Laparoscopic splenectomy: operative technique and outcome in three cats

Abstract

Clinical summary:

The clinical findings, treatment and outcome for three cats that underwent laparoscopic splenectomy using bipolar vessel-sealing devices for resection of diffuse splenic disease are described. In each case, a three-portal laparoscopic technique was used. The spleen was manipulated and its mesentery and associated vessels sequentially cauterized and ligated to enable removal through a portal incision with minimal hemorrhage. Each of the three patients recovered from anesthesia without incident and was able to be discharged to the owner the next day.

Practical significance:

Laparoscopic splenectomy may be a safe and effective alternative to celiotomy in a select group of cats requiring splenectomy.

The feline spleen is affected by a variety of disease processes, the most frequently encountered being primary and metastatic neoplasia, hyperplasia, hematomas and splenitis.^1–4 The most common neoplasms affecting the feline spleen include mastocytoma, lymphosarcoma and hemangiosarcoma.^1–4 Splenectomy has been shown to improve survival time in cats with neoplasia of the spleen, especially in patients that do not demonstrate weight loss preoperatively. ³

In human medicine, splenectomy is often performed as a treatment modality for immune-mediated thrombocytopenia, hemolytic anemia, spherocytosis, splenic artery aneurysm, and some selected splenic malignancies and myeloproliferative disorders.^4,5 Laparoscopic splenectomy has been performed routinely in human medicine since the late 1990s. Multiple studies have shown that, despite being associated with prolonged surgical times compared with open splenectomy, laparoscopic splenectomy results in shorter hospitalization times and a reduction in pulmonary, wound, gastrointestinal and infectious complications in people.^6–8

In veterinary medicine there has been considerable interest recently in providing some of the advantages of laparoscopy for our small animal patients. Demonstrated benefits of laparoscopy in small animals include a reduction in postoperative pain, a more rapid return to normal activity and possibly a reduction in postoperative surgical site infection rates.^9–11 While several laparoscopic procedures have been described in dogs, few reports of feline laparoscopic procedures exist. In general, cats tolerate pneumoperitoneum and laparoscopic surgery very well and a limited number of feline laparoscopic procedures have been described.^12–17

Several reports exist in the veterinary literature documenting laparoscopic splenectomy in both healthy dogs and those with splenic lesions.^18–20 In one report, healthy dogs undergoing laparoscopic splenectomy exhibited fewer signs of pain, had fewer wound complications and experienced less blood loss than those undergoing open surgery, although the laparoscopic technique did require longer surgical time compared with open splenectomy. ¹⁸ To the authors’ knowledge, this is the first report of laparoscopic splenectomy in cats.

Case selection

The medical records of cats undergoing laparoscopic splenectomy between 2008 and 2011 at the School of Veterinary Medicine of the University of California–Davis and the School of Veterinary Medicine of the University of Pennsylvania were reviewed. Data recorded for each case included history, physical examination findings, the results of preoperative bloodwork and imaging, details of surgical procedure, and postoperative outcome.

Clinical summary

The medical records search identified three cats that had undergone laparoscopic splenectomy. Signalment and clinical characteristics, as well as outcomes, are summarised in Table 1. Splenectomies were performed as treatment for the following conditions: cutaneous mast cell tumors (case 1), chronic episodic anemia (case 2) and an abdominal mass (case 3). Surgical procedures were performed by, or under the direct supervision of, board-certified surgeons with extensive experience in minimally invasive surgery.

Table 1

Clinicopathological data for three cats that underwent laparoscopic splenectomy

Case	Signalment	Presenting complaint	Surgical procedure(s)	Histopathology	Postoperative outcome (days)
1	8-year-old 5.5 kg FS Ocicat	Cutaneous MCT onmuzzle	Laparoscopic splenectomy	Spleen – MCT Liver – within normal limits	Alive at 494
2	10-year-old 4.5 kg FS DSH	Chronic anemia	Laparoscopic splenectomy	Spleen – multifocal histiocytic and neutrophilic capsulitis and subcapsular splenitis consistent with FIP	Euthanased at 88
3	10-year-old 6 kg MC DSH	Abdominal mass, lethargy, inappetence, diarrhea	Laparoscopic-assisted splenectomy and intestinal resection and anastomosis	Spleen – splenic congestion Jejunal mass – MCT Mesenteric LN – MCT	Lost to follow-up

FS = female spayed, MC = male castrated, DSH = domestic shorthair, MCT = mast cell tumor, FIP = feline infectious peritonitis, LN = lymph node

Laboratory testing

A complete blood count (CBC) and serum biochemical screen were within normal limits for case 1. Cytology following fine-needle aspiration of cutaneous masses located on the left rostral maxilla, left shoulder and left pelvic limb confirmed mast cell tumors.

