Essure is designed to cause permanent blockage of the fallopian tubes. This blockage is not immediate but happens slowly over time. During the Essure procedure, the doctor inserts a single Essure micro-insert device into the opening of each fallopian tube.
Each Essure device is a pair of coils. The outer coil expands and anchors the coil into the fallopian tube. The inner coil contains fibers, which promote scar tissue formation. The formation of scar tissue within the tube is what causes the tube to heal with scar tissue and become permanently blocked.
The larger, wider outer coil is an expanding coil made from a nickel titanium alloy, otherwise known as nitinol. The purpose of the outer coil is to expand after insertion and to firmly anchor the device into the fallopian tube.
The smaller inner coil is made of stainless steel. Wrapped around this inner coil are polyethelene (PET) fibers. The PET fibers acts as an irritant and cause the ingrowth of scar tissue, which will firmly anchor the entire system in place and cause permanent blockage of the fallopian tube.
The outer coil is designed to both remain in position inside the fallopian tube and hold the inner coil in place. The inner coil is designed to hold the PET fibers in place and the PET fibers are intended to promote scar tissue formation. Once the scar tissue has formed then the fallopian tube will be permanently blocked.
Essure outer coil
Nickel titanium alloy
The outer Essure coil is composed of nitinol, which is a 50:50 mixture of the metal nickel and titanium. Nitinol has a long history of use in the medical field for various applications. Nitinol is commonly used in orthodontics (braces), vascular stents, and orthopedic implants.
The alloy is thought to be ideal because of its unique temperature changing properties. The alloy can be designed to hold a predesigned shape when warmed and a different predesigned shape when at room temperature.
When a nitinol stent is placed inside the human body, the temperature change causes the alloy to reconfigure, or transform, to its designed coil like state. In orthodontic use the increase temperature inside the mouth causes the metal wires to contract and apply tension to the teeth. When nitinol is used in vascular stents the increased body temperature causes the stents to expand to a pre-designed shape to keep the blood vessels open. In the Essure micro-insert system the nitinol causes the outer coil to expand and conform to the shape of the fallopian tube.
Although nitinol is commonly used in medical applications there are three main limitations of this alloy: stress fatigue (breaks easily), allergenicity (allergy causing) and carcinogenicity (cancer causing).
Stress fatigue: Nitinol is commonly used in applications that require flexibility and motion. Stress fatigue happens with most metals when used in demanding situations. Nitinol is felt to be superior to most other metals but nitinol metal fractures and fatigue have been observed in medical uses where the metal is being exposed to the most amount of stress.
Allergenicity: Nickel is a component of nitinol and nickel is a known allergenic substance in humans. Nickel is well known to cause contact dermatitis when exposed to the skin. The primary manifestations of nickel allergy are skin rash, hypersensitivity, swelling in the area of contact, and pain.
Initially allergy or hypersensitivity to nickel was a contraindication for patients to have Essure; however, in 2011 the FDA removed the nickel contraindication based on data submitted by Conceptus.
Although nickel is a well-known allergen it was determined the highest amount of nickel released into the blood stream from the Essure coils was 0.14 micrograms per day. By comparison, the average daily consumption of nickel is estimated to be around 300 micrograms per day. It was determined the chance of having a nickel related adverse event (nickel allergy) from Essure was approximately 1 in every 10,000 procedures.
Carcinogenicity: Nickel is also carcinogenic in lab animals. Although reasonably suspected of being carcinogenic in humans, nickel has never been conclusively proven to cause cancer in humans.
Conceptus did perform animal studies prior to FDA approval and there was no observed increased risk of cancer in laboratory animals.
Essure inner coil
The inner Essure coil is composed of stainless steel, which is an alloy of steel and chromium. Stainless steel is often chosen for applications were durability is required. The primary appeal of stainless steel is the metal is strong, durable, and will not rust with exposure to moisture. Stainless steel is commonly seen in surgical instruments and orthopedic implants.
Polyethylene (PET) fibers
Polyethylene terephthalate (PET) fibers are a plastic material and a member of the polyester family. The PET fibers are wrapped around the inner stainless steel coil. The inner coil keeps the fibers in place and the PET fibers form a matrix for scar tissue ingrowth.
Although very controversial, polyethylene terephthalate is speculated to possibly be an endocrine disrupter under certain conditions. An endocrine disrupter can cause abnormalities with a person’s endocrine system (ovaries/testes, thyroid, pancreas, adrenals, etc.).