Abstract
Laparoscopy has evolved significantly from its first inception and is considered a very safe and effective surgical approach. Obese patients have similar rates of complications to nonobese patients. Given that laparoscopy requires pneumoperitoneum, special consideration should be given to patients with cardiopulmonary disease or who are pregnant. Positioning is critical to successful laparoscopy, and the surgeon must be aware of positioning injuries, including nerve injuries, rhabdomyolysis, and compartment syndrome. The surgeon must understand the underlying principles, appropriate use, and risks of various electrosurgical technologies. Access injuries, while rare, are potentially devastating and may occur with any access method. Robotic and laparoscopic surgery has limited haptic feedback and care must be taken not to injure vasculature or cause visceral injuries during dissection. Complications do occur, and the surgeon must be facile in their identification and take the proper steps to correct the insult.
Keywords
Laparoscopy, Robotic-assisted laparoscopy, Laparoscopic nephrectomy, Robotic-assisted laparoscopic prostatectomy, Pneumoperitoneum, Insufflation, Pregnancy, Patient positioning, Nerve injury, Rhabdomyolysis, Electrosurgery, Electrocautery, Monopolar, Bipolar, Ultrasonic, Harmonic scalpel, Laparoscopic stapler, Self-locking clips, Laparoscopic access, Laparoscopic bowel injuries, Laparoscopic vascular injuries, Port site hernia, Plural injuries
Key Points
- 1.
Laparoscopy is associated with excellent outcomes and low complication rates in properly selected patients.
- 2.
Careful patient positioning and knowledge of specific neuromuscular injuries are critical to prevention, recognition, and management of neuromuscular injuries.
- 3.
The laparoscopic surgeon must be facile with laparoscopic access, quickly recognize and manage associated complications, and be equipped to convert to an open approach when necessary.
- 4.
The laparoscopic surgeon should understand the instruments, tools, and electrosurgical technology used. The laparoscopic surgeon should be aware of hazards of direct injury, insulation failure, and capacitive coupling.
- 5.
Always consider the potential for injury to the superior mesenteric artery during left-sided nephrectomy, and the inferior vena cava during dissection of the right gonadal vein, particularly when the anatomy is distorted by tumor, lymph nodes, or prior surgery.
- 6.
Bowel injuries require prompt diagnosis and management.
Introduction
Since the performance of the first laparoscopic nephrectomy in 1991, the expansion of surgical technology has enabled application of laparoscopic techniques to nearly every operation in urology. In fact, laparoscopic approaches have become the standard of care for many of these operations with advocates citing decreased patient pain, shorter hospitalizations, lower intraoperative blood loss, and, in some cases, decreased technical difficulty. When laparoscopy was initially introduced complications were often attributed to novel technical difficulties and surgeon inexperience. However, large contemporary series of urologic laparoscopic surgery report overall intraoperative and postoperative complication rates of 4.7% and of 17.5%, respectively, which are similar to historical series, thus suggesting that not all complications can be circumvented via technologic advancement and experience.
Although laparoscopic techniques are often analogous to open surgery, there are many salient differences in patient selection, instruments, and technique as well as complications unique to laparoscopy. It is incumbent upon the urologic laparoscopist to be aware of these factors in order to prevent complications when possible and to promptly recognize and expertly manage them when they do arise. In this chapter we aim to outline many of the special considerations and unique complications of urologic laparoscopy with a focus on diagnosis and management.
Patient Selection and Anesthetic Considerations
Appropriate selection of patients for surgery is critical to ensure a good outcome and is especially important when determining optimal surgical approach. Historically there were considered to be several absolute contraindications to laparoscopic surgery; however, laparoscopy may now be safely undertaken in almost any patient. Despite the expanding role of laparoscopy and its relative safety, certain patient factors, including uncontrolled bleeding diathesis, active bowel perforation or obstruction, extensive past surgical history, or a history of diffuse peritonitis, are associated with greater risk of complication and should give the surgeon great pause before pursuing a laparoscopic approach.
