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 diseases. Since his appointment as Chief Physician of the Department of General and Visceral Surgery at the Bassum Clinic in Lower Saxony in January 2023, he has been contributing his extensive expertise to the medical care of the region. His professional qualifications, complemented by numerous additional certifications and his training as a health economist, make him a leading representative of modern, patient-centered high-performance medicine. His medical profile combines in-depth knowledge of specialized surgical techniques with a strong understanding of efficient clinical workflows.
He has many years of experience in treating complex diseases of the gastrointestinal tract, thyroid, and vascular system. Previously, he served as Chief Physician at renowned clinics where he established innovative standards in bariatric surgery and chronic wound management. Prof. Dr. Carus enjoys an excellent reputation both regionally and in the professional community — not only as an experienced surgeon but also as the author of numerous scientific publications.
Particularly noteworthy is his widely published textbook, the “Atlas of Laparoscopic Surgery,” which has gained international recognition. With his move to Bassum Clinic, the Landkreis Diepholz clinic network has gained a specialist whose commitment to medical quality, interdisciplinary collaboration, and modern treatment methods resonates far beyond the region. Working within a high-performing team and with state-of-the-art medical technology, Prof. Dr. Carus is setting new standards in surgical care — always with the goal of treating patients as effectively, gently, and holistically as possible.
The Leading Medicine Guide editorial team had the opportunity to learn more about laparoscopic bowel surgery in a conversation with Prof. Dr. Carus.
Laparoscopic bowel surgeries represent a significant advancement in modern visceral surgery. In this minimally invasive technique, the procedure is performed not through a large abdominal incision but through several small skin incisions, through which specialized instruments and a camera are inserted into the abdominal cavity. This approach allows for precise visualization of the surgical field while preserving surrounding tissue. Especially in conditions like diverticulitis, colorectal cancer, or chronic inflammatory bowel diseases, the laparoscopic method has established itself as a gentle yet effective alternative to open surgery. Patients often benefit from less postoperative pain, shorter hospital stays, and quicker recovery times. Despite these advantages, the laparoscopic approach requires a high degree of surgical experience and technical equipment — both critical factors for treatment success.
Whether a bowel surgery can be performed laparoscopically — that is, using keyhole techniques — depends on a variety of medical, anatomical, and technical factors. Fundamentally, the minimally invasive approach aims to offer patients the least invasive procedure possible, with shorter recovery time, less pain, and a lower risk of wound infections. However, not every case is automatically suitable for this approach.
“When deciding whether a bowel surgery can be performed laparoscopically, several factors come into play. In modern clinics, the laparoscopic approach is now considered the standard procedure — recent developments have led to the point where we hardly debate whether to operate openly or laparoscopically. Instead, the current discussion revolves around whether to operate purely laparoscopically or robot-assisted laparoscopically. Technological advancements have made a clear impact here and have already been established in many institutions. Still, there are clear guidelines, especially for colorectal cancer procedures. For colon cancer, for example, laparoscopic surgery is not unconditionally recommended but tied to specific prerequisites. The surgical treatment of benign bowel diseases such as diverticulitis is generally possible laparoscopically unless it involves severe or acute emergencies. In contrast, laparoscopic surgery for colon cancer requires special expertise — only experienced surgeons should perform this procedure to achieve oncological outcomes comparable to open surgery,” explains Prof. Dr. Carus, and continues:
“Even though in some countries like the United Kingdom, the laparoscopic method for colon cancer has been broadly recommended for years, the rate in Germany currently remains below fifty percent. The current German guidelines confirm that with appropriate surgeon qualification and suitable patient selection, laparoscopic surgery can deliver the same oncological outcomes as open surgery. At the same time, there is still insufficient data for newer procedures such as robot-assisted surgery. Therefore, its use is currently only recommended within the framework of clinical studies. Accordingly, even today, it is by no means wrong to perform certain bowel surgeries openly — what matters are the individual circumstances and the experience of the treating surgeon.”
