EMBRYOGENESIS OF GASTROINTESTINAL TRACT

As a result of cephalocaudal and lateral folding ofEmbryo , endoderm lined yolk sac is incorporated into The embryo to form primitive gut.

Primitive gut is blind ended however midgut is connected To yolk sac by means of vitelline duct / yolk stalk.

Pharyngeal gut : buccopharngeal membrane to tracheoBronchial diverticulum.

Foregut : caudal to pharyngeal tube extends upto Liver outgrowth.

Midgut :caudal to liver upto right 2/3rd to left 1/3rd of Transverse colon.

Hindgut :left 1/3rd of transverse colon to cloacal Membrane

Endoderm forms lining of git , perenchyma of glands ; Liver and pancreas

Splanchnic mesoderm forms muscle , connective tissue & peritoneal components.

Mesoderm dictates type of struture i.E. Lung in thoraxVia hox code.

Mesentry is double layers of peritoneum that enclose An organ and connect it to body wall (intraperitoneal)

At 5 wks gut is suspended by dorsal mesentry which Extends from lower esophagus to cloaca.

Ventral mesentry is derived from septum transversum

Imaging

Barium is contraindicated in the immediate postoperative period, followingrecent rectal biopsy, or any other circumstance in which anintraperitoneal or mediastinal leak could occur.

It should also be avoided in patients at high risk of aspiration

In neonates ,it is advisable to use water solublecontrast agents rather than barium for both upper and lowergastrointestinal studies.

Low osmolar water-soluble contrast agents include iohexol(Omnipaque 240, 300) and iopamidol (Niopam 200, 300).

They have little adverse effect if extravasated into the peritoneum ormediastinum, or aspirated into the respiratory tract.

generally used undiluted or mildly diluted for a contrast meal and diluted approximately1 in 2 for an enema.

Earlier hyperosmolar water-solubleagents such as meglumine/sodium (Gastrografin) and iothalamate meglumine (Conray) were associated with considerable fluid shifts,drawing water into the bowel lumen with the risk of severe dehydrationand haemodynamic compromise in infants.

If aspirated,they may result in severe pulmonary oedema.

The only remaining indication for Gastrograffin, used in dilution, is in the enema treatmentof meconium ileus, when hyperosmolarity is beneficial.

For a contrast meal examination, barium or water-soluble contrast can be administered via a cup-and-straw, feeding bottle, or cautiously syringed directly into the mouth if necessary.

Contrast should be introduced just over thebase of the tongue so that the infant still will have to swallow.

Contrast should not be delivered with the patient in the supineposition.

The infant should be in the lateral or right anterior-obliqueposition, because this guards against aspiration.

With contrast enema examinations in newborn and younginfants, the most important practical point is to have adequateocclusion of the anus.

A Foley catheter is preferred and should be inserted beforetaping of the buttocks.

When one is looking for low rectalpathology, such as Hirschsprung's disease, it is best not to blow upthe balloon.

In manycases, extensive preparation of the colon is not required and, inHirschsprung's disease, is contraindicated.

Omit the feeding before the examination.

Overnight fasting is not required and is detrimental.

In the neonate and young infant, fluid and electrolyte balance is delicate, and it is mostimportant that these infants not be dehydrated for prolongedperiods

FOREGUT

ESOPHAGUS

AT 4th WK RESPIRATORY DIVERTICULUM APPEARS AT VENTRAL WALL OF FOREGUT.

ESOPHAGOTRACHEAL SEPTUM

RESPIRATORY PRIMORDIUM (VENTRAL)

ESOPHAGUS (DORSAL)

MUSCULAR COAT IS FORMAD BY SPLANCHNIC MESENCHYMESTRIATED IN UPPER 2/3rd (VAGUS)SMOOTH IN LOWER 1/3rd (SPLANCHNIC PLEXUS)

In neonatal esophagus mucosal folds are not as prominent as in adults, but indentations by the aortic arch, left main stembronchus, and normal left atrium are frequently noted, even in the neonate

Normal peristaltic activity usually is evident atbirth but may not be as pronounced as in later life.

Normal esophagus. Latera view showing normal indentationsproduced by aortic arch (A) and left main bronchus (B).

In the recumbent position, emptying of the esophagus may be somewhat prolonged.

In the neonate, the esophagus is flexible and can assumepeculiar configurations during various phases of the respiratory cycle.

The resulting bizarre, tortuous configuration of theesophagus at any level may at first appear startling, but repeat studyusually demonstrates a normal esophagus

Tortuous esophagus. A. Bizarre,tortuous-appearing esophagus in young infant. B.Moments later, the esophagus appears normal.

Air in the Esophagus (Pneumoesophagus)

Many infants demonstrate small amounts of air in the esophagus onregular chest films, and the finding is entirely normal.

some infants demonstrate massive collections of air in theesophagus, or so-called mega-aeroesophagus .