Obesity is becoming increasingly more common in the Western world. While obesity was historically considered an absolute contraindication to laparoscopic surgery, contemporary series suggest that while obese patients may be at higher risk of overall complications this risk is not increased by use of a laparoscopic surgical approach. Proper positioning of the obese patient can be challenging, but is also critical for prevention of deep vein thrombosis, neuropraxia, and rhabdomyolysis for which obese patients are at higher risk irrespective of surgical approach. Often special operative tables and equipment are necessary, and the surgeon must be aware of weight limitations of commonly used equipment. When placed in the steep reverse Trendelenburg position, obese patients have increased pressure on the diaphragm resulting in decreased respiratory compliance and subsequent difficulty with mechanical ventilation. If the anesthesia team is having difficulty ventilating a patient, it is often necessary to decrease the pneumoperitoneum pressure, although this may increase the technical difficulty of the operation. In contrast to the Trendelenburg position, obese patients tolerate the flank position well, both from a hemodynamic and a respiratory standpoint. Please see Chapter 9 for more information.
Patients with cardiopulmonary disease are at unique risk during laparoscopy using carbon dioxide insufflation. Carbon dioxide is highly soluble and readily diffuses into extra-pulmonary tissues and fluids, which may lead to hypercarbia even many hours postoperatively. Patients with chronic obstructive pulmonary disease (COPD) may be unable to increase their ventilation to respond to hypercarbia and should be closely monitored with serial ABGs postoperatively. COPD is not an absolute contraindication to laparoscopy, but in the setting of severe COPD and/or anticipated long operative time an open surgical approach should be considered. Helium is a physiologically inert and noncombustible gas that does not contribute to hypercarbia and can be used as an alternative insufflant. Although helium is significantly more expensive than carbon dioxide, it can be used to salvage a case complicated by severe hypercarbia that may otherwise be aborted or converted to an open approach.
While surgical indications should be carefully considered in pregnant patients, pregnancy itself is not an absolute contraindication to laparoscopy. Performing laparoscopy on pregnant patients presents several unique considerations with regard to obtaining initial access, port placement, and prolonged pneumoperitoneum. Initial access should be away from the gravid uterus and is generally obtained at Palmer’s point located in the left upper quadrant in the subcostal midclavicular line. Port placement is generally more cephalad and should be performed under direct vision in order to minimize the risk of uterine injury. Pneumoperitoneum pressure should be set at 10 mm Hg and should not be increased above 15 mm Hg as venous return is already compromised by a gravid uterus. Prolonged pneumoperitoneum should be avoided as hypercarbia could have harmful effects on the fetus.
Positioning
Careful attention to appropriate patient positioning is critical to minimize the risks of nerve injury and rhabdomyolysis during and following laparoscopic surgery. In a review of 4000 insurance claims, complications related to nerve injuries accounted for 16% of claims associated with laparoscopic surgery. Of these, ulnar nerve injuries were most frequent (28%) followed by brachial plexus injuries (20%). Mechanisms of nerve injury related to positioning include stretching, compression, and ischemia. Ulnar nerve injuries are often related to external compression of the nerve as it courses behind the medial epicondyle in the antecubital tunnel where it is not shielded by muscle or bone. Injury to the ulnar nerve results in hypoesthesia of the medial half of the fourth finger and the entire fifth finger. Weakness can lead to difficulty with thumb adduction. Claw hand may be seen due to hyperextension of the fourth and fifth digits at the metacarpophalangeal joints, and flexion at the interphalangeal joints. Careful attention to avoid compression injury through adequate padding of the elbow is necessary, especially with the use of gutter armrests. The brachial plexus is at highest risk of stretch injury when the arm is abducted and extended, especially in deep Trendelenburg and with use of shoulder braces. Signs of brachial plexus injuries vary widely but most commonly include sensory deficit to the shoulder area and impairment of upper arm abduction.
