Avoiding vascular injury at laparoscopy
An expert traces distances between trocar entry and vascular landmarks, describes the safest insertion techniques, and outlines decisive action in case of injuries.
- Distances between the entry trocar and the aorta bifurcation increase directly with body mass index, mainly because of the commensurate increase in abdominal wall thickness.
- The mean thrusting force for insertion of a disposable trocar is 10.2 lb versus 17.53 lb for a reusable device, and the time to penetrate is shorter for the disposable trocar: mean of 3.54 seconds versus 11.64 seconds. Thus, greater caution is warranted when inserting a disposable trocar.
- Thrust the primary trocar into the midline of the abdomen at a 45° to 60° angle relative to the plane of the abdominal wall, with the trocar pointing toward the uterus, to avoid injuring the iliac vessels.
- When injury occurs, call for a vascular surgeon immediately, perform a laparotomy using a vertical incision, and get accurate inputs, outputs, and blood-loss estimates.
Major vessel injury is a two-sided coin: It can occur with alarming speed, but it is preventable.
Fortunately, the laparoscopic surgeon can avoid the problem by following simple precautions and steering clear of scenarios that increase the risk of injury. This article tells how to accomplish both objectives.
In the process, it reviews the evidence, details management for any injuries that occur, and includes a comprehensive table listing typical distances between the entry trocar and vascular structures, to help the surgeon adjust entry strategy.
Adequate prevention depends on:
- familiarity with the vascular anatomy, particularly in relation to the umbilicus, presacral space, infundibulopelvic ligament, and ovarian fossa.
- creating a proper pneumoperitoneum, especially when using disposable trocars.
- careful attention to primary trocar thrusting techniques to ensure midline insertion at the proper angle. Also exercise caution when placing secondary trocars. Specifically, during far lateral insertion, avoid cleaving the inferior epigastric artery from the external iliac or directly hitting the external artery or vein.
- avoiding long trocars, which are unnecessary to penetrate the peritoneal cavity.
- reliance on laparotomy if trocar insertion proves too difficult, vision is obscured, or appropriate anatomic dissection planes cannot be developed.
- when injury occurs, performing laparotomy using a vertical incision.
Insufflating the wrong space: A recipe for disaster
A 36-year-old woman with a body mass index of 38.2, indicating severe obesity, is scheduled to undergo hysteroscopy and dilatation and curettage for irregular bleeding, as well as laparoscopic bilateral partial salpingectomy for elective sterilization. The setting is an outpatient surgery center without a blood bank.
After general anesthesia, the surgeon makes a 1.5-cm incision just below the umbilicus, inserts a Verres needle, and insufflates carbon dioxide gas to a volume of approximately 3.4 L. He then inserts a disposable trocar and places a laparoscope, but views fat. Unbeknownst to him, he has insufflated the properitoneal fat space rather than the peritoneum.
The surgeon finally enters the peritoneum with a “long” trocar after several more attempts. Since the uterus and adnexa appear to be normal, he inserts a second trocar and places a probe. As he is moving the intestines, however, he observes blood, and the field suddenly becomes unclear. He removes the probe and, when the gas-pressure valve of the secondary trocar is opened, blood spews from the site.
The surgeon removes all trocars and performs an emergency laparotomy using a Pfannenstiel incision. He and 2 general surgeons, who arrive within 20 to 30 minutes, work for 2 hours to repair what they believe is a hole in the inferior vena cava. The woman is brought out of anesthesia and transferred to the local community hospital, where she goes into cardiac arrest and dies. A postmortem reveals injury to the right common iliac artery and vein. No sutures were observed in either vessel. Cause of death: exsanguination.
What went wrong?
Three serious errors contributed to the patient’s death:
- He made multiple attempts to insert the trocar without considering the possibility that the wrong space had been insufflated.
- He inserted the trocar off the midline and at the wrong angle relative to the abdominal wall.
- In his frustration, he switched to a “long” trocar, which made it more likely that vascular structures would be injured.
Operating on an obese patient in a center without a blood bank also was unwise, as obese women of short stature are at greatest risk for vascular injury.
How big is the problem?
A French study1 of 103,852 laparoscopic procedures—of which 15.7%, or 16,000 operations, were gynecologic—reported 47 cases of major vascular injury for an incidence of 0.5 per 1,000 cases and a mortality rate of 17%. Several additional articles2-8 reported a range of vascular complications of between 0.1 and 6.4 per 1,000 laparoscopies.
In a study9 conducted in 7 gynecologic laparoscopy surgery centers in France over 9 years and involving 29,966 diagnostic and operative cases, the overall complication rate was 4.64 per 1,000 laparoscopies (n = 139). Of the 21 major vascular injuries associated with gynecologic surgery, the majority occurred during set-up, and 84.6% during insertion of the primary trocar. Two patients died from their injuries.
Bhoyrul and colleagues10 analyzed data reported to the US Food and Drug Administration and found that 408 of 629 trocar-related injuries involved major blood vessels, as did 26 of 32 deaths (81%). Most of the deaths (87%) were linked to the use of disposable trocars equipped with safety shields; 9% with direct-view trocars. Although surgeons asserted that the trocar malfunctioned in 41 cases, that claim was confirmed in only 1 case (2%).
Another study found that 37 of 79 (46.8%) serious complications involving optical-access trocars between 1994 and 2002 involved major vessels, injuring the aorta, iliac vessels, or vena cava.11
A study12 carried out in the Netherlands in 1994 evaluated the relative number of complications that occurred within a total of 25,764 laparoscopic procedures. The study divided complications into those occurring as the result of the laparoscopic approach (eg, trocar insertion) versus those happening during the performance of the operation. Fifty-seven percent of the 145 complications were caused by the laparoscopic approach; the 2 reported deaths also were secondary to that approach.
