2.1 Pathogenesis and Prevalence
Postoperative peritoneal adhesions are a physiologic response to surgical injury, peritonitis, or endometriosis. They serve to provide structural support, ward off infections, and deliver collateral circulation. Peritoneal trauma from surgical transection and ligation of vessels cause devascularization. Tissue ischemia, along with bleeding and lymphatic fluid drainage, stimulates a cascade of anaerobic metabolism, oxidative stress, and the formation of free radicals. When normal peritoneal and adhesion fibroblasts are exposed to free radicals such as superoxide, there is an increase in inflammatory mediators, histamines, cytokines, and growth factors. The impact of these mediators, including TNF-α, TGF-β, VEGF, IL-6, PAI-1, COX-2, type 1 collagen, fibronectin, and tissue inhibitors of metallproteinases (TIMP), is the formation of an impaired tissue plasminogen activator (tPA) system, resulting in decreased fibrinolysis and persistence of the early fibrinous adhesions (Figure 2.1). Continued fibrin deposition and capillary in-growth result in the development of permanent adhesions .
Figure 2.1 Pathogenesis of adhesion formation.
Adhesion phenotypes have been defined based on the biological characteristics of adhesion fibroblasts compared to normal peritoneal fibroblasts . Extensive research has demonstrated that adhesion fibroblasts exhibit decreased NO, a decreased ratio of tPA/PAI-1, decreased apoptosis induced by hypoxia, and a greater production of TGF-β1 and extracellular membrane molecules . There are two prominent types of adhesions: a thin filmy, avascular type and a thick cohesive, vascular type, with the former affording simple blunt lysis and the latter requiring careful sharp dissection to avoid injury to adjacent structures (Figure 2.2).
Figure 2.2 Thin filmy adhesions and dense cohesive adhesions.
The sites, extent, and tenacity of adhesions can be quite variable and may involve the uterus, ovaries, fallopian tubes, peritoneum, omentum, or bowel and other organs. With respect to the fallopian tubes, this may result in agglutination of the fimbriae to complete occlusion with intraluminal damage, resulting in hydrosalpinges. Adhesions around the ovary or uterus can result in anatomic distortion due to adherence to adjacent organs and/or the pelvic sidewall. Adhesions can result in obliteration of the anterior and posterior cul-de-sacs.
Several risk factors have been directly associated with an increased risk of postoperative adhesion formation, including genetic polymorphisms of the IL-1 receptor antagonist, increased exposure to estrogen, and endometriosis . Patients with endometriosis have been found to have increased levels of IL-6 and IL-8 in their peritoneal fluid and, moreover, the concentration of these cytokines has been correlated with the severity of adhesion formation . The pro-inflammatory cytokines associated with endometriosis are believed to activate PAI-1, impairing fibrinolysis, and increased the propensity for adhesion formation in this population . Factors that increase the risk of fibrosis are indirectly related to increased adhesion development, such as genetic polymorphisms in PAI-1, diabetes mellitus, metabolic syndrome, hyperglycemia, obesity, depression, binge alcohol consumption, anti-Parkinsonian therapy, oral hormone therapy, pregnancy, and malignancy .
Adhesions occur in up to 94% of patients following open abdominal or pelvic surgery. Laparoscopic abdominal or pelvic surgery may have comparable risk for adhesion related complications, including small bowel obstruction, impaired fertility, and abdominal or pelvic pain . The extent of tissue injury is the predominant factor for adhesion development, rather than the surgical approach (laparotomy vs. laparoscopy), though the length of the abdominal incision is related to the risk for de-novo abdominal wall adhesions .
In order to facilitate patient management decisions by predicting outcomes such as pregnancy rates in cases of infertility caused by adhesions, numerous scoring systems have been developed; however, none have been clinically validated.
2.2 Clinical Consequences
The clinical implications and economic burden of intraperitoneal adhesions are significant, with an estimated $5 billion cost to the United States health care system annually . A number of studies have examined the impact on health care including the inpatient burden of adhesiolysis. In one report of more than 350,000 hospitalizations, 23% were for primary adhesiolysis and almost 77% for secondary adhesiolysis with an average length of stay of 7.8 days . In another study, approximately one-third of patients who had undergone laparotomy experienced an average of two hospital readmissions over the 10 years following initial surgery due to adhesions. In particular, ovarian surgery had the highest readmission rate as a direct result of adhesions (7.5/100 initial operations) .
There are a number of major consequences of adhesion formation (Box 2.1), including increased operative time and the risk of bowel-related injuries . The distortion of normal anatomy, compromised exposure, and need for lysis of bowel adhesions may lead to sharp or thermal injury to the bowel with resultant postoperative morbidity. Chronic abdominal or pelvic pain associated with adhesions has been attributed to visceral pain due to limited organ mobility, although the definitive relationship remains uncertain. Nerve fibers have been identified in pelvic adhesions, yet their prevalence and extent is not necessarily greater in those with more severe pain . Fertility may be disturbed by peritoneal adhesions that distort the anatomic relationship between the tubes and ovaries, which compromise oocyte pickup. In addition, intrauterine adhesions may interfere with embryo implantation. Screening for uterine and tubal factor infertility may be accomplished through hysterosalpingography (HSG) or sonohysterosalpingography.