Such air collections are readily visible onplain chest films and can be startling

In most of these cases, the underlying problem usually is gastroesophageal reflux , but excessive air in the esophagus also can be a sign ofthe presence of a tracheoesophageal fistula.

Massive pneumoesophagus (i.e .. mega-aero esophagus). A. Note the markeddistention of the air-filled esophagus (arrows). This air is much more voluminous than that seenunder normal circumstances. Most often, such massive distention of the esophagus is the result ofgastroesophageal reflux. B. Premature infant. Supine position with air reflux from the stomachinto the esophagus (arrows).

Transient Esophageal Hypotonia of the Neonate

In some newborn infants, the esophagus appears almost totallyinactive, and even with prolonged examination, little peristaltic activity is noted

These infants frequently have difficultywith swallowing, and regurgitation is common.

This is why they are referred to the radiologist for examination.

No obstructing lesions are found, and the phenomenon is transient.

Within a week or less, normal peristaltic activity prevails, feeding difficulties disappear, and theinfant has no further problems.

This lack of normal motility issimply a reflection of normal, but transient, neuromuscular immaturity.

Transient esophageal hypotonia of the neonate. On thesefour spot films, taken in rapid sequence, note that there is no suggestion ofperistaltic activity of the esophagus. Anyone of the spot films could beinterpreted as normal, but when it is noted that on none is there evidence ofperistalsis of the esophagus, transient hypotonia should be suspected.

Most Common Causes of GI Tract Obstruction byAgeAge Cause of Obstruction0–1 month Congenital anomalies

Atresia/stenosisMalrotation/volvulusHirschsprung diseaseMeconium plug/small left colonsyndromeMeconium ileus

1–5 months Hernias

5 months–3 Intussusceptionyears

3 years and older Perforated appendicitisAdhesionsRegional enteritis

Causes of Esophageal ObstructionCongenital atresia/stenosisWeb/diverticulumForeign bodyStricture (peptic, caustic)Extrinsic compression (cysts, neoplasms, vascular)Achalasia

The trachea and oesophagus arise from the common foregut.

Anomalies in the separation of these two structures by the oesophagotracheal septum result in oesophageal atresia, with or without an associated tracheo-oesophageal fistula, with an incidence of 1 in 2-4000 live births.

Diagnosis may be suspected on antenatal ultrasound if thegastric bubble is small or not visualised, or if a distended proximaloesophageal pouch is seen.

ESOPHAGEAL ATRESIA & TRACHEOESOPHAGEAL FISTULA :

Polyhydramnios is commonly associ-ated.

Postnatally, infants present with drooling, choking, coughingand episodes of cyanosis on feeding.

When attempts to pass a naso-gastric tube are made, resistance is met and a chest radiograph will showthe tube coiled in a dilated air-filled proximal oesophagealpouch

Since air usuallyis seen in the stomach within 1 5 minutes afrer birth, an airlessabdomen in the neonate should suggest the strong possibilityof esophageal atresia with no tracheoesophageal fistula.

ESOPHAGEAL ANOMALIES

ESOPHAGEAL ATRESIA & TRACHEOESOPHAGEAL FISTULA :

Atretic segment usually at the junction of proximal & middle 1/3rd.

If TOF is present , found proximal to carina.

Mortality with esophageal atresia is due to congenital Anomalies.

TYPES:•O.A. With trachea and distal esophageal fistula (85%)•O.A. Without fistula (10%)•Isolated tracheoesophageal fistula,h-type (5%)•O.A. With proximal fistula (rare)•O.A. With proximal & distal fistula (rare)

ANTENATAL DIAGNOSIS

•Polyhydroamnios•Absent fundic bubble

NEONATAL DIAGNOSIS•Excessive salivation , coughing and choking•Orogastric tube curls in proximal esophageal pouch

Plain radiography•Air filled proximal esophageal pouch •Gasless abdomen in isolated O.A. Or O.A. With proximal fistula.•Gas in abdomen means distal fistula•Aspiration pneumonia•Vertebral anomalies (vater)

Contrast study for proximal fistulas 1 ml OF LOCM TO BE USED IN LATERAL POSITION . H - TYPE FISTULA DEMONSTATED IN PRONE POSITION

Figure 2: (a) Contrast swallow showing an oesophageal atresia, overflow of contrast into the bronchial tree and a distal tracheooesophageal fistula with contrast in the stomach Figure 2: (b) Lateral chest X-ray demonstrating a contrast-fi lled blind ending proximal oesophagus and trachea outlined by aspirated contrast

Oesophageal atresia with tracheo-oesophageal fistula. A coiledtube is seen in the dilated proximal oesophageal pouch (toparrow). The presence of distal air-filled bowel implies an associated tracheooesophageal fistula. Thirteen pairs of ribs are noted, compatible with VATERsyndrome (lower arrow

H-type fistulas generally present later in infancy or childhoodwith episodes of choking or apnoeas during feeding or recurrentlower respiratory tract infections.

If suspected clinically, a 'tubeoesophagram' should be performed.

