This case takes place in Virginia and involves a plaintiff who suffered from stress urinary incontinence. She received a pelvic mesh implant that was manufactured by defendant. She alleges that at the time of her surgery, the defendant knew of FDA and medical professionals’ safety concerns about the mesh implants causing vaginal shortening, vaginal tightening and vaginal pain. The mesh caused conditions that required additional surgeries.
Plaintiff filed this lawsuit three years after her surgery. She asserts claims for negligence, design defect, manufacturing defect, failure to warn, breach of implied and express warranties and loss of consortium. Among her allegations is that the mesh is biologically incompatible with human tissue. Plaintiff retained experts specialize in urogynecology and biomaterials for this matter.
Question(s) For Expert Witness
- 1. Is the mesh bioincompatible?
- 2. Did plaintiff’s mesh show signs of incompatibility?
Expert Witness Response
A small amount of inflammation near the interface between the foreign body and the tissue is related to better biocompatibility. A typical reaction to a biocompatible mesh is characterized by mild inflammation, foreign body giant cells, and mild to moderate degree of fibrosis. The presence of this reaction and its accompanying cells and their associated extracellular matrix (proteins outside of the cells) is expected following any tissue-damaging event, including surgery and the implantation of a device; it does not signal a problem with the device.
The integration of mesh by connective tissue surrounding the mesh filaments is important to provide support to the mesh. Thus, it is important for the mesh to allow tissue to grow into the pores between the mesh filaments. However, there is a balance between appropriate integration and excessive formation of scar tissue, which is disfavored.
Defendant’s mesh is the standard of care for the treatment of stress urinary incontinence in women. It is supported by numerous randomized controlled trials and other clinical studies. The defendant’s mesh evokes a minimal or mild acute inflammatory response that transitions to a minimal or mild chronic inflammation, with a minimal to mild fibrotic reaction and neovascularization. It contains pores that are large enough to allow the cells responsible for the immune and inflammatory responses to enter the mesh spaces. It contains pores that are several times larger than necessary. It does not potentiate infection due to its material properties as well as its knitted structure. There is no evidence to support the belief that the mesh is carcinogenic or tumorigenic. There have been numerous studies evaluating the product in the nearly 20 years since it was introduced; none has described cancers in humans. Further, rat studies on sarcoma formation cannot be extrapolated to the human experience.
Plaintiff never complained of pain to any of the physicians who treated her in the three years following her surgery. Nine months after filing suit, she was seen for pelvic pain. The mesh ultimately was removed. Examination showed no erosion or infection of the mesh.
Plaintiff’s expert claims that defendant’s mesh is cytotoxic in humans. This is not supported by the scientific evidence. I examined plaintiff’s mesh and found healthy cells and tissues that had integrated in the pores and around the filaments of the mesh. In my opinion, a cytotoxic implant left in a host for almost 4 years would show signs of necrosis and would not have healthy tissues in and around it.
Based on my review of plaintiff’s pathology specimens, I conclude the following:
· No mesh distortion is identified. The pore architecture is retained.
· No evidence of infection or edema is present. No evidence of mesh exposure or erosion is present.
· There is no evidence of any tumor growth.
· Good tissue integration is present within the mesh pores. No scar or scar bridging is present.
· The degree of chronic inflammation and foreign body giant cells found in this specimen is within normal limits.
There is no histologic evidence to support pain or dyspareunia complained by the patient.
The expert is an obstetrics and gynecology pathology professor who has published more than 130 peer-reviewed articles on gynecologic pathology and oncology.