After several months of chemotherapy, some people are told that the disease is no longer visible on imaging — and then, in the same visit, are referred to a surgeon. Hearing good news and an operation mentioned in the same breath is confusing. What the surgical team often proposes is a diagnostic laparoscopy. When peritoneal disease was documented before treatment, the same procedure may be called a second-look laparoscopy, because its purpose is to re-examine the response with the eye rather than the scanner.
The peritoneum is one of the areas CT and PET-CT miss most easily. Peritoneal deposits often spread as thin sheets or scattered millimetre-sized nodules rather than as a round mass, and below a few millimetres they simply fall under the resolution of the image. Some tumour types, such as signet ring cell or mucinous gastric cancers, take up glucose weakly and may not stand out on PET. For that reason, "no evidence of disease" on a report is not the same sentence as "there is no disease"; it is closer to "not visible with the tools used today." The reverse is also true: shadows that remain after treatment may be scar tissue or fibrosis rather than living tumour.
A diagnostic laparoscopy is performed under general anaesthesia through a few small ports. The camera allows direct inspection of the peritoneal lining, the bowel surface, the area under the diaphragm and the floor of the pelvis — surfaces that imaging judges poorly. Suspicious areas are biopsied, and even when nothing is visible, saline is often instilled and retrieved to look for free cancer cells under the microscope. This is peritoneal washing cytology. The findings are usually recorded separately as the extent of visible spread and the result of the cytology, and the two do not always agree.
The result determines which road comes next. If nothing is visible and the cytology is negative, removing the primary tumour — conversion surgery — can be discussed. If disease remains, systemic or intraperitoneal chemotherapy is usually continued or changed. In the middle situation, where nothing is seen but the washing is positive, it is common to postpone surgery and keep treating with drugs. In other words, the procedure is not there to declare a cure; it is there to answer whether an operation is likely to help at this moment. Because that judgement depends on tumour type, stage, response and overall fitness, the same test leads to different plans for different people.
A few things are worth writing down before the surgical appointment: the date of the last chemotherapy dose and the next scheduled one, recent platelet and neutrophil counts, any anticoagulant, antiplatelet or diabetes medication, previous abdominal operations and possible adhesions, how long the procedure and admission take, how many days the biopsy and cytology results need, when chemotherapy can restart after the wounds heal, and whether the existing port can still be used. Past difficulties with anaesthesia are also worth mentioning.
One more note about pain. Relief from abdominal pain is a welcome change, but the presence or absence of pain does not always track the state of the disease. Conversely, when a test finds an abnormality and the original symptom continues unchanged, it is reasonable to ask whether that finding really explains everything. Repeated vomiting, a belly that keeps swelling while gas and stool stop, a fever of 38°C or higher, or sudden severe abdominal pain are reasons to contact the treating team rather than wait for the next appointment.
This article is general health information for understanding and does not replace individual diagnosis or treatment. Whether and when to undergo this procedure, and what follows it, depend on your own situation — please discuss the decision with your medical team.