Laparoscopic cryptorchidectomy in 10 equids using a single incision laparoscopic surgery (SILS) port device

Abstract

Minimally invasive laparoscopic surgical techniques are desirable in horses and other equids. A new approach called “modified single incision laparoscopic surgery (SILS) for equine cryptorchidectomy” is described, along with the postoperative outcomes of 10 equids. A SILS Port device (Covidien) was placed via a 30- to 40-millimeter linea alba incision in combination with 1 or 2 15-millimeter para-inguinal incisions to exteriorize the intra-abdominal testicles. Ten animals, 2 bilateral abdominal cryptorchid horses and 8 unilateral abdominal cryptorchid equids, underwent cryptorchidectomy using the SILS technique. The median surgical and anesthesia times were 90 min (range: 75 to 135 min) and 150 min (range: 120 to 195 min), respectively. No intraoperative complications occurred. Two cases had transient pyrexia after surgery. No other postoperative complications were recorded. This technique reduced the risk of iatrogenic damage of the gastrointestinal tract, eliminated the need for additional instrument portals, provided an excellent maintenance of the pneumoperitoneum, and allowed easy testicle removal. None of the animals in the study developed postoperative emphysema.

Key clinical message:

The modified SILS technique was an effective approach for testicle removal in abdominal cryptorchids that did not result in any complications in the cases presented.

Different techniques have been reported for laparoscopic removal of intra-abdominal testes in horses (1–4), and equine minimally invasive surgery continues to gain acceptance. In 2023, Bonomelli and Bonilla’s survey showed that ~87% of Board-certified surgeons do laparoscopic cryptorchidectomies on standing horses (65%) or horses under general anesthesia (22%) (5). Single incision laparoscopic surgery (SILS) is intended to reduce surgical trauma and improve postoperative outcomes. This system has been used successfully for more than a decade in small-animal surgery for abdominal procedures such as ovariectomy (6,7), ovariohysterectomy, cryptorchidectomy (8), enterotomy, and enterectomy (9). However, the use of SILS in equine abdominal laparoscopic cryptorchidectomy has not been described. The commercially available SILS Port device (Covidien) is a flexible, soft-foam port that helps maintain pneumoperitoneum by conforming to the animal’s abdominal wall. It is designed to provide access for multiple instruments or a camera through a single incision.

With equine dorsally recumbent laparoscopic cryptorchidectomy, exteriorization of the testicle has been described as either through an extension of the parainguinal approach or with linea alba incisions. Extending the linea alba incision helps avoid additional trauma to the musculature and vasculature associated with para-inguinal incisions (10). However, this incisional extension can result in the loss of the abdominal seal that maintains pneumoperitoneum. The SILS port device addresses this issue by allowing a larger incision to be made for its insertion, where it then conforms to the animal’s abdominal wall, preserving pneumoperitoneum.

The SILS system, which has been used extensively in both human and small-animal laparoscopy, does pose technical challenges, such as instrument crowding, intra- and extracorporeal instrument collision, and reduced maneuverability (11). These issues can be more evident in the equine because of the larger working distance. However, some advantages of the SILS system may still be applied in the equid with modifications.

The objective of this study was to describe the SILS technique and report outcomes of horses undergoing a modified SILS technique for removal of intra-abdominal testicles.

CASE DESCRIPTIONS

Abdominal cryptorchid equids admitted for cryptorchidectomy were included in the study. Data, collected from May 2022 to March 2024, included breed, age, weight, history, retained testis, duration of hospitalization, surgical time, anesthesia time, and intraoperative and postoperative complications. The 10 equids included 4 American quarter horses, 1 standardbred horse, 1 Welsh pony, 1 hackney pony, 1 Shetland pony, 1 mixed-breed pony, and 1 miniature donkey. The median age was 3 y (range: 1 to 8 y). The median weight was 245 kg (range: 100 to 535 kg).