A nasogastric tube is passed andwater-soluble contrast instilled while the tube is slowly withdrawn the oesophagus.

Most fistulas involve the proximal third of theoesophagus and care should he taken to distend this segment well inorder to maximise visualisation of a fistula which passes anteriorlyand superiorly between the oesophagus and the trachea, in more ofan `N' than an `H' configuration

Contrast oesophagram demonstrating oblique track (arrows) of atracheo-oesophageal fistula with contrast filling the tracheobronchial tree.

It is important for thesurgeon to know whether the aortic arch is right or left sided tofacilitate surgical repair. This can be difficult to demonstrate inneonates, and magnification, high-kilovoltage techniques, and CTand MR examinations have been used to meet this end.

Ultrasonography also can identify the aortic arch and determinewhether it is left or right sided, but the study is not always easy toaccomplish.

Congenital esophageal stenosis is a far less common cause ofcongenital esophageal obstruction.

As in esophageal atresia,esophageal stenosis arises from faulty tracheal and esophagealseparation, where tracheobronchial cartilage remnants remain in thewall of the esophagus.

On barium swallow, small diverticula (mucousglands) can be seen in the areas of stenosis

ESOPHAGEAL STENOSIS

Congenital esophageal stenosis without O.A. Is associated:•Tracheobronchial remnants•Intraluminal membranes

TRACHEOBRONCHIAL REMNANTS represent abnormal rests of Respiratory tissue in esophageal wall.Localized narrowing of distal esophagus with proximal Dilatation.Multiple small diverticulum like structures (Tracheobronchial glands) perpendicular to esophagus

INTRALUMINAL MEMBRANEThin radioluscent defect that traverses esophageal Lumen at rt. Angle.Degree of obstruction depends upon size of aperture.

ESOPHAGEAL BRONCHUS

Abnormal origin of bronchus from esophagusCause:incomplete cleavage b/w trachea and esophagus In utero.Recurrent , persistent infection in the area supplied by Abnormal esophagus

FOREGUT CYSTS

•BRONCHOGENIC•GASTROENTERIC•NEURENTERIC

CLASSIFIED AS :

BRONCHOGENIC CYSTS :Cause : Abnormal ventral branching of tracheobronchial tree

Lined by respiratory epitheliumSymptomatic due to compression of trachea or incidental

Plain radiographyOval or round mediastinal mass in subcarinal or right Paratracheal region.Foregut cysts push the carina forward and esophagus Backward; thyroidal masses and aberrant left pulmonary Artery behave similarly

ON BARIUM EXTRINSIC COMPRESSION OF ESOPHAGUS BY MASS

CT : THIN WALLED WATER DENSITY MASSES OR SOFT TISSUE MASSES (CONFUSED WITH TUMOUR)

GASTROENTERIC CYST

Known as esophageal duplication cyst

Cause : arise from diverticulum of primitive foregut orAbnormal recanalization of gut.

Clinically silent or may cause dysphagia , pain

Imaging similar to bronchogenic cyst except•Posterior mediastinum•Thick wall•On barium extrinsic or intramural compression

Variety of enteric cysts communicate with esophagus.

Tc 99m identifies enteric duplication cysts if they contain gastric mucosa.

Extrinsic mass causes displacement of esophagus towards the right and

mass effect on the esophagus.

Cyst behind the carina deviating the esophagus to the right side.

NEURENTERIC CYST

Incomplete seperation of foregut from notochord

Cyst wall contains gastrointestinal Neural elements

Round or oval lobulated mass in posterior mediastinum b/w Esophagus and spine.

Associated with congenital anomalies of spine i.e.Hemivertebra, spina bifida.

MRI to delineate intraspinal anomalies.

VASCULAR ANOMALIES

•Double aortic arch•Right aortic arch with aberrant left subclavian a.•Aberrant left pulmonary artery

Clinical presentation •Dysphagia•Recurrent respiratory infection •Dyspnea

Suspicion (aortic)•Trachea deviated to left side•Tracheal indentation on right or posteriorly•Absent aortic arch on left

Barium swallow•Posterior indentation of esophagus(lateral view)•Unilateral/ bilateral indentation (frontal view)

Preoperative ct/ mri/ dsa for vascular anatomy

ABERRANT ORIGIN OF LEFT PULMONARY ARTERYKnown as pulmonary slingLeft pulmonary arise from right pulmonary artery

Diagnosis

Plain radiograph NormalObstructive emphysema rt. Lung

Barium swallowIndentation on anterior wall of esophagus at the levelOf carina

ABERRANT SUBCLAVIAN A. ABERRANT PULMONARY A.

STOMACHFUSIFORM DILATION OF FOREGUT IN 4th wk.

