Expert Interview with Prof. Thomas Carus - Laparoscopic Bowel Surgery

Prof. Dr. med. Dr. habil. Thomas Carus, FACS, is a recognized specialist in general, visceral, and vascular surgery with a particular focus on minimally invasive surgery, bariatric surgery, and abdominal disorders. Since his appointment as Chief of the Department of General and Visceral Surgery at Klinik Bassum in Lower Saxony in January 2023, he has been contributing his extensive expertise to the region’s medical care. His professional qualifications, complemented by numerous advanced training programs and his education as a health economist, make him a leading advocate of modern, patient-centered high-performance medicine. His medical profile combines in-depth knowledge of specialized surgical procedures with a strong understanding of efficient clinical processes.

He has many years of experience treating complex conditions of the gastrointestinal tract, the thyroid, and the blood vessels. Previously, he served as chief physician at renowned hospitals, where he established innovative standards in bariatric surgery and in the management of chronic wounds. Prof. Dr. Carus also enjoys an excellent reputation both nationally and among his peers—not only as an experienced surgeon but also as the author of numerous scientific papers.

Of particular note is his textbook *Atlas of Laparoscopic Surgery*, which has been reprinted multiple times and has garnered international attention. With his move to the Bassum Clinic, the Diepholz County Hospital Network gains a specialist whose commitment to medical quality, interdisciplinary collaboration, and modern treatment methods extends far beyond the region. As part of a high-performing team and using state-of-the-art medical technology, Prof. Dr. Carus is setting new standards in surgical care—always with the goal of providing patients with the best possible, gentle, and holistic treatment. The editorial team of the Leading Medicine

Guide was able to learn more about laparoscopic intestinal surgeries in a conversation with Prof. Dr. Carus.

Laparoscopic bowel surgery represents a significant advance in modern visceral surgery. In this minimally invasive procedure, the surgery is performed not through a large abdominal incision but through several small skin incisions, through which special instruments and a camera are inserted into the abdominal cavity. This technique allows for precise visualization of the surgical site while minimizing damage to surrounding tissue. The laparoscopic method has established itself as a gentle yet effective alternative to open surgery, particularly for conditions such as diverticulitis, colorectal cancer, or inflammatory bowel disease. Patients often benefit from less postoperative pain, a shorter hospital stay, and a faster return to daily life. Despite these advantages, the laparoscopic approach requires a high degree of surgical experience and technical equipment—factors that are crucial to the success of the treatment.

Whether bowel surgery can be performed laparoscopically—that is, using the “keyhole” technique—depends on a variety of medical, anatomical, and technical factors. In principle, the minimally invasive method aims to provide patients with the gentlest possible surgical procedure, featuring a shorter recovery time, less pain, and a lower risk of wound infections. However, not every case is automatically suitable for this approach.

“Various factors play a role in deciding whether intestinal surgery can be performed laparoscopically or not. In modern hospitals, the laparoscopic approach is now considered the standard procedure—developments in recent years have led to a situation where there is hardly any discussion today about whether to perform open or laparoscopic surgery. Rather, the discussion now centers on whether the surgery should be performed using purely laparoscopic techniques or robot-assisted laparoscopy. Technological advances have made a significant impact in this area and are already well-established in many hospitals. Nevertheless, there are clear guidelines, particularly for procedures involving colorectal cancer. In the case of colon cancer, for example, laparoscopic surgery is not recommended without restriction but is subject to certain conditions. For example, surgical treatment of benign intestinal conditions such as diverticulitis is generally possible via laparoscopy, unless the case involves severe or acute emergencies. In contrast, laparoscopic surgery for colon cancer requires special expertise—only experienced surgeons should perform this procedure, as only then can oncological outcomes comparable to those of open surgery be achieved,” explains Prof. Dr. Carus, adding:

“Even though in some countries, such as the United Kingdom, the laparoscopic approach for colon cancer has been widely recommended for years, the rate in Germany currently remains below fifty percent. The currently valid German guideline confirms that, provided the surgeon is appropriately qualified and patient selection is appropriate, laparoscopic surgery can deliver the same oncological outcomes as open surgery. At the same time, there is not yet sufficient data available for newer procedures such as robot-assisted surgery. For this reason, their use is currently recommended only within the context of clinical trials. In this respect, it is by no means wrong today to perform certain bowel procedures using open surgery—the decisive factors are always the individual circumstances and the experience of the treating surgeon.”