The SILS Port device (Covidien, Minneapolis, Minnesota, USA) (Figure S1, available online from: Supplementary Materials) is a flexible soft-foam port that maintains pneumoperitoneum by conforming to the patient’s abdominal wall. The device is designed for multiple instrument or camera access to the abdominal cavity, through a single incision, for conducting minimally invasive laparoscopic procedures. It contains an insufflation/smoke evacuation tubing and stopcock and it is suitable for use with standard instrumentation ranging from 5 to 12 mm.

For each equid, forage was discontinued 72 h before surgery and pelleted feed was offered until 24 h before surgery, at which time all feed was withheld. All cases were admitted on the day before surgery.

In each case, the inguinal region was palpated externally to confirm that the testis was not located in the scrotum or inguinal region. All animals were examined via transabdominal ultrasonography in a standing position (12) to locate the testicle(s). If a testicle was not identified, the ultrasound examination was repeated once the animal was anesthetized. A GE Logiq E Portable Ultrasound System computer was used. The studies were initiated with a GE C1-5-RS Wideband Convex Array Probe, followed by a GE 12L-RS Wideband Linear Array Probe for enhanced detail (GE Healthcare, Mississauga, Ontario).

In preparation for surgery, an indwelling short-term catheter was placed aseptically in the right jugular vein. Every animal received sodium penicillin (22 000 IU/kg, IV), gentamicin (6.6 mg/kg, IV), and flunixin meglumine (1.1 mg/kg, IV) before surgery.

Each horse was premedicated with xylazine hydrochloride (1 mg/kg, IV). Anesthesia was induced with ketamine hydrochloride (2.2 mg/kg, IV) and diazepam (0.05 mg/kg, IV) and maintained with intermittent positive-pressure ventilation with isoflurane in > 95% oxygen. A multiparameter monitor was used for oscillometric blood pressure, side-stream capnography, end-tidal isoflurane concentration, pulse oximetry, and electrocardiography. Each animal was placed under general anesthesia in dorsal recumbency. Isotonic fluids (lactated Ringer’s solution) were administered at 5 mL/kg per hour throughout anesthesia, and blood pressure was supported by administration of dobutamine at 0.5 μg/kg per minute, adjusted as required. An indwelling urinary catheter was placed to maintain decompression of the bladder during surgery. The prepuce was closed in a simple continuous pattern using USP 0 polypropylene (Surgipro; Covidien).

The ventral abdominal area was clipped from the pubis region to the xyphoid with wide margins, aseptically prepared, and draped for surgery in a routine fashion. A 50-millimeter-length skin/subcutaneous incision for a 30 to 40-millimeter incision of the linea alba was made over the umbilicus (Figure 1). The peritoneum was penetrated digitally and a lubricated SILS Port device (3 laparoscopic portals; Covidien) was introduced with the aid of Carmalt forceps (Figure 1). A lubricated rigid laparoscope (diameter 10 mm, 30°, length 37 cm) was introduced through 1 of the 3 openings of the SILS port device (Figure S2, available online from: Supplementary Materials). The other 2 openings were sealed with the blunt trocars within the 5-millimeter laparoscopic sleeves. The abdomen was insufflated with carbon dioxide to a maximum pressure of 10 to 12 mmHg. The horse was placed in the Trendelenburg position and the intra-abdominal testicle(s) was/were located (Figure S2, available online from: Supplementary Materials).

FIGURE 1.

A — Photograph showing the location of the incision for the single incision laparoscopic surgery port device, indicated with a red mark [1]. The para-inguinal portals are indicated by green [2] and blue [3] marks. B and C — The surgical model demonstrates a Carmalt forceps grasping the ventral portion of the single incision laparoscopic surgery port [1] for insertion into the abdomen through the incision made at the umbilicus. Views are shown from both a caudal-to-cranial perspective (B) and a lateral perspective (C).