Longitudinal axis rotationRotates 90 degree clockwiseLeft side face anteriorly(left vagus)Right side face posteriorly(rt. Vagus)Posterior wall grows faster (greater curvature)Dorsal mesogastrium pulled towards rt. Side formingLesser peritoneal sac or omental bursa

Anteroposterior axis rotation Pyloric part moves to right& upwardsCardiac portion to left & downwards

CONGENITAL ANOMALIES

Situs solitus : stomach bubbble on left sideSitus invesus : stomach bubble on rt. SideSitus ambigus :associated with polysplenia/ asplenia

Duplication of stomach

Bowel has additional loop or cystic componentAntrum esp. Along greater curvatureF>mInfant with vomiting , fever , pain

Diagnosis :Usg:echogenic bowel wall surrounded by hypoechoicmuscle with cyst full of echofree fluid

Tc99m: TUBULAR OR COMMUNICATING CYSTS

MICROGASTRIA & AGASTRIA

ABSENT STOMACH (AGASTRIA)

SMALL UNDERDEVELOPED STOMACH (MICROGASTRIA)ASSOCIATED WITH:

•MALROTATION •CHD•AGANGLIONOSIS•ASPLENIA

GASTRIC ATRESIA / WEB

•FAILURE OF LUMEN TO DEVELOP IN STOMACH•PARTIAL / COMPLETE•SECONDARY TO ISCHAEMIA

DIAGNOSIS

PLAIN RADIOGRAPHY:

COMPLETE: DISTENDED STOMACH WITH NO SMALL BOWEL GAS BARIUM STUDY RARELY INDICATED

PARTIAL : BARIUM STUDY WITH TANGENTIAL PROJECTION

Gastric diaphragm. A, Note the thin membrane (arrows) crossing the fluid-filled gastric antrum. B, The samediaphragm seen during a contrast upper GI series (arrows).

ECTOPIC PANCREAS

Small areas of ectopic pancreas may be found anywhere in GIT

Gastric antrum with rudimentary duct(commonest)

Diagnosis

•Asymptomatic•Smooth , sessile polyp- type mass projecting into Gastric antrum below pylorus on greater curvature•Duct system on barium study seen as central niche Mimics ulcer•USG : FOCAL ANTRAL THICKNING UPTO 5 mm(unreliable)

HYPERTROPHIC PYLORIC STENOSIS

•Pyloric muscle hypertrophy•Unknown etiology•First born male•PRESENTS SOON AFTER BIRTH UPTO 10 wks

Clinical features:•Projectile vomiting•Palpable lump

Diagnosis:Palpation of olive shaped tumour,rarely radiologyRequired for diagnosis

Usg :•Fill stomach with dextrose•Failure of passage of gastric contents•Marked gastric peristalsis•Shouldering & beaking•Single / double curved echogenic structures on Long. Section(central mucosa)•LENGTH >15mm ABNORMAL•12 – 15 mm BORDERLINE

BARIUM MEAL

•USG CAN MISS 8 % OF CASES•LONG, CURVING SINGLE OR DOUBLE PYLORIC CANAL(STRING SIGN)•SHOULDERING TO ANTRUM•MUSHROOM SHAPED APPEARANCE OF DUODENUM•DELAY UPTO 20min. CAN BE NORMAL

The classic appearance of pyloric stenosis on ultrasound is that of

(a)elongation of the pyloric canal;(b) persistent spasm of the pyloric canal with little, if any, fluid passing into the duodenum;(c) persistent thickening of the circular muscle in the elongatedcanal; and (d) a sonolucent donut (thickened muscle) on cross section

The thickness at whichthe muscle is considered hypertrophied is 3 mm orgreater.

Pyloric canal length of 1.5 cm is considered diagnostic of pyloric stenosis when seen in conjunctionwith thickened pyloric muscle.

In practice, however,normal canal length is much shorter than this and is often impossible to measure.

Measurement of canallength is more problematic than measurement of musclethickness and therefore a less reliable criterion.

Pylorospasm and Minimal Muscular Hypertrophy

In some vomiting infants, sonography shows a persistentlycontracted and elongated canal, but the degree ofmuscular thickening is less than the criterion of 3 mm for surgically correctible HPS.

With extended observation, eventually the canal opens and fluid is seen to passinto the duodenum,but the periods of spasm predominate

In the vast majority of cases,there is no thickening of the pyloric muscle or mucosa,and the problem is primarily nonspecific pylorospasm(antral dyskinesia)

This condition can accompany milk allergy or other forms of gastritis.

In some cases the pyloric muscle is mildly thickened,measuring 2 to 3 mm.

Such patients should be distinguishedfrom those with normal muscle thickness(<2 mm)

because some patients with minimal musclehypertrophy can eventually progress to classic pyloricStenosis

Many of these infants willrespond to medical therapy and require no surgery

Normal stomach. Normal antrum ofstomach (S), pyloric canal (P), and proximal duodenum (D). Fourgastric wall layers are visible (from inside out): echogenic mucosa,hypoechoic muscularis mucosae, echogenic submucosa,

Pyloric stenosis. AXR showing distended gastric air bubble.hypoechoic outer circular muscle.

