Electrocautery (Bowel Injury) with Laparoscopy Case File

Electrocautery (Bowel Injury) with Laparoscopy Case File

Eugene C. Toy, MD, Konrad P. Harms, MD, Keith O. Reeves, MD, Cristo Papasakelariou, MD, FACOG

Case 6

You are performing an operative laparoscopy on a 28-year-old woman with a history of pelvic pain, dyspareunia, and a left adnexal mass. She had a history of PID 2 years ago and had an exploratory laparotomy for endometriosis 10 years ago. You place the initial trocar infraumbilically using an open technique. Upon inserting the laparoscope, you find a loop of bowel adherent to the abdominal wall next to your trocar. Multiple adhesions are also present in the lower abdomen and pelvis.

Additional trocars are placed under direct visualization. The procedure is tedious and challenging, but you are able to expose the pelvic organs. You free the adnexal mass from the rectosigmoid colon using sharp and blunt dissection. Hemostasis was achieved using electrosurgical devices. A left salpingo-oophorectomy was performed to remove a large endometrioma. The patient is discharged the next day. Three days later, she calls your clinic late in the afternoon complaining of lower abdominal discomfort. You see her the next morning in your clinic, and she has diffuse abdominal pain, nausea, and feels feverish. On examination, she appears ill. She has a temperature of 101°F, an HR of 120 beats/minute, and BP of 90/60 mm Hg. Her abdomen has hypoactive bowel sounds and rebound tenderness.

➤ What is the most likely diagnosis?

➤ What are the mechanisms of the condition?

➤ What factors contribute to this patient’s condition?

ANSWERS TO CASE 6:

Electrocautery (Bowel Injury) with Laparoscopy

Summary: A 28-year-old white woman underwent laparoscopy for pelvic pain and a left adnexal mass. The surgery was difficult. Three days later, the patient has lower abdominal pain, nausea, fever, and rebound tenderness.

➤ Most likely diagnosis: Probable peritonitis from an unrecognized bowel injury. I would also consider an unrecognized bladder injury, a severe urinary tract infection, reactivation of PID, and a ruptured appendix.

➤ Mechanism of bowel injuries in laparoscopic surgery: Most bowel injuries occur with Veress needle insertion or initial trocar placement.1 Other causes include electrical burns or traumatic injury during adhesiolysis or bowel manipulation.

➤ What factors contributed to the risk of bowel injury: The main risk factor for bowel injury was adhesions from previous abdominal surgery. PID and endometriosis also contributed to a difficult dissection. The use of electrosurgical devices, especially monopolar instruments, can lead to unrecognized thermal injuries.

ANALYSIS

Considerations

Initial entry into the abdomen with the laparoscope has always been a cause for concern, especially when the patient has had previous abdominal surgery. Many different techniques, such as the “open” technique, and many types of trocars have been advocated to reduce this risk, but none have been completely successful. The problem is that bowel is adherent in close proximity to the trocar and laparoscope, and injury is not completely avoidable. Currently, many authors are advocating for using the left upper quadrant as a “safe” entry point in patients at high risk for intra-abdominal adhesions.2,3 The trocar is placed in the midclavicular line 2 cm below the costal margin. Using the left upper quadrant as an entry point is probably a better choice than the infraumbilical site. Once the trocar is safely inserted inside the abdominal cavity, the adhesions can be evaluated, and any further trocars must be inserted under direct visualization only. The use of electrosurgical instruments is commonplace with laparoscopy, but one must be cognizant of the risks and how to avoid them. Good visualization of the surgical site is critical. Certainly, the surgeon should always be able to clearly see the tips of the scissors when dissecting adhesions. Traction on the adhesions using a grasping device is helpful, but care must be taken when activating an electrode near a metal grasper, or other conductive instrument, and causing an injury due to the direct coupling effect. Such would be the concern with the segment of bowel that was adherent at the insertion site and lying close to the laparoscope. Effective smoke evacuation is necessary for good visualization. Good hemostasis is also important as small amounts of blood may obscure the operating field when viewed through the laparoscope. Once the pelvis is visualized, one must make a decision about the safest way to proceed. Dissecting an endometrioma off the rectosigmoid colon can be extremely difficult in any circumstance. The surgeon must possess the laparoscopic skills necessary to safely complete the dissection. If the surgeon does not possess those skills, a more experienced surgeon should be consulted or the case should be converted to an open laparotomy. Slow, deliberate sharp dissection using good surgical technique is important in preventing iatrogenic injury. When utilizing electrosurgical instruments, always try to keep bowel away from the active electrode and be aware of the proximity of other devices capable of conducting electrical current to the active electrode. This is especially important when dissecting adhesions away from bowel or other structures in tight spaces where additional instruments are needed to help with exposure. Electrical energy should be used judiciously, for the shortest duration, and at the lowest power settings to minimize tissue damage. At the completion of the procedure, the surgeon must carefully inspect the surgical site for any sign of injury. Serosal and partial thickness defects of the bowel wall should be repaired. Any evidence for perforation necessitates an intraoperative surgical consult. If there was a question about a possible perforation, the pelvis can be filled with fluid and air introduced into the rectum.4 Bubbles resulting from this would indicate a perforation. Depending on the size of the defect, bowel resection, with or without a colostomy, may be indicated. The patient should be started on broad-spectrum antibiotics and the pelvis irrigated with copious amounts of irrigation fluid to reduce bacterial contamination.

