Surgical Anatomy of the Stomach

8/11/2019 Surgical Anatomy of the Stomach

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SURGICAL ANATOMY OF THE STOMACH

Dr.M.Ardaale


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ANATOMY:

The stomach J-shaped. The stomach has

two surfaces (the anterior & posterior),

two curvatures (the greater & lesser), two

orifices (the cardia & pylorus).

It has fundus, body and pyloric antrum.


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STOMACH

The lesser curvature :forms the right border &extends from the cardiac orifice to thepylorus.It is suspended from the liver by the

lesser omentum.The greater curvature :forms the left border,

the greater omentum extends from the lowerpart to the transverse colon& the gastro-splenic omentum extend from the upperpart to the spleen .


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CONT..

The mucus membrane forms many folds called

rugaethat are longitudinal in direction.

It has 3 muscular layers: longitudinal ,

circular & oblique.

The stomach function is :storage of food ,mix

the food with gastric secretions to form

chyme, & the delivery of the chyme to the

small intestine.

Capacity: 1.5 L food; max capacity 4L (1

gallon)


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BLOOD SUPPLY:

. The left gastric artery

. Right gastric artery

. Right gastro epiploic artery

. Left gastro epiploic artery

. Short gastric arteries

The corresponding veins drain into portalsystem. The lymphatic drainage of thestomach corresponding its blood supply.


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DUODENUM

The 2ndpart: is 8 cm long runs vertically downward infront of the right kidney & on right side of L1,2vertebrae. Its medial border receives the bile duct &the main pancreatic ducts in major duodenal papilla &receive the accessory panc. Duct higher up in the

minor duod. Papilla.The 3rdpart: is 8 cm long ,runs horizontally to the left, in

front of the vertebral column& the lower margin of thehead of panc.

The 4thpart: is 5 cm long, runs upward & to the left tothe duodeno-jejunal flexure.

The mucus memb. Is formed in circular folds calledPlicae circularis


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BLOOD SUPPLY OF DUODENUM

Blood supply:

superior

mesentericartery;

Veins drain intohepatic portal

vein


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HISTOLOGY OF STOMACH

Parietal cells:

These are in the body (acid-secreting portion) of

the stomach and line the gastric crypts, more

abundant distally. These are responsible for the production of

hydrogen ions to form hydrochloric acid, which

has a pH of around 1.

The hydrogen ions are actively pumped by the

proton pump, a hydrogenpotassium APTase

(Sachs) which exchanges intraluminal potassium

for hydrogen ions.


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CONT..

a key factor in gastric acid secretion.

In addition, there are large numbers of

somatostatin-producing D cells throughout

the stomach, and

somatostatinhas a negative regulatory role.


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DUODENUM

The duodenum is lined by a mucus-

secreting columnar epithelium.

In addition, Brunners glands lie beneath

the mucosa and are similar to the

pyloric glands in the pyloric part of the

stomach.

Endocrine cells in duodenum produce

cholecystokinin and secretin


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PHYSIOLOGY OF THE STOMACH AND

DUODENUM

The stomach mechanically breaks upingested food and, together with

the actions of acid and pepsin, forms

chymethat passes into the duodenum. In contrast to the acidic environment of the

stomach, that of the duodenum is alkaline,as a result of the secretion of bicarbonate

ionsfrom both the pancreasand theduodenum.


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CONT..

This neutralisesthe acid chyme and adjusts

the osmolarityto approximately that of

plasma.

Endocrine cells in the duodenum produce

cholecystokininthat stimulates

the pancreas to produce trypsinand the gall

bladder to contract.


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CONT..

Secretinis also produced by the endocrine

cells of the duodenum.

This hormone inhibits gastric acid

secretion and promotes production of

bicarbonate by the pancreas.


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GASTRIC ACID SECRETION

The secretion of gastric acid and pepsin

tends to run in parallel,

although the understanding of the

mechanisms of gastric acid secretion is

considerably greater than that of pepsin.

Numerous factors are involved

to some degree in the production of the

gastric acid.


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CONT..

These include neurotransmitters,

neuropeptidesand peptide hormones, and

several other factors.

As mentioned above, hydrogen ions are

produced by the parietal cell by the

proton pump.


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GASTRIC MUCUS AND THE GASTRIC MUCOSAL

BARRIER

The gastric mucous layer is essential to theintegrity of the gastric mucosa.

It is a viscid layer of mucopolysaccharides

produced by the mucus-producing cells ofthe stomach and the pyloric glands.

Gastric mucus is an importantphysiological barrier to protect the gastricmucosa from mechanical damage, andalso the effectsof acid and pepsin.


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CONT..

Its consider-able bufferingcapacity is

enhanced by the presence of bicarbonate

ions within the mucous.

Many factors can lead to the break down ofthis gastric mucous barrier.

