25% of patients by ultrasound at day 1) and pseudoaneurysms can coexist with or mimic collagen plugs. 2
Do not wait for symptoms to worsen before seeking imaging—pseudoaneurysms inevitably enlarge if untreated, and rupture with active hemorrhage requires emergency surgical repair. 4
If the lump persists beyond 6 weeks, enlarges, or becomes painful, obtain duplex ultrasound to exclude pseudoaneurysm, arteriovenous fistula, or infected hematoma. 2, 1