Investigations needed in Constipation

Investigations needed in Constipation

Investigations are needed to confirm the findings on history and physical examination. Many cases of constipation diagnosis does not need investigations as cause is known already or it is simple cause like wrong dietary habits.

Bristol stool chart

Bristol stool chart is used to classify the stool according to hardness. stool is categorized in 7 types according to hardness.
Type 1: consists of stony hard seaparate lumps which are very difficult to pass.Type 2: This lumpy sausage shaped stool, it is also slightly difficult to pass.Type 3 and 4 consists of normal stool.Type 5, 6, 7 consist of soft stool anf type 7 is watery stool.

Investigations are needed when underlying disease is suspected as cause of constipation and confirmation is needed with tests. Lets see which tests are needed to do the diagnosis of underlying cause. Investigations are just complimentary guiding the diagnostic process for the accurate treatment.

USG abdomen: 

An ultra-sonography of abdomen and pelvis confirms the findings on physical examination. Sometimes cases of constipation present as lump in abdomen. This lumps is visible on USG and can be identified as different from other causes. The abdominal cramps can be the presentation of the constipation. It may be consfused with intestinal obstruction or volvulus or appendicitis, these can be ruled out using USG abdomen. Tumors of intestine and can be detected on USG abdomen.

Blood tests:

  • HBCBC: This test detects hemoglobin level and other parameters like wbc count and platelet count and also RBC indices. Many patients of the constipation have blood loss in the stool. This repeated blood loss leads to loss of iron from the body. This loss of iron leads to iron deficiency anemia. Which needs to be treated.
  • Thyroid function test; In some patients thyroid disease is suspected as a cost of constipation. In these cases symptoms and signs of hypothyroidism along with blood test to detect hypothyroidism which include free T3, Free T4, and TSH confirm the diagnosis. These tests may also be needed for the monitoring of treatment of thyroid disease.
  • Parathyroid tests: In some cases of constipation parathyroid disease is suspected as cause of constipation. This cases PTH levels, serum calcium, Vit D3 levels and serum phosphate and ALP levels may be needed for the diagnosis.
  • ABG: Arterial blood gas detects the acidosis and helps diagnose the renal tubular acidosis. Renal tubular acidosis is dysfunction of kidneys which can be treated. 
  • Serum electrolytes and renal function tests: Serum electrolyte test detect Serum sodium, serum potassium. Renal function tests detect serum urea and creatinine along with serum electrolytes. Electrolyte imbalance and renal dysfunction can cause constipation. These causes are diagnosed by these tests.
  • LFT: Liver function tests can be used to diagnose the dysfunction in liver and as some liver diseases are known to cause constipation. Additionally constipation can deteriorate the condition of the patient in case of acute liver failure.
  • Serum Ttg and anti-gliadin antibody levels: these tests are done if the cause of constipation is suspected to be celiac disease which is now a days very common.
  • Blood sugar and HbA1c: When the cause of the constipation is suspected as diabetes mellitus these tests are used for diagnosis. These tests are also helpful in monitoring the treatment of the patients.

Barium enema

  • This test is used to detect defects like Hirschprung disease.
  • This test is also used to detect anatomical defects like mal-rotation of the gut.
  • This test is also used to detect luminal lesions like tumors and polyps.

Colonic transit time

This tests is used to detect the time needed to transit the content of colon through the length of colon. Time more than 7 days is considered as decreased motility of the colon.

Anorectal manometry

  • This test detects the pressure in rectum and anus. This is good for diagnosing the disease like Hirschprung’s disease in which the inhibition of the muscles of distal gut is lost.
  • This test is also used in diagnosing the cases of functional constipation which shows decreased sensitivity to rectal distention and elevated anal sphincter pressure.

Pelvic floor electromyography

Next test in investigations needed in constipation is pelvic floor electromyography. This test gives information about pelvic floor activity. It is used to detect whether pelvic floor is causing functional colonic outlet obstruction. This condition can be causative factor for functional constipation. 




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