Initially for unilateral and bilateral abdominal cryptorchids, needles (20 G, 3.5 inch) were inserted in the left and right para-inguinal regions for instrument portal positioning under endoscopic guidance (Figure S3, available online from: Supplementary Materials). To create the instrumental portal, 2 15-millimeter incisions were made through the skin and subcutaneous tissue, followed by a stab incision through the aponeurosis of the external and internal abdominal oblique muscles, as well as the peritoneum, at the desired site in the para-inguinal region (Figure S3, available online from: Supplementary Materials). A 12-millimeter-diameter cannula and blunt obturator (Covidien) was then inserted (Figure S3, available online from: Supplementary Materials). Babcock forceps (length 45 cm) were used to isolate the testicle(s) using the ipsilateral laparoscopic portal and transfer to a traumatic grasping forceps through the contralateral instrument portal (Figure S4, available online from: Supplementary Materials).

The vessel-sealing device (LigaSure Atlas Laparoscopic Sealer/Divider Instrument; Covidien) was introduced through the ipsilateral inguinal instrument portal to transect the testicle (Figure 2). Another traumatic grasping forceps was introduced through 1 of the 3 SILS port device openings to grab the testicle and exteriorize it under endoscopic guidance until the SILS port device was reached (Figure 3). Finally, the SILS port device, the traumatic grasping forceps with the testicle, and the scope were removed simultaneously through the umbilical incision (Figure 4). The SILS port device was replaced in the abdomen for removal of the 2nd testicle and the abdomen was reinsufflated.

FIGURE 2.

A — Photograph showing a surgical model with a rigid laparoscope (diameter 10 mm, 30°, length 37 cm) inserted through 1 of the 3 channels of the SILS port device [1], along with a vessel-sealing device inserted through the right [2] para-inguinal portal and traumatic grasping forceps inserted through the left [3] para-inguinal portal. B and C — Intraoperative images showing the vessel-sealing device through the right [2] para-inguinal portal transecting the spermatic cord (white arrow) while the traumatic grasping forceps through the left [3] para-inguinal portal hold the right testicle (white asterisk).

FIGURE 3.

A — Photograph showing a surgical model with a rigid laparoscope (diameter 10 mm, 30°, length 37 cm) [1′] and traumatic grasping forceps [1″] inserted through 1 of the 3 channels of the single incision laparoscopic surgery (SILS) port device [1], along with another set of traumatic grasping forceps inserted through the left [3] para-inguinal portal. B — An intraoperative image showing the traumatic grasping forceps through the left [3] para-inguinal portal transferring the testicle (white asterisk) to the traumatic grasping forceps [1′] inserted through 1 of the 3 channels of the SILS port device. C — An intraoperative image showing the traumatic grasping forceps [1′] inserted through 1 of the 3 channels of the SILS port device as it pulls the testicle (white asterisk).

FIGURE 4.

The sequence of images illustrates the simultaneous exteriorization of the laparoscope [1′], traumatic grasping forceps [1″], and single incision laparoscopic surgery port device [1] as the intra-abdominal testicle is removed through the umbilical incision, with the right [2] and left [3] para-inguinal portals also visible.

As experience was gained, the 2nd instrument portal was not needed for unilateral cryptorchids. The testicle could be transferred from the Babcock forceps in the ipsilateral portal to a grasping forceps passed through 1 of the channels of the SILS port (Figure 5). The vessel-sealing device was introduced through the ipsilateral inguinal instrument portal to transect the testicle. After the testicle(s) was/were removed, the abdomen was decompressed and the surgical table was returned to a horizontal position.

FIGURE 5.

The photograph shows a surgical model set up for a unilateral cryptorchid procedure, with a rigid laparoscope (diameter 10 mm, 30°, length 37 cm) [1′] and traumatic grasping forceps [1″] inserted through 1 of the 3 channels of the single incision laparoscopic surgery port device [1]. In addition, Babcock forceps are inserted through the right [2] para-inguinal portal.

