**4. Intraoperative ultrasound in colorectal surgery**

### **4.1 Early and precise detection of liver metastases with consecutive treatment: Resection, RFA, cryosurgery**

According to Walker and collab [11], up to two-thirds of colorectal cancer (CRC) patients develop colorectal liver metastases (CRLMs), with one-quarter of patients having synchronous metastases.

Surgical resection for CRLM provides the best chance of a successful outcome. Computerized tomography and magnetic resonance imaging are often used to stage CRC prior to surgery.

Intraoperative ultrasound (IOUS) and contrast-enhanced IOUS (CE-IOUS) scans have been shown to detect additional metastases not visible on preoperative imaging.

Colorectal surgeons do not commonly use IOUS during primary resection for CRC.

The confident use of IOUS/CE-IOUS after primary resection of CRC can aid decision-making by giving the most sensitive type of liver staging, even when compared to magnetic resonance imaging. This is especially significant in the age of laparoscopic procedures, as the colorectal surgeon loses the ability to palpate the liver and its lesions.

The use of IOUS/CE-IOUS by colorectal surgeons has been hampered by a number of factors.

Time constraints, familiarity with procedures, a perceived learning curve, cost effects, and numerous limitations of the modality due to operator variations are just a few of them.

Incorporating IOUS into colorectal surgeons' basic training and subsequent research into the potential benefits of IOUS/CE-IOUS could theoretically lower these barriers, allowing for more widespread use of IOUS during primary resection for CRC. In a research performed by Desolneux and coauthors [12], the central idea was to determine the clinical utility (CU) of contrast-enhanced intraoperative ultrasound (CE-IOUS) using sulfur hexafluoride microbubbles during CRLM surgery. The conclusion was that although the primary endpoint was not met for one protocol violation, secondary endpoints indicate that CE-IOUS has an intermediate added value for surgeons treating CRLMs (**Figure 4**).

#### **4.2 Localization of colorectal tumors**

In a study published by Greif and collab [13] with the goal of determining the accuracy of intraoperative ultrasound (IOUS) as a localizing technique for colorectal resections and its impact on surgical management, it was discovered that IOUS can be used as a sole method of intraoperative localization and provide additional information in patients with small polyps and early cancers of the colon and rectum.

Furthermore, a study by Luck and team [14] discovered that in an *in vitro* setting, a direct ultrasound of the colon utilizing a high-frequency surgical probe gave accurate pictures of neoplastic tumors. This method may play a part in the

#### **Figure 4.**

*(a) Standard intraoperative transducer position for liver scanning. (b) Rotational transducer movement, the probe is rotated clockwise or counterclockwise on a fixed point, in order to see in two planes. (c) Rocking/tilting the transducer without (above) or with (down) saline immersion. (d) Positions of the probe in order to look at the biliary tree—Main divisions.*

intraoperative location of lesions and assessment of colorectal cancer. Furthermore, the same research adds to the overall picture by stating that excellent ultrasound images were obtained, particularly when the colonic lumen was filled with saline.

This technique found and correctly located all lesions, as well as several impalpable synchronous polyps.

The remains of a malignant polyp not evident with intraoperative colonoscopy were discovered by specimen ultrasound in two specimens.

The image's clarity allowed for cancer staging.

The benefit of using laparoscopic high-resolution ultrasonography in conjunction with color power Doppler to locate colonic polyp lesions during a laparoscopic colon resection, as stated by Panaro and coauthors [15], is that intraoperative colonoscopy is avoided.

Intraoperative colon ultrasonography can pinpoint colonic polyp lesions that are not visible during laparoscopy, and it is a quick and painless alternative to other imaging techniques.

## **4.3 Guidance of the technique of quadratus lumborum block for postoperative pain management in colorectal surgery**

In an article authored by Deng [16], it was underlined that laparoscopic ultrasound can be used for guiding the injection site in quadratus lumborum block

#### *Intraoperative Ultrasound in Colorectal Surgery DOI: http://dx.doi.org/10.5772/intechopen.100411*

(QLB) for pain management. The study looked at 74 patients who were scheduled for laparoscopic colorectal surgery and were divided into two classes at random.

Following surgery, patients were given a single dose of QLB or TAPB administered bilaterally using ultrasound guidance.

Twenty-microliter of 0.375% ropivacaine was injected into each hand.

All patients were given sufentanil as a patient-controlled intravenous analgesia (PCIA), and the results showed that the QLB is a more powerful postoperative analgesia than the TAPB in patients undergoing laparoscopic colorectal surgery because it decreases sufentanil intake.

#### **4.4 Doppler assessment of flow and vessel division**

AS early as 1980, studies evaluating colonic blood flow through intraoperative Doppler ultrasound showed that laser Doppler flowmetry represents a potentially very interesting non-invasive, continuous method for the quantitative study of human intestinal blood flow, such as the one performed by Ahn and team [17]. In parallel to the study on humans and completing the general picture with valuable information regarding blood flow, a study by Kashiwagi and collab [18] will be further described. In order to determine the minimal threshold of tissue blood flow (TBF) for safe colonic anastomosis, an experiment was performed in dogs: The wound healing process of anastomotic sites was correlated with varying degrees of TBF, measured by laser Doppler velocimetry (LDV). The conclusion of the abovementioned study was in terms of TBF, if the LDV value at the anastomotic site is at least 1.0, equivalent to about 30% of the TBF of the intact colonic wall, then the anastomosis is considered healthy and dehiscence is unlikely.

In a study presented by Seike and coauthors [19], colonic blood flow at the proximal site of the anastomosis was measured by laser Doppler flowmetry in 96 patients with the rectum and sigmoid colon cancer while clamping IMA or LCA, and the conclusion of the research that looked at which point of ligature would be optimal was that colonic blood flow at the proximal site of the anastomosis was crucial. Patients who undergo ultralow anterior resection and have a high reduction by IMA clamping need various intraoperative efforts to avoid ischemia at the stage of the anastomosis.

According to another study reported by Hallbook [20], laser Doppler flowmetry was used to measure transmural colonic blood flow before the formation of a plain (*n* = 16) or pouch (*n* = 14) anastomosis during the surgery. Before dissecting the bowel, the vascular supply was recorded at two locations: one near to the intended bowel end and another 8 cm away.

After dissection and, where possible, pouch creation, but before the anastomosis was completed, a second recording was made at the same sites.

Following bowel dissection, blood flow levels at the site intended for the anastomosis were substantially reduced in the end-to-end anastomosis community.

Following bowel dissection and pouch building, blood supply levels at the site of the anastomosis were comparable in the pouch community (side-to-end anastomosis).

Unaffected blood supply at the pouch anastomosis site can be a beneficial factor for anastomotic healing, according to the findings.

Furthermore, when it comes to the small bowel partner of an anastomosis, such as the ileocolic anastomosis after right hemicolectomy or the confection of a small bowel J pouch, blood flow supply must be assessed.

This can now be done more accurately with the aid of an ICG quantitative flow technique, but laser Doppler can still be used for orientation, as demonstrated in a study published by Johansson and coauthors [21]. The precision of the blood

flow evaluation by Doppler is such that one can look at the sutureline blood flow in colonic anastomoses, to compare the impact of a mechanical versus a manual anastomosis on the blood supply to the anastomosed area, as was emphasized by Chung and team [22].