Prof. Dr. Carus adds: “For benign intestinal conditions, laparoscopic surgery is generally the standard of care today—this is also enshrined in the guidelines. The main reason for this is the lower complexity of these procedures. In contrast to oncological surgeries, in which not only the diseased segment of the intestine but also all associated lymph nodes must be radically removed, the procedure for benign lesions is often limited to the removal of a section of the intestine without additional tissue structures. Oncological surgeries require a much more precise and extensive approach, in which deeper anatomical structures must be exposed and carefully removed. This is technically more demanding, especially with laparoscopic procedures, since the surgeon cannot work directly with their hands in the surgical field.”

Minimally invasive techniques—particularly in bowel surgery—have a proven positive impact on reducing postoperative complications. Compared to open surgery, the laparoscopic method offers several advantages that affect both short-term recovery and the long-term risk of complications.

“Minimally invasive techniques offer patients a whole range of positive effects after surgery, which are particularly significant in the case of major procedures. For minor surgeries, such as an appendectomy, the difference between a small open incision and a laparoscopic approach is clinically barely noticeable. The situation is different for major surgeries, such as procedures on the intestines. In these cases, a large abdominal incision along the midline—often 15 to 20 centimeters long—would typically be necessary as an alternative. It is well documented that pain medication use increases with the length of the incision, which actually stands to reason. A larger incision means more pain, which makes it harder for patients to get out of bed. It is known that this also impairs lung function—solely due to the pain—and that, in turn, increases the risk of pneumonia. Reduced mobility also increases the risk of thrombosis and pulmonary embolism. Hospital stays are also longer with open surgery, time off work is longer, and it takes significantly longer to return to normal physical activity. In the long term, open surgery can also lead to more internal adhesions, some of which cause lifelong discomfort and often require follow-up surgeries. Larger incisions are also more frequently associated with subsequent incisional hernias, which in turn require surgery—all of which are significantly less common with the laparoscopic approach. Added to this is the cosmetic aspect, which also plays a role for many patients today. And very importantly: it’s also a matter of when one can resume full physical activity and exercise. After a large abdominal incision, this is naturally very limited at first. With laparoscopy, the patient can, in principle, get up on the day of the surgery, move around freely, and go to the bathroom independently. Of course, the removed tissue has to be extracted from the body somewhere—that’s what the so-called retrieval incision is for. It measures about four to five centimeters and is the largest of the small incisions. It causes only very minor discomfort, including in terms of pain,” says Prof. Dr. Carus.

Despite all the advantages, the most significant complication—whether the surgery is open or laparoscopic—remains intestinal anastomotic insufficiency, that is, a suture rupture at the anastomosis.

“These anastomotic leaks usually occur on the fourth or fifth day after surgery. So even if everything looks good at first, you can’t say for sure after two days that the healing process will proceed without complications. Despite all the surgical experience, the rate of such failures is about five to ten percent—meaning this complication occurs in one out of every ten to twenty patients. “That is why patients generally remain hospitalized for five days; during this time, they are fully mobilized and can then be discharged on a normal diet,” explains Prof. Dr. Carus.

In Germany, the trend toward outpatient care is gaining ground slowly but steadily, albeit with a significant delay compared to the United States. There, many surgeries can already be performed on an outpatient basis, a practice that has so far often been held back in Germany out of caution.

Prof. Dr. Carus explains: “One example where this shift is already noticeable is inguinal hernia surgery—it is now performed on an outpatient basis in many cases, as are numerous endoscopic procedures. With the introduction of so-called hybrid DRGs, a uniform reimbursement system has been established that applies regardless of whether a patient is discharged on the same day or the following morning. This regulation will also be extended to gallbladder surgery in 2026. Whereas patients used to stay in the hospital for two weeks after open gallbladder surgery, many now ask to be discharged as early as the first day—and this is increasingly being made possible, in some cases even that same evening. Until now, however, the German billing system has been a stumbling block: For certain procedures, such as colon surgery, there was a mandated minimum hospital stay. Anyone who discharged a patient early risked having to reimburse the health insurance provider. But that is set to change.

It’s quite conceivable that in the future, patients who have undergone colon surgery will also be able to go home—for example, after two or three days—provided that no drains need to be inserted and their clinical condition is stable. This would require close follow-up care with blood tests and clinical checkups at the outpatient clinic. If, for example, a complication were to arise on day five, it would still be possible to respond by readmitting the patient to the hospital. In fact, many patients remain in the hospital for the first five days after surgery without much medical intervention taking place—purely as a precaution. Of course, patient safety plays a major role in this. Many people initially find early discharge after major surgery unsettling. It’s understandable to wonder how this is compatible with one’s sense of security. But you can also look at it positively: For 90 to 95 percent of patients, everything goes smoothly. If you communicate this and make it clear that medical intervention can be provided at any time should symptoms arise, you can effectively convey to many patients the idea of safe outpatient follow-up care.”