Pyloric muscle tangential imaging artifacts. A, When imaging the antrum in cross section, the musclewill appear thickened if obtained through plane 1, but will show normal thickness if obtained through plane 2. B, Longitudinal scan,tangential plane (T), shows pseudothickening. Imaging in center (C) shows true normal muscle thickness. C, Tangential scan shows musclepseudothickening (arrows); D, duodenum. D, Antrum distended with fluid shows normal muscle (arrows).

HPSA, Longitudinal scan shows markedly thickened, hypoechoicgastric antral muscle (arrows). Elongated canal isnearly 2 cm in length. B, Transverse scan shows typical,hypoechoic “doughnut” (arrows). Central echogenicmucosa with anechoic fluid-filled crevices.

Pylorospasm. A, The pylorus remained contracted early in the examination of this infant, but the muscle is normalin thickness (arrows). B, After slightly extended period of viewing, the pylorus relaxed and appeared normal (arrows)

Pyloric stenosis. Barium meal showing an elongated pyloric canaland shouldering of the antrum due to the hypertrophied pyloric muscle.

Empty stomach artifact. A, Before fluid is administered, the antrum is contracted and the pyloric muscle appearsthickened (arrows). B, When fluid distends the antrum, the true normal thickness of the muscle is seen (arrows).

Midgut & hindgut

MIDGUT

5 wks embryo suspend by short dorsal mesentryRapid elongation of gut &mesentry form primaryIntestinal loop.

Cephalic limb:•Distal part of duodenum•Jejunum •Part of ileum

Caudal limb :•Lower portion of ileum•Caecum , appendix•Asc. COLON & PROX 2/3 rd OF TR. Colon

Malrotation and midgut volvulus is one of the major paediatricsurgical emergencies and the role of radiology in its diagnosis critical.

Delay in diagnosis can result in infarctive necrosis of the entiresmall bowel and is potentially fatal.

At approximately week 6 of gestation the duodenojejunaland ileocolic segments of the primitive gut herniate intothe extraembryonic coelom in the umbilical cord.

Both loops elongateand rotate 270° anticlockwise around the axis of the superiormesenteric artery.

By the end of the third month of gestation thebowel loops are returned to their final positions in the abdominalcavity, with their mesenteries becoming fixed to the parietal peritoneumat several sites.

The duodenal loop is fixed with the duodenojejunaljunction (DJJ) in the left upper quadrant at the ligamentof Treitz and the ileocaecal junction fixed in the right lower quadrant.

The normal DJ flexure lies to the left of themidline (at least over the vertebral pedicle) at the level of thepylorus. In malrotation, it is displaced medialy, inferiorly or both

The normal small bowel mesentery therefore has a broaddiagonal base across the abdomen.

Physiological hernia :

During 6 th wk.Rapid elongation of cephalic limbRapid growth of liverAbdominal cavity is small so contents herniateinto extraembronic cavity

Rotation of midgut

Around SMA axis 270 degree counterclockwise Rotation viewed from front•Rotation during herniation (90 deg.)•Return of intestinal loops(rem. Of 180 deg.)•Caecum forms during herniation

Elongation of intestinal loops continue

Retraction of herniated loops

At 10 wks•Regression of mesonephric kidney•Reduced growth of liver•Expansion of abdominal cavity

Proximal jejunum first part to enter (lies on left)

Caecal bud last part to enter back(below rt. Lobe of Liver)

Appendix develops during descent of caecum, Frequently retrocaecal/ retrocolic

MALROTATION

Any child with bilious vomiting considered to haveMalrotation unless proved otherwise

Malrotation is associated with malfixation so GI study to locate DJ junction

Normally to the Lt. of left vertebral pedicle at the Level of duodenal cap

DJ junction is mobile in children less than 4 months

SMV is ventral or to the Lt. of artery in malrotationSMV spirals around SMA , artery shows hyperdynamicCirculation

Band of ladd’s gives z-configuration of DJ junction

TYPE I MALROTATION (NONROTATION)

STOP ROTATING AFTER 90 DEG. COUTERCLOCKWISE

DJ JUNCTION LIES ON RT. SIDE

CAECUM LIES ON LT. SIDE

CLINICALLY INSIGNIFICANT BECAUSE OF GOOD FIXATION

TYPE II MALROTATION (REVERSED MALROTATION)

B/W 6WKS– 10WKS

AFFECTS DUODENUM ONLY

DUODENUM ENDS UP IN FRONT OF SMA OR OBSTRUCTED BY LADD’S BAND

MIMICKS DUODENAL ATRESIA

DJ JUNCTION ON RT. & CAECUM ON RT. SIDE

TYPE III MALROTATION

ERROR IN ROTATION AFTER 10 WKS

DJ JUNCTION & CAECUM USUALLY MIDLINE

MOST DANGEROUS FORM OF MALROTATION

VOLVULUS , GANGRENE & DEATH COMMON.

VOLULUS GIVES BEAKED APPERENCE(COMPLETE OBST.) CORKSCREW (INCOMPLETE OBST.)