A large majority of lower-extremity positioning complications are related to compression of the peroneal (fibular) nerve as it passes laterally to the head of the fibula. Peroneal injuries manifest as paresthesia over the lateral foot and inability to dorsiflex the foot (foot drop). Sciatic nerve injuries are less common and are caused by excessive hip flexion in lithotomy. This injury is exacerbated when the knees are minimally flexed as this increases stretch on the sciatic nerve. Sciatic nerve injuries present as paresthesia over the posterior legs and feet and weakness in foot extension and flexion. To avoid these lower-extremity injuries patients in lithotomy must be carefully positioned to ensure the weight of the leg is supported in the heel, external rotation and hip flexion are not excessive, and the lateral aspect of the leg is appropriately padded ( Table 30.1 ).
| Nerve | Location | Mechanism of Injury | Deficit |
|---|---|---|---|
| Ulnar nerve | Unprotected near medial elbow | External pressure on medial elbow, especially with arm gutters | Paresthesia of 4th and 5th finger, claw hand |
| Brachial plexus | Axilla | Hyperextension or abduction of arm, deep Trendelenburg, use of shoulder braces | Variable, paresthesias and weakness of upper extremity |
| Sciatic nerve | Well protected in thigh | Excessive hip flexion especially with extended knees | Paresthesia and weakness posterior leg, foot |
| Peroneal nerve | Lateral leg | External compression as it passes head of fibula, external hip rotation | Paresthesia over lateral foot and foot drop |
Rhabdomyolysis following laparoscopic surgery is a severe and potentially life-threatening complication with a reported incidence ranging from 4.9% following laparoscopic renal surgery to 0.13% in a series of over half a million patients following urologic surgery. In the surgical setting, rhabdomyolysis most commonly occurs secondary to prolonged direct pressure on soft tissues resulting in structural changes and necrosis of skeletal muscle. Once the pressure is released, ischemia-reperfusion injury can occur and the intracellular components of lysed cells are released into the systemic circulation. This leads to myoglobinuria, which has a direct toxic effect on renal tubules and can cause devastating acute renal failure, particularly when occurring in the context of extirpative renal surgery. The clinical signs of rhabdomyolysis are myglobinuria, muscle weakness, pain, and acute renal failure. The creatinine kinase (CK) is elevated and is usually between 1000 and 100,000 IU/L.
Gelpi-Hammerschmidt et al. attempted to quantify the risk of postoperative rhabdomyolysis, reporting a 1.8% incidence in patients with any three of the following five risk factors: operative time greater than 5 hours, robotic surgery, obesity, male gender, and Charlson comorbidity index greater than 2. Other identified risk factors include preexisting renal disease, high intraoperative blood loss, and positioning factors such as poor padding of bony prominences, operative table flexion, and use of the kidney rest. A recent review also suggests that robotic surgery presents a greater risk for rhabdomyolysis compared to laparoscopic or open renal surgery likely due to comparatively longer operative times. Rhabdomyolysis is often a devastating complication causing major collateral morbidity as well as increased resource utilization. As such, once a clinical suspicion of rhabdomyolysis is established, aggressive treatment focused on vigorous hydration, urinary alkalization, and renal replacement therapy should not be delayed. While a less common complication of rhabdomyolysis, compartment syndrome is life threatening and requires decompressive fasciotomy for definitive management. In cases involving lithotomy for greater than 5 hours, sequential compression devices may increase the risk of compartment syndrome and should be used with caution ( Box 30.1 ).