Objectives

1. Discuss basic concept of an electrical current and how it applies to electrosurgery.
2. Understand the differences between cutting waveforms and coagulating waveforms.
3. Understand the differences between monopolar electrodes and bipolar electrodes.
4. Know the causes of burn injuries with electrosurgical instruments and how to avoid them.

APPROACH TO

Bowel Injuries from Laparoscopy

DEFINITIONS

ELECTROSURGERY: Term used to describe the passage of high-frequency electrical current through tissue to create a desired tissue effect

CAPACITOR COUPLING: The establishment of currents between two conductors that are separated by an insulator

DIRECT COUPLING: Intended or unintended contact between an active electrode and tissue

BIPOLAR: Electrosurgical current that is passed between two electrodes with a small volume of tissue between the two electrodes to complete the electrical circuit

MONOPOLAR: Electrosurgical current that is dispersed through the patient to a return electrode which then returns energy to the generator to complete the electrical circuit

CLINICAL APPROACH

Heat and cautery have been used for hundreds of years to control bleeding. In the early nineteenth century, a French physicist, Becquerel, used direct current electricity to heat a wire which was then used to cauterize tissue.5 In the late 1920s, William Bovie and Harvey Cushing developed the first electrosurgical unit to be used in human surgery.5 Nearly 100 years later, electrosurgery is still an integral part of most surgeons’ practice. In laparoscopic gynecologic procedures, electrosurgery is still a mainstay for cutting tissue and obtaining hemostasis.

A basic understanding of electricity and electrical currents is necessary to understand the principles behind electrosurgery. Electrical current is generated when electrons are forced to move through a circuit. Power is the energy produced by the current.6 Voltage is the force which drives the electrons through the circuit, and heat is generated when the electrons meet resistance within the circuit. Lastly, electricity needs a continuous circuit to flow. The electrosurgical unit provides the voltage for the flow of electrons. Modern electrosurgical generators utilize alternating current at radiofrequency levels.5 When the electrosurgical unit is activated, current flows through the active electrode which is applied to the patient. The patient’s tissue provides the resistance and heat is generated which produces the clinical effects desired by the surgeon. The current then flows either through the patient back to the electrosurgical unit through a return electrode (“grounding pad”) or through another conducting instrument. The different tissue effects depend on the density of the electrical current, the time the current is applied to the tissue, the resistance of the tissue, the electrode size, and the waveform of the current.7 Some common uses of electrosurgical energy in gynecologic laparoscopy include lysing adhesions, controlling bleeding, destroying areas of endometriosis, interrupting tubal patency for female sterilization, and treating ectopic pregnancies.

Two basic waveforms of electrical current are generated by the electrosurgical unit. They are a “cut” waveform and a “coagulation” waveform. The “cut” waveform is a continuous radiofrequency sine wave which creates higher current but lower voltage (Figure 6–1A and B).5 This waveform produces intense local heat and is used to vaporize tissue. It is the vaporization of the tissue which creates the “cutting” effect. Cutting waveforms produce less tissue charring and less tissue damage. The “coagulation” waveform is composed of intermittent radiofrequency sine waves which have higher voltage but lower current than cutting waveforms.5 The waveform consists of small bursts of energy followed by a “cooling-off” period. This cooling-off period allows the coagulation effect to begin. The coagulation waveform can be used to fulgurate or desiccate tissue. A “blended” waveform is a modification of the cutting waveform and allows the surgeon to both cut and coagulate tissue at the same time.8 The ratio of voltage to current is modified by diminishing the current and increasing the voltage so that the power remains constant. This allows for more or less coagulation effects, depending on the settings.

