Gastroscopy (OGD)

What is it, and what is it for?

A gastroscopy test, or ‘OGD’ is a flexible camera test of the gullet, stomach and first part of the small bowel (‘duodenum’).  It is a simple diagnostic procedure that takes around 5 minutes, and patients go home the same day.  It involves gently passing a flexible telescope through the mouth, down the gullet and through the stomach to the small bowel before carefully withdrawing it. 

Gastroscopy is a useful test for investigating symptoms such as upper abdominal pain, indigestion, heartburn, weight loss, swallowing problems, nausea and vomiting (especially if blood is present), and for investigating blood test abnormalities such as anaemia, iron and vitamin deficiencies.  Sometimes small tissue samples (‘biopsies’) are taken with tiny forceps, which does not cause any discomfort.  Occasionally extra growths of tissue or ‘polyps’ are seen on the stomach wall and these can be painlessly removed with the camera.

Other procedures can be carried out during a gastroscopy: 

  • Benign narrowings in the gullet, usually caused by acid related scarring, can cause swallowing difficulties which can be improved with gentle stretching (‘dilatation’) using a balloon passed through the camera
  • Symptoms from cancerous narrowings of the gullet, stomach or small bowel can be improved by placing an expandable wire mesh tube (‘stent’) across the affected area
  • Bleeding areas such as stomach or duodenal ulcers, vascular lesions or enlarged veins in the gullet or stomach (‘varices’) can be identified and treated effectively
  • Long-term feeding tubes (‘PEG’ or ‘Percutaneous Endoscopic Gastrostomy’ tubes) can be placed through the abdominal wall directly into the stomach to allow patients with long term feeding difficulties to safely receive nutrition

What are the alternatives?

Gastroscopy is the ‘gold standard’ investigation for examining the gullet, stomach and duodenum.  Contrast x-ray (barium swallow) is a useful complementary test for investigating swallowing difficulties.  Contrast x-ray of the stomach (‘barium meal’) is an old-fashioned test that is rarely used.  Although it can pick up obvious problems such as large ulcers or cancer it can miss more subtle things, and does not allow tissue samples to be taken.  It also requires considerable radiation exposure.

Is there anything I need to do before the test?

It is very important that the stomach is clear of food prior to gastroscopy so that problems are not missed and to minimise the risk of vomiting during the procedure.  For most people a six hour fast (both food and drink) is all that is required – for a morning procedure you should take nothing by mouth from midnight the night before.  For an afternoon procedure you can take an early (7am) light breakfast and then nothing by mouth until after.  If you take warfarin or clopidogrel (blood thinners), or are diabetic, the doctor will give you some specific advice when you see him in clinic about what to do with your tablets.

What will I feel during the test?

The test is usually performed just with local anaesthetic spray to the back of the throat.  Patients who are nervous and have someone to take them home afterwards can have it done under mild sedation.  This requires a needle in the arm and an injection of a mild sedative.  You will be awake but drowsy.  The test itself is very quick.  You may feel the camera at the back of the throat before it passes into the gullet (less so if you have had local anaesthetic throat spray) and it may cause you to gag until the camera has passed down.  The test does not affect your breathing and you can breathe freely throughout.  Once the camera is in the gullet the test takes a further 3-4 minutes.  It is not painful but you may belch wind or retch during the procedure – this is normal and not dangerous.  More complex procedure (dilatation of strictures, insertion of stents, PEG insertion etc.) can take longer and are usually done with sedation and/or painkillers.

What happens after the test?

After the test you may feel slightly drowsy for an hour or if you have had sedation.  Although you may feel  normal after this the drugs are still in your system for 24 hours and you should not drink alcohol, drive a car, go swimming, sign legal documents etc. within this period.  You may feel bloated after the test – this passes fairly quickly.  You will be allowed to drink after the test as soon as the throat spray has worn off (if you have had it) or as soon as you are awake enough for it to be safe.  You can eat normally as soon as you feel up to it.  Usually patients are allowed to go home within 30-60 minutes of the procedure if they have had throat spray, or after an hour or so if they have had sedation, when they are feeling awake enough and have had something to eat and drink.  Patients are usually kept in hospital for several days following a PEG procedure.

Are there any risks?

Gastroscopy is a very safe diagnostic procedure and the risks, although present, are tiny.  A common problem is a sore throat, caused by retching during the procedure, which usually wears off within 24-48 hours.  The main serious complication is damage (‘perforation’) to the back of the throat, gullet or stomach as the camera passes down.  This can occur after a routine diagnostic procedure but is incredibly rare, in the order of 1 in 5000-10000 procedures.  The risk is higher if narrowings have been dilated (stretched) or stents inserted, with a risk of up to 1 in 50-100 procedures.  A perforation might be suspected if there is significant pain following the procedure which is not getting better.  If suspected, a chest x-ray or CT scan would be performed, and the patient may be kept in hospital overnight.  If confirmed, an operation may be required although a small perforation may seal itself with gut rest and antibiotics.  There is a tiny risk of bleeding following gastroscopy, again in the order of 1 in 5000-10000 procedures.  Placement of feeding tubes (PEG procedure) has a small risk of bleeding, infection and bowel perforation, which can be minimised but not eliminated with good technique.