- ■
Robotic surgery (independent risk factor)
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Operative time greater than 5 hours
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Obesity
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Diabetes mellitus
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Male gender
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Poor padding
- ■
Prolonged use of the kidney rest
Access Injuries
Obtaining initial peritoneal access is often the most dangerous step in laparoscopy, and multiple initial entry techniques have been described, each with the goal of minimizing morbidity ( Fig. 30.1 ). These techniques can be broadly classified into “open” methods in which trocars are placed into the peritoneal cavity under direct vision, and “closed” methods in which instruments are passed blindly through the abdominal wall prior to insufflation. Of these, the most commonly used are the “open” Hasson and the “closed” Veress methods. However, other techniques including direct trocar entry, radially expanding trocars, primary insufflation through a hand assist port, and optical trocars may be used. No method of primary laparoscopic entry is absolutely safe, and experts disagree on which method provides the safest, most expedient, and most reliable means of obtaining laparoscopic access. This controversy is compounded by a lack of high-quality clinical data.
The surgeon should be comfortable with multiple methods of laparoscopic access. Because the Veress needle is inserted blindly, it should be used carefully ( Box 30.2 ). The needle should be checked to make sure the spring-loaded blunt center is functioning. Once placed, multiple maneuvers may be employed to confirm intraperitoneal position of the Veress needle. First, the needle should be aspirated to make sure there is no blood or succus indicative of vascular or visceral injury. Second, as a saline-filled syrine is disconnected from the Veress needle hub, the saline remaining in the needle hub should quickly drop into the abdomen in the so-called “drop test.” If the fluid does not freely flow into the abdomen this may indicate that the needle is either not intraperitoneal or is abutting a structure that is limiting flow. During initial insufflation intraperitoneal pressures should not exceed 6 mm Hg, and higher pressures and/or a rapid rise in measured pressure may indicate extraperitoneal position. The abdomen may also be percussed during insufflation; asymmetric tympani could represent pre-peritoneal or colonic insufflation. If any of these steps raises concern for a visceral injury, the Veress needle should be left in place and alternate access should be obtained. Once access is obtained, the original Veress site should be inspected for any signs of injury. Veress needle injuries to bowel and bladder can usually be managed conservatively while trocar injuries invariably require operative repair.
- ■
Check the needle and ensure spring-loaded blunt tip is working
- ■
Incise the skin prior to Veress placement
- ■
Once placed, aspirate to observe for blood or succus
- ■
Perform the saline drop test prior to insufflation
- ■
Observe the insufflation pressures and stop and replace Veress if initial pressure reaches 6 mm Hg
- ■
Percuss insufflating abdomen for asymmetric tympani
- ■
If concerned about Veress placement, leave Veress in place, obtain another access, and observe Veress location with laparoscope
An optical port may be utilized to place the initial trocar using a 0-degree laparoscope under direct vision either with or without initial insufflation. The layers of the abdominal wall (subcutaneous fat, anterior fascia, rectus, posterior rectus sheath, transversalis, and peritoneum) should be visualized during advancement to confirm intraperitoneal position. The tip of the optical trocar is usually radially dilating so rotation is important to traverse the layers of the abdominal wall. If this technique is employed prior to insufflation the initial access site should be located off midline so the layers of the abdominal wall can be visualized. The remaining ports should be placed under direct vision, and any adhesions seen near the desired port location should be taken down prior to trocar insertion.
Open access is considered very safe as the surgeon retains direct visualization; however, it can be more technically challenging and complicated by pneumoperitoneum leakage ( Box 30.3 ). The technique is similar to a mini-laparotomy where a small incision is made near the umbilicus and taken down to fascia. The fascia is incised, the peritoneal cavity opened, and the trocar placed using a blunt obturator. Once in an intraperitoneal position fascial sutures are placed to secure the Hasson trocar and the balloon is inflated to create a seal between the trocar and the peritoneal edges enabling establishment of pneumoperitoneum.