LATE PRESENTATION

Midgut volvulus presenting as a classic 'corkscrew' appearance of the duodenum and proximal jejunum on lateral view

on ultrasound in a patient with volvulus, vigorous peristalsis ofthe obstructed duodenal C-loop is seen with characteristictapering of the distal, twisted end

When color Doppler ultrasoundis used, the twisted mesenteric vessels are seenswirling in a clockwise direction (whirlpool sign), andthis finding is highly suggestive of midgut volvulus

Midgut volvulus. Vigorous peristalticactivity fails to empty the duodenum, and the third portion of theduodenum has beak deformity (arrow); S, stomach

Midgut volvulus: altered relationshipof mesenteric vessels. A, Normal superior mesenteric vein (V) lies to the right of the superior mesentericartery (A). B, Intestinal malrotation and midgut volvulus; thevein (V) lies to the left of the artery (A). C, Color Doppler shows a clockwise whirlpool of vessels (arrows) around a volvulus.(

DUODENAL ATRESIA & STENOSIS

•1 IN 6000 LIVE BIRTHS•ATRESIA MORE COMMON THAN STENOSIS•ASOCIATED WITH DOWN’S SYNDROME, ESOPHAGEAL ATRESIA ,ARM, LADD’S BAND, RENAL ANOMALIES,BILIARY ATRESIA

TYPES :

TYPE I WEB (DIAPHRAGM OCCLUDING LUMEN)

TYPE II BLIND END CONNECTED BY FIBROUS CORD

TYPE III (MOST COMMON) NO CONNECTING CORD WITH DEFICIT OF MESENTERY

TYPE IV MULTIPLE ATRESIAS

ANTENATAL DIAGNOSIS•DOUBLE BUBBLE•POLYHYDROAMNIOS

CLINICAL FEATURESBILIOUS VOMITING(DAY 1)

PLAIN RADIOGRAPHY•DOUBLE BUBBLE APPERENCE•GAS DISTAL S/O INCOMPLETE ATRESIA

Because an abdominal fluid collection can have other etiologies, it is important to demonstrate a continuum between the stomach and the cystic mass on ANC scan.

A prominent incisura angularis of the stomach may be mistaken for a “double bubble” if these are in different planes, but a careful real-time longitudinalexamination of the stomach can eliminate this possibility.

Duodenal atresia in a fetus with trisomy 21. A, Transverse fetal pelvis at 18weeks with echogenic bowel (arrow E). B, Same fetus at 21 weeks. Transverseview of abdomen with stomach (arrow S) on left and fluid-filled duodenum (arrow D). C, Same fetus at 25weeks. There is a “double bubble.” The stomach isvisible inferiorly (S), with the dilated proximal duodenum(D) visible crossing the midline.

DOUBLE BUBBLE APPEARENCE DUODENAL WEB

DUODENAL ATRESIA

most common congenital anomaly of the pancreas.

Pancreatic tissue encircles the descending duodenum andnarrows its lumen.

the bilobed ventral component of the pancreas fuses with the dorsal pancreas on both sides of the duodenum.

often presents in childhood, especially in children with Down syndrome, about half of cases do not present until adulthood.

Symptoms in adults -nausea, vomiting, abdominal pain, and occasionally jaundice.

ANNULAR PANCREAS

PREOPERATIVE DIFFERENTIATION FROM DUODENAL ATRESIA IS DIFFICULT

DIAGNOSISThe UGI series typically demonstrates eccentric or concentric narrowingof the descending duodenum

CT pancreatic tissue seen surrounding 2nd part of Duodenum

ERCP a segment of pancreatic duct encircling theDuodenum

Annular Pancreas. Upper GI seriesdemonstrates a 3-cm long circumferentially narrowed segment(arrows) of the descending duodenum. No ulceration wasevident. CT confirmed an annular pancreas. Db, duodenal bulb.

Annular pancreas. A, Axial T1-weighted fat-suppressed MR image demonstrates pancreatic tissue completelycircumscribing the descending portion of the duodenum B, Corresponding MRCP shows the extrinsic compression around the secondportion of the duodenum

PREDUODENAL PORTAL VEIN

PRESENTS AS DUODENAL ATRESIA/ STENOSIS

PORTAL VEIN LIES ANTERIOR DUODENUM

ASSOCIATED WITH•SPLENIC ANOMALIES•MALROTATION

USG CAN DEMONSTRATE VEIN ANT. TO DUODENUM

Pre-duodenal portal vein seen anterior to duodenum, and posterior to intra-peritoneal pancreas (arrow)

Jejunal /ileal atresiaCommonest bowel atresia

EtiologyIntrauterine ischaemic insultPrimarySecondary : due to antenatal volvulusSeverity of ischaemia determines extent of atresia

Proximal jejunum & distal ileum are common sites

Clinical features •Bilious vomiting•Abdominal distention •Meconium passage depends upon time of insult & Site of obstruction