In case 2, the CBC revealed a mild non-regenerative anemia (hematocrit 27.6%, reference interval [RI] 30–50%; reticulocytes 42,000/µl, RI 7000–60,000/µl), as well as proteinuria and bacteruria. The biochemistry screen was within normal limits. A urine culture revealed a positive growth of Escherichia coli. Polymerase chain reaction in case 2 was positive for Mycoplasma turicensis and Mycoplasma haemominutum.

Case 3 had a severe leukocytosis (white blood cell count 51,100/µl, RI 4500–14,000/µl) characterized by a mature neutrophilia (19,930/µl, RI 2000–9000/µl) with a left shift (bands 510/µl, RI rare) and a severe monocytosis (2560/µl, RI 50–600/µl) and eosinophilia (25,550/µl, RI 150–1100/µl). The biochemistry screen showed a mild hyperkalemia (4.9 mmol/l, RI 3.5–4.8 mmol/l), low alanine aminotransferase (25 U/l, RI 33–152 U/l) and hypocholesterolemia (94 mg/dl, RI 96–248 mg/dl).

Diagnostic imaging

Abdominal ultrasound (including splenic echotexture) was unremarkable for case 1. Thoracic radiography performed for case 1 revealed two pulmonary nodules that were unchanged in size from previous radiographic studies, with possible development of a third lesion in the left caudodorsal lung, as well as static lower airway disease. Thoracic radiographs obtained for case 2 showed mild cardiomegaly and abdominal ultrasound revealed hepatomegaly, splenomegaly with mottled echotexture, poor renal corticomedullary distinction, mild pyelectasia, hyperechoic mesentery and mild mesenteric lymphadenopathy. Abdominal ultrasound in case 3 revealed mesenteric lymphadenopathy, and thoracic radiographs revealed mild cardiomegaly.

Surgical technique

Cases 1 and 2 both had splenectomy performed using a full laparoscopic technique. The cats were placed in dorsal recumbency and a 1 cm ventral midline incision was made in a subumbilical location 1 cm caudal to the umbilicus. A 5 mm camera portal was established with a 6 mm trocar-cannula assembly using a modified Hasson technique. A mechanical insufflator (Endoflator; Karl Storz Veterinary Endoscopy, Goleta, CA, USA) was used to create a pneumoperitoneum of 8–12 mmHg using carbon dioxide. A 5 mm laparoscope (Hopkins; Karl Storz) was inserted through the camera portal and visual examination of the abdomen was performed. Two further portals were established using 6 mm trocar-cannula assemblies (Endotip; Karl Storz) under direct visualization on the ventral midline 3–5 cm cranial and 3–5 cm caudal to the subumbilical camera portal (Figure 1).

Figure 1

Alexis wound retractor in position at the umbilical location and two 5 mm instrument portals positioned cranially and caudally

A laparoscopic blunt probe was initially placed into the cranial instrument portal and a Ligasure V vessel-sealing device (Covidien, Mansfield, MA, USA) was placed into the caudal portal. The spleen was manipulated with the blunt probe so that the splenic vasculature could be visualized. The spleen was linearly cauterized and transected using the Ligasure sealing device, moving from the splenic tail towards the head of the spleen, with minimal resultant hemorrhage (Figure 2). The spleen was retracted and mobilized with the blunt probe. The splenic mesentery and vessels were able to be completely transected close to the hilus. The spleen was retrieved using a specimen retrieval bag through the caudal portal in case 1, and through an enlargement of the camera portal into which a 2–4 cm Alexis wound retractor (Applied Medical, Rancho Santa Margarita, CA, USA) was placed in case 2. Prior to splenic removal, biopsy samples were taken of the liver in cases 1 and 2 using laparoscopic cup biopsy forceps and submitted for histopathological analysis. The abdomen was inspected for hemorrhage before withdrawing the portals. Portal sites were closed in a routine fashion.

Figure 2

The spleen is elevated against the body wall by a blunt probe, while a Ligasure vessel-sealing device is used for dissection of the splenic hilus

In case 3, a laparoscopic-assisted technique was used for splenectomy as the cat also had a jejunal mass that required resection concurrently. The incisions, portal positions and establishment of CO₂ pneumoperitoneum were similar to those described for cases 1 and 2. In this cat, a laparoscopic-assisted intestinal resection and anastomosis was performed using the Alexis device, as described previously. ¹⁷ A mesenteric lymph node was also biopsied prior to splenectomy. Thereafter the spleen was exteriorized and an Enseal device (Ethicon Endo-Surgery, Cincinnati, OH, USA) was used to transect the splenic pedicle along the hilus, moving progressively from the tail of the spleen up to the head of the spleen. Once the spleen had been removed, closure of the portal sites was performed in a routine fashion.

Histopathology

In all three cats the resected spleen was submitted for histopathological analysis, the results of which are summarized in Table 1.