Factors Facilitating Safe Placement of Trocars During Laparoscopic Surgery
- ■
Low table height
- ■
Noting of anatomic landmarks and abdominal scars
- ■
Adequate skin incision size for trocar
- ■
Application of appropriate axial force during trocar insertion
- ■
Use of the Trendelenburg position (for umbilical access)
- ■
Elevation or stabilization of abdominal wall
- ■
Transillumination of abdominal wall vessels
- ■
Avoidance of lateral deviation of needle or trocar
- ■
Avoidance of angling of needle or trocar toward the midline
The Cochrane Collaboration released in 2015 a systematic review of all available prospective randomized controlled trials (RCTs) comparing laparoscopic entry techniques. In a review of three RCTs including 795 patients comparing open versus closed primary entry techniques, no differences were found with respect to incidence of visceral or vascular injury. In the same series, the risk of failed entry, extraperitoneal insufflation, and omental injury were all less likely with use of open entry techniques, although the authors note that all reviewed studies were of low or very low quality. Visualized trocar entry without insufflation (“direct trocar entry”) is becoming increasingly popular as initial studies support its superior safety and speed. The Cochrane report included systematic review of five RCTs that reported lower risk of vascular injury with direct trocar entry, but no difference with respect to visceral injury. See table 30.3 for a summary of randomized controlled trials comparing methods of initial laparoscopic access.
Another area of controversy is the necessity of laparoscopic trocar site closure in order to prevent hernia formation. The absolute incidence of trocar site hernia is unknown, but is estimated to be between 0.65% and 2.80% by large general surgery series and is likely underreported. Although uncommon, such hernias may result in small bowel obstruction or incarceration and as such represent a serious source of morbidity and mortality in laparoscopic surgery. Initial studies of bladed trocars supported the necessity of trocar site fascial closure as hernia rates at 12-mm trocar sites fell from 8.0% to 0.22% with formal closure. Since the development of bladeless and radially dilating trocars that permit atraumatic separation of the abdominal wall, the necessity of fascial closure is less clear. A randomized prospective trial comparing bladed to bladeless trocars concluded that routine closure in the absence of risk factors was not necessary. Another study of 747 patients undergoing laparoscopic Roux-en-Y bypass with the use of radially dilating trocars reported no hernias at extraumbilical sites that were not closed; however, there was a 1.2% rate of hernia at the umbilical site of Hasson entry despite formal fascial closure. The authors similarly concluded that routine closure of extraumbilical trocar sites was unnecessary.
It is imperative to maintain a high index of suspicion for trocar site hernias as clinical signs and physical exam findings can be deceiving. This was demonstrated in a recent retrospective review of 1055 patients undergoing either RALP or laparoscopic renal surgery at a single center. The authors describe seven hernias (0.66%), all of which occurred at 12-mm trocar sites where fascia was not closed. Six of the seven patients with hernia presented with signs and symptoms of bowel obstruction, and all required operative intervention. Although diagnosis of hernia was made on cross-sectional imaging, four of the seven patients were noted to have intra-fascial hernias (occurring between the transversalis and internal oblique fascia) at the time of surgery and were without overt evidence of hernia on physical exam.
Currently it is our practice to close all 12-mm port sites and remove all trocars under direct vision to minimize the risk of hernia.
Minor Vascular Injuries
Vascular injury is the most common intraoperative complication of urologic laparoscopy, ranging from 2.6% to 19.8% in large series. The majority of these injuries occur while obtaining laparoscopic access or during dissection. Types of vascular injury include injury to the abdominal wall vasculature, great vessel injury, or mesenteric artery injury.
The inferior epigastric vessels are the most common site of minor vascular injury, occurring in 2.5% of laparoscopic hernia repairs. Although injury to the vasculature of the abdominal wall is less likely to be life threatening, it may confer considerable morbidity requiring conversion to an open approach, transfusion, and the need for additional procedures or operations. The anatomic location of the inferior epigastric vessels at the lateral aspect of the rectus sheath place them at risk for injury that invariably occurs during placement of secondary cannulas. Significant injury is most common in the lower abdomen, as the epigastric vessels exist as a plexus in the upper abdomen rather than a discrete vessel vulnerable to laceration.