Energy from the electrosurgical unit is delivered to the tissue by either a monopolar electrode or bipolar electrodes. With the monopolar electrode, the electrical current passes from the tip of the electrode to the tissue, then goes through the patient, and is returned to the electrosurgical generator through

Figure 6–1. Cut waveform (A) demonstrates a continuous sine wave, whereas the coagulation waveform (B) shows an intermittent, higher peak voltage, when both are set at equal wattages. Blend currents have different proportion of “cut” and “coagulation” waveforms. (Reproduced, with permission, from Doherty GM. Current Diagnosis & Treatment: Surgery, 13th ed.New York: McGraw-Hill, 2010.)

a return electrode placed on the patient’s body.5 Monopolar devices can be used for cutting tissue, fulgurating tissue, or desiccating tissue. With bipolar electrodes, the current is passed from the active electrode through the tissue to the return electrode to complete the circuit.4 With the bipolar electrodes, the active and return electrodes are within the same instrument being used at the site of the surgery. Tissue damage is limited to the tissue between the electrodes. Bipolar electrodes are used primarily for desiccating tissue and coagulation. It requires lower power settings, but takes longer to be effective and creates more tissue charring. Both devices can utilize cutting or coagulating waveforms of current (Figure 6–2A and B).

Figure 6–2. A demonstrates a unipolar scissors in which the current travels from the electrode through the tissue to the grounding plate. B shows bipolar device in which the current travels from one electrode to the other electrode.

Types of Thermal Injuries

The greatest fear with using electrosurgical instruments in laparoscopic surgery is unintended thermal injury to the patient. Electrosurgical thermal burn injuries occur primarily by misapplication of the active electrode or “stray energy” as the result of capacitor coupling, direct coupling, or insulation

failure. Misapplication of the active electrode usually occurs when the electrode is activated away from the intended target. Poor visualization may lead to misidentification of the targeted tissue. This may be due to bleeding, smoke, or distorted anatomy due to pathologic changes or adhesive disease. Hopefully, these injuries are recognized and addressed when they occur. Injuries from “stray energy” are infrequent, usually occur out of the view of the surgeon, and may not be immediately recognizable. It is important to have some understanding of how these unrecognized transfers of electrical current occur.

Capacitor coupling involves the storage of energy between two conductors separated by an insulator.5 An electromagnetic field is established when an insulated electrode is placed through a metal cannula/trocar and activated. Electrical current is induced into the metal cannula through a process known as capacitance.9 Energy is stored in the capacitator until the generating force of the current is deactivated or a pathway to complete the electrical circuit is established. In most instances, the current stored in the metal cannula/trocar is in direct contact with the patient and dispersed through the patient back to the return electrode. If there is an insulator (ie, a plastic anchoring collar) between the metal cannula and the patient, current cannot pass through to the patient and is stored in the cannula (ie, a capacitator). When the net charge in the capacitor exceeds the insulator’s capacity, current is produced and passed to other conductive material (ie, tissue). Thermal injuries can result.

Capacitative coupling is highest when voltages are high. This happens when the electrode is activated in an “open circuit” away from the targeted tissue. High voltage coagulation current creates the same problem.9 Using all metal or all plastic cannulas/trocars avoids the problem entirely, but hybrid systems are to be avoided. Direct coupling or “probe” coupling occurs when the active electrode comes in contact with another metal instrument, thus directly passing the electrical current to the other instrument.10 This may be intentional when a bleeding point is grasped with a metal grasper; the grasper is then touched by the active electrode to produce a cauterizing effect. Inadvertent injury occurs when the active electrode accidently touches a metal object (ie, probes, graspers, suction devices, etc) which is in contact with other nontargeted tissue.