BARIUM ENEMA

Preoperative enema is required to exclude Distal atresias

Locm is preferred

Microcolon is normal finding exceptHigh obstruction Low obstruction with late intrauterine insult

Diagnosis•Dilated bowel loops to the level of atresia•Meconium peritonitis with calcification present if Intrauterine perforation has occured

Apple peel syndromeIntrauterine occlusion of distal sma•Proximal jejunal atresia•Agenesis of mesentery•Absence of mid small bowelDistal ileum spirals around it’s narrow vas. Pedicle

Malrotated microcolon usually present

•multiple sites of severe stenosis and a spiral configuration of theatretic segment. This condition tends to be familial

TRIPLE BUBBLE APPEARENCE

JEJUNAL ATRESIA

Jejunal Atresia. Plain film shows distention ofthe stomach (S), duodenum (D), and loops of the upper intestine(arrows). No air is present distal to the proximal jejunum

DILATED BOWEL LOOPS MICROCOLON WITH REFLUX INTO TERMINAL ILEUM

ILEAL ATRESIA

MECONIUM ILEUS

High protein content of meconium cause distal bowelObstruction90%have cystic fibrosis

Clinical features•Bilious vomiting•Abdominal distention •Failure of passage of meconium

Antenatal diagnosisMultiple echogenic fociMeconium cysts

Plain radiographyBubbly pattern of bowel gas in rt. Iliac fossaDilatation of small bowel

Barium enema

To determine true nature of obstruction

In uncomplicated therapeutic as well as diagnostic

Isoosmolar contrast medium

Gastrograffin diluted half strenght with saline or water

Barium sulphate inspissates & risk of perforation

1/3rd pt. Too sick--require surgery

1/3rd pt. Enema unsuccessful

1/3rd pt. One or more enema req. To remove sticky meconium

Usg : dilated loops with echogenic material

Complicated meconium ileus

Intraabdominal calcification

Bowel wall calcification

Soft tissue mass

In utero perforation causes chemical peritonitis (Snow storm appearance) on usg

Meconium pseudocyst is due to vascular compromise

MECONIUM ILEUS

BUBBLY APPEArance

Meconium Ileus. A. Plain film shows thesoap-bubble effect of air mixed with meconium in thenumerous distended loops of intestine. B. Contrast enemademonstrates a typical microcolon with reflux into the terminalileum, which is filled with pellets of meconium (arrows).

misleading name for a condition caused by functional immaturity and abnormal peristalsis of the distal colon.

Also known as small left colon syndrome, this conditionshould not be confused with meconium ileus.

a normal to dilated proximal colon filled with meconiumand an empty distal descending colonic segment are characteristic

The meconium in infants with this condition is normaland is not the cause of obstruction.

Meconium plug syndrome

more common innormal large infants and infants of diabetic mothers.

functional obstruction is transient and can often be treated by rectal stimulation or saline enemas

Normal ganglion cells are present in these infants, and once the meconium has passed, the patient will defecateNormally.

Meconium Plug Syndrome (Small Left ColonSyndrome). A. Numerous loops of intestine are distended withair. Also, note air in the relatively narrow rectosigmoid colon(arrow). B. Contrast enema demonstrates a small left colon withthe characteristic transition zone (arrow). These findings mimicthose of Hirschsprung disease.

VITELLINE DUCT ANOMALIES

Meckel's diverticulum

•2--4 % population vitelline duct persist•40--60 cm FROM IC JUNCTION

CLINICAL FEATURES

•BRIGHT RED PAINLESS RECTAL BLEEDING•Obstruction secondary to intussusception

Vitelline cyst / enterocystoma cause strangulation or volvulus

Vitelline fistula : duct patent entire length (fecal discharge)

Tc pertechnate scan dignostic for heterotrophic pancreatic tissue ,gastric mucosa

Meckel Diverticulum. A scan performed withtechnetium-99m-pertechnate shows an abnormal collection oftracer in the right lower quadrant (arrow), whose intensityparallels that of the stomach (S). Gastric mucosa within theMeckel diverticulum is responsible for the tracer localization. B,bladder.

HINDGUT

HINDGUT GIVE RISE TO DISTAL 1/3rd OF TR. Colon,descending colon Sigmoid , rectum & upper part of rectal canal

Terminal portion of hindgut enters posterior reg. Of cloaca (Primitive anorectal canal )

Allantois enters anterior portion ,primitive urogenital sinus

Urorectal septum forms perineum

Ectodermal proliferation closes distal most part of anal canal which is recanalized

Junction b/w ectoderm & endoderm , pectinate line

Normal appearance in neonate

Haustral patterns are hardly developed

Large bowel is redundant, sigmoid reaching upto hepatic Flexures

Caecum can appear higher

Lymphoid follicles , tiny nodular filling defect,upto 2mm Upto 5 yrs is s/o good coating

Lymphoid hyperplasia >3 mm ,found in • dysgammaglobulinemia• Ibd• Lymphoma

Lymphoid hyperplasia

Large bowel atresia

Rarer than small bowel atresia

Clinical features•Failure to pass meconium•Abd. Distention•Vomiting

Types :type I -- web Type II -- gap bridged by atretic cord Type III -- complete seperation (most com.)