The surgeon’s experience plays a central role in the selection and successful performance of minimally invasive procedures such as laparoscopic bowel surgery—perhaps even a greater role than with open surgery. While open surgery is based on established techniques that many surgeons have learned over decades, the minimally invasive method requires specialized training, a high degree of technical precision, and excellent spatial awareness.

“In modern surgery, laparoscopic techniques have long been an integral part of training. Young resident physicians begin with simple procedures such as laparoscopic appendectomy or cholecystectomy—procedures that simply involve removing something, which is technically rather straightforward. As training progresses, the demands increase, for example with laparoscopic hernia surgery. Here, a very good understanding of anatomy and fine motor skills are already required, as a great deal of dissection is involved. This stage is already considered more challenging and is typically performed by resident physicians in the middle of their training. The next major step in becoming a skilled laparoscopic surgeon is suturing and connecting organs within the abdominal cavity—that is, creating what are known as anastomoses. These techniques are used, for example, in bowel resections. This involves not only removing diseased sections but also carefully reconstructing the anatomical structures. These are highly complex procedures that require dissection, cutting, suturing, and layering—all performed with specialized instruments, some of which are remote-controlled. It takes many years to truly master these skills with confidence. Typically, training begins no earlier than the fifth or sixth year of residency under supervision, until one eventually performs surgeries independently as a specialist or senior resident. “However, true confidence in these procedures usually comes only after about ten years of experience,” emphasizes Prof. Dr. Carus.

The surgical procedure is particularly challenging, especially in cases of malignant diseases such as colorectal cancer.

“It’s not enough to simply remove the tumor—an entire block of blood and lymph vessels, as well as adjacent lymph nodes, must be excised. Figuratively speaking, this is like a large slice of cake that must be cleanly removed. This oncologically radical resection requires a high degree of precision. In open surgery, this is often easier to accomplish, since the surgeon can work and palpate directly inside the abdominal cavity with their hands. With laparoscopy, on the other hand, the surgeon must lift, hold, and stretch the tissue with instruments while simultaneously maintaining a clear view and precision—a real challenge. In practice, this also explains why the same patient receives different recommendations at two different hospitals: While the procedure is performed open at one hospital, it is performed laparoscopically at the other. This is often due to the individual experience of the surgeons. Older surgeons in particular, who have built their expertise in open surgery, often stick with this approach—not out of convenience, but because they are trained in it and achieve excellent results. Although some studies show isolated advantages of laparoscopy—such as less blood loss or less impairment of the immune system—complete tumor removal remains the decisive factor. And this is possible with both open and laparoscopic surgery—what matters is expertise,” says Prof. Dr. Carus.

In hospitals that primarily perform open surgery, a distinction is therefore often made between benign and malignant conditions: Benign findings are treated with minimally invasive surgery, while malignant ones are treated with traditional open surgery. Each patient is informed about both options, including the fact that a laparoscopic procedure can be converted to open surgery at any time if complications arise.

Prof. Dr. Carus comments: “For me personally, the laparoscopic approach is the standard, provided there are no clear reasons against it—such as massive adhesions following previous surgeries. Even then, I usually start laparoscopically to perform at least some steps as minimally invasively as possible and to limit the open procedure to a minimum. What laparoscopy lacks is the sense of touch provided by the fingers—a sense that is particularly well-developed and finely honed in surgeons. Tiny structures, such as lymph nodes, can often be palpated more reliably with the fingers than with a camera and instruments. In open surgery, I can immediately feel even the smallest irregularities, as if I were feeling under a tablecloth. This isn’t possible with laparoscopy. However, I do have other advantages: I work with state-of-the-art 3D camera systems, can get very close to the tissue, and thus have enormous magnification and sharpness of detail—better than with the naked eye in open surgery. The distance to the surgical field is about 50 centimeters with the open technique, whereas with laparoscopy, the camera is just a few millimeters away from the tissue. This allows for a view that is almost microscopically precise. Modern developments such as fluorescence-enhanced imaging also help, for example, to visualize lymph nodes that would otherwise have to be palpated. This increasingly compensates for the only real disadvantage of laparoscopy—the lack of palpation.”

Robot-assisted systems—most notably the Da Vinci system—have revolutionized minimally invasive surgery in many areas. These systems allow the surgeon to control the instruments with extreme precision via a console. The robotic arms are highly maneuverable and can perform movements that are more precise than what would be possible with the human hand alone.

