A guide to exploratory laparotomy (2023)

Exploratory laparotomy or celiotomy is commonly performed for the diagnosis, treatment or prognosis of traumatic, inflammatory, infectious, neoplastic and congenital abdominal conditions. While preoperative diagnoses such as radiography, ultrasound, and CT scans can provide information about the underlying condition, the results of these tests do not always correlate with intraoperative findings. For example, major discrepancies in diagnosis were seen in 25% of patients who underwent abdominal ultrasound and subsequent exploration.¹Full exploratory laparotomy is a key component of abdominal surgery.

preoperative preparation

Perioperative antimicrobial agents are administered to animals with existing infection or prophylactically to surgical wounds classified as cleanly contaminated, contaminated, or dirty. Prophylactic antimicrobials are administered intravenously 30 to 60 minutes before the incision and may be repeated during the procedure, depending on the duration of surgery, anticipated contaminants, and drug metabolism in the species in question. In dogs, an intramuscular or subcutaneous dose of cefazolin may be administered concurrently with the intravenous dose to provide prolonged prophylaxis.^2,3

The patient's entire abdomen and caudal thorax are cut and prepared aseptically. In male dogs, the preputial cavity is washed with saline or water before applying an antiseptic solution, as antiseptics are inactivated by organic material.⁴For dogs with suspected urinary tract obstruction, the perivulvar area is also cut and prepared so that it can be covered for intraoperative catheterization. Before beginning the procedure, the surgeon and anesthesiologist or veterinary nurse should review a surgical checklist that includes preoperative and intraoperative medications, various surgical sponges, and a list of surgical and anesthetic concerns.BOX 1indicates the surgical equipment that should be available.

abdominal incision

For a full exploratory laparotomy, the abdomen is incised from the xiphoid to the pubis. In male dogs, the cutaneous and subcutaneous incisions diverge laterally around the prepuce; branches of the caudal superficial epigastric vessels may require ligation or cauterization. Once the subcutaneous tissue has been incised, the abdominal cavity is entered through an incision in the linea alba (FIGURE 1). If the lines are difficult to identify, the subcutaneous tissue can be neatly cut with scissors at its midline attachments (FIGURE 2).⁵

The falciform ligament often obscures visualization of the cranial abdominal components and requires lateral transection and cranial ligation. A self-retaining retractor (eg, Balfour) helps maintain visualization, especially of the cranial abdomen; the surgeon must verify that there are no organs trapped between its lateral leaves and the abdominal wall. Moistened laparotomy sponges can be placed under retractor blades to protect the underlying skin and muscles.

Once the abdomen is opened, the presence, quantity and quality of the fluid must be assessed. If septic effusion is observed, samples should be obtained for culture and Gram stain. For patients with heoperitoneum, blood loss can be calculated by adding the amount of blood in the suction cup to the estimated amount of blood-saturated gauze. When completely soaked, a 4 × 4 gauze pad will contain approximately 12 mL of blood, while a 30 cm × 30 cm laparotomy sponge will contain approximately 100 mL of blood.⁶

Assessment

A proper exploratory laparotomy depends on the veterinarian's knowledge of anatomy.FIGURE 3) and attention to detail. To avoid missing injuries, a consistent and systematic technique is used. A common method is to sequentially examine structures iabdomen cranium (membrane, liver, gallbladder, stomach, pylorus, proximal duodenum, spleen), right and left gutters (descending duodenum, pancreas, kidneys, adrenal glands, ovaries, descending colon) and caudal abdomen (bladder, ureters, uterus, urethra, prostate, sublumbar lymph nodes) before you " conduct" the intestines (i.e., examine and palpate them for lesions). If no lesions are found, the surgeon must be prepared to collect multiple samples for diagnosis, particularly in patients with digestive tract signs.

intermediate floor

The central diaphragmatic tendon and pars lateralis and costal muscles are usually tight and concave. Looseness or loss of concavity may indicate the presence of pneumothorax, pleural effusion, intrathoracic masses, or diaphragmatic hernia. Any of these findings should trigger a request for monitoring and immediate ventilatory support. Diaphragmatic visualization requires retraction of the liver, gastrointestinal tract, and spleen.

Liver and Gallbladder

The liver consists of the left lateral, left medial, quadrate, right medial, right lateral, and caudate lobes. The gallbladder lies between the right medial and square lobes of the liver; the apical half is visible, while the rest is attached to the surrounding liver tissue. Normal hepatic lobes are dark red, smooth, and well delimited. A normal gallbladder is oval or round, thin-walled, and easy to extract in dogs. Because the common bile duct and pancreatic duct in cats can be connected or open in close proximity, gallbladder expression is not recommended in cats.⁷Liver abnormalities include changes in size, texture or color; marginal rounding; and bleeding or mass-like lesions. Abnormal vesicles are usually firm, distended, discolored, or attached to other organs.