These include bile, nonsteroidal anti-

inflammatory drugs (NSAIDs), alcohol,trauma and shock.


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CONT..

The stomach is the most sensitive to

ischaemia following a hypovolaemic insult

and also the slowest to recover.

This may explain the high incidence of

stress ulceration in the stomach.


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PEPTIDES AND NEUROPEPTIDES IN THE

STOMACH AND DUODENUM

Many peptides recognized as hormones

may also be produced by neurons, hence the

term neuropeptides.

The term messenger can be used to

describe all such products.

There are three conventional modes of

action which overlap.


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CONT..

The autocrinemode of action should be

mentioned for completeness.

Here messengers are released from cell to

act on receptors on the same cells surfacemembrane.

Many growth factors such as epidermal

growth factor and transforming growthfactors alpha and beta work in this way.


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INVESTIGATION OF THE STOMACH AND

DUODENUM

Flexible endoscopy

Amongst all of the methods used toinvestigate and image the stomach

and duodenum, flexible endoscopy is nowthe gold standard.

The original gastroscopes were fibre-optic

(Hirschowitz), but now most use a solid-state camera mounted at the

instruments tip.


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ULTRASONOGRAPHY

Standard ultrasound imaging can be used toinvestigate the stomach, particularly inpatients with neoplasia.

Thickening of the gastric wall can be seen in malignancy, some assessment

made of local invasion, and liver andperitoneal diseaseis often detected.

However, used, conventionally, it is lesssensitive than other modalities.


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CONT..

By contrast, endoluminal ultrasound and

laparoscopic ultrasound are probably the

most sensitive techniques available in the

preoperative staging of gastric

cancer. In endoluminal ultrasound the

transduceris usually attached to

the distal tip of the instrument.


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CONT..

Five layers of the gastric wall may beidentified on endoluminal ultrasound andthe depth of invasion of a tumour can be

assessed with exquisite accuracy (90 percent accuracy for the T

component of the staging). Enlarged lymphnodes can also be identified

and the techniques accuracy in thissituation is about 80 pet cent.


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OTHER INVESTIGATIONS

Laparoscopy: (gastric cancer, peritoneal

Disease such as patients ascitesor bulkyintraperitoneal disease)

Gastric emptying studies:(gastricdysmtility disorders, follow gastric surgery)

Tests of gastric acid secretion and of pH

monitoring(gastric acid secretion commonlyfound in patients with duodenal ulcerdisease)

24-hour intragastric pH monitoring


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MEASUREMENT OF PLASMA GASTRIN

The measurement of plasma gastrin by

radioimmunoassay is of use in the diagnosis

of gastrinoma (ZollingerEllison syn-

drome). In most assays the normal fasting gastrin

level is about 50 ng/litre, but in gastrinomas

very high levels, some-times manythousands of ng/litre, can be found.


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CONT..

the other common cause of

hypergastrinaemia is hypochlorhydria

associated with gastric atrophy and very

high gastrin levels are found in perniciousanemia.


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CONT..

In some cases there seems to be a familial

association.

In such families the mother has suffered

from the condition in 50 per cent of cases,

and 10 per cent of male siblingsand 2 per

cent of female siblings are affected.


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PATHOLOGY

The classical feature is that the musculature

of the pylorusand adjacent antrum is

grossly hypertrophied,

the hypertrophy being maximum in the

pylorus itself.

The mucosa is compressed such that only

a probe can be inserted.


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CLINICAL FEATURES

First-born male child that is most

commonly affected.

This condition is seen at 4 weeks after birth

ranging from the third week to, on rare

occasions, the seventh.

A premature infant will also develop the

condition at about 4 weeks after birth.


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CLINICAL PRESENTATIONS

Vomiting is the presenting symptom that

after 23 days becomes forcible and

projectile.

The child vomits milk and no bile ispresent. Immediately after vomiting the baby

is

usually hungry.

Weight loss is a striking feature and rapidly

the infant becomes emaciated and de-

hydrated.


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DIAGNOSIS

Feeding tube (NG tube)

This may produce characteristic peristaltic

wavesthat can be seen to pass across the

upper abdomen.

At the same time, using a warm hand, the

abdomen is palpated to detect the lump


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PYLORIC STENOSIS CONT.

Signs:

1.Vis ib le per istal t ic waves pass ing from lef t to

right across the upper abdomen (golf ball

waves).

2.A palpable tumor in the

epigastr ium or r ight

hypochondr ium (most important).


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IMAGING

Ultrasonographyis the investigation ofchoice as it can, with-out difficulty, detect the

classical features in the pyloric canal.

Differential diagnosis:

GERD

UTI

Intestinal obstruction


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TREATMENT

Correct dehydration level (with low sodium,chloride and potassium, and a metabolic

alkalosis).