Right colon is mostly involved

Diaphragm prolapse in retrograde fashion into dilated prox.Segment, windsock appearence

Functional motility disorder

Hischprung's disease

1 in 5,000 live births, m>f

Absence of myenteric ganglion in distal large bowel

Hypertonic aganglionic segment

Zone of transition gradual change from ganglionosis to aganglionosis

Rectosigmoid region is most common (70%), 25% extend to the splenic flexure or transverse colon (long segment) and 5% involve the entire colon (total colonic Hirschsprung's disease).

Cause : due to arrest in the normal cranial-to caudal neural cell migration, resulting in absence of ganglion cells within the myenteric plexus of the bowel wall

Clinical features

failure to pass meconium within the first 48 h of life.

A smaller number present with intractable constipation later in childhood and occasionally into adulthood.

Enterocolitis occurs in 15% of patients and can be the initial presentation, with fever and diarrhoea.

Diagnosis

Biopsy is definitiveRadiology and manometery helpful

Plain radiographyOBSTRUCTION ( >3 cms)Cross table lateral with pt . prone for zone of transition

Contrast enema

No bowel preprationWater soluble contrast media preferredLateral position to recognize zone of transition Absence of tr. Zone does not exclude diseaseDelayed film showing retention is also s/o diseaseReversal of rectosigmoid ratioIrregular saw tooth contractions in aganglionic seg.

The normal neonatal rectum is of greater calibre than the sigmoid colon.

Inversion of the rectosigmoidindex, often in association with irregular contractions of theaganglionic rectum and difficulty in obtaining good rectal distension,is indicative of Hirschsprung's disease

Hirschsprung's disease. An abrupt transition zone is seen atthe rectosigmoid junction on this lateral rectal view from a contrast enemaperformed on a 2-day-old boy with failure to pass meconium. The rectumwas difficult to distend well and showed irregular contractions.

Enteric duplication cyst

Additional portion of gut developsNon communicating with bowel except tubular typeMesenteric side of iileum , common siteMuscle layer continuous with bowelwall

Clinical features

•Vomiting due to obstruction•Abdominal pain •Palpable abdominal mass

Usg :

•Unilocular anechoic cystic mass•Double layered•Tc 99m req. In tubular & communicating cyst

Mesenteric cyst / lymphangioma

Sequestration of lymphatic vessels

Omental cysts ( in omentum)

Intermitent symptoms

Soft & mobile , difficult to palpate

Usg :•Uniloculated / multiloculated•Thin or thick septationsAnechoic or echogenic debris

Anorectal malformation

Absence of normal anus, First day presentation with obstruction1 in 5,000 live birthsMale > female

Cause : abnormality in formation of cloacaPosterior portion of cloaca is small so hindgut opening Shifts anterioly

Classification :On basis of rectum above or below puborectalis sling•High•Intermediate•Low

Low variety No communication with gu tractVisible perineal opening anterior (ectopic anus)

High varietyNo visible perineal openingComm. With gu tract present

Imperforate anusNo anal opening , lack of recanalization of lower Portion of anal canal.

Associations:Oeis (5%) omphalocele-exstrophy-imperforate anus-spinal defects)Vacterl (45%)Down syndrome (2-8%)Currarino's triad;anorectal stenosis Scimitar sacrum Presacral mass lesions

Plain radiograph

Distal bowel obstruction Invertogram no more used , cross table lateral taken.Intravesicle air s/o high varietyCalcified intraluminal meconium (high variety)Vertebral anomalies (vater)

Usg :Renal tract anomalies( ectopic, horseshoe)Spinal usg to rule out cord tetheringTransperineal for distance b/w anal dimple & distal large bowel

Loopogram :Size of bowel distal to colostomyAny fistulaTo look for leaks or obstruction after pull through surgery or Before colostomy closure

Ct/ mri ;Indicated if incontinence or constipation after operation

BODY WALL DEFECTS

Omphalocele

Herniation of abdominal viscera covered by amnion through enlarged umblical ring

Cause : failure of bowel to return to body cavity from physiological herniation

2.5/ 10,000 live births

Mortality 25%

Cardiac anomalies 50%

Antenatal presence of sac with umblical insertion

Gastroschisis

1/ 10,000 live birts

Increased incidence with cocaine use

Herniation of bowel contents directly into amniotic cavity

Right lateral to umblicus (regression of rt. Umblical vein)

Not covered by amnion or peritonium

No chromosomal anomalies

Bowel are short, edematous & coated with fibrocollagenous Coating

Excellent survival

Gastroschisis. Several air-filled extra-abdominal loops of bowelare seen in this infant of 26 weeks gestation. A small left congenitaldiaphragmatic hernia was also

present.

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