Increased operating time in subsequent surgery
Small bowel obstruction
Postoperative intraabdominal adhesions are the most common cause of small bowel obstruction, responsible for 74% cases of bowel obstruction in 552 patients . An often-unappreciated aspect is subsequent emergent cesarean section for fetal hypoxia. There are significant concerns related to delayed delivery due to difficult access to the uterus from adhesions resulting in lifelong morbidity including cerebral palsy, intraventricular hemorrhage, and respiratory distress syndrome .
2.3 Treatment Techniques
Surgical lysis of adhesions must begin with safely entering the abdominal or pelvic cavity (see Video 2.1). Even slow and methodical entry by laparotomy may result in injury to bowel that is densely adherent to the abdominal wall. Intraoperative recognition and repair is the key to preventing delayed complications. Access to the abdominal cavity during laparoscopic surgery with insertion of the trocar through the umbilicus carries a risk of injury due to bowel to abdominal wall adhesions. Primary trocar entry in the left upper quadrant (Palmer’s point, 3 cm below the left costal margin in the mid-clavicular line) should be considered to minimize the risk of bowel perforation (Figure 2.3) . Adhesions occurring at this point are less frequent, affording an assessment of the location and extent of adhesions for planning the sites for ancillary trocar insertions (see Video 2.2). As with all laparoscopic procedures, but especially with left upper quadrant trocar entry, it is essential that the stomach be decompressed with nasogastric tube suction to avoid injury to that organ.
Figure 2.3 Palmer’s point.
If adhesions are observed, a structured approach can be undertaken with an initial step that includes lysis of adhesions along an avascular plane to ensure minimal bleeding. The utilization of traction and countertraction creates tension and allows for clearer identification of an avascular plane. Adhesiolysis can be achieved by both sharp and blunt dissection techniques. Sharp dissection is the primary technique employed for dense adhesions but can by followed by blunt dissection for the remaining fine adhesions.
Scissors are the preferred instrument to lyse adhesions. With the magnification of the laparoscope, most anterior abdominal wall, pelvic, and bowel adhesions can be clearly visualized and carefully divided with minimal bleeding. Scissors may aid in adhesiolysis not only through cutting but also via blunt mechanical tissue separation. Inserting scissors in a closed position and withdrawing it in the open position may separate loose fibrous tissue. Natural planes may be developed with the assistance of a partially open blunt scissor tip while pushing the tissue. Blunt or rounded-tip scissors with one stable blade and one moveable blade may be used to sharply divide thin and thick bowel adhesions (Figure 2.4).
Figure 2.4 Dissection with rounded-tipped scissors while the adhesions are placed on traction.
Aquadissection has also been employed in the dissection of adhesions where instillation of pressurized fluid displaces the tissue to create planes in the path of least resistance. Aquadissection can produce edematous, distended tissue when instilled into closed spaces behind peritoneum or adhesions, which may allow for safer tissue division with blunt scissor dissection, laser, or electrosurgery after surgical planes are developed.
If anatomic planes are not evident, or vascular adhesions are anticipated, electrosurgery and lasers enable both dissection and hemostasis. Monopolar electrosurgical current can be used provided all vital structures are safely out of the way to avoid injury from electrical and thermal spread. If working on the bowel, bipolar desiccation may be employed, as it causes less spread. It is also more effective for larger vessel hemostasis . Various types of lasers have been employed including argon, potassium-titanyl-phosphate (KTP-532), neodymium:yttrium-aluminum-garnet (Nd:YAG), and carbon dioxide, though none have been shown to be superior to scissors or electrocautery to justify the increased cost.
The harmonic scalpel has the ability to grasp, cut, and cauterize simultaneously utilizing ultrasonic energy, which avoids electrical injury and limits thermal spread. However, there are no studies demonstrating better clinical outcomes or reduced complications compared to other surgical modalities. Both robotic and conventional laparoscopy may be utilized effectively, with robotics affording greater visualization and articulation, and conventional laparoscopy allowing haptic feedback. Comparative studies reported longer operative times and greater cost with robotic surgery for benign gynecologic procedures with no offsetting benefit in terms of long- or short-term clinical outcomes.
2.4 Surgical Results
The effectiveness of lysis of bowel or adnexal adhesions on pain control has yet to be reliably demonstrated. A randomized study of laparotomy with adhesiolysis versus laparotomy alone in patients with chronic pelvic pain revealed an impact only in those having dense adhesions involving the bowel . Another randomized control trial (RCT) evidenced relief of pain with laparoscopic lysis of mild abdominal adhesions, but with no greater improvement than placebo surgical intervention . Regarding infertility, only one small retrospective study evaluated lysis of adnexal adhesions at laparotomy in women with otherwise-unexplained infertility. Cumulative pregnancy rates at 1 and 2 years were higher in those who underwent lysis compared to untreated controls . As such, adhesiolysis in and of it itself is associated with a risk of intraoperative complications, including inadvertent bowel, bladder, ureter, and vascular injury  and prevention strategies are of paramount importance.