Injury to the abdominal wall vasculature is most commonly identified at the time of initial port placement, but can also be recognized when ports are removed, or present in a delayed fashion as abdominal wall or rectus sheath hematomas. Techniques to avoid abdominal wall vascular injury include use of the smallest appropriate cannula, transillumination of the body wall to identify and avoid large vessels, an adequate skin incision to avoid use of excessive force, not angling trocars toward the midline, and placement of cannulas under direct laparoscopic vision. Particularly in obese patients use of a “finder” needle with local anesthetic can be useful in planning port placement and avoiding minor vascular injury. This additionally allows infiltration of local anesthetic, which can aid postoperative pain control.
Once an injury to the inferior epigastric vasculature is identified, there are multiple techniques available to obtain hemostasis. Initially, direct pressure can be applied by angling the laparoscopic cannula to tamponade the bleeding vessel. The vessels can be suture ligated either by extending the port site skin incision to gain adequate exposure for direct suturing or by use of a laparoscopic-assisted, transabdominal suture technique with either a Carter-Thommason device or Keith needle. In either case, placement of either interrupted or horizontal mattress sutures or a wide-based figure-of-eight suture is usually necessary to control hemorrhage. As a last ditch maneuver, a Foley catheter can be placed through the abdominal wall fascia, the balloon inflated intraabdominally, and pulled snug against the abdominal wall to provide tamponade for 24–48 hours or until hemostasis is achieved.
Abdominal wall vascular injury can also result in rectus sheath hematoma, which most commonly presents in a delayed fashion with palpable abdominal mass and severe abdominal pain. While all patients are at risk for developing a rectus sheath hematoma, those on anticoagulation are at higher risk. Computed tomography is the imaging study of choice in diagnosis of rectus sheath hematoma. The majority of rectus sheath hematomas are self-limiting, resolving with careful observation and reversal of anticoagulation if applicable; however, hemorrhagic shock occurs in 37.5% of cases with mortality as high as 25% in anticoagulated patients. In severe cases selective angioembolization is preferred to surgical exploration, as the latter will release any tamponade, is less likely to be definitive as localization of the injury may be challenging or impossible, and carries considerable morbidity.
Major Vascular Injuries
Major vascular injuries are rare during laparoscopy, but are the most common cause of intraoperative death at up to 15%, second only to anesthetic complications. While the specific incidence of these injuries is lacking in the urologic literature, it ranges from 0.03% to 0.30% in large series in the general and gynecologic surgical literature. Most vascular injuries occur during initial establishment of pneumoperitoneum with a Veress needle (39.8%), but can also occur with placement of the primary trocar (37.9%) or with secondary trocars (22%). Of interest, a large French series found that while the rate of overall complications decreased with increasing surgeon experience, the rate of vascular injury remained static at 0.02% independent of surgeon experience.
The anatomy of the retroperitoneal vasculature places the distal aorta and common iliac vessels at highest risk of injury during periumbilical laparoscopic access (see Fig. 30.1 ), as these vessels can be as close as 2 cm from the anterior abdominal wall in thin patients. Arterial injuries are most common, and when venous injuries do occur they are usually in conjunction with arterial injury. A review of vascular injury during gynecologic laparoscopy reported that distal aortic injury was most common (25%), followed closely by injury to the right common iliac artery (21%), with the remainder of arterial injuries being distributed between the bilateral external and internal iliac arteries (29%). Injury to the inferior vena cava (IVC) occurred in 11% of patients. The IVC is at particular risk during dissection of the gonadal vein during right-sided nephrectomy. As such, it is critical to release the gonadal vein away from the ureter and allow it to return medially in order to avoid avulsing the gonadal vein from the IVC.
Major vascular injuries occurring during the access phase of laparoscopy are most commonly signified by identification of a large retroperitoneal hematoma. Depending on the location and nature of the injury, blood within the peritoneal cavity may be scant or absent. Additional signs of injury include hypotension and hemorrhagic shock, as well as decreased end-tidal carbon dioxide as a result of carbon dioxide embolism. Lastly, if there is significant intraperitoneal bleeding, absorption of visible light by hemoglobin may result in poor laparoscopic visibility serving as another clue as to possible vascular injury.