Prof. Dr. Carus adds: “For benign bowel diseases, laparoscopic surgery is now typically the standard — this is also reflected in the guidelines. The main reason lies in the lower complexity of these procedures. In contrast to oncological surgeries, where not only the diseased bowel segment but also all associated lymph nodes must be radically removed, the procedure for benign changes often involves simply removing a bowel section without additional tissue structures. Oncological surgeries require much more precise and extensive work, where deeper anatomical structures must be exposed and carefully removed. This is technically more demanding, especially with laparoscopic methods, because the surgeon cannot work directly with their hands in the surgical field.”
The minimally invasive technique — especially for bowel surgeries — has a demonstrably positive impact on reducing postoperative complications. Compared to open surgery, the laparoscopic approach 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 major procedures. In smaller surgeries, such as an appendectomy, the clinical difference between a small open incision and a laparoscopic approach is hardly noticeable. It’s a different story with larger operations, like those involving the bowel. In these cases, the alternative would usually be a large abdominal incision along the midline — often 15 to 20 centimeters long. It’s well documented that pain medication use increases with incision length, which is quite intuitive. A larger incision means more pain, making it harder for patients to get out of bed. We know this also affects lung function — simply due to the pain — which in turn raises the risk of pneumonia. Reduced mobility also increases the risk of thrombosis and pulmonary embolism. Hospital stays are longer with open surgeries, time off work is extended, and it takes significantly longer to return to normal physical activity. In the long term, open procedures can also lead to more internal adhesions, which can cause lifelong discomfort and often require follow-up surgeries. Larger incisions are also more frequently associated with later incisional hernias, which again need surgical correction — all of this is much less common with the laparoscopic approach. There’s also the cosmetic aspect, which is increasingly important to many patients nowadays. And crucially, it’s also about how soon one can fully engage in physical activity and sports again. After a major abdominal incision, this is naturally very limited at first. With laparoscopy, the patient can basically get up, move around, and go to the bathroom independently on the day of the surgery. Of course, the removed tissue has to be taken out of the body somewhere — for this, we use the so-called retrieval incision. It’s about four to five centimeters long and represents the largest of the small incisions. It causes very little impairment, even regarding pain,” says Prof. Dr. Carus.
Despite all advantages, the most critical complication — whether operated openly or laparoscopically — remains the insufficiency of the bowel connection, that is, an anastomotic leak.
“These leaks usually occur on the fourth or fifth day after surgery. So even if everything looks good initially, you can’t be sure after just two days that the healing process will remain complication-free. The rate of such insufficiencies remains at about five to ten percent despite all surgical experience — meaning that this complication occurs in roughly one in ten to one in twenty patients. That’s why patients generally stay hospitalized for five days, are fully mobilized during this time, and can then be discharged on a normal diet,” explains Prof. Dr. Carus.
In Germany, the trend toward outpatient care is progressing slowly but steadily, although with a considerable delay compared to the U.S., where many procedures are already performed on an outpatient basis, something that is still often held back here out of caution.
Prof. Dr. Carus elaborates: “A good example where this shift is already noticeable is inguinal hernia surgery — it’s now often done on an outpatient basis, as are many endoscopic procedures. With the introduction of the so-called hybrid DRGs, a uniform reimbursement system has been established that applies regardless of whether a patient is discharged the same day or the next morning. This regulation will be extended to gallbladder surgery in 2026. Whereas patients used to stay in the hospital for two weeks after an open gallbladder surgery, today many ask about discharge on the very first day — and increasingly, this is made possible, sometimes even that same evening. Until now, however, the German billing system has been a hindrance: For certain procedures like colon surgery, there was a prescribed minimum length of stay. Discharging earlier meant risking repayment to the health insurance fund. But that’s going to change.
It’s quite conceivable that in the future, patients will go home even after major bowel surgery — for example, after two or three days — provided no drains are needed and the clinical situation is stable. This would require close outpatient follow-up with blood tests and clinical checks. If, say, a complication were to arise on day five, one could still intervene and readmit the patient. In fact, many patients spend the first five days after surgery in the hospital without much happening medically — purely as a precaution. Of course, patient safety plays a major role. Many people initially find early discharge after a major procedure unsettling. It’s understandable to wonder how this aligns with one’s sense of security. But you can also look at it positively: In 90 to 95 percent of patients, everything proceeds without problems. If you communicate that clearly and make it known that any emerging issues can be addressed promptly, many people can be reassured about the idea of safe outpatient follow-up care.”
