THE ROLE OF TRANSABDOMINAL ULTRASOUND EXAMINATION <US> IN THE DIAGNOSIS OF SOME AFFECTIONS OF THE DIGESTIVE  TRACT

Like any other imagery method, US hs its limits and notable feats, helping at the exclusion or confirmation of a diagnosis.

Although its role is limited in the diagnosis of the affections of the digestive tube, in the past years, through the improvement of the de US devices (new software , with 3D-4D programs real time or sono-CT) great images were obtained from the digestive tube.

In the clinic, the value of the transabdominal US of the digestive tractu is often underestimated. This is due to the way of the sonographical presentation of the segments of the digestive tube, from the anatomical point of view (e.g. – the posterior wall is hard to be seen because of the bubble gas present in its interior).

There are some diseases in which US plays an important role: the intestinal obstruction, appendicitis, diverticulitis, the Crohn disease.

However this thing depends very much on the operator’s experience, on the imagery doctor. Moreover, we have a real-time diagnosis with minimum trauma or secondary effects for the patient, especially if the patient is a child or a pregnant woman.

Excepting the emergency cases, for the ecography you need a certain preparation, this thing being necessary to realize a better sonic window, avoiding the artifacts given by the presence of the gas, the alimentary rests, or the increase of the secretion in the interior of the lumen from the digestive tube(e.g. the existence of fluid in the gut can be a sign of obstruction, inflammable disease or bad absorbtion).

The ecographical examination is made after an alimentary rest of about 4-6 hours. An exception is made for the ones with sugar diabetes who are allowed to have a light breakfast!

The examination is made with a sounder with 3-5 Mhz frequence. You can use also sounders of 5-10 Mhz for children or thin patients, especially if there is a previous diagnosis.

From the anatomical point of view, the digestive tube has 5 layers. The thickness of the wall is variable: from 5 mm (antral stomach – the horizontal portion of the belly) to 1-2mm (duodenum and slim gut). At the level of the colon, the thickness is about 3 mm, and if the colon is full of air, it reduces very much. The diameter of the digestive tractu varies very much in width – in the slim gut this being under 2cm.  

A good thing of the US is the possibility of the peristaltic analysis (the movements of the digestive tube) in real time. For example, in the intestinal obstruction, this seems akinetic or the loops have  hiperperistaltic contractions, a thing often met also in the intestinal infections.

The US diagnosis for some troubles

of the digestive tube:

1. The acute appendicitis:

The appendix is retrocecally localized (the first part of the upward) and appears as a tubular structure, round /ovalar with a closed end, without peristaltical movements and often with intraluminal air. It has a previo-hinder diameter of about 6mm. It is compressible with a ecogenity similar to the slim gut. In the acute appendicitis its diameter increases, it loses its compressibility, has an accentuated vascularisation on its area and, very important, it is painful at examination and at the pressing with the transductorul.

2. Colonic diverticulosis

It is characterised by anomalies of the colon which appear as some „POCKETS” of the mucous and under mucous membrane, which crosses the wall going out of its contours. Their incidence is of 50% for adults and is frequently localized at the level of the sigmoid and the downward colon.

US has a sensitivity of about 84% and a specificity of about 85% in their diagnosis if we use 2-4 Mhz transductors and with abdominal compression. This appears as a round/oval structure with increased ecogenity and a posterior attenuation, with a mixt content of air/ gases/ faecalexcrements. 

3. Colon cancer:

It is specific for the persons older than 40-50 years. The heredity plays an important role, next to an alimentation which lacks fibres. In here we can find colon adenoids, familial colonic poliposis or inflammable intestinale diseases.

The US diagnosis of this one is incidental and it is possible only to dimensions greater than 2 cm. What captures our attention is a irregular thickening of the colonic wall, the absence of the normal bowel movements and of the anatomical layers of the colonic wall, and at palpation we feel a round abdominal tumoural mass fixed on the posterior abdominal wall. The main role of the ecography is to visualize more precisely possible the secondary intrahepatic determinations, this thing depending on the examiner’s experience, on the device’s performances and on their dimension. In the majority of cases, these appear as hiperecogenic lesions (related to the hepatic ecogenity), but they can also be hipoecogene with shining center – goal aspect, multi centered, relatively uniformly alloted in the both hepatic lobes. We can see ecographical in the colonic tumours the followings: the affected segment, the infiltration of the foreign structures and organs, adenopaties, the degree of the stenosis and the risk for intestinal occlusion.

4. The inflammatory diseases of the colon:

We can enumerate some of them: the Crohn disease or the colita ulcero-hemoragica. These are diseases which affect great segments of the colon or the slim gut, with thickness modifications of the wall, without a complete penetration of the later, with the disappearance of the peristaltics and modifications of the pericolic fat (curly modifications from the Crohn disease). The ecography is used for the monitoring of the disease’s evolvement.

The infectious colitis, specific for the downward colon, are diagnosed through US – thickenings of the mucous and sub mucous membrane (which become hipoecogene), with normal pericolic fat. We may also notice a little intraperitoneal colection or adenopatia.

5. Ulcerative afflictions: (gastritis, ulcer) are not usually visualized at US, their diagnosis being given after an endoscopy and a contrast exam (barium) . The punctured ulcer can be easily diagnosed if pneumoperitoneum is present. In tumoral diagnosis, the US has a limited role.

Advanced Gastric cancer (linita plastica) is easily to be diagnosed by US through the accentuated thickening of the wall (more than 10mm) with the loss of the normal stratification these modifications couldn’t be seen through other imagery methods (mentioned above). The gastric wall is rigid in real time!

The antral gastric tumours can be emphasized easily after the previously administration of water to the patient.

6. The intestinal occlusion:

US is useful in the emergency situations: in the case when we have a good window (we do not have pneumoperitoneum or intestinal gas content in excess) we can put a diagnosis of intestinal occlusion, specifying its type (MECANIC, DYNAMIC), and its oldness.

7. Rectum:

It is very hard to be investigated, its examination being made differently depending on the anatomical segment, the rectal ampula can be se transabdominally examined, the rest of the segment being examined transperineal or trasrectal (at women it is also transvaginal visible). It has 5 layers with a 4mm thickness.

The rectal tumours represent about 58% from the malignant tumours of the thick gut. Ecographycally we can appreciate the tumour’s place, its penetration in the walls’ thickness and the organs around, and its vertical extension and its link with the anal sphincter. Moreover, with this exam we can also notice the adenopaties.

CONCLUSIONS: The US exam is very useful for the diagnosis of the affections of the digestive tube (tumours, inflammable diseases, neoplasm stadialisation, the accentuation of regional and further adenopaties, the metastasis), for the diagnosis of the acute affections at children and in emergency conditions.