Current Applications of Hernia Repair

In: Recent Advances in Laparoscopy and Thoracoscopy, Wilson D.G. (Ed.). International Veterinary Information Service, Ithaca NY (www.ivis.org), Last updated: 18-Apr-2001; A1112.0401
Current Applications of Hernia Repair

D. G. Wilson
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, SK, Canada

Summary

Laparoscopic inguinal herniorrhaphy is a minimally invasive approach to surgical correction of congenital herniation. The procedure is performed under general anesthesia with the foal in dorsal recumbency. Following reduction of the hernia, laparoscopic castration is recommended before the vaginal ring is closed with endolaparoscopic staples. Preservation of the testis can be achieved in both congenital and acquired herniation using a mesh herniorrhaphy technique. Postoperatively, patient morbidity is lower than that with traditional open herniorrhaphy.
Introduction

Scrotal and inguinal hernias are usually seen as a congenital condition in foals. The hernias are indirect and involve no disruption of the abdominal wall. The intestine enters the common vaginal tunics through the vaginal ring and is contained along with the testis. This is in direct contrast to the situation in man, where the hernia is direct and involves physical disruption of the body wall. Most foals present with an enlarged scrotum; however, strangulation of the intestine is infrequent. These hernias may resolve spontaneously and most clinicians recommend reducing the hernia several times a day. When the hernia doesn’t resolve by the time the foal is 30 to 60 days of age, surgery is recommended. This conservative approach can be effective; however, achieving client compliance can be difficult. The anxiety associated with the wait-and-see approach can be considerable, and traditional open herniorrhaphy carries the risk of significant morbidity. Laparoscopic herniorrhaphy has become the standard of practice in humans. A laparoscopic technique for herniorrhaphy in foals has recently been described [1].
Indirect scrotal hernias in breeding stallions often become evident shortly after breeding. Frequently, the stallion exhibits abdominal distress; however, there are instances when the hernia is asymptomatic. Most surgeons recommend unilateral castration at the time of open herniorrhaphy. That approach may be unacceptable to the owner, who wants to preserve the testis, yet attempts to save the testis are fraught with complications because the security of the herniorrhaphy must be compromised to ensure the vascular supply to the testis. Prosthetic mesh herniorrhaphy is routinely performed laparoscopically in man and has been used in mature stallions [2].
Anesthesia and Patient Preparation

Feed is withheld from mature stallions undergoing elective herniorrhaphy. Foals are not fasted before surgery. The horse is placed under general anesthesia and positioned in dorsal recumbency. The ventral abdomen is clipped and prepared for aseptic surgery. Draping is applied to give access to the umbilical area and the areas immediately cranial to the external inguinal rings. The prepuce is sutured closed and care is taken to isolate the prepuce from the surgical field. Intermittent positive pressure ventilation is commenced before the hindquarters are elevated into Trendelenburg’s Position.
Laparoscopic Inguinal Herniorrhaphy in Foals

Laparoscopic inguinal herniorrhaphy is especially well suited to the surgical management of congenital herniation in foals. Unless the foal is showing signs of strangulation, the procedure is considered elective.
To avoid umbilical structures on the midline, a teat cannula is introduced into the abdomen 3 cm lateral to the umbilicus. Intraperitoneal placement of the cannula is confirmed using a hanging drop technique. The abdomen is insufflated with CO₂ to a pressure not greater than 25 mm Hg. The teat cannula is removed and the laparoscope cannula with its sharp obturator is introduced through the same incision. The obturator is withdrawn and the laparoscope is placed into the abdomen. Upon visually confirming intra-abdominal scope placement, the hindquarters are elevated allowing cranial displacement of the viscera facilitating viewing of the internal inguinal area. A 10 - 12 mm diameter instrument cannula is placed 5 cm lateral to the ventral midline, 10 cm cranial to each external inguinal ring. The hernia frequently resolves spontaneously when the hindquarters are elevated, but if that doesn’t occur, an atraumatic grasping forceps can be used to apply gentle traction to return the herniated intestine to the abdomen

Fig. 1 .The herniated intestine is visually inspected.
Inguinal hernia showing traction being applied to the jejunum. J: jejunum; arrow: vaginal ring. To view click on figure

If the client is in agreement, laparoscopic castration is performed at the same time as the herniorrhaphy. The testis is drawn into the abdomen by applying traction on the mesorchium and spermatic vessels (Fig. 2). The ligament to the tail of the epididymis is coagulated using bipolar electrocautery and divided with scissors. The mesorchium is further dissected to develop a vascular pedicle. A pre-formed ligating loop is inserted through the ipsilateral instrument cannula and a grasping forceps placed through the contralateral cannula is passed through the ligating loop before the testis is grasped (Fig. 3). The loop is manipulated over the testis and tightened around the spermatic vessels and vas deferens (Fig. 4).