In generalized or peripheral liver disease, a guillotine biopsy can be performed by ligating a portion of the lobe's edge with an absorbable loop of suture tied with a single surgical drape (FIGURE 4). Liver tissue is excised distally to the ligature, which is left in place. The likelihood of obtaining diagnostic specimens increases when multiple liver lobes are biopsied.⁸Focal or central lesions are sampled with a skin biopsy. If bleeding continues after sample removal, a clotting aid can be applied to the defect.

If hepatobiliary infection is suspected, cholecentesis may be performed in conjunction with liver biopsies and cultures. If the bile is thin, a 25-gauge needle may be sufficient for gallbladder aspiration. The needle can be inserted through adherent liver tissue to reduce leakage; if inserted through the apex of the gallbladder, the gallbladder must be completely drained to reduce the riskof bile leakage. Cholecentesis should be avoided in patients with biliary mucoceles, doubtful gallbladderwall integrity or complete biliary obstruction.⁹

Stomach

The stomach is composed of cardia, fundus, body and pylorus. The dorsal aspect of the stomach is seen by making a hole in the ventral leaf of the greater omentum to enter the omental bursa. The left branch of the pancreas and the vasculature of the spleen can be examined through the omental aperture at the same time. The only solid part of the stomach is the pylorus. The abdomen should be evaluated for abnormal color, thickness, or vascular pattern. The biopsy is performed through a full-thickness gastrotomy. For surgeons unfamiliar with normal pyloric size and thickness, pyloric assessment may require gastrotomy and digital insertion.

Milt

The spleen is in close connection with the greater curvature of the stomach and is connected to it by the gastrosplenic ligament. A normal spleen is dark purple with smooth, rounded edges, but the size and color can vary depending on the degree of splenic contraction and the effect of anesthetics. The spleen is evaluated for changes in size, symmetry, and texture; capsule integrity; and vascular supply (eg, tears, thrombosis, torsion). Although splenic biopsy can beperformed using a guillotine or wedge incision techniqueand closure, the spleen is usually removed completely if neoplasia, thrombosis, or infection is suspected.

Descending duodenum and right branch of the pancreas

The descending duodenum is the most dorsal intestinal structure in the right duct and is easily identified by the associated right branch of the pancreas. The blood supply to the descending duodenum forms an arcade from the anastomosis of the craniopancreaticoduodenal and caudopancreaticoduodenal branches of the cranial mesenteric artery; these vessels usually pass through the right branch of the pancreas. The body of the pancreas is adjacent to the pylorus, while the left branch of the pancreas lies within the greater omentum along the splenic artery and vein and is adjacent to the stomach and transverse colon. The common bile duct enters the serosal surface of the descending duodenum and travels intramural about one centimeter before opening intraluminally into the greater duodenal papilla. In animals with a dilated common bile duct, the surrounding pancreas should be evaluated for signs of inflammation or scarring, and the free and intramural portions of the duct can be gently palpated for choledocolytics or obstructive masses.

Pancreatic lobar tissue is generally white to pink, soft, thin, and flexible. The tissue can be gently palpated for nodules if an insulinoma is suspected; however, extensive or rough palpation may cause pancreatic ischemia or inflammation.¹⁰Pancreatic biopsy can be performed by blunt dissection of the lobules or ligation of a free edge using a guillotine technique. Avoid sampling areas containing large vessels or pancreatic ducts; if the pancreaticoduodenal vessels are damaged, the blood supply to the duodenum may be cut off.

Kidneys and adrenal glands

The kidneys lie in the retroperitoneal space and are often surrounded by fat. Both kidneys should be approximately the same size and shape and have a smooth exterior. Due to their retroperitoneal position and surrounding fat, the ureters are usually not visible as they exit the renal pelvis. Renal cortical biopsies are most commonly performed with a 16-gauge automated biopsy needle; for best results, 2 core samples are recommended.¹¹The renal parenchyma bleeds extensively; however, needle biopsy bleeding usually decreases with local digital pressure.

The adrenal glands are elongated, whitish tan and firm. The left gland lies medial to the cranial pole of the left kidney and is usually visible lateral to the caudal vena cava and below the left phrenicoabdominal vein. The right adrenal gland is more cranial and may be located dorsally to the caudal vena cava, making it difficult to visualize. The glands can be examined and palpated for enlargement or nodules, but due toadjacent vascular structures, sampling is not recommended unless the surgeon has advanced training.

Ovaries and uterine horn

In intact females, the ovaries and proximal uterine horns lie caudodorsally to the kidneys. They are usually located by retracting the descending duodenum or descending colon and associated viscera on the animal's left or right, respectively, to visualize the "gutters" in the abdominal cavity. Normal ovaries and uterus vary in size and shape depending on the reproductive stage. They should be examined for masses and cysts. In ovariectomized animals showing signs of estrus, the peritoneal tissue caudal to the kidneys and adjacent intestinal mesentery or omentum should be examined and palpated for nodules; these will be more evident if the animal is in heat. Ovarian remnants may be above the ureters and therefore must be carefully dissected.

