The ability to place ports in the appropriate locations for specific procedures is the first step in successfully performing minimally invasive surgery (MIS). If there are anatomic reasons why ports cannot be placed safely in the required location, such as previous adhesion to the body wall from other procedures (stomach, urinary bladder), the procedure should be performed open. In humans, any type of previous abdominal or thoracic surgery may be a relative contraindication because up to 30% of reoperative patients have bowel or other organs that are directly adherent to the abdominal scar,^2-7 and in autopsy studies, 75% to 90% of patients with previous abdominal surgery had adhesions.⁸ Care must be taken to develop a thorough anamnesis to ensure no previous surgeries may interfere with proposed port placements. In the reoperative abdomen, several early prospective human studies illustrated fewer injuries when the Hasson or open “cut-down” method was used compared with the blind “Veress” needle (VN) port insertion method.^9-11 However, the risk is quite low with either technique as long as the first port is placed distant to the previous abdominal incisions. Failure to produce a pneumoperitoneum after two or three passes of the VN is considered sufficient cause to switch to the Hasson technique. New optical trocars, discussed in detail elsewhere, are another option that allows the surgeon to view the layers of tissue as they are ­traversed.

Preexisting septic peritonitis was once thought to be a contraindication to laparoscopic procedures because of the potential for abscess formation at the port sites. There have been multiple studies looking at laparoscopic appendectomy and closure of peptic ulcers that have illustrated no greater incisional complication rate compared with open procedures, so this is a relative contraindication and left up to the surgeon’s discretion.^18-21 Most veterinary cases of septic peritonitis do not have a localized diagnosis before surgery, and many patients are quite unstable. Although the presence of sepsis in and of itself is not a contraindication, the surgeon would have to determine the best way to effectively and efficiently explore the abdomen and treat the problem after it is found in these critically ill patients. Bedside diagnostic laparoscopy²² for critically ill patients suspected of having intraabdominal sepsis has been performed in humans and holds the benefit of a highly accurate diagnosis with decreased morbidity. An important point to consider is the well-documented effect of pneumoperitoneum on translocation of bacteria into the circulation at certain intraabdominal pressures,^23,24 but much controversy exists over the effect of CO₂ insufflation on the innate immune system of the peritoneum (morphology of peritoneal mesothelium and macrophages).^25-28

Another relative anatomic contraindication is mechanical bowel obstruction, which leads to a decrease in the available working space and increased risk of bowel injury (serosal tearing or enterotomy). This topic is again controversial with some authors feeling strongly that laparoscopy should not be used in these cases and others reporting decreased healing times and improved gastrointestinal (GI) function postoperatively.^29-32 Baiocchi et al. report specific standards that should be followed if laparoscopic treatment for small bowel obstruction is to be considered, although no such guidelines exist in veterinary medicine.³³ These factors include proximal obstruction, small bowel dilation less than 4 cm, single adhesion band, mild abdominal distention, partial obstruction, and previous appendectomy. Reported success rates range from 46% to 84%,^34,35 with an overall rate of intestinal damage during the procedure of 5.8%.²⁴ The threshold for conversion should be very low in these cases, especially during the first few cases, and if possible, the GI tract should be decompressed preoperatively (orogastric tube placement after induction).

The cardiopulmonary effects of CO₂ insufflation for establishment of a pneumoperitoneum have been established. Insufflation with CO₂ is associated with two potential problems: (1) absorption of CO₂ across the peritoneal surface may cause hypercarbia, leading to respiratory acidosis, and (2) transmission of increased intraabdominal pressure through the diaphragm raises intrathoracic pressures by 5 to 15 mm Hg, depending on diaphragmatic compliance. Absorption of CO₂ and the ensuing hypercarbic acidosis require intraoperative compensation by the anesthetist. Increasing the minute ventilation, usually by hyperventilation, lowers the PaCO₂ and raises the pH. In patients with marginal pulmonary reserve (e.g., obese patients) or those who require positive end-expiratory pressure for adequate oxygenation, adequate compensation may not be possible; in these cases, refractory respiratory acidosis may develop. End-tidal CO₂ monitoring is essential in the management of the ventilation of patients undergoing laparoscopy but may underestimate the true arterial paCO₂ by as much as 10 mm Hg in an individual with chronic lung disease.¹ Therefore, arterial monitoring is recommended in these patients. In children and in patients who cannot be adequately ventilated during laparoscopic surgery, lower peak insufflation pressures should be used. If this fails, alternative measures, including the use of an abdominal wall-lifting device (gasless technique), administration of an alternative insufflation gas such as nitrous oxide or helium, or conversion to an open technique should be considered.^41-43

Venous return to the heart is decreased in response to peritoneal insufflation. This is most often seen in hypovolemic patients because insufflation compresses the low-pressure caudal vena cava and other large veins. In a well-hydrated patient, return is near normal. Cardiac output will be decreased if venous return is decreased, which can then lead to metabolic acidosis because of decreased visceral perfusion. This is why laparoscopic procedures were once thought to be contraindicated in elderly humans, but with improved anesthetic techniques and monitoring, this is no longer true, and there have actually been studies showing improved outcomes.⁴⁴ Patients with severe cardiac disease or hypovolemic shock may not compensate well and may manifest a dramatic drop in cardiac output during peritoneal insufflation. Although laparoscopy has been used as a diagnostic tool in some intensive care unit patients,⁴⁵ it should not be recommended in patients with acute hemorrhagic shock.

Any intracranial pressure concerns should be taken into account before laparoscopic procedures are chosen. A combination of the Trendelenburg (head-down) position and peritoneal insufflation can cause increased intracranial pressure, and with an accompanying metabolic acidosis, this can be severe; therefore, these procedures should be avoided in patients with acute brain injury. There have been reports of ventriculoperitoneal shunt failure after laparoscopic procedures as well as a theoretical risk of intracranial insufflation if the one-way valve fails. Some surgeons recommend exteriorizing the shunt before insufflation and then replacing it.^45,46

There have been many studies on laparoscopic procedures during pregnancy and the effects on the mother and fetus. Although the need for surgery during pregnancy may be rare in veterinary medicine, it is not impossible to think there may be certain necessary situations. In experimental studies, peritoneal insufflation has been found to increase intrauterine pressure, decrease uterine blood flow, and cause maternal and fetal acidosis.⁴⁷ There have been clinical studies showing that adverse outcomes were rare when laparoscopy was performed in the second trimester, but these do not illustrate long-term effects on the development of the child.^48-51 In human medicine, any elective procedures are recommended during the second trimester to avoid the teratogenic effects of anesthetics and the obliteration of peritoneal space by a gravid uterus.

A preexisting coagulopathy was once thought to be a definitive contraindication for laparoscopic surgery in human medicine, but this is rarely the case now because of improved operative techniques and recombinant coagulation factors. Any congenital coagulopathy should be corrected before any surgery, laparoscopic or open, because an uncorrected coagulopathy holds the same risk of uncontrolled hemorrhage with both procedure types. There are some specific diseases of the hemolymphatic system, such as medically refractory immune thrombocytopenia purpura, that are almost exclusively treated with laparoscopic splenectomy in humans.^1,52