Figure 2. Traction being applied to the testicular vessels to pull the testis into the abdomen. Arrow: vaginal ring. To view click on figure

displayFig2()]Figure 3[/url]. Ligating loop in the abdomen with grasper placed through the loop. To view click on figure

[()]Figure 4[/url]. Ligating loop in place around testicular vessels. T: testis; B: urinary bladder. To view click on figure

Endolaparoscopic scissors are used to transect the spermatic vessels, the mesorchium and vas deferens. One of the instrument cannulas is replaced with a 16-mm diameter tissue cannula (Endopath Surgical Trocar, Ethicon Endo-Surgery, Cincinati, OH, USA) to allow the testis to be removed from the abdomen without losing insufflation

Fig. 5[/url]).

()]Figure 5[/url]. Tissue cannula with testis being removed from the abdomen. T: testis; C: tissue cannula. To view click on figure

Four to six endolaparoscopic staples ( Endopath Multifeed Stapler, Ethicon Endo-Surgery) are used to appose the peritoneal edges of the vaginal ring. Staple placement is facilitated by inserting the stapler through the ipsilateral cannula Fig. 6[/url] and ()]Fig. 7[/url]). The procedure is repeated on the contralateral side. The abdomen is decompressed and the abdominal fascia is closed with number 1 or 2 monofilament absorbable sutures. Subcuticular absorbable sutures are used to appose the skin.

()]Figure 6[/url]. Vaginal ring stapled closed. Arrow: vaginal ring. To view click on figure

Figure 7[/url]. Vaginal ring stapled closed. Arrow: vaginal ring. To view click on figure

Postoperatively, exercise restriction is not required. Swelling is typically limited to the area of instrument and laparoscope portals. The scrotal and inguinal swelling associated with traditional open herniorrhaphy does not occur.
Laparoscopic inguinal herniorrhaphy is not only minimally invasive, the procedure offers other advantages as well. The condition of the herniated intestine can be visually assessed without performing a celiotomy. Umbilical structures can be evaluated. Foals are especially sensitive to tissue trauma. The laparoscopic procedure allows bilateral herniorrhaphy without the attendant morbidity associated with two inguinal dissections. Traditional open herniorrhaphy requires both scrotal and inguinal dissection and incisional complications are common. The laparoscopic technique does not require such dissection, and staple closure of the vaginal ring is technically easier than suture closure of the external inguinal ring.
Laparoscopic Inguinal Herniorrhaphy in Adult Stallions

Stallions with asymptomatic inguinal hernias are candidates for scrotal herniorrhaphy when testicular preservation is desired. Stallions in acute abdominal distress should be avoided if the abdomen is distended.
A teat cannula is inserted into the abdomen through a 1 cm incision at the umbilicus. The abdomen is insufflated and the teat cannula is withdrawn to be replaced with the laparoscope. When intra-abdominal positioning of the laparoscope has been visually confirmed, the hindquarters are elevated. In horses with asymptomatic hernias, the intestine often returns to the abdomen when the horse is placed in Trendelenburg’s position. Gentle traction on the intestine may allow reduction in horses with strangulated hernias; however, the vaginal ring may need to be enlarged in others. With the hernia reduced, the peritoneum is elevated circumferentially around the vaginal ring. The vas deferens and testicular vessels must be preserved. A prosthetic mesh is positioned around the spermatic vessels and under the vas deferens and stapled to the musculature adjacent to the internal vaginal ring with endolaparoscopic staples. The peritoneum is replaced and stapled over the mesh. Technically, achieving mesh coverage with the peritoneum is difficult, and the simple onlay technique reported in man [3], may be an acceptable alternative.
References

1. Klohnen AA, Wilson DG. Laparoscopic repair of scrotal hernia in two foals. Vet Surg 1996; 25:414-416. - PubMed -
2. Fischer AT, Vachon AM, Klein SR. Laparoscopic inguinal herniorrhaphy in two stallions. J Am Vet Med Assoc 1995; 207:1599-1601. - PubMed -
3. Fitzgibbons RJ, Nguyen N, Camps J, et al. Laparoscopic inguinal herniorrhaphy using an intraabdominal or preperitioneal prosthesis. Laparscopic Surg 1994; 2:99-110.

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