The umbilical incision was closed following these steps: i) The linea alba was closed in a simple continuous pattern with absorbable material (Vicryl; Ethicon, Raritan, New Jersey, USA) USP 2-0 on a tapered needle, ii) the subcutaneous tissue was closed in a simple continuous pattern with absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a tapered needle, iii) the skin was closed in a simple continuous pattern using absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a cutting needle. The para-inguinal incisions were sutured following these steps: i) The external lamina of the rectus abdominis muscle was closed with 1 cruciate suture with absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a tapered needle, ii) the subcutaneous tissue was closed with a simple continuous pattern with absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a tapered needle, iii) the skin was closed in a simple continuous pattern using absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a cutting needle.

The animals with a descended testicle underwent closed castration, with primary closure of the incision consisting of the following steps: i) The deep fascia layer was closed in a simple continuous pattern with absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a tapered needle, ii) the subcutaneous layer was closed in a simple continuous pattern with absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a tapered needle, iii) the skin was closed with absorbable material poliglecaprone (Monocryl; Ethicon) USP 2-0 on a tapered needle in a simple continuous pattern.

In the cases reported herein, the total surgical time was defined as time elapsed from when the 1st incision was made until suturing was completed, including the descended testicle in unilateral cryptorchids. Ten equids in which a modified SILS technique was used for removal of intra-abdominal testicles were included in the case series. Transabdominal ultrasonography was useful in 7 of the 10 cases for identifying the testicle in the abdomen in the inguinal region. In the 3 cases for which the testicle was not identified on ultrasonography, it was located in the inguinal region of the abdomen during surgery. Two animals were bilateral abdominal cryptorchids, 5 were left unilateral abdominal cryptorchids, and 3 were right unilateral abdominal cryptorchids. The SILS port device provided for an excellent pneumoperitoneum throughout the procedure. All testicles were located in the inguinal region of the abdomen. No intraoperative complications occurred. For the final 2 unilateral cryptorchid cases, only 2 incisions were made.

Overall, the mean surgical and anesthesia times were 90 min (range: 75 to 135 min) and 145 min (range: 120 to 195 min), respectively. All animals recovered uneventfully from anesthesia. The mean anesthesia recovery time was 55 min (range: 30 to 96 min) and the mean recovery score was 1.4 (range: 1 to 2) (13) before surgery. Two animals received antimicrobial therapy for 5 d as they displayed transient pyrexia (mean: 39.2°C, range: 38.9 to 39.6°C) postoperatively that trended down to within normal reference range in 24 h. Anti-inflammatory therapy was continued on a tapering dose (median: 6 d, range: 5 to 8 d). Median hospitalization time was 2 d (range: 2 to 3 d). No other postoperative complications were recorded. None of the 10 animals developed subcutaneous emphysema. For recovery, each animal was kept on stall rest with daily hand walks for 3 wk, followed by an additional 3 wk of limited turnout in a small paddock. The median follow-up duration was 2 y (range: 0.5 to 3 y). No complications were reported at the time of follow-up via phone communication with the owners.

DISCUSSION

Over the past decade, SILS has gained popularity in companion animal surgery for various abdominal procedures (6–9). The modified SILS technique described herein allowed visualization and therefore confirmation of placement of the SILS port device in the abdominal cavity, reducing risk of iatrogenic damage to the gastrointestinal tract or misplacement of the trocar (14). No surgical complications were observed during the procedures. In view of the results, we suggest that the modified SILS technique may have clinical benefits.

