Diagnosing Abdominal TB or TB peritonitis.

Remember the patient in the ascites and diarrhoea blog? She is 60 years old, has gross ascites, edema, is malnourished and has been unwell for 6 months. She has also had chronic diarrhoea for this period. As she lives in a resource poor country like Pakistan she is exposed to Mycobacterium tuberculosis, probably has family and friends who suffer from TB or have been treated for TB. She will have certainly encountered AFB in the dust on the roads and pathways as spitting out sputum is a national habit. Ask first if she has symptoms common to chronic infections or inflammation. These are: fever, night sweats, poor appetite, weight loss, malaise and tiredness. Get into the habit of asking for all these symptoms in a group. She will have these symptoms if she has small intestinal TB, large gut TB, TB of the liver, peritoneum, mesentery or abdominal lymph nodes or miliary TB. She will also have them if she has ulcerative colitis, Crohn’s disease, lymphoma of the stomach and gut or peritoneal malignancy. So now we can ask more specific questions and may get nearer the diagnosis or at least we will be able to plan sensible investigations. Most candidates are just asking questions. They are often not listening to the answer and are certainly not interpreting the answer nor are they making a differential diagnosis as they go along.

Focused history. The next task is to establish reasonable evidence for contact with a patient with pulmonary TB. This is the more recognisable form of TB that most patients will know about. Ask for contacts in the close family, distant family specially if they have visited her home recently. (Go back 4-6 weeks at least before the onset of her illness as that is the minimal incubation period, be prepared to talk about latent TB.) Ask if a spouse, sibling or child has died of TB or been treated for TB. Ask if the patient herself was ever treated for pulmonary TB. The infection can lie latent and manifest itself as abdominal TB. Here overcrowding, poor ventilation in the home, poor diet because of a low-income becomes relevant. Women in our country rarely smoke but she may have worked in a factory with smoke and fumes. It is worth a try. This is the right time to ask. *Focused history*. The examiner, who is listening to you, will realise that you know what you are doing.

Why has she developed TB abdomen at this age? As people grow older they have hypochlorhydria: remember pernicious anemia: B 12 deficiency anemia, intrinsic factor deficiency and achlorhydria occurs in older people: the frequent use of PPI’s (our GPs tend to prescribe them as if they are essential for life) adds to loss of one layer of security against bacteria entering the small gut: gastric hydrochloric acid. Disease or loss of the gall bladder removes another safety factor: bile salts.

* Focused history* Intestinal motility disorders become commoner in diabetes mellitus, which also reduces immunity. Ask about diabetes now. Less likely causes of poor intestinal motility are amyloidosis, polymyositis and myopathies. Don’t wast time asking for these unless something in the history or examination gives you a strong clue. Asking a lot of questions for which you expect to get a negative answer is not a good idea and gives the impression that you do not understand the history and are fishing in the dark.  Putting your ignorance on display is a bad idea.

CIPO (chronic idiopathic pseudo-obstruction) of the gut is a rare disorder but paraneoplastic pseudo-obstruction may be found more frequently ie uterine and ovarian malignancy, intestinal lymphoma. Ask if the patient had recurrent episodes of intense vomiting, abdominal cramps and severe constipation lasting a few days in the past. Motility disorders also lead to small intestine bacterial overgrowth (SIBO) which can contribute to the persistence of diarrhoea. Adhesions, strictures, previous surgery, reversed segment,  radiotherapy are important causative factors.

Cirrhosis of the liver predisposes patients to abdominal tuberculosis. Ask if she was ever tested for hepatitis B, C or whether she had been treated for ascites in the past. May be her spouse had hepatitis B or C. She could also be suffering from protein losing enteropathy which is associated with gross cirrhosis. The resultant malnutrition can predispose her to tuberculosis. Cirrhosis also predisposes to chronic pancreatitis which will need to be looked for.

So what do you think this lady is suffering from?

  • My first option would be abdominal tuberculosis with TB peritonitis and intestinal TB both being active.
  • My next option would be cirrhosis of the liver with portal hypertension and either intestinal TB or protein losing enteropathy as the cause of diarrhoea, possible chronic pancreatitis.
  • Secondary deposits in the peritoneum from a primary malignancy in the gut could account for the diarrhoea and ascites.
  • Ulcerative colitis is another option but gross ascites is usually not seen nor is it a feature of Crohn’s disease though you can mention both these if you like.
  • A gross nephrotic syndrome needs to be excluded, membranous glomerulonephritis is most likely at this age. It would not explain the diarrhoea unless significant loss of proteins leads to poor immunity and superimposed abdominal TB. Check the urine for proteins. It is a bad idea to ask the patient if the urine is frothy. She probably uses a squatting plate type of utensil and cannot see over her distended abdomen any way.

 

Presenting your case.

