Introduction

Laparoscopy offers a minimally invasive alternative to laparotomy for exploring the abdominal cavity in our feline patients. The widespread acceptance of laparoscopy stems mainly from the successes and technological advances in a variety of procedures in the human field compared to those of traditional open surgery. Though many surgical procedures performed in human beings will have little applicability in cats, many of the procedures used for diagnostic purposes will offer value due to its relative ease, effectiveness, and decreased of morbidity compared to more traditional interventions.

Diagnostic Laparoscopy: Is It for the Feline Practitioner? Does Laparoscopy Present Any Advantage to the Patient? What Are the Advantages for the Owners

Often times in feline practice, the clinician is faced with owner hesitation in putting a cat through traditional exploratory surgery for the sake of diagnostic purposes. With that in mind, clinicians will often have to rely on indirect and incomplete information provided by blood tests and imaging studies to arrive at a ‘most likely’ diagnosis. The psychological barrier for pursuing surgical biopsies seems greatly reduced when a minimally invasive alternative is offered as an alternative to open surgery.

It’s been well established in the human field that laparoscopic procedures greatly reduce patient morbidity, post-operative pain and post-operative recovery times. In both human and veterinary literature, it’s been well documented that larger incisions are considerably more painful compared to smaller incisions.^1-3 Recovery times (and how well the patient recovers) are also important factors when deciding on minimally invasive surgery, not only for the patient, but also their caregivers during the convalescence period. In addition to reduced incision size, cytokine and other inflammatory mediator release are greatly reduced, not only due to minimal trauma during tissue manipulation, but also directly due to carbon dioxide insufflation. The latter has been shown, in vitro, to cause a marked cytosolic acidification in peritoneal macrophages which suppresses cytokine release for up to 24 hours.⁴

Can the Practitioner Benefit from It?

Over the years, placing an endoscope into a cavity (or ‘hole’) has brought a tremendous amount of diagnostic information to the clinician. Laparoscopy gives the internist an extra opportunity to carry out a thorough visual inspection of the abdominal cavity, in a highly magnified and illuminated environment.^5,6 This is particularly advantageous in very small patients particularly when attempting to gain access into relatively inaccessible spaces (e.g., between liver and diaphragm). Laparoscopy allows for procurement of excellent quality (and size) tissue samples^5-7 in a controlled environment (e.g., controlling haemostasis).

The idea of minimally invasive surgery, as well as the idea of offering the state-of-the-art technology, will certainly push cat owners to request for minimally invasive procedures.

Disadvantages

I’ve described the desirable advantages to kitty keyhole surgery…so what are the disadvantages? One drawback is the initial financial outlay and training required to acquire the skills and safely perform these procedures in feline patients. Another drawback is the overly compliant abdominal cavity in the cat, coupled with a small working space for triangulation and reduced depth perception which can make abdominal access more challenging compared to dogs.^5,6 In addition, there’s a need to development of a ‘6th sense’ due to lack of direct tactile feedback by relying on instruments as an extension of our fingers. For example, the use of a palpation probe can be used not only to manipulate organs but it’s also used palpate textures and ‘ballot’ organs (e.g., gall bladder for signs of inflammation/thickness) as additional information beyond gross appearance. The key to success to making the transition over to ‘the other side’ is to be patient and taking a step-by-step approach when acquiring new skills, receiving formal tuition from experienced endoscopists (e.g., university training centres), and refrain from being too ambitious when being released into the real world!

Indications for Diagnostic Laparoscopy

Full evaluation of abdominal organs for signs of disease, biopsy liver, pancreas, lymph nodes, kidney, small intestine (‘laparoscopic-assisted’ full-thickness), abdominal mass evaluation, and cholecystocentesis.^5,6

Contraindications

Cardiovascular instability, inappropriate equipment, inexperienced/untrained surgeons, diaphragmatic hernia, extreme obesity, septic peritonitis, adhesions, coagulopathy, any condition in which conventional surgical intervention is indicated.

History/Clinical Examination/Pre-surgery Diagnostics

As for any surgical candidate, a full clinical history, clinical examination, and appropriate pre-surgery diagnostics should be performed prior to any exploratory intervention. Ultrasonography by a skilled imager is extremely useful to help isolate a specific area, and extent, of disease. Diagnostic imaging is considered to be a complementary part of any medical investigation and should ideally be considered prior to any laparoscopic assessment. A full clotting profile should also be performed prior to surgery (PT, APTT, and total platelet count); however, if this is not possible, then performing an activated clotting time, total platelet count and buccal mucosal bleeding time should be performed as a bare minimum. Despite the latter recommendation, clinical experience (and experience of fellow colleagues) suggest that abnormal bleeding times may not necessarily preclude performing diagnostic laparoscopy as abnormal clotting times do not always correlate with excessive bleeding at biopsy sites. There are studies in human medicine that indicate that in vitro coagulation tests do not accurately predict the probability of hepatic bleeding times.^8,9

Liver Biopsy

Once the abdomen has been thoroughly examined, a suitable area on the liver is selected for collecting a biopsy using a 5 mm laparoscopic ‘clamshell’ biopsy instrument.^5-7 This can be placed through the same accessory cannula as the blunt probe, thus avoiding the need to place an additional port. These types of instruments obtain much larger specimens compared to fine needle or core biopsy samples. If excessive bleeding occurs, the palpation probe is used to apply direct compression over the biopsy site until a clot has formed. If bleeding is still uncontrolled then laparoscopic forceps can be used to place a piece coagulation material into the biopsy defect.

