The gatekeeper & his tools

Recently a patient, who had had part of the liver and the common bile duct removed for cancer several months ago, came to see me for a second opinion. The patient had been having pain in the abdomen and back in the past two months. Despite a number of X-ray studies, the senior doctor could not find the cause of the pain and reassured the patient that nothing serious was afoot. After the consultation, I ordered a CT scan and checked the blood level of the tumour marker, CA 19.9. The CT scan quite clearly showed the cause of the pain and the elevated tumour marker confirmed the CT findings of the cancer having recurred. Clearly confused why this was not detected by the original doctor, the patient’s son asked “Is the X-ray machine better in the private sector? Is that why the original doctor could not find the cause of the problem but you could?”

The crux of the matter is not so much “how new is your machine” but ‘how your gatekeeper utilizes the tools” at his or her disposal. Who is the gatekeeper? He or she is the doctor who is in charge of your case. What are the tools? That is obvious isn’t it – laboratory tests and X-ray imaging machines, right? Actually, there is something else. A doctor’s most important tools are his / her sight, hearing, smell, touch and thought processes. Based on what he has heard, seen and felt on the patient, the doctor must order the right tests to get the correct answers to either confirm or refute his suspicion. If the doctor does not order the test which might give the answer to the question, then he will not make the correct diagnosis. When the radiologist examines the X-ray films in front of him, he can only report on what he sees on the film. If the X-ray the gatekeeper requested was not performed specifically to answer the question the gatekeeper has in mind, the films will not show the problem and the radiologist will not be able to see the problem (and neither will the gatekeeper) when he reads the X-ray films. When your doctor did not consider a particular possible diagnosis, he will not order the relevant tests for that diagnosis.

Before operating on bile duct cancers high up by the liver (called hilar cholangiocarcinoma), much effort is put into the assessment on whether the cancer can be completely removed at the time of surgery. Many doctors now would argue that magnetic resonance imaging (MRI) and endoscopic ultrasound examination of the bile ducts are much more accurate than computed tomography (CT) scanning for pre-operative assessment. However, that does not mean CT scans are now obsolete. A study from the University of Texas M.D Anderson Cancer Center examined the accuracy of high-resolution computed tomography (HRCT) to pre-assess the operability of bile duct cancer in 32 consecutive patients (Am J Surg 2007; 193: 702 – 706). The X-ray findings were compared to the operative findings. At operation, 18 patients were found to be operable and 14 patients were not. In the operable group, HRCT correctly predicted that 17 out of the 18 patients were operable (94% sensitivity). In the inoperable group, HRCT correctly predicted that 11 of the 14 patients were inoperable (79% specificity). In the 3 cases that were found to be inoperable, HRCT did not detect the very tiny cancer deposits outside the bile duct in 2 cases and the extension of the cancer in the distal part of the bile duct in one case. As a result of the study, the researchers are using HRCT as a pre-operative assessment of patients with hilar cholangiocarcinoma.

The study emphasized two important points. Firstly, no test can be 100% accurate. Even if MRI were to be used, it is very likely that the 2 patients with the very tiny cancer deposits outside the bile duct would not have been detected before surgery. Secondly, if you know the repertoire of what a particular scanning method can do, it can still give you the answer you are looking for.

While technology has become very advanced, the technology can only answer your queries if you use it appropriately. If you use the wrong technology, you will get a negative answer. In the medical world, a negative answer may not mean there is no underlying health problem, it merely means that you have not demonstrated it. Why not? Is it because the machine or the technology is old? Perhaps, but you might also want to ask “Has my gatekeeper used the relevant tools?”