7 Sept 2015
Louise Southwood
Job Title
Figure 2. Proxima drape (Medline) with adhesive around the 30cm fenestration (towel clamps are not necessary), plastic pockets to facilitate keeping abdominal contents moist and maintaining bowel on the horse’s ventral abdomen, and hook and eye tape tabs to attach suction or other instruments/devices to the drape. The partially open gauze sponge is 20cm long and is used to demonstrate the approximate length of the incision (approximately 22cm to 23cm).
A team approach is critical for a successful outcome following any abdominal surgery.
The team will be different depending on the surgical facility and will generally include a theatre nurse or unscrubbed assistant, surgeon, assistant surgeon and an anaesthetist. Interns, residents and students are also a critical part of the surgical team at many hospitals.
Every member of the surgical team has a responsibility to be prepared to assist and must also come with a positive attitude (even at 2am). Remember, “better teamwork and adherence to practices known to enhance patient safety can prevent many errors”1,2.
The most common reason for abdominal surgery in equines is diagnosis and treatment of colic caused by gastrointestinal disease. Caesarean section is probably the most emergent reason. The intern and nurse are critical for patient preparation, anaesthetic induction and recovery, and assistance during surgery.
The specifics of patient preparation will vary between hospitals; however, many of the basic principles should be similar.
A few key tips for patient preparation are shown in Table 1.
The horse is positioned in dorsal recumbency and the ventral abdomen is clipped and prepared. Preparation of the prepuce varies between hospitals from simply placing gauze sponges in the preputial orifice and towel clamping closed to exteriorising and cleaning the penis/prepuce and oversewing the preputial orifice (a great job for an intern). Most hospitals have a clean drape to cover the feet.
The skin of the ventral abdomen must be clean prior to beginning the five-minute sterile prep. The cleanliness of the skin can be checked by wiping with a gauze sponge, which should remain clean following wiping (“white glove test”).
Sterile preparation is usually performed with chlorhexidine or povidone-iodine scrub. Either sterile water or alcohol is used to remove the scrub. Evidence in the literature suggests a chlorhexidine scrub is superior to povidone-iodine scrubs3,4. Similarly, the surgeon scrub should begin with clean hands. Chlorhexidine gluconate aqueous scrubs appear to be superior to povidone-iodine aqueous scrubs at reducing colony- forming units (CFU) on the hands5. Alcohol-based rubs are as effective as aqueous scrubs at reducing CFUs5.
An instrument and sponge count should be performed (Figure 1). The risk of leaving an instrument or sponge in the abdomen can be reduced by counting instruments and sponges before and at the completion of abdominal surgery before body wall closure is started6,7. Having an instrument checklist is an important aspect of veterinary surgical practice.
The surgeon and surgical assistant should be meticulous about removing any instruments or sponges from the horse’s ventral abdomen during surgery. Placing used gauze sponges in a separate bucket or on a towel (that is, not completely discarding them) will facilitate counting during surgery.
In the event an instrument is not accounted for at the completion of surgery, radiographs can be used to locate the instrument if it is indeed in the abdomen. Once located, the abdomen should be reopened to retrieve the item. Earlier retrieval of unintentionally retained surgical items is, not surprisingly, associated with a lower patient morbidity8.
The assistant surgeon (intern) should also be responsible for keeping the instruments rinsed of blood during surgery and the table in order. A good assistant “anticipates the needs of the surgeon” and, therefore, must have reviewed the procedures and be engaged in the surgery. The assistant surgeon can also facilitate communication between the surgeon and the theatre nurse, for example, if only two gauze sponges are on the table and the surgery is far from over, he or she should ask the nurse for an additional pack – not forgetting to count any added sponges or instruments.
Similarly, if the surgeon is preparing to perform a resection and anastomosis, the assistant surgeon should anticipate what is needed and have the table organised so there is no wasted time and the procedure is performed efficiently.
The horse is usually draped with four quarter drapes and a large fenestrated drape. The ideal fenestrated drape has adhesive around the fenestration so towel clamps are not necessary in the surgical field, and has a plastic pocket to assist with keeping the bowel on the ventral abdomen moist. Hook and loop fastener tabs can also be useful for securing suction to the drape (Figure 2).
An iodine-impregnated incise drape may also be used by some surgeons.