The child should be rehydrated withdextrosesaline and potassium (2.5 per

cent dextrose plus 0.45 per cent sodium

chloride plus 1 g of potassium chloride per500 ml of

fluid).


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DEFINITIVE MANAGEMENT(SURGERY)

Ramstedtsoperation:

it is important that the stomach is emptied

and washed out with saline, and that

hypothermia is avoided.

Procedure:transverse incision placed

in the upper abdomen over the right rectus

sheath, which is opened in the same line.


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Treatment :

Treatment is theoperation of

pyloromyotom

(Ramstedts

operation).


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CONT..

The rectus muscle is then split along theline of its fibresand the posterior rectus

sheath opened in the line of the skin incision.

The hypertrophied pylorus is delivered androtated so that its superior surface comes

into view .

Thus, the least vascular portion can beselected for incision.(Pyloratomy).


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DUODENAL ATRESIA

This occurs at the point of fusion betweenthe foregut and midgut, and therefore lies in

the neighborhood of the ampulla of Vater.

There is a diaphragm, which is usuallycomplete, across the duodenum at this point

and the condition is frequently accompanied

by other defects.


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CONT..

The diagnosis is now made antenatally inmost cases through the use of

ultrasound.

This shows the characteristic appearanceof a

dilated stomach and first part of the

duodenum (double bubble). The child vomits from birth and the vomitus

is bile stained.


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DIFFERENTIAL DIAGNOSIS

High intestinal obstruction

Pyloric stenosis

Treatment:(surgery)

operation of the

duodenoduodenostomyin which the

dilated proximal duodenum isanastomosedto the atrophic distal

duodenum.


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GASTRITIS

Type A gastritis:

This is an autoimmune condition in which

there are circulating antibodies to the parietal

cell.

This results in the atrophy of the parietal

cell mass, hence hypochlorhydria and

ultimately achlorhydria.


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CONT..

As intrinsic factor is also produced by theparietal cell there is malabsorption of vitaminB12,

which, if untreated, may result in perniciousanaemia.

In type A gastritis the antrum is not affectedand the hypochlorhydria leads to the

production of high levels of gastrin from theantral G cells.

This results in chronic hypergastrinaemia.


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TYPE B GASTRITIS

Most commonly type B gastritis affects

the antrum, and it is these patients who are

prone to peptic ulcer disease.

Helicobacter-associated pangastritisis also

a very common manifestation of infection,

but gastritis affecting the corpus alone

does

not seem to be associated.


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CONT..

Patients with pangastritis seem to be mostprone to the development of gastric cancer.

Intestinal metaplasia is associated with

chronic pangastritis with atrophy.Although intestinal metaplasiaper se is

common, intestinal metaplasia associatedwith dysplasia has significant malignantpotential,

and if this condition is identified the patientshould be regularly screened

endoscopically.


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EROSIVE GASTRITIS

This is caused by agents which disturb thegastric mucosal barrier; NSAIDs andalcohol are common causes.

The nonsteroidal-induced gastric lesion isassociated with inhibition of the cyclo-oxygenase type 1

(Cox 1) receptor enzyme, hence reducing theproduction of cytoprotectiveprostaglandins in the stomach.


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STRESS GASTRITIS

This is a common sequel of serious illnessor injury and is characterized by a reduction

in the blood supply to superficial mucosa

of the stomach.


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MNTRIERS DISE SE

This is an unusual condition characterized bygross hyper-trophy of the gastric mucosal

folds, mucus production and

hypochlorhydria. The condition is premalignant and may

present with hypoproteinaemia and

anaemia. There is no treatment other than a

gastrectomy.


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CONT..

The disease seems to be caused by over_expressionof transforming growth factor

alpha (TGF-alpha).

Like epidermal growth factor (EGF), this

peptide also binds to the EGF receptor.

The histological features of Mntriers


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LYMPHOCYTIC GASTRITIS

This type of gastritis is seen rarely.

It is characterizedby the infiltration of

the gastric mucosa by T cells and is

probably associated with H. pylori infection.


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OTHER FORMS OF GASTRITIS

Eosinophilic gastritis appears to have an allergicbasis, and is treated with steroids andchromoglycate. Granulomatous gastritis isseen rarely in Crohnsdisease and also may be

associated with tuberculosis.Acquired immunodeficiency syndrome (AIDS)

gastritis is secondary to infection withcryptospirodiosis.

Phlegmonous gastritis is a rare bacterialinfectionof the stomach found in patients withsevere intercurrent illness.It is usually anagonal event.


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ASSIGNMENTS

Duodenal ulceration

Gastric ulcers

Malignancy in gastric ulcers

Operations for duodenal/Gastric

ulceration

Small stomach syndrome

Haematemesis and melaena

Surgical Anatomy of the Stomach

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