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Last updated: 18-Oct-2026
Dr Harsh Shah
MS, MCh (Surgical Gastroenterology), DrNB (Surgical Gastroenterology)
Registered with Gujarat Medical Council, Reg. No. G-38738
Robotic Cancer Surgeon (GI)
Apollo Hospital, Bhat, Gandhinagar · Gota OPD, Ahmedabad · 18 years of experience
★★★★★ Google: 4.9 from 53 reviews (Gota clinic) · 5.0 from 25 reviews (Apollo, Bhat)
In short
Side-wall lymph nodes lie along the blood vessels on each side of the pelvis. They sit outside the envelope that a standard rectal cancer operation removes.
The MRI decides. A side-wall node that stays enlarged after chemoradiation is usually removed. A node that shrinks back to a small size can usually stay, with close checks.
The robot gives a steady, magnified view and wristed tools deep in the narrow pelvis. It does not remove more nodes. The team’s care and experience matter more.
This page covers the side-wall nodes only. Staging, treatment before surgery and the main operation are on the robotic rectal cancer surgery in Ahmedabad page.
The rectum sits in a fatty envelope called the mesorectum. The standard cancer operation, TME, removes the rectum inside this envelope. The nodes inside it come out with it.
A second group of nodes lies outside the envelope. These nodes run along the blood vessels on the side walls of the pelvis. Surgeons call them lateral pelvic nodes.
| Space | Where it is | What runs through it |
|---|---|---|
| Internal iliac space | Along the inner blood vessels of the pelvis. | Vessels to the bladder, the buttock and the pelvic floor. |
| Obturator space | Further out, against the inner wall of the pelvis. | The obturator nerve, which helps move the thigh inward. |
TME does not reach these spaces. If cancer sits in a side-wall node, it has to be taken out on purpose. That extra step is called lateral pelvic lymph node dissection, or LPLND.
This is mainly a problem of low rectal cancer. That means a tumour below the fold of the belly lining, in the lower part of the rectum. Cancers higher up rarely spread this way.
The risk is higher when the tumour has grown through the bowel wall. A larger tumour adds to it. Sometimes the side wall holds cancer even when the nodes inside the envelope are clear. So the side walls are checked on every MRI for low rectal cancer.
A side-wall node does not mean the cancer has spread far. It is still a pelvic problem, and it can be treated with a planned operation.
A rectal MRI measures each side-wall node across its short side. The radiologist also notes its shape and its edge. The scan is repeated a few weeks after chemoradiation.
| MRI finding | Usual plan |
|---|---|
| Small node, under 5 mm, before treatment. | TME alone. No side-wall surgery. |
| Node between 5 and 7 mm before treatment. | Chemoradiation, then a repeat MRI decides. |
| Node 7 mm or more that shrinks well after chemoradiation. | Usually TME alone, with close checks. Some teams still remove it. This is discussed at the tumour board. |
| Node that is still 4 mm or more after chemoradiation. | TME with side-wall dissection on that side. |
| Very large or fixed node, stuck to bone, nerve or main vessel. | A larger operation may be needed. It is planned separately. |
| Spread to the liver or lungs that cannot be removed. | Medicines first. The side-wall surgery waits. |
In Japan, some teams remove the side-wall nodes routinely, without radiation first. Most Western and Indian teams give chemoradiation first. Then they remove only the nodes that stay large. Both paths now rely on the MRI to choose.
Most often, only one side shows a suspicious node. Then only that side is cleared. The other side is left alone, which spares its nerves.
When both sides show suspicious nodes after treatment, both sides may be cleared. This adds time and some risk. Your surgeon weighs it with you.
The side-wall nodes lie deep in a tight, bony space. The work happens close to large vessels and fine nerves. This is where good vision and fine tools help.
| Point | Robotic | Keyhole | Open |
|---|---|---|---|
| The cancer operation | The same spaces are cleared. | The same spaces are cleared. | The same spaces are cleared. |
| View deep in the pelvis | Steady, magnified, 3D view held by the surgeon. | Magnified view held by an assistant. | Direct view through a long cut. |
| Tools | Tools bend like a wrist. | Straight tools. | Hand tools. |
| Nodes removed | Not more than keyhole. | Similar in trained hands. | Similar. |
| Most useful for | A narrow pelvis, a male pelvis or a heavy build. | Many patients at an experienced centre. | Bulky or fixed nodes, or vessels that need repair. |
An Indian study from Tata Memorial compared keyhole and robotic side-wall surgery. In expert hands, the results were close. So the machine is a help, not the reason for a good result.
This is not a routine add-on. It needs a rectal cancer team that does this work often. It is fair to ask how often your team does it.
The side walls carry the nerves for the bladder and for sexual function. The obturator nerve runs there too. Each one is found and kept, unless the cancer has grown into it.
The main branches of the inner pelvic vessels are kept as well. The CT is read before surgery for unusual vessels. One such artery near the pubic bone can bleed badly if it is missed.
Keeping the nerves is the main safeguard for passing urine and for sexual function. It is planned before surgery, not left to chance.
Your own figures are discussed at the consent meeting.
No. Side-wall nodes are still inside the pelvis. They are treated with a planned operation, often after chemoradiation.
Sometimes. If the node shrinks to a small size on the repeat MRI, it can usually be watched. A node that stays enlarged is usually removed.
No. Both clear the same spaces. The robot mainly helps with the view and the fine work deep in the pelvis.
Some people do for a few weeks. The urine tube stays for about a week, and the bladder is trained before it comes out.
No. It is added only when the MRI shows a suspicious side-wall node. Most rectal cancer operations do not need it.
Rectal cancer surgery at this centre is covered on the robotic rectal cancer surgery page. The envelope operation itself is on the deep-pelvis robotic TME page. For questions before you travel, call +91-63590-11009.
Shah’s Gastro, Cancer & Robotic Surgery Centre, Gota, Ahmedabad
Consultation, review of scans and biopsy reports, second opinions and follow-up.
Apollo Hospital, Bhat, Gandhinagar
Admission, robotic and open surgery, and inpatient care.
Has your rectal MRI report mentioned a lateral, internal iliac or obturator node? The MRI films and reports, from before and after radiation, can be sent ahead on WhatsApp. The plan is decided at the consultation, after examination. Call +91-63590-11009 Send your MRI before the visit
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