The surgeon’s experience plays a central role in the selection and successful execution of minimally invasive procedures like laparoscopic bowel surgery — possibly even more so than with open procedures. While open surgery is based on established techniques that many surgeons have learned over decades, the minimally invasive approach requires specialized training, high technical precision, and excellent spatial awareness.
“In modern surgical training, laparoscopic techniques are now a firmly established part. Young residents start with simpler procedures like laparoscopic appendectomy or cholecystectomy — procedures that primarily involve removal, which is technically less demanding. As training progresses, the complexity increases, such as with laparoscopic hernia surgery. This stage already requires a very good anatomical understanding and fine motor skills, as a lot of delicate dissection is involved. It’s considered more challenging and is typically undertaken by residents midway through their training. The next major step in developing into a skilled laparoscopic surgeon is suturing and connecting organs in the abdomen — that is, creating so-called anastomoses. These techniques come into play during bowel resections, where not only diseased sections must be removed but also the anatomical structures carefully reconstructed. These are highly complex procedures involving dissection, cutting, suturing, and stapling — all with specialized, often remote-controlled instruments. It takes many years to master this safely. Typically, you start this no earlier than the fifth or sixth year of training under supervision, and eventually, as a specialist or senior physician, you perform these procedures independently. True confidence in these techniques usually comes only after around ten years of experience,” emphasizes Prof. Dr. Carus.
Especially in malignant diseases like colorectal cancer, the surgical approach is particularly demanding.
“It’s not enough to simply remove the tumor — an entire block of blood and lymphatic vessels as well as adjacent lymph nodes must be taken out. Figuratively, you’re removing a large wedge of tissue cleanly. This oncologically radical resection requires high precision. In open surgery, this is often easier to achieve because you can work directly in the abdominal cavity with your hands and feel the tissues. Laparoscopically, on the other hand, you have to lift, hold, and tension the tissue with instruments while maintaining excellent visualization and precision — a real challenge. In practice, this also explains why the same patient might receive different recommendations in two different hospitals: while one hospital might recommend open surgery, another might suggest a laparoscopic approach. This often depends on the individual experience of the surgeons. Especially older surgeons who have honed their expertise in open techniques often stick with them — not out of convenience, but because they are highly trained and achieve excellent results with them. Although studies have occasionally shown advantages for laparoscopy, such as less blood loss or lower immune system impact, what ultimately matters is the complete tumor removal. And that can be achieved both openly and laparoscopically — the key is expertise,” says Prof. Dr. Carus.
In clinics where open surgeries predominate, a distinction is often made between benign and malignant conditions: benign cases are operated on minimally invasively, malignant ones classically open. Every patient is informed about both options, including the fact that a laparoscopic procedure can always be converted into an open surgery if complications arise.
Prof. Dr. Carus explains: “For me personally, the laparoscopic approach is the standard unless there are clear reasons against it — such as massive adhesions from prior surgeries. Even then, I usually start laparoscopically to perform at least parts of the procedure as minimally invasively as possible and limit the open portion to a minimum. What laparoscopy lacks is the tactile sense of the fingers — a sense that is especially refined and trained in surgeons. Tiny structures, like lymph nodes, can often be felt more reliably by hand than detected with a camera and instruments. In open surgery, I can immediately sense even the slightest irregularities, like feeling under a tablecloth. Laparoscopically, that’s not possible. But I do have other advantages: I work with the most modern 3D camera systems, can move very close to the tissue, and thus achieve enormous magnification and detail resolution — better than the naked eye in open surgery. In open techniques, the distance to the surgical field is about 50 centimeters, whereas in laparoscopy, the camera is just millimeters away from the tissue. This allows for almost microscopic precision. Modern developments like fluorescence-guided imaging additionally help make lymph nodes visible that you would otherwise have to feel. As a result, the only real drawback of laparoscopy — the lack of tactile feedback — is increasingly being compensated for.”
Robot-assisted systems — foremost the Da Vinci system — have revolutionized minimally invasive surgery in many areas. These systems allow the surgeon to control the instruments with extreme precision from a console. The robotic arms are highly maneuverable and can perform finer movements than human hands alone.