Pancreatic Biopsy

The pancreas can be biopsied from the distal-most portion of the right limb for diffuse disease, or directly into a lesion, using a 5 mm endoscopic biopsy punch forceps. It’s vital to avoid the pancreatic ducts in the proximal portion of the limb, next to the duodenum. The same technique for collecting a liver biopsy, applies to pancreatic biopsies.

Cholecystocentesis

Bile aspirates for cytology and culture/sensitivity are important when performing gastrointestinal investigations in cats, particularly those suspected of having triaditis. Laparoscopic cholecystocentesis is considered safe and easy to perform. The author will typically use a spinal needle (18–20 G x 3–6” or 20–22 G depending on fluid viscosity) with an inner stylet that can be removed once the lumen of the gall bladder has been penetrated. The needle entry site on the external abdominal wall should be identified by ballottement visualised through the endoscope and should be caudal to the diaphragm. Depending on the intracystic pressure, it can be challenging to penetrate the wall with the needle. A quick forceful ‘jab’ will usually facilitate entry. Complete aspiration of all contents should be attempted to reduce the risk of bile leakage and peritonitis. In the author’s experience, this is a rare occurrence.

Intestinal Biopsies

Biopsy of the small intestine is usually performed using a laparoscopic-assisted technique. A ‘mini-laparotomy’ is usually performed by exteriorising a small bowel segment through a port incision. As an alternative approach in cats (compared to dogs), the author will often perform intestinal/lymph node biopsies at the end of the exploratory procedure using a wound retractor (Alexis 2–4 cm)¹⁰ placed in the caudal camera port. Because pneumoperitoneum will be lost, it is advisable to perform intestinal biopsies at the end of the procedure.

Post-Operative Care

Most cats (if no intestinal biopsies were obtained), will often be discharged the same day as the procedure. If intestinal biopsies were collected, then overnight observation is advised as per open surgery until the patient is eating with no signs of post-operative complications such as intestinal wound dehiscence.

References

1.  Hancock RB, Lanz OL, Waldron DR, et al. (2004) Comparison of postoperative pain following ovariohysterectomy via harmonic scalpel-assisted laparoscopy versus traditional ovariohysterectomy in dogs. ACVS Scientific Presentation Abstracts E18.

2.  Culp WTN, Mayhew PD, Brown DC (2009) The effect of laparoscopic versus open ovariectomy on postsurgical activity in small dogs. Veterinary Surgery 2009; 38, 811–817.

3.  Devitt CM, Cox RE, Hailey JJ. (2005) Duration, complications, stress, and pain of open ovariohysterectomy versus a simple method of laparoscopic-assisted ovario-hysterectomy in dogs. J Am Vet Med Assoc 227, 921–92.

4.  West MA, Hackam DJ, Baker J, Rodriguez JL, et al. (1997) Mechanism of decreased in vitro murine macrophage cytokine release after exposure to carbon dioxide relevance to laparoscopic surgery. Annals of Surgery 226 (2), 179–190.

5.  Robertson EE, Twedt D, Webb C. (2014) Diagnostic laparoscopy in the cat, rationale and equipment. J Feline Med Surg 16, 5–16.

6.  Robertson EE, Webb C, Twedt D. (2014) Diagnostic laparoscopy in the cat, common procedures. J Feline Med Surg 2014 16, 18–26.

7.  Cole TL, Center SA, Flood SN, Rowland PH, Valentine BA, Warner KL, et al. (2002) Diagnostic comparison of needle and wedge biopsy specimens of the liver in dogs and cats. J Am Vet Med Assoc 220, 1483–1490.

8.  Ewe K. (1981) Bleeding after liver biopsy does not correlate with indices of peripheral coagulation. Dig Dis Sci 26, 388–393.

9.  McGill DG. (1981) Predicting hemorrhage after liver biopsy. Dig Dis Sci 26,385–387.

10.  Runge JJ (2014) Evaluation of minimally invasive abdominal exploration and intestinal biopsies. (MIAEB) using Novel wound retraction device in cats: 31 cases (2005–2013). In: Proceedings of the American College of Veterinary Surgical Symposium, San Diego.