Case 1 A man with iron deficiency

Jeff is a 53-year-old man who returned from a two-week holiday visiting family in Kenya with symptoms of a febrile illness. He had taken antimalarials but was concerned about malaria. He consults Dr Wallace. She finds that he is apyrexial and looks well but she requests a full blood count and films for malarial parasites. The films are negative for parasites. The FBC shows a haemoglobin of 12.3 g/dL and a MCV of 67 fL (normal ranges > 13.5 g/dL and 70 to 100 fL). The results are filed.

What would you have done with the results?

Four months later Jeff consults another of GP in the practice, Dr Rennie, with a two-week history of a dry cough and fatigue. Examination is unremarkable, urinalysis and TFTs are normal but the Hb is 10.7 g/dL with a MCV of 66 fL. Dr Rennie diagnoses an iron deficiency anaemia, requests haematinics, starts Jeff on ferrous sulphate and requests a repeat blood test in two months. The serum ferritin is 10 mcg/l. Dr Rennie suggests doing three faecal occult bloods. Two are done and are negative. Two months later the repeat FBC result comes back to the ST2 trainee, Dr Bordley. The man’s haemoglobin is now 13.6 g/dL with a MCV of 70 fL.

What would you do now? What is your differential diagnosis?

Dr Bordley asks the receptionists to contact Jeff for a routine appointment. Unfortunately Jeff fails to make an appointment as requested.

Six months later Jeff consults Dr Rennie again, this time with fatigue. He is clinically anaemic. He stopped taking the ferrous sulphate some months earlier. Abdominal examination suggests a right lower quadrant abdominal mass. A FBC shows a Hb of 9.1 g/dL with an MCV of 66 fL. Dr Rennie refers Jeff urgently to a consultant gastroenterologist and a colonoscopy shows a circumferential, stenosing caecal carcinoma. He undergoes a right hemicolectomy and the cancer is staged as Dukes C1.

Jeff sues the three general practitioners on the premise that his iron deficiency anaemia should have been investigated one year earlier and that this would have led to an earlier diagnosis of the cancer with a better prognosis.

Expert opinion

As with many medico-legal cases there are often a number of errors which compound the delay in diagnosis. Iron deficiency in a man in the developed world is rarely due to dietary deficiency (Goddard et al., 2005). In contrast, menstruating women can easily tip into a negative iron balance because of a significant monthly loss with menstruation. Anaemia indicates significant iron deficiency following exhaustion of the marrow stores. Iron deficiency anaemia in a man is rare and always needs investigating. It must never be assumed to be dietary because such an assumption is unsafe and rarely true.

Since July 2000 the UK ‘Two Week Rule’ referral guidelines have recommended urgent referral for men with an iron deficiency anaemia of less than 11 g/dL in a man and 10 g/dL in a non menstruating woman (NHS Executive, 2000). However, the 2005 British Society of Gastroenterology (BSG) guidance is to refer for investigation all men and women with an unexplained iron deficiency anaemia of any degree (Goddard et al., 2005). The likely causes are occult blood loss from a carcinoma or peptic ulceration (particularly with NSAIDs) or malabsorption due to, for example, Coeliac’s disease. Most right-sided colorectal cancers present with an isolated iron deficiency. Right-sided colorectal cancers often do not cause the characteristic alteration in bowel habit (to loose, frequent stools) that occurs with left-sided cancers. Cancers proximal to the splenic flexure will also not produce rectal bleeding.

One study of 695 patients with iron deficiency anaemia referred under the BSG guidance found colorectal cancer in 6.4% (James et al., 2005). A second study of 431 patients with a haemoglobin below 12 g/dL in men and 11 g/dL in women found 7.4% had colorectal cancer (Logan et al., 2002). Another case-controlled study using a retrospective analysis of primary care computerized records identified 6442 patients with colorectal cancer and 45 066 controls. For men with an iron deficiency anaemia the positive predictive value of iron deficiency anaemia for colorectal cancer was 13.3% (Hamilton et al., 2008).

The request for faecal occult bloods is an example of a clinician not understanding the performance characteristics (sensitivity and specificity) and therefore significance of a requested test. The test was incorrectly being requested as a ‘rule out test’ – if the FOBs were negative the GP would consider that occult bleeding had been ‘ruled out’. However, the sensitivity of the test was too low to be a ‘rule out test’. The sensitivity of three FOBs is only 50% to 90% for colorectal cancer (Hewitson et al., 2007). Many people with colorectal cancer will still have three negative tests. To rule out a diagnosis, the test has to have a high sensitivity (like a barium enema) and be negative. The acronym is SnOUT – high sensitivity negative test rules it out.

The initial assessing GP, Dr Wallace, should have recognized that iron deficiency anaemia in a man, even if mild, requires confirming with a serum ferritin level and then investigating if it is confirmed. Jeff would not have met the criteria for an urgent ‘Two Week Rule’ referral (the Hb needs to be below 11 g/dL) but should have been referred non-urgently for specialist gastroenterological opinion.

The second GP Dr Rennie correctly requested a repeat full blood count and a serum ferritin but should then have referred the patient urgently to see why he had an iron deficiency anaemia. The faecal occult blood tests were inappropriate. They are colorectal cancer screening tests for an asymptomatic population.

The ST2 doctor Dr Bordley should have recognized that there was a high probability that Jeff had serious gastro intestinal disease (cancer or an ulcer) and ensured that he was seen rather than have merely delegated contacting the man to a receptionist.

Legal comment

Expert comment confirms that Dr Wallace ought to have also carried out a serum ferritin test to rule out iron deficiency anaemia, an indicator of colorectal cancer. Although Jeff did not meet the criteria for an urgent two-week referral he ought to have been referred non-urgently for specialist gastroenterological opinion because of the low haemoglobin results.

Four months later Jeff returned to his GP practice with a dry cough and fatigue and saw Dr Rennie. Although Dr Rennie diagnosed iron deficiency anaemia she failed to refer Jeff for investigation of the unexplained iron deficiency.

The mistakes continued when the ST2 Trainee Dr Bordley failed to recognize the high probability that Jeff had serious gastro intestinal disease from the results of the repeat FBC.

Six months later Jeff consulted Dr Rennie again when she found a right-sided abdominal mass on examination and appropriately referred Jeff to a consultant gastroenterologist.

All three doctors failed to consider any differential diagnoses. They appeared not to be aware of BSG guidance or the Two Week Rule guidance. Communication between all three doctors about Jeff’s unexplained anaemia appears to have been poor. A breach of duty by the GPs seems clear. The next question is what the results of that breach were. It is fortunate that the cancer seems to be confined to the right side of the colon and has not spread beyond it. Had Jeff been properly diagnosed with iron deficiency anaemia and appropriately referred to a specialist gastroenterologist at the outset, his prognosis may not have been any different. (He may still have required surgery.) If expert opinion confirms that it is unlikely that the prognosis would have been any different had the cancer been identified earlier, then Jeff could expect to be awarded damages for approximately one year’s pain and suffering with contributions being made by all three doctors.

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