“Although there is currently no scientifically proven evidence that robot-assisted surgeries deliver better oncological outcomes than classic laparoscopy — such as five-year survival rates or tumor recurrence rates — the robotics offer clear technical advantages, especially for more complex procedures. Our clinic also plans to introduce a robotic system like the Da Vinci robot in the near future once funding is secured. This robot provides enhanced 3D visualization and transmits the surgeon’s movements from a control console directly to the instruments inside the patient’s body. At the console, the surgeon works with hand controls and foot pedals, gaining significantly more freedom of movement compared to conventional laparoscopy. While laparoscopy uses rigid, rod-shaped instruments with limited rotational capability, the robotic instruments have fully articulating tips — similar to a human hand. When the surgeon moves their hand left or right, the instrument tip follows that movement with millimeter precision inside the body. Another advantage is motion scaling: the robot can reduce the surgeon’s movements by up to a factor of five — an external hand movement of five centimeters is reduced to just one centimeter at the surgical site. This allows for extremely precise work, particularly in narrow anatomical regions or hard-to-reach areas. This is where the special benefit of robotics lies, for example in low rectal cancers in the narrow pelvis, where space is especially limited in male patients. Robotics can also offer advantages in the upper abdomen, such as at the esophagus or gastric entrance — wherever complex suturing or dissection is required.”
At Bassum Clinic, over 100 bowel resections are performed annually, around 80 percent of which are done laparoscopically. Minimally invasive techniques play a particularly important role in benign conditions.
“A classic example is diverticulitis, which is initially treated conservatively with antibiotics during milder episodes. However, in cases of recurrent or severe attacks, the affected bowel segment is surgically removed. Another common benign indication is large colon polyps that cannot be removed endoscopically — here too, a surgical procedure is required. A particularly positive example in bowel surgery involves patients with a temporary colostomy, known as an ‘anus praeter.’ Even if the initial procedure was performed through an open incision, the reversal can often be done laparoscopically after three to six months. This means that the stoma reversal typically no longer requires a large abdominal incision. For patients, this represents an important perspective, as a temporary stoma by no means has to mean a permanent limitation. The management of artificial bowel outlets has also improved considerably over the past decades. Modern supply techniques are much more advanced today, greatly facilitating patients’ daily lives. Moreover, stomas are now created far less frequently than in the past. Previously, protective stomas were commonly placed to relieve a fresh bowel connection — an anastomosis — and improve healing. Today, however, suturing techniques are so refined that these connections reliably heal even under stool passage, allowing surgeons to forgo additional stomas in most cases,” Prof. Dr. Carus emphasizes.
When a patient is diagnosed with colorectal cancer, it is crucial for optimal treatment that they present at a specialized center like Bassum Clinic, where a so-called tumor board is established.
“In a tumor board, therapy is coordinated interdisciplinarily — involving internists, radiologists, pathologists, and surgeons — and the best treatment pathway is carefully considered for the individual case even before surgery. Not every tumor is treated the same: a low-lying rectal carcinoma generally requires prior radiochemotherapy, while a higher tumor in the sigmoid colon is usually tackled directly with surgery. Such decisions follow medical guidelines and are made jointly by the tumor board. It also makes sense to seek a second opinion — after all, this is a major procedure with far-reaching implications. In most cases, however, general practitioners are well informed about which clinics specialize in major tumor surgeries and can guide patients accordingly. In Germany, one can generally assume that medium- to large-sized hospitals have sufficient experience in colorectal cancer surgery. Additionally, hospital websites often indicate whether oncological procedures are routinely performed — a clear sign of professional routine. If patients are interested in specific technical methods such as robot-assisted surgery, they should address this openly during medical consultations. No surgeon can claim that using a robot is inherently better.
In certain situations — such as an unfavorably low-lying tumor in the narrow pelvis — the robotic approach can indeed offer advantages, especially if the clinic is experienced with the technology. It may well be that one surgeon opts for open surgery because they are confident in that technique, while a neighboring hospital offers robotic procedures with equal routine. Ultimately, the key is to rely on an experienced and transparently advising surgeon during the consultation — someone who understands the patient’s individual circumstances and offers a well-founded, honest recommendation for the best treatment approach,” concludes Prof. Dr. Carus, and with that, we end our conversation.
Thank you very much, Prof. Dr. Carus, for this highly informative interview!