Caudal Urogenital Treatment

A normal, distended urinary bladder is thin-walled, smooth, and relatively vascular. If the bladder is enlarged and obstructs visibility, it can be emptied by manual expression, cystocentesis, or catheterization. The decompressed bladder can be retracted caudoventrally out of the abdominal cavity to expose the ureters, which enter the trigone, and underlying dorsal structures such as the uterus/cervix, descending colon, and sublumbar lymph nodes.

The bladder narrows at the trigone and proximal urethra, which are hidden by the prostate in male dogs. The dog prostate is normally bilobed and can be quite small and firm in neutered dogs. It should be examined for abnormal enlargement, pockets of fluid (cysts or abscesses), or masses. Collateral to the bladder, trigone and urethra, vas deferens and testisthe vessels become intimately connected as they descend towards the inguinal canals. A cryptorchid testicle can be locatedfollowing the testicular artery and vein oflevel of the kidneys or vas deferens of the prostate.

body wall

While the abdominal gutters are exposed or the bladder is exteriorized, the dorsal and lateral surfaces of the peritoneumthe body wall can be examined. Distortion or disturbancemay be indicative of trauma or retroperitoneal bleeding, abscess, or masses (FIGURE 5).

gastrointestinal tract

Although various parts of the gastrointestinal tract are already examined visually, a final examination is performed by palpating the entire tract for changes in surface texture, color, diameter, thickness, and peristalsis.FIGURE 6). The jejunum is the longest, most mobile part of the small intestine and the region most likely to be blocked by intestinal foreign bodies. Peyer's patches are clusters of lymphoid follicles located in the small intestine; these should not be misinterpreted as neoplastic lesions.

The ileum is easily identified by its antienteric branches of the ileocecal artery and vein. The adjacent appendix is ​​a C-shaped, gas-filled protrusion. The ileococolic junction is another common site of foreign body entrapment. The colon consists of ascending, transverse, and descending parts, with the descending colon continuing as the rectum at approximately the level of the pelvic brim.

Intestinal biopsy can be performed using a scalpel blade or skin biopsy to remove a full-thickness piece of tissue (FIGURE 7). Intestinal closure requires precise apposition to avoid postoperative leakage or dehiscence; the most commonly absorbable 3-0 or 4-0 monofilament suture material is used. After closure, the bowel segment can be checked for leaks by occluding the lumen orally and aborad to the site and dilating the closed segment with sterile saline injected through a 25-gauge needle. 19 mL of saline should be injected if digital occlusion is used, while 12 to 15 mL of saline should be injected if Doyen forceps is used.¹²The omentum should be glued over the incision to improve the seal and reduce the risk of leakage.¹³

lymph nodes

Enlarged or abnormally textured lymph nodes may be collected by aspiration, incisional biopsy, or excisional biopsy (FIGURE 8). If possible, the lymph node should be dissected free of the surrounding mesentery or peritoneum. If complete excision is uncertain, a biopsy of a free end can be performed using a guillotine technique, or a piece of the lymph node can be removed with a wedge or scrape.

preparation for closing

Prior to closure, consideration should be given to the need for postoperative enteral nutrition and fluid support. Nasogastric tubes can be easily placed and removed, and if the anesthesiologist advances the tube intraoperatively, the surgeon can confirm its placement in the stomach, eliminating the need for postoperative radiographs.

If the gastrointestinal tract has been entered, gloves and instruments are changed. The stomach can be flushed with warm sterile saline to decrease inflammatory mediators, remove bacteria or contaminants, and warm the patient.^14,15If the procedure has minimal contamination, irrigation can be limited to the area around the biopsy or incision site. If septic peritonitis is suspected, the peritoneum should be irrigated until the return fluid is clear; this may require more than 200 ml/kg of sterile saline.¹⁶If significant contamination is still present after irrigation, continuous suction drains can be placed for postoperative fluid removal.¹⁷

After completion of all intra-abdominal procedures, sponges and laparotomy pads are counted to confirm that none are left in the abdomen.

Close

A simple continuous or interrupted pattern can be used to place the line or outer hem of the rectum; the peritoneum should not be included. During subcutaneous tissue closure, fat may intermittently adhere to the outer sheath of the rectum to reduce the risk of seroma formation.^18,19Skin edges can be secured with buried intradermal sutures, external sutures, or staples.

postoperative considerations

General postoperative care should include intravenous fluids, pain management, and nursing care. Unless significant contamination has occurred or infection is present, postoperative antibiotics are usually not required. Incisional complications are reported in 4.6% of animals undergoing laparotomy and may include infection or inflammation of the surgical site, dehiscence, pain and seroma formation.^18-20

References