Snapshot of vascular injury: A series of 31 patients
In 2003, I published data13 on 31 cases of major vessel injury associated with gynecologic laparoscopy (see). These cases were collected from a variety of sources: medicolegal case files, hospital morbidity-mortality presentations, and quality-assurance departments. Eight cases involved diagnostic procedures, while 23 involved operative laparoscopy.
The medical records of these cases provided details on the nature of the injury. The cases were categorized by body mass index (BMI) and cause, ie, whether they occurred as the result of the laparoscopic approach (ie, entry-related) or arose during surgery.
Of the 31 cases, 22 (71%) involved women with BMIs from 25 to more than 30 (overweight or obese). A large majority—28 cases (90%)—were related to entry. Only 3 injuries occurred during surgery.
In several women, more than 1 vessel was damaged. Of the 49 total injuries, 38 (78%) involved the iliac vessels. Seven (23%) women died as a result of their injuries, all of which involved venous trauma.
Damage to structures in the vicinity of the injured vessels was substantial in 16 cases. Major morbidity included ureteral, nerve, and intestinal injury; arterial and venous thrombosis; compartment syndrome; and suturing of the wrong vessel.
Some patients also experienced edema or pain in an extremity (vascular insufficiency); infection; diffuse intravascular coagulation and/or adult respiratory distress; cardiac arrest; central nervous system injury (stroke); or hospitalization of more than 1 week. Cases also were categorized as early or late diagnosis, depending on whether shock had supervened. Diagnosis was early in 8 cases (26%) and late in 21 (68%). Two patients were diagnosed postoperatively; ie, they had gone to the recovery room prior to developing shock.
The volume of blood loss ranged from 1,000 mL to 7,000 mL, with a mean loss of 3,400 mL. All patients received packed red blood cells and/or a mixture of other blood products. The time required for cross-matching and receiving blood ranged from 10 to 120 minutes.
In all cases, a vascular or general surgeon was called to consult on the case.
Mapping vascular structures to ensure safe trocar entry
Knowing the distances between blood vessels and laparoscopic entry trocars is critical if injury is to be avoided. In pursuit of this goal, Hurd and colleagues14 performed a retrospective study involving women who had undergone magnetic resonance imaging or computed tomography scans of the abdomen. Investigators measured the distance between the lower abdominal wall and the aortic bifurcation in these women, who were all unanesthetized and in the supine position.
Distances increased with BMI
This occurred in the study by Hurd et al,14 as well as in a prospective study by Narendran and Baggish,15 who calculated body mass index in 101 consecutive women who were undergoing diagnostic or operative laparoscopy. These women were anesthetized, with pneumoperitoneum established and a laparoscope inserted; all were in the lithotomy position.
In this study, Narendran and Baggish measured the following distances from the entry trocar:
- perpendicular distance to aortic bifurcation,
- oblique distance to the right and left common iliac vessels,
- oblique distance to the superior margin of the bladder,
- perpendicular distance from the peritoneum to skin at the umbilicus (abdominal wall thickness), and
- oblique distance from the subumbilical peritoneal opening to the right and left common iliac vessels.
Wide range of BMIs
In the study by Narendran and Baggish, successful measurement panels were created for 99 of the 101 cases. Of these, 49 women had a BMI of less than 25 (normal), 29 had a BMI greater than 25 but less than 30 (overweight), and 21 had a BMI greater than 30 (obese).
A significant difference was observed in the perpendicular distance from the entry trocar to aortic bifurcation (TABLE 1). Specifically, as the BMI increased, so did the distance. The only other significant BMI-related increase was the abdominal wall thickness, which also varied directly with the BMI.
Other distances increase with height
The distance between the primary trocar and the iliac vessels and urinary bladder consistently increased with the patient’s height.
However, no significant change in distance between the great vessels and the primary trocar site occurred when the patient’s position changed from level to Trendelenburg.
Trocar insertion: Disposable devices require less force
Laparoscopic trocar thrusting is a dynamic process, and we observed that process in our study.15 When force is applied via trocar to the anterior abdominal wall, that structure is displaced toward the abdominal cavity in the direction of the posterior abdominal wall—even when countertraction is taken into consideration. The movement is more apparent in obese women because of greater elasticity created by the larger mass of properitoneal and subcutaneous fat. We measured the distortion and determined that the depression can be 5 cm or more.
In contrast, thin women have rigid, relatively unyielding anterior abdominal walls and therefore experience minimal displacement. In thin women, the greater risk is the shorter passive distance between the anterior abdominal wall and the great vessels.
Comparing force curves
We16 calculated the force required to thrust a disposable or reusable trocar through the anterior abdominal wall during actual laparoscopic surgery. We used a 25-lb compression load cell connected to the trocar by an Ultem handle, which could be sterilized between cases. A linear variable displacement transducer detected displacement, and the measuring apparata fed data into a computer. Ten women were randomized to a disposable trocar and 10 to a reusable device.
The mean thrusting force for disposable trocars was 10.2 lb versus 17.53 lb for the reusable device. The time to penetrate was likewise significantly shortened for disposable trocars: mean time of 3.54 seconds versus 11.64 seconds. Overall work tilted in favor of disposable trocars: 14.34 pound-seconds versus 103.88 pound-seconds.
The disposable trocar has the advantage for 2 reasons: its razor-sharp cutting edge and streamlined design.
FIGURE 1 shows typical force curves of disposable and reusable trocars.
FIGURE 1 Reusable trocar requires more force than disposable trocar
A considerable difference in force is required for insertion, depending on type of device, as this graph of typical force curves shows. The reusable trocar requires 18 to 20 lb of force over 12 seconds; the disposable, only 5 lb over 2 seconds.