A ventral approach using a traditional surgical technique is the most appropriate for the majority of horses with acute colic.
The ventral midline approach is started at 1cm cranial to the umbilicus and extended 20cm to 30cm (15cm in a foal) in a cranial direction (Figure 2). The incision is made through the skin, subcutaneous tissue and linea alba. Bleeding is controlled by applying haemostats or electrocautery.
After the body wall is incised, the surgeon bluntly enters the peritoneum with digital pressure. All instruments and sponges must be removed from the ventral abdomen prior to entering the peritoneal cavity. Exteriorised bowel must be kept moist at all times.
Exploratory laparotomy has been reviewed in detail9 and it is critical for interns and students to have excellent knowledge of gastrointestinal anatomy and common lesions affecting the various parts of the equine gastrointestinal tract.
Needle decompression is performed commonly in the large colon and caecum during abdominal surgery for colic. A 14-gauge 1.5in needle in adult horses (18-gauge 1.5in needle for foals and small intestine) is attached to tubing connected to suction. The needle should penetrate the serosa, be tunnelled within the submucosa and then passed through the mucosa into the intestinal lumen.
When all the gas is removed, the site of needle penetration should be grasped with a moistened gauze sponge and the needle removed. The gauze sponge is immediately discarded and the site inspected for feed material, leakage or bleeding. The needle hole may be oversewn, if necessary (Table 2)9.
A pelvic flexure enterotomy is performed on the antimesenteric aspect of the bowel and the incision is oriented longitudinally. The large colon is placed on a tilted table (colon tray) that is draped and abutted to the flank of the horse (left side). Digesta is removed through the enterotomy by placing a hose with warm tap water within the lumen to hydrate the digesta. The digesta is massaged toward the enterotomy site. A large colon enterotomy is closed using 2-0 synthetic absorbable (Table 2) suture material in a full thickness simple continuous pattern oversewn with a Cushing pattern.
The types of stapling equipment generally used in abdominal surgery are the ligate-divide-staple for
vessel ligation – for example, during resection of a long portion of jejunum; TA-90 (thoracoabdominal stapling device) for resection of any portion of bowel creating a blind end; and the ILA-100 or GIA-100 for creation of an anastomosis (can also be used for resection of bowel).
Staples may also be used in the skin. Generally, staplers consist of a resterilisable instrument with a disposable staple cartridge that slides into the stapler. Stapling devices generally shorten surgical time and decrease peritoneal contamination when performing bowel resection and anastomosis; however, they are expensive.
The body wall is generally closed using number 2 or number 3 polyglactin 910 in a simple continuous (SC) pattern, the subcutaneous tissue using a 2-0 synthetic absorbable suture material in a SC pattern, and the skin using either staples, absorbable suture in a SC pattern, or skin glue9.
The general approach to the abdomen for a caesarean section is similar to that for an abdominal exploratory surgery; however, there is typically increased urgency to have a successful outcome for both the mare and foal.
A ventral midline approach is used for a caesarean section; however, the incision is typically longer (40cm to 45cm or longer) depending on the size of the fetus. The abdomen is not initially explored during a caesarean section, but the hindlimb of the fetus is identified and exteriorised through the body incision from the hoof to the hock. Tilting the table or the mare toward the proposed site of delivery can facilitate exteriorising the fetus.
Laparotomy sponges should be used to protect the body wall incision. Using a fresh scalpel blade, a hysterotomy incision is made through the greater curvature of the gravid horn (usually from the fetal hoof to the hock). It is important the hysterotomy incision is full thickness through the uterine wall without incising the fetal skin. The membranes typically need to be opened to deliver the fetus.
Once the uterus and fetal membranes are open, the hind hooves are identified, obstetric chains are placed, and the fetus is delivered by an unscrubbed team of assistants. Care must be taken to ensure the uterus remains exteriorised to prevent contamination of the peritoneal cavity. The umbilicus should be clamped (and may need to be ligated). Large uterine vessels are ligated and many surgeons use a haemostatic suture line to prevent uterine haemorrhage postoperatively.
The hysterotomy is closed using no2 polyglactin 910 in a simple continuous or Cushing pattern, which is oversewn using a Cushing (or Lembert) pattern. The uterus is lavaged. A brief abdominal exploration may be performed at this time.