While the principles of managing significant intraoperative hemorrhage during laparoscopy are the same as during open surgery, the specific techniques differ. If the site of vascular injury is immediately apparent, laparoscopic grasping and dissecting instruments can be used to apply direct pressure and obtain initial control. Care should be taken not to injure adjacent structures or worsen the vascular injury through careless maneuvers or inappropriate use of instruments. Once temporary control is obtained, the anesthesia team can be notified to allow for appropriate resuscitation and to ensure availability of blood products. The insufflation pressure can be increased to 20 mm Hg in order to help tamponade bleeding; however, this maneuver carries the risk of causing venous gas embolism should there be a significant venous injury. If bleeding is sufficiently controlled and visibility maintained, it is reasonable to continue laparoscopic dissection to further expose the site of injury. Once definitively identified, the source of bleeding can be controlled with electrocautery, surgical clips or staplers, suture ligation, or hemostatic agents. Additional ports, including hand-assist ports, may be placed in order to improve exposure and facilitate passage of instruments.
If bleeding cannot be controlled using laparoscopic methods, or if an injury is identified that will require formal vascular repair, conversion to an open surgical approach may be necessary. It is important that this decision be made quickly because even experienced surgical teams can take a considerable amount of time to convert and significant blood loss can occur in the interim. Open surgical instruments should be at hand during all laparoscopic cases, and it is prudent to plan the open incision site at the beginning of difficult cases where conversion is more likely. If laparoscopic or robotic instruments are being used to provide direct pressure, these instruments should remain in place and pneumoperitoneum maintained during conversion to aid hemostasis and tamponade. The open incision should be planned in order to gain optimal exposure for vascular repair; however, extension of an existing port site is preferable as laparoscopic instruments, or the laparoscope itself, can be used to expose and facilitate division of the abdominal wall.
Superior Mesenteric Artery Injury
A special consideration during laparoscopic renal surgery is the possibility of injury to visceral vasculature, particularly the superior mesenteric (SMA) and celiac axis (CA). Anatomic studies by Brunet et al. demonstrated that the average proximity of the ostia of the left renal and superior mesenteric arteries, and the ostia of the CA and SMA, are 11.3 mm and 3.8 mm, respectively. This close anatomic proximity places these vascular structures at high risk of injury during laparoscopic renal surgery, especially in the setting of large renal or adrenal masses, adenopathy, adherence of the kidney to surrounding tissues, and accessory renal vessels that may distort normal anatomy. Anomalies of the renal vasculature are frequent, with Kaneko et al. noting 21.1% of renal arteries with multiple origins, while aberrations of the aorta and mesenteric vasculature are extremely rare. Therefore it is imperative to review preoperative imaging to identify all renal arterial branches and to exercise extreme caution prior to vascular ligation when operative findings do not correlate with preoperative imaging. In difficult laparoscopic dissections, the gonadal vein can be used as a guide to definitively identify the hilar vessels. While difficult hilar dissection and failure to progress are commonly cited reasons to convert from a laparoscopic to open surgical approach, only 7% of reported SMA injuries during left nephrectomy occurred during laparoscopy, suggesting that open surgical exposure does not completely protect from these injuries.
Injury to the SMA may be detected intraoperatively by identification of hemorrhage, signs of hemorrhagic shock, worsening metabolic acidosis due to bowel ischemia, and oliguria due to shock and massive fluid shifts to the bowel. Notable clinical signs of bowel ischemia such as serosal color change, loss of palpable arterial pulses, and lack of intestinal peristalsis may occur late or not at all depending on the level at which the SMA was ligated. Postoperatively significant mesenteric arterial injury classically presents with severe epigastric abdominal pain as well as the above listed signs; however, pain may be masked in the postoperative setting. As unrecognized SMA injuries generally result in acute intestinal ischemia and death in most patients, a high index of suspicion for vascular injury is critical especially for left-sided renal surgery, and prompt vascular surgical consultation should be obtained if there is any question of mesenteric vascular injury.