Insulation failure occurs when there are breaks in the insulation covering the active electrode shaft, allowing current to leave the electrode and find an alternate pathway to complete its circuit back to the return electrode.9 Thus, energy can be transferred from the shaft of the electrode to other conductive, nontargeted tissue that might be in contact with the shaft, resulting in an unrecognized injury. These injuries typically occur on the portion of the instrument that is beyond the field of view of the laparoscope but distal to the protective trocar. A recent study revealed that 20% of reusable instruments had insulation defects, and that 18% of the defects were in the portion of the electrode that is exposed but “out of sight” of the surgeon.11 All electrodes should be examined or tested prior to use for insulation defects, although these defects may be quite small and difficult to appreciate.

Prevention of Thermal Injuries

Prevention of electrosurgical injuries is paramount. Safe laparoscopic surgery requires a common sense approach to the use of electrosurgical devices. All laparoscopic instruments should be in good working order. All OR personnel should be familiar with the electrosurgical generators, how they are to be

operated, and the safety features of each particular unit. They should also know how to assemble all the electrosurgical devices and have the proper connecting cords immediately available. The surgeon should specify the type of energy source he/she would like to use and be familiar with all aspects of its use. Bipolar rather than unipolar electrosurgery should be used when possible. It minimizes damage to the surrounding tissue and avoids the problems of “stray energy.” When monopolar electrodes are going to be used, the surgeon must ensure that the return electrode pad is properly placed on the patient. The surgeon should inspect the electrodes for any breaks in the insulation. The tip of the electrode should always be visible to the surgeon when it is activated, and the electrode should only be activated when the surgeon is sure of its intended target. The electrode should never be activated in an open circuit (ie, in the abdomen away from the intended target)! Care must always be taken when activating the electrode when it is in close proximity to another metal or other conductive instrument. Metal cannulas are the safest operating channels for active electrodes, and any metal/plastic hybrid cannulas should not be used.7

When using either monopolar or bipolar instruments, the lowest possible power settings should be used for the shortest period of time necessary to achieve the desired clinical effect. Cut waveforms should be used whenever possible because they require lower voltage settings.5 The electrodes (or paddles with bipolar devices) should always have any coagulum removed as this increases resistance and causes the electrode to adhere more to the tissue. Finally, when the electrode is not in use, it should be placed in a protective, insulated holster rather than just left lying in the surgical field. This simple step eliminates accidental burns to the patient and reduces the risk of starting a fire in the OR.

Safety Features

The surgeon should also know which safety features are being used with their particular electrosurgical unit. The modern electrosurgical unit is an isolated solid-state generator.5 In this system, the current can only return to the generator through the return electrode pad. This has been a major factor in reducing alternate site burns. Contact quality monitoring systems now being used also prevent the unit from being activated if the return electrode pad is not in proper contact with the patient. This eliminates patient burns at the site of an improperly placed pad.5 An active electrode monitoring system is available which detects and shields the patient from stray energy from insulation failure or capacitor coupling.12 Recently, tissue response technology has come into use. Vessel sealing devices using bipolar energy and tissue response technology can seal arterial vessels up to 7 mm in diameter while reducing thermal spread to surrounding tissue.13 This technology uses computers to sense tissue resistance and then automatically adjusts the output voltage to maintain a constant effect to the targeted tissue. These devices have been associated with less blood loss, shorter operating times, and shorter hospital stays.14

In the end, however, nothing is more important than a well-prepared, knowledgeable surgeon who possesses good manual dexterity, excellent handeye coordination, and sound clinical judgment. Knowledge of electrosurgical principles and proper use of electrosurgical devices should enable the laparoscopic surgeon to operate safely and effectively.

Comprehension Questions

6.1 A 48-year-old woman is undergoing laparoscopy for assessment of a 6-cm left adnexal mass. Which of the following is the most significant risk factor for bowel injury?

A. Prior cesarean

B. Prior PID

C. Endometriosis

D. Prior cervical dysplasia with cryotherapy

6.2 A 44-year-old woman underwent a laparoscopy for chronic pelvic pain. The patient developed bowel symptoms 5 days after the surgery. Which of the following is the most likely mechanism for this complication?

A. Laceration with the Veress needle

B. Laceration with the trocar

C. Thermal injury

D. CO2 embolism

6.3 In considering the possibility of bowel injury, which of the following can decrease the severity of these complications?