Outcome

All cats were discharged from the hospital at day 1 postoperatively. Buprenorphine hydrochloride was prescribed on discharge, at 0.01 mg/kg q6–8h, for cases 1 and 2; no analgesic drugs were prescribed for case 3. At the time of writing, case 1 was alive 494 days postoperatively. Case 2 was euthanased 88 days postoperatively due to chronic refractory immune-mediated hemolytic anemia. Case 3 was lost to follow-up after discharge.

Discussion

Splenic disease in cats is relatively uncommon. Non-neoplastic disease, including congestion, lymphoid hyperplasia, capsulitis, extramedullary hematopoiesis and hyperplastic nodules, represents about 50% of all feline splenic disorders.^21,22 Neoplastic diseases that most commonly affect the cat include lymphoma ²³ and the visceral form of mastocytosis (systemic or splenic), which has been reported to comprise up to 50% of all feline mast cell disease.^24,25 Hemangiosarcoma also occurs in the cat, although the visceral form is observed less frequently than in dogs and carries a grave prognosis. ²⁶

Traditional open splenectomy is generally performed through a ventral midline celiotomy and is a common procedure in small animal practice. In dogs and cats, the results of open splenectomy have been widely reported and it is generally considered a technique with low procedure-related morbidity. ²⁷ In humans, laparoscopic splenectomy has been performed for over 10 years now as a routine procedure for many forms of neoplastic and non-neoplastic disease.^4–8 The conversion rate to open surgery in a meta-analysis of 26 comparative human studies was 6.6%, with hemorrhage being the most frequent reason for conversion. ⁷ As well as a low conversion rate, the laparoscopic procedure is associated with a low complication rate, with significant reductions in pulmonary and wound complications having been reported in comparison with open splenectomy in people. ⁷ In the few reports in the literature on canine laparoscopic splenectomy, complications have included some hemorrhage during splenic manipulation but no conversions to open surgery were required in the small numbers of cases reported.^18–20

No information is available in the literature on complications or conversion rates in feline laparoscopic splenectomy. In the three cats in this report, no conversion to an open approach was required, although one cat was approached in a laparoscopic-assisted fashion as it was undergoing concurrent laparoscopic-assisted intestinal resection, making a laparoscopic-assisted splenectomy technically easier in this patient. If a laparoscopic-assisted approach is elected, hilar dissection is usually initiated at the tail of the spleen and progresses towards the splenic head. Gentle digital traction can be used to retract the spleen out of the portal incision as dissection progresses and the hilar vessels are sealed using the vessel-sealing device. Note that it is crucial not to cause iatrogenic hemorrhage from overzealous retraction. If tension is judged to be excessive during digital retraction, the telescope can be placed through the Alexis device with simultaneous elevation of the body wall to allow visualization of the area of the head of the spleen.

The full laparoscopic technique relies on intra-abdominal manipulation of the spleen with laparoscopic instruments, which has to be undertaken with care to avoid hemorrhage from the inherently friable splenic capsule. In the two cases described here most of the necessary manipulation was performed using a blunt probe. Tilting the cat over towards the right side, either by manually manipulating the cat underneath the drapes or by using a mechanical tilt table, aided in obtaining better visualization of the head of the spleen and the short gastric vessels. The area of the head of the spleen where the feline pancreas is naturally closely apposed to the spleen was the most challenging part of the dissection in these cats and care must be taken not to cause iatrogenic damage to the pancreas. The short gastric vessels tether the splenic head to the greater curvature of the stomach and make retraction without capsular damage somewhat challenging. However, in the two cases performed entirely laparoscopically, complete dissection of the splenic hilus in this area was possible without the need for conversion to an open approach.

All three cats were maintained overnight on standard doses of analgesics and discharged to their owners the day following surgery.

While certain advantages of minimally invasive surgery have been evaluated in dogs, such as diminished postoperative pain and a more rapid return to normal activity,^9,10 controlled clinical trials have not been performed in cats to date. It is, therefore, difficult to quantify what advantages laparoscopic splenectomy may provide in cats, especially based on this small number of cases. However, the authors hypothesize that similar advantages of minimally invasive surgery as have been demonstrated in canine and human studies may be realized in the feline population also. Further studies will be required to corroborate this hypothesis.

Conclusions

With all laparoscopic procedures, and especially more advanced techniques, patient selection is extremely important in order to minimize complications and the need for conversion to an open approach. Based on this early experience with only three cases it is difficult to define strict selection criteria for laparoscopic splenectomy in cats. However, based on their experience to date, the authors would recommend laparoscopic splenectomy in cats with mild to moderate splenomegaly and modestly sized splenic masses. During the early part of a learning curve, suggested contraindications to laparoscopic splenectomy in feline patients include severe splenomegaly, the presence of large splenic masses (>5 cm diameter) and lack of surgical experience or availability of appropriate equipment. Further studies will be needed to refine these selection criteria in the future.