Electrosurgery
Urology has always been on the leading edge of medical technology. Understanding how surgical technology works is critical to operating safely and addressing issues when they arise. Electrosurgery is the single most used piece of surgical technology, but is often poorly understood and is also one of the most common causes of litigation. While often used incorrectly, the term “electrocautery” actually refers to a direct current heating a probe that in turn burns tissue (e.g., portable ocular cautery stick) and is used very rarely in modern surgical technique. Electrosurgery or diathermy refers to the application of a current to the tissue itself and is most commonly used in the operating room.
Monopolar is the most commonly utilized electrosurgical modality. This technology passes an alternating current through a circuit coursing from the generator, to the electrode (pencil or instrument), through the patient, and then back to the generator via the return electrode (“grounding pad”). Central to the utility of monopolar electrosurgery is the concept of current density. The monopolar current density is highest at the point of contact between the electrode and the patient’s tissue and rapidly decreases further from the electrode. As the rate of tissue heating is proportional to the square of the current density, only this tissue near the tip of the electrode is heated. Therefore the smaller the surface contact of the electrode to the tissue, the greater the current density and the more quickly that tissue is heated and desiccated. Conversely, the larger the surface contact between the electrode tip and the tissue, the more slowly the tissue is heated and dissected.
Monopolar electrosurgical injuries result from the unintentional application of current to tissue due to unintentional direct contact, direct coupling, poor return electrode application, insulation failure, or capacitive coupling. Unintentional direct contact is self-explanatory and usually occurs when the electrode is activated when the instrument is not in view. Direct coupling occurs when the electrode is in contact with a metal instrument that is in turn contacting tissue. An example of intentional direct coupling is the application of monopolar current to a pair of forceps grasping a bleeding vessel. In this case, the area of tissue contact is small, the current density is high, and the energy applied to the tissue is also high resulting in coagulation of the vessel. Conversely, if the forceps accidentally contacts a surface outside the immediate operative field such as the abdominal wall in addition to the vessel, the current density is low and the energy imparted to intended tissue will also be low (noted as “grounding out”). Lastly, direct coupling can cause injury if the return electrode is malpositioned such that it contacts a small surface area, thereby creating an area of high current density that may inadvertently injure tissue. Unintentional direct coupling can also occur during laparoscopy through similar mechanisms, such as by inadvertent coupling of current to the laparoscope lens that is also touching bowel. In this case the current will be coupled to the metal sheath of the scope and applied directly to the bowel, potentially resulting in serious injury. Laparoscopic and robotic instruments typically have insulation protecting the nonvisible portion of the instrument; however, it is important to remain vigilant as insulation failure can occur as a result of forceful manipulation or manufacturing defects and result in potentially devastating injury.
Capacitive coupling occurs when a conductor (metal device or tissue) is in parallel with an active electrode but is not in direct contact. This results in the electrode inducing current within the other conductor, the magnitude of which depends on the proximity and level of insulation between the electrode and the conductor. Again, the degree of tissue damage is dependent on the current density applied. An illustration of this concept can be seen with the use of metal robotic trocars. A monopolar current traveling through a robotic arm within a metal trocar will induce a current in the metal trocar. This is normally harmless as the large contact area between the metal trocar and the abdominal wall minimizes current density. The greatest risk of injury occurs when a metal trocar is placed through a plastic outer trocar. In this scenario, the metal trocar is insulated as it passes through the abdominal wall and any area of contact, such as with bowel, will have a very high current density resulting in likely injury. To avoid such injuries it is imperative to ensure that all metal trocars are well “grounded,” meaning they have a large area of contact with the skin and are not passed through insulating trocars ( Figs. 30.2, 30.3, 30.4 ).
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