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FloSeal — Flowable Gelatin-Thrombin Hemostatic Matrix

FloSeal is a flowable hemostatic matrix that combines bovine-derived cross-linked gelatin granules with human thrombin to deliver a hybrid passive-plus-active hemostatic in a single syringe-based product. It is the go-to agent for diffuse oozing on irregular surfaces — the renal bed after partial nephrectomy, the pelvic sidewall after lymphadenectomy, the retropubic space after complex reconstruction — particularly in patients with impaired clotting capacity (heparinization, coagulopathy).[1][2]

Composition and Mechanism​

ComponentRole
Gelatin matrix (bovine)Passive mechanical scaffold; contact-activates platelets; swells to fill irregular cavities
Human thrombinConverts fibrinogen → fibrin directly; bypasses the intrinsic/extrinsic coagulation cascade
Combined effectPassive matrix + active thrombin = hemostasis independent of the patient's own coagulation status

Mechanism sequence​

  1. Syringe delivers flowable gel onto the bleeding surface
  2. Gelatin granules swell (up to 20%) as they absorb blood and tissue fluid
  3. Thrombin converts local fibrinogen → fibrin immediately, catalyzing clot formation
  4. Mechanical tamponade of the bleeding surface as the gel conforms to irregular anatomy
  5. Matrix resorbs over 6–8 weeks

GU Reconstruction Applications​

1. Partial nephrectomy renal bed​

The highest-yield application:[1][2]

  • Combined with sliding-clip renorrhaphy (suture hemostasis of the parenchymal bed)
  • FloSeal fills the tumor excision defect, controlling diffuse parenchymal oozing after tumor removal
  • Shorter warm ischemia time, reduced need for additional cautery, no disruption of adjacent parenchyma
  • Used in both open and robotic partial nephrectomy — the syringe tip is trocar-compatible

2. Pelvic sidewall / lymphadenectomy​

  • After pelvic lymph node dissection during radical cystectomy, prostatectomy, or deep endometriosis resection
  • Controls capillary and small-venous oozing without cautery near iliac vessels or obturator nerve

3. Retropubic space​

  • After complex bladder-neck reconstruction (Y-V plasty, complex pelvic fistula repair)
  • After radical prostatectomy when anterior urethral / puboprostatic ligament dissection has created a raw surface

4. Deep pelvic dissection​

  • Presacral venous plexus bleeding
  • Pelvic sidewall after extensive dissection
  • Post-exenteration bleeding

5. High-risk patient populations​

  • Heparinized patients — the active thrombin component works independently of heparin-affected clotting
  • Coagulopathic patients — cirrhotic patients, patients on DOACs, thrombocytopenic patients
  • Radiated tissue — where tissue quality is poor and standard suturing is unreliable

Preparation and Application​

Preparation (at the scrub table)​

  1. Reconstitute the thrombin (~5 minutes)
  2. Combine with the gelatin matrix in the supplied syringe connector
  3. Mix back-and-forth between the two syringes ~20 times until homogeneous
  4. Attach the applicator tip
  5. Ready for use

Application​

  1. Dry the surgical field as much as possible (suction nearby; dry the surface with gauze)
  2. Apply the gel directly to the bleeding surface with the applicator tip
  3. Tamponade with a dry sponge gently for 2 minutes
  4. Irrigate gently to remove excess
  5. Check for hemostasis; repeat if needed

Volume​

  • Standard kit: 5 mL, 10 mL sizes
  • Typical GU application: 2–5 mL covers a moderate renal bed or pelvic sidewall
  • Large irregular cavities may require 10 mL or repeat application

Advantages​

  • Active + passive combined — effective even in coagulopathic / heparinized patients where passive matrices underperform
  • Conforms to irregular surfaces — flowable delivery reaches crevices inaccessible to sheet products
  • Trocar-compatible — direct laparoscopic / robotic application
  • Excellent for parenchymal surfaces (renal bed, liver in GU-adjacent trauma)
  • Strong evidence base in partial nephrectomy and spine surgery

Limitations​

  • Cost — FloSeal is substantially more expensive than Surgicel or Arista (~$200–500/kit)
  • Swelling — 20% expansion; can compress nerves or narrow spaces (use sparingly in spinal canal, pelvic sidewall near nerves)
  • Bovine gelatin origin — rare anaphylaxis reported; contraindicated in patients with known bovine allergy
  • Not for intravascular use — thrombin can cause pulmonary embolism if injected into a vessel
  • Preparation time — reconstitution takes a few minutes; not instantly available if unanticipated bleeding
  • Urinary-tract collecting-system contact — as with other hemostatic matrices, avoid direct contact with the urinary collecting system (stone nidus concern, though shorter-duration than Surgicel/Gelfoam)

Evidence Base​

FloSeal has substantial evidence in urology:

  • Multiple studies in robotic and open partial nephrectomy demonstrate reduced operative bleeding, shorter warm ischemia, and reduced need for transfusion
  • Pelvic reconstruction and radical cystectomy series show reduced overall operative blood loss with routine use
  • Spine surgery data (not GU but foundational) established FloSeal as the benchmark active hemostatic against which newer products are compared

See Also​

References​

1. Hidas G, Kastin A, Mullerad M, Shental J, Moskovitz B, Nativ O. Sutureless nephron-sparing surgery: use of albumin glutaraldehyde tissue adhesive (BioGlue). Urology. 2006;67(4):697–700. doi:10.1016/j.urology.2005.10.064

2. Msezane LP, Katz MH, Gofrit ON, Shalhav AL, Zorn KC. Use of novel hemostatic agents in robotic laparoscopic partial nephrectomy. Can Urol Assoc J. 2009;3(4):324–30.