Laparoscopic Ultrasonography

History of LUS

Combining the advantages of diagnostic laparoscopy with those offered by intraoperative ultrasonography seems a logical development, particularly for the assessment of liver tumors.2 The first report of a technique combining LS with US dates back to 1963, when Yamakawa41 described A-mode US scanning of a gallbladder cancer under LS guidance. But it was not until 19812 that Ohta42 and Oda43 reported their pilot studies using laparoscopic real-time B-mode scanning techniques. In 1983 Frank et al44 constructed a new "sonographic probe" with a 7 MHz linear transducer integrated in a laparoscope. A year later, Okita45 reported their experience with an "ultrasonic laparoscope" in 20 patients. A 3.5 and 5 MHz linear array was incorporated in a 13 mm laparoscope with a flexible tip. They found it to be especially useful for detecting small HCC deep in the right liver lobe and to diagnose early stage pancreatic cancer. In 1992, Miles et al46 inventively described the use of a rigid, 5 MHz endorectal US probe, passed through a (20 mm) large-bore trocar. They obtained unexpected findings in 6 out of 7 patients with hepatic tumors. At about the same time, Cuesta et al47 reported promising results, using a similar transducer, in 25 patients with hepatobiliary and pancreatic malignancies. Several different LUS probes have since been developed, from rigid to semi-flexible (tip) to fully-flexible designs, with 5 and/or 7.5 MHz transducers, and from 9-13 mm in diameter. These technical refinements have now yielded several commercially available LUS systems.

Patient Selection-Indications and Contraindications

When selecting patients for LUS it is important to consider the overall plan of management. There must be a clear understanding of the potential benefits offered by the procedure. The patient who is unable to tolerate a diagnostic laparoscopic procedure due to his/her general condition is unlikely to be a candidate for more extensive surgery.

Contraindications:

a) The principal contraindication to performing LUS is when the information that might be gained will not be meaningful in making therapeutic decisions.

b) Another reason is when open abdominal exploration is inevitable regardless of the possible findings of LUS.

c) Finally, there will be some cases where the liver and biliary tract are inaccessible due to adhesions or altered anatomy following previous surgery.

indications

There are three goals to performing diagnostic laparoscopy with ultrasonog-raphy in patients with hepatobiliary tumors: to establish the correct diagnosis, to provide an accurate staging of the disease, and to determine the appropriate treatment (i.e., surgical resectability). These goals are usually complementary, but each may be individually applied to three different categories of patients. Diagnostic

The diagnosis of intrahepatic lesions incidentally discovered during abdominal imaging (e.g., US for gallstones or pregnancy) which are suspicious but cannot be accurately differentiated externally.

Staging

The differential diagnosis of intrahepatic lesions detected during the workup or staging of malignancies;

i) non-gastrointestinal tumors (e.g., breast cancer), where the correct diagnosis is essential to decide appropriate therapy.

ii) gastrointestinal malignancies (e.g., esophageal or lower rectal cancer), where the correct diagnosis will influence the extent of surgery required or where other palliative procedures are available (e.g., endoscopic stenting or cryosurgery).

iii) uncertain lesions detected during follow-up for colon cancer, or raised CEA levels without obvious metastatic or recurrent tumor.

Treatment

To determine resectability and surgical strategy in all patients planned to undergo curative resection of a hepatobiliary malignancy.

i) liver metastases from colorectal or other primary tumors, (synchronous or metachronous). The exact number, size and segmental localization

will determine suitability for resection. Extrahepatic disease, particularly peritoneal implants and hepatic nodal involvement, can be excluded.

ii) primary liver malignancies. Exact size and location, the presence of satellite lesions, extension into surrounding structures (e.g., diaphragm, vena cava, duodenum) or intrahepatic vascular invasion (esp. portal vein) and the state of the hepatic parenchyma (cirrhosis) may all be assessed. Evaluation of candidates for liver transplant is another indication.

iii) gallbladder and proximal bile duct cancer. To determine the extent of local invasion, nodal or hepatic involvement, and exclude peritoneal spread.

Surgical Technique

There are several excellent monographs on various techniques of performing LS and LUS.48-52 The following is a detailed description of the procedure we use to stage potentially resectable hepatobiliary tumors.

General Aspects

Diagnostic laparoscopy with laparoscopic ultrasonography is usually planned as a separate procedure as this allows the most efficient planning of operating theater time, and may have psychological advantages when discussing therapeutic options with the patient. Alternatively, it may be done directly before laparotomy. The operation is preferably performed under general anesthesia as this permits the greatest freedom for a complete and precise examination. The entire procedure takes approximately 40 minutes. Patients may be discharged after several hours making it possible to use "day-care" facilities if available. Performing the LUS examination in collaboration with a radiologist is certainly advisable during the learning phase. It also provides an independent observer for interpreting the US images, one who is less likely to be biased by a motivation for resection.

Positioning of the Patient and Trocars

The patient is placed in a supine position and supported to allow tilting of the operating table as necessary. The surgeon stands on the left side with the radiologist opposite. Video monitor and ultrasound screen are on the upper right side (Fig. 8.1). Many patients will have a history of previous abdominal surgery, certainly those coming for the evaluation of colorectal metastases. The placement of trocars obviously depends on existing abdominal scars, but also on the type of surgery the patient has undergone. Although creative improvisation is necessary, there are certain guidelines for safe and effective positioning (Fig. 8.2). Abdominal insufflation may often be achieved using blind puncture with a Veress needle in the right upper abdomen (after left colonic surgery) or left subcostal region (after right-sided colon resections), with the patient placed in anti-Trendelenburg position. It is also possible to visualize intra-abdominal adhesions with transcutaneous ultrasound by observing the so-called "visceral slide". The safest technique, however, is through open placement of a Hasson trocar. Once the laparoscope has been introduced, secondary trocars are placed under visual control, which may require taking down adhesions. It is preferable to use disposable 10/11 mm ports to avoid damaging the LUS transducer surface with metallic valves. In the absence

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