The device allowed an excellent seal of the pneumoperitoneum in comparison to studies in which the umbilical incision was enlarged for removal of the testicle through the umbilical incision (10). The 3 openings in the SILS port device permitted the access of grasping forceps for exteriorization of the testicle without moving the laparoscope to the para-inguinal instrument portals, leaving the transected testicle in the abdomen, or creating additional portals (4,15). The umbilical incision made for the SILS device was of an appropriate length for testicle removal, which eliminated the need for later modification of the incision at the umbilicus or at the instrument portal and decreased the risk of losing the testicle in the abdomen during its removal through a too-small incision (4,14,15). The larger portal incision necessitated by the SILS device allowed ease of removal and replacement following retrieval of the 1st testicle of a horse with bilateral cryptorchidism. The flexible, soft-foam device conformed seamlessly to the animal’s abdominal wall, quickly restoring pneumoperitoneum.

Removal of the SILS port device in the Trendelenburg position allowed complete evacuation of the CO₂ infused into the abdomen, which could explain the lack of emphysema after surgery compared to other reports (15). Similar to our present finding (10), this complication was not reported in a previous investigation in which the intraabdominal testicle was removed through an enlarged umbilical portal (10).

The main technical challenges of the SILS system are instrument crowding, intra- and extracorporeal instrument collision, and reduced maneuverability (11). These difficulties were encountered in the equids. The SILS with the 3-port device did not allow a working triangulation because of the long distance between the testicles and the SILS device. As the surgeons became more comfortable using the device, unilateral cryptorchids were conducted using only 2 portals, the SILS port in the umbilicus and the ipsilateral instrument portal. The lengths of the instruments and the size of the horse were not limiting factors when using the SILS port device. The true benefit would be the ability to carry out the entire procedure through the SILS port device — especially for smaller animals, such as miniature equids and ponies, that could greatly benefit from this approach. The implementation of an appropriate articulating laparoscopic device (FlexDex Surgical) for large animals could be a solution to complete the surgery using only the SILS device (16). The articulating instruments would create a triangulation work area closer to the surgical site of interest, in contrast to the straight instruments, for which the triangulation is limited by the foam device.

Among the most common complications of laparoscopic cryptorchidectomy is hemorrhage at the stump, often due to improper cauterization (17,18). The introduction of the LigaSure device (Covidien) has improved the procedure by offering rapid and effective hemostasis, eliminating the need for residual foreign materials, minimizing thermal injury to surrounding tissues, and reducing the extent of surgical dissection (17,18). Hemorrhage at the stump can also occur with the traditional inguinal approach, typically as a result of ligature failure (19). Further complications may arise during the insertion of the trocar and cannulas that carry a risk of injury to abdominal wall vessels such as the caudal epigastric and caudal superficial epigastric arteries and veins — complications that are not encountered in a conventional inguinal approach (15,18,20). In laparoscopic cryptorchidectomy, the vaginal ring is not stretched to accommodate the testis, thereby reducing the risk of evisceration (19).

The median surgical time was similar to the range previously reported for laparoscopic cryptorchidectomy, at 105 min (range: 90 to 120 min) (14,21). The total surgical time was defined as time elapsed from when the 1st incision was made until suturing was completed, including the descended testicle in unilateral cryptorchids.

Peritoneal inflammation caused by CO₂ insufflation during laparoscopy could account for the elevated body temperature observed in 2 cases. This typically resolves on its own within 24 to 48 h after surgery (22,23). However, if fever develops ≥ 2 d post-surgery, it is important to assess the animal for potential infection (24). The fever resolved in 24 h in both cases. The duration of prophylactic antimicrobial therapy has been shown not to influence infection rates, suggesting that extended prophylaxis is unnecessary (25). Consequently, antimicrobial therapy should be reserved for animals with a confirmed bacterial infection.

Overall, the preoperative diet plan for the present cases, in which forage was withheld for 72 h and pelleted feed provided in preparation for surgery allowed a good surgical visualization of the testicles and inguinal rings; the bowel did not obscure the sites of interest. Previous reports only documented the time that food was withheld and specifications on the feeding plan were not described (10,15,21).

In conclusion, the modified SILS technique was an effective and simple approach for abdominal cryptorchids that did not result in surgical complications in the equine cases presented. CVJ