A. Bowel preparation

B. Open laparoscopy technique

C. Use of a pneumoperitoneum

D. Use of a bipolar rather than unipolar current

ANSWERS

6.1 C. A prior cesarean typically does not lead to significant adhesions of the bowel to the abdominal wall. Prior PID leads to adnexal adhesions and tubal scarring, but unless there was tubo-ovarian abscess, there is usually no bowel involvement. Endometriosis can lead to widespread adhesions and fibrosis.

6.2 C. The delay in symptoms is likely related to thermal injury, which can be manifest up to a week postoperatively. Lacerations during surgery typically cause symptoms immediately.

6.3 A. A bowel preparation with both cleansing the bowel (mechanical) as well as antibiotics can decrease the bacterial load of the intestinal contents. Thus, if bowel laceration or injury occurs, less contamination occurs. Neither the use of a pneumoperitoneum or Veress needle or open laparoscopy techniques has been shown to decrease the incidence of bowel injuries.

Clinical Pearls

See Table 1-2 for definition of level of evidence and strength of recommendation

➤ Tissue necrosis and subsequent perforation of affected bowel can occur 72-96 hours after surgery (Level B).

➤ The return electrode pad should be placed on a clean, dry area of skin over a large muscle mass (Level C).

➤ Superficial thermal injuries of the bowel should be oversewn with suture being placed in healthy tissue well beyond the area of injury (Level C).

➤ Insulation defects are found in 20% of reusable electrodes (Level B).

➤ An all metal cannula system is the safest choice for the operating cannula containing the active electrode (Level B).

REFERENCES

1. Schäfer M, Lauper M, Krähenbühl L. Trocar and Veress needle injuries during laparoscopy. Surg Endosc. 2001;15:275-280. 

2. Parker J, Reid G, Wong F. Microlaparoscopic left upper quadrant entry in patients at high risk of periumbilical adhesions. Aust N Z J Obstet Gynaecol.199;39:88-92. 

3. Sepilian V, Ku L, Wong H, Liu CJ, Phelps JY. Prevalence of infraumbilical adhesions in women with previous laparoscopy. JSLS. 11;1:41-44. 

4. Shirk J, Johns A, Redwine DB. Complications of laparoscopic surgery: how to avoid them and how to repair them. J Minim Invasive Gynecol. 2006 Jul- Aug;13(4):352-359. 

5. Wang K, Advincula AP. “Current Thoughts” in electrosurgery. Int J Gynaecol Obstet. 2007 Jun;97(3):245-250. 

6. Jones CM, Pierre KB, Nicoud IB, Stain SC, Melvin WV. Electrosurgery. Curr Surg. 2006 Nov-Dec;63(6):458-463. 

7. Wu MP, Ou CS, Chen SL, Yen YET, Rowbotham R. Complications and recommended practices for electrosurgery in laparoscopy. Am J Surg. 2000 Jan;179(1): 67-73. 

8. McCauley G. Understanding electrosurgery. Bovie/Aaron Medical. Copyright 2003. 

9. Nezhet C, Siegler A, Nezhat F, Nezhat C, Seidman D, Luciano A. Electrosurgery. In: Operative Gynecologic Laparoscopy: Principles and Techniques. 2nd ed. New York: McGraw-Hill; 2000:73-80. 

10. Odell RC. Electrosurgery: principles and safety issues. Clin Obstet Gynecol. 1995;38:610-621. 

11. Montero PN, Robinson NR, Weaver JS, Stiegmann GV. Insulation failure in laparoscopic instruments. Surg Endosc. 2009;24:462-465 [Epub 2009 Jul 2]. 

12. Safety technology for laparoscopic monopolar electro surgery; devices for managing burn risks. Health Devices/ECRI. 2005 Aug;34(8):259-272. 

13. Hubner M, Demartines N, Muller S, Dindo D, Calvien P-A, Hahnloser D. Prospective randomized study of monopolar scissors, bipolar vessel sealer and ultrasonic shears in laparoscopic colorectal surgery. Br J Surg. 2008;95:1098-1104. 

14. Campagnacci R, de Sanctis A, Baldarelli M, Lezoche G, Guerrieri M. Electrothermal bipolar vessel sealing device vs. ultrasonic coagulating shears in laparoscopic colectomies: a comparative study. Surg Endosc. 2007 Sep;21(9):1525- 1531 [Epub 2007 Feb 8].

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