May 19, 2017
More than half a million patients undergo surgeries involving the gastrointestinal (GI) tract to manage neoplastic or inflammatory disorders of the digestive tract or for bariatric indications. Post-surgical complications such as perforations, leaks and fistulas can be devastating, as they prolong hospitalization and are the source of considerable morbidity and mortality.
Typically these defects are managed either with rescue surgery when the defect is identified early after surgery, or with a wait-and-watch strategy followed by secondary surgery if the symptoms persist. Spontaneous closure rates with a conservative approach are highly variable, ranging from 16 to 46 percent. In patients who fail conservative treatment and undergo surgical intervention, mortality increases, and recurrence after surgical repair also is not uncommon.
The subpar success rate, high morbidity and mortality, as well as a tenfold increase in cost of care for patients who experience these post-surgical complications (an overall health care burden of approximately $10 billion each year), underscore the urgent need to develop, institute and optimize novel interdisciplinary approaches to managing leaks and fistulas.
As an integral component of management of leaks and fistulas, endoscopic interventions include primary closure by tissue apposition and leak containment by diversion or drainage of gastrointestinal contents away from the defect site. In a majority of cases, these interventions are applied in a stepwise manner or in an institutional expertise-dependent manner.
While successful up to an extent, these multimodal interventions have limitations, as they are primarily driven by the capabilities of current devices and accessories, rather than by the fundamental concepts underlying the persistence of leaks or fistulas.
Variables that influence resolution of leaks and fistulas
A variety of important variables influence the resolution of leaks and fistulas, including:
- Location in the gastrointestinal tract
- Extent of luminal discontinuity
- Chronicity of the leak
- Coelomic versus extracoelomic leakage
- Contained versus free coelomic leaks
- Low- versus high-pressure gradient across the leak
- Tissue health at the origin, around the leak as well as anatomy of lumen distal to the leak
Therefore, careful assessment and avoiding an urge to use one approach for all or a "shotgun approach" are critical when planning the management of GI defects and leaks.
It is also prudent to set clear and achievable expectations as conservative measures, as radiological drainage and endoscopic intervention might only be useful as bridging therapy until the patient can undergo more definitive surgical treatment instead of a definitive therapy. Although existing and evolving strategies driven by what devices have to offer are essential, recognizing their limitations and pitfalls is key in making the switch to concept-based strategies that address what drives the persistence of leaks or fistulas.
Imaging-guided transcutaneous drain placement is a common first step due to widespread availability of this expertise. This approach, which is also called lateralization of leak, could convert a leak into a fistula. Even though the goal of this centripetal approach is to drain the leaked contents and to create negative pressure to collapse the cavity, for several reasons it can actually perpetuate the leaks in many patients.
This approach promotes the extrusion of epithelial lining and scarring in the vicinity of the leak, leading to a fixed opening. If the size of the fixed opening is larger than the drain size, or if the cavity resides next to gut wall, the lateral drains are typically unable to create enough negative pressure in the cavity. This limitation allows liquid or gaseous gastrointestinal contents to continue to fill the cavity. Furthermore, extension of epithelium into the tract and the cavity, caused by lateral flow of the contents, prevents spontaneous healing and interferes with attempts at luminal closure. In other words, well-intentioned lateral drainage could end up perpetuating the leakage.
Analogous to an infected cutaneous wound management by a vacuum-assisted closure system, endoscopic vacuum therapy is being applied to treat leaks from the proximal or distal gastrointestinal tract. The negative pressure generated by this approach assists wound healing by draining exudates and secretions, which promotes granulation tissue.
This approach is limited by the distance that such sponge-laden drains can reach in the gut, as well as by a cumbersome twice weekly need to replace the entire system, which puts patients at risk of complications related to the procedure or sedation. In addition to anatomic limitations, if the opening of the cavity is small, it needs endoscopic dilatation, which creates the potential for additional adverse events.
Endoscopic clipping and suturing are evolving techniques to close the gut discontinuity. However, through the scope (TTS) clips and over-the-scope clips (OTSC) as well as suturing devices have several limitations. The wingspan and the approximation force of TTS clips are insufficient to approximate most leaks except acute linear perforations. OTSC placement is also challenging where there is limited access and restricted mobility, and where the target lesion is suboptimally aligned.
In these situations, incorrect or ineffective OTSC deployment may result in complete luminal closure or make subsequent repair very difficult. Placement of endoscopic sutures can obviate these limitations but typically does not provide a seal-proof closure. Excessive tightening of the sutures to achieve seal-proof closure can result in cheese wiring of the tissue and eventual failure of repair.
Diversion of contents with the help of stent placement is another endoscopic approach to deal with leaks and fistulas. Several factors make the use of stents impractical in many situations. These include: the limitation of a delivery system used with partially or fully covered stents, tissue injury resulting from the stents, high risk of migration (20 percent unless it is feasible to stitch in place), and need for frequent exchanges.
Post-surgical esophageal leak management
Large post-surgical esophageal leak and mediastinal abscess management using Endoscopic Negative Intracavitary Pressure (Endo-NIP) before-and-after images.
"At Mayo Clinic, we have a multidisciplinary team of experts who review, discuss and manage leaks and fistulas," explains Navtej (Nav) S. Buttar, M.D., a gastroenterologist and chair of Endoscopy at Mayo Clinic's campus in Rochester, Minnesota. "Novel endoscopic concepts are an integral part of this program for patients when conventional management strategies either fail or are not feasible."
Mayo staff members are also investigating a novel approach using fistula plug-delivered stem cells derived from a patient's abdominal fat pad to address the needs of patients referred for increasingly complex surgical intervention who are at high risk of post-surgical complications. "Our program exploits this unique drug-device combination, which, like drug-eluting stents in cardiology, will revolutionize therapeutic advances," says Dr. Buttar.