“While there is currently no scientifically substantiated evidence that robot-assisted surgeries yield better oncological outcomes than traditional laparoscopy—for example, in terms of five-year survival rates or tumor recurrence rates— Nevertheless, robotics offers clear technical advantages that are particularly beneficial during more complex procedures. Our clinic also plans to introduce a robot-assisted system such as the Da Vinci robot in the near future, as soon as funding is secured. This robot provides an enhanced 3D view and transmits the surgeon’s movements from a control console directly to the instruments inside the patient’s body. At this console, the surgeon operates using hand controls and pedals, enjoying significantly greater freedom of movement than during conventional laparoscopic procedures. While laparoscopy uses rigid, rod-shaped instruments that can only rotate and move to a limited extent, the robotic instruments are fully movable at their tips—similar to a human hand. When the surgeon turns his hand to the left or right, the tip of the instrument follows this movement with millimeter precision inside the body. Another advantage lies in the scaling of the movements. The robot can scale down the surgeon’s movements by a factor of 5: an external hand movement of five centimeters is reduced to just one centimeter in the surgical field. This enables extremely precise work, especially in narrow anatomical regions or hard-to-reach areas. This is precisely where the particular benefit of robotics lies, for example, in cases of deep-seated rectal cancers in the pelvis, where space is very limited, especially in male patients. The robot can also offer advantages in the upper abdomen—for example, near the esophagus or the entrance to the stomach—anywhere where complex suturing or dissection is required.”

At Bassum Clinic, over 100 bowel resections are performed annually, about 80 percent of which are done laparoscopically. Minimally invasive techniques play a major role, especially in the treatment of benign conditions.

“A classic example is diverticulitis, which is initially treated conservatively with antibiotics in milder episodes. However, if recurrent or severe episodes occur, the affected segment of the intestine is surgically removed. Another common benign indication involves large colon polyps that cannot be removed endoscopically—here, too, surgical intervention is necessary. A particularly positive example in the field of colorectal surgery involves patients with a temporary artificial bowel outlet, known as an anus praeter. Even if this was initially created via an abdominal incision, the reversal can be performed laparoscopically in many cases. This means that, after about three to six months, the stoma can usually be reversed without the need for another major abdominal incision. This is an important prospect for patients, as a temporary stoma by no means has to mean a permanent limitation. The management of artificial bowel openings has also improved considerably in recent decades. Stoma care technology has advanced significantly today, which makes daily life much easier for those affected. In addition, stomas are created much less frequently today than in the past. Previously, it was common practice to create so-called “protective stomas” to relieve pressure on a fresh intestinal suture—an anastomosis—and allow it to heal more effectively. Today, however, surgical techniques have advanced to the point where these connections heal reliably even with the passage of stool, so that an additional stoma is usually not necessary,” explains Prof. Dr. Carus.

When a patient is diagnosed with colorectal cancer, it is crucial for the best possible treatment that they seek care at a specialized center such as the Bassum Clinic, where a so-called tumor board is in place.

“In a tumor board, the treatment plan is coordinated on an interdisciplinary basis—that is, with the involvement of internists, radiologists, pathologists, and surgeons—and the appropriate course of treatment for each individual case is carefully considered even before surgery. After all, not every tumor is treated the same way: A deep-seated rectal carcinoma typically requires preoperative chemoradiotherapy, whereas a tumor located higher up in the sigmoid colon is usually treated directly with surgery. Such decisions are based on medical guidelines and are made collectively by the tumor board. It is also advisable to seek a second opinion—after all, this is a major procedure with far-reaching implications. In most cases, however, primary care physicians are well-informed about which hospitals specialize in major cancer surgery and can refer patients accordingly. In general, one can assume in Germany that medium-sized to large hospitals have sufficient experience in colorectal cancer surgery. Furthermore, hospital websites often indicate whether oncological procedures are performed there on a regular basis—a clear indication of routine expertise in the field. Anyone who is also considering specific technical procedures, such as robot-assisted surgery, should openly discuss this during their consultation with their doctor. No surgeon can make a blanket statement that the use of a robot is always better.

In certain situations—such as when a tumor is located at an unfavorable depth in the narrow pelvis—robotic surgery can offer advantages, especially if the hospital has experience with this technique. It is therefore entirely possible that one surgeon might opt for open surgery because he feels confident in that technique, while a neighboring hospital has robotic equipment and routinely performs surgeries using it. Ultimately, it is crucial to be able to rely on an experienced surgeon who provides transparent advice during the consultation—someone who recognizes the patient’s individual circumstances and offers a well-founded, honest recommendation for the best treatment approach,” is the urgent advice from Prof. Dr. Carus, and with that we conclude our conversation.

Thank you very much, Prof. Dr. Carus, for this very informative conversation!