When you present this case start something like this:

This sixty year old lady who is a housewife from interior Sind, has come to Karachi for medical care. her main problems are watery diarrhoea and enlarging abdomen for the past 6 months. She has sought medical aid near her village but has not had any formal investigations done. At one stage she was told that she had high blood pressure but did not take the prescribed medicine and does not remember her blood pressure being checked again. She is not aware that she has diabetes or heart disease. (You have tried to high light her major symptoms and also mentioned some of the likely co-morbids). During this period she has felt tired, has had a poor appetite and has had malaise. She has avoided eating chappatis as she feels more bloated and has more frequent diarrhoea when she does so but in general solid food makes her unwell so probably the avoidance of chappatis is not very significant but I need to consider gluten intolerance. (You have not specifically mentioned coeliac disease because gluten intolerance can occur in chronic diarrhoea states and you do not want to discuss coeliac disease as a major differential diagnosis). Bloating, flatulence and abdominal cramps are prominent features of her illness. She feels as if she has fever but has not documented it and has night sweats almost every night. She has been losing weight and says that her face and arms have become very thin, and her skin has become loose. (Having said that please do not discuss scleroderma as a cause of her chronic diarrhoea). If there is a significant  drug history i.e. therapeutic  or recreational mention that. Please do not say “This lady is not an addict” say “She does not take drugs for recreation purposes. If there is a significant family history of infectious disease or hereditary disease mention that. Most students forget the family history of infectious disease which in a resource poor country is more important than a history of genetically transmitted disease. If she has any lab reports or imaging results please mention those or talk about them when you have presented the clinical findings. Please also mention her own interpretation of what is wrong with her and also what her doctor has told her about the disease.

Clinical findings. Start by mentioning the fact that though she is uncomfortable she is not breathless or orthopneic. Say has gross distension of the abdomen caused by ascites. remember you have already examined her so you can give the conclusion you have come to. If you are challenged as to why you are calling it ascites you can say that you have examined her and have found fluid thrill and shifting dulness. mention that she has pitting edema up to the thighs but her face is pinched and dehydrated and the skin on her arms is loose because she appears to have lost weight. It is a good idea to put her on a weighing machine.  Give her vital signs, mention lack og jaundice but detectable anemia. Mention that she does not have palpable lymph nodes nor an enlarged thyroid. Note; I have not mentioned clubbing as it is not significant, its absence will not lead you to a diagnosis so as a potential consultant you are entitled not to mention it. Give the abdominal findings next, remembering to mention signs of chronic liver disease and portal hypertension, then the findings in the chest to include heart and lungs. Be sure to talk about a pleural effusion or the lack thereof. For the CNS I think it is sufficient to say that she is mentally alert, has a good memory, has generalised muscle weakness attributable to her weight loss with poor motor tone again caused by her age and malnutrition, (your opinion is what the examiners are listening for), she does not appear to have peripheral neuropathy as her sensations are intact and the planter reflexes are downgoing. If asked what is the importance of the planter reflexes mention subacute combined degeneration of the spinal cord from B12 deficiency which can occur as a single nutrient malabsorption in chronic diarrhoea: the plantar reflex may be absent but the ankle jerk may be exaggerated,  and that areflexia can occur in older patients specially women. Now you are exhibiting knowledge but wait to be asked. Mention signs of protein malnutrition. Please remember that in the presentation you give signs depending on the relevance or appropriateness not the order in which med students are taught. You can say for example  “the ascites is so gross that I cannot make out the size of the liver and spleen and will do an ultrasound of the abdomen for an accurate assessment”. Now you are beginning to sound like a consultant.

Give your D/D without being asked: start talking about investigations that you like to have done. Explain your reasons as you go along; e.g I will look for the degree and type of anemia in the blood picture, would like to see if there is leucocytosis or neutropenia or relative lymphocytosis. A raised ESR or CRP will be helpful for pointing to chronic infection or inflammation. By mentioning both these you are showing that you know that both can present with similar manifestations but are different entities. Mention liver function tests with the reason why they are important, blood sugar and HbA1c , creatinine and electrolytes, serum albumin etc. Serology for hepatitis C and B is a good idea. A stool examination for bacteria, parasites, blood and leucocytes will be needed. mention that fecal calprotein and lactoferritin estimation can give better information than fecal leucocytes. Mention markers of neoplasia. Talk about imaging next: X ray chest, ultrasound of the abdomen and if findings are equivocal then a CT abdomen. Be prepared to talk about the use of a contrast for the CT scan, know the names of the dyes commonly used and be prepared to talk about contrast induced nephropathy.

How will you prove SIBO?

The carbohydrate breath test. The lactose/glucose breath test is diagnostic of SIBO if any one of the following criteria are met: an absolute increase in hydrogen by ≥20 ppm above baseline within 90 minutes, or a methane level ≥10 ppm, Part of your preparatory study should be about how to prepare the patient for this test and how to interpret it.

Ileal aspirate for culture.

Endoscopy of the colon and jejunum though non-specific may help.

Motility tests. Video capsule studies are used most often for bleeding from the gut but will also show motility. There are three small bowel capsules (PillCam SB, EndoCapsule, and MiRo capsule) and one esophageal capsule (PillCam ESO) that are available. A colonic capsule is also available in Europe, the United States, and Japan (PillCam Colon).

More in my next blog.

 

 

 

Published by

shaheenmoin

I am a Professor of Medicine and a Nephrologist. Having served in the Army Medical College, Pakistan Army for 27 years I eventually became the Dean and Principal of the Bahria University Medical and Dental College Karachi from where I retired in 2016. My passion is teaching and mentoring young doctors. I am associated with the College of Physicians and Surgeons Pakistan as a Fellow and an examiner. I find that many young doctors make mistakes because they do not understand how they should answer questions; basically they do not understand why a question is being asked. My aim is to help them process the information they acquire as part of their education to answer questions, pass examinations and to best take care of patients without supervision of a consultant. Read my blog, interact and ask questions so that I can help you more.

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