Pediatric GI

Pyloric Stenosis

• Non-bilious vomiting

• May just seen distended stomach with air fluid level in on XR

• 3W to 3 months old

  • Not in newborns or older kids

• More common in first born males

• Measurements

  • > 3 mm wide

  • > 15 mm long

• Double track sign = basically two muscular walls of the pylorus are so thick they look like two tracks

• Antral/mucosal heaping sign = pylorus becomes so hypertrophic that it pushes into the gastric antrum and indents it

• Managed with pylorotomy

• If you have findings consistent with pyloric stenosis on US you need to extend the exam by 3-5 minutes to confirm the pylorus is still closed and does not allow passage of gastric contents

  • If in 3-5 minutes it opens up and contents can pass freely then you are looking at a pylorus spasm which is managed medically

Intraluminal calcifications of the bowel Ddx:

• Total colon Hirschsprung disease

• Multifocal intestinal atresia (results in stasis of stool and subsequent calcifications)

• Anorectal malformation resulting in mixing of stool and urine

• Rectourethral fistula

Colon & Rectum

Duodenal obstruction

• Double-bubble

  • Dilated stomach in LUQ

  • Dilated proximal duodenum in RUQ

• Polyhydraminos

  • Cant get food through so eat less, so more fluid

• Need to see an image where the two bubbles connect to ensure it is not another cystic structure

• If do not connect, consider

  • Enteric duplication cyst

  • Choledochal/ovarian/splenic/liver cyst

• Pseudo-dubble-bubble

  • US scan traverses the gastric fundus and antrum-BOTH STOMACH

  • Here both bubbles will be in the LUQ

  • Get image showing connection and will show just stomach basically

Jejunum & Ileum

• Normal diameter <7 mm

• Normal length <15 mm

• Normally seen with minimal fluid

• Atresia typically a result of a vascular event

• Jejunal atresia

  • Triple bubble sign

Small Left colon syndrome (Meconium plug syndrome)

• I think this may be the same thing as functional immaturity of the colon, but unsure

• Seen on contrast enema typically with caliber change at splenic flexure - caliber change is not glaringly obvious

• Associations -

  • Maternal DM

  • Maternal pre-eclampsia because of use of magnesium-sulfate

• Treatment = contrast enema with water soluble contrast

Biliary Atresia

• Presents with jaundice and essentially signs of cirrhosis in a young child

• Extrahepatic biliary duct destruction with progression to involve the intrahepatic ducts

• Triangular cord sign - echogenic tissue adjacent to right portal vein which represents fibrotic remnant of bile duct

• Ghost Gallbladder triad (multiple findings to say a small and fucked up GB)

  • Irregular and discontinuous GB wall

  • Hypoplastic/atretic GB

  • Irregular GB contour

• Can see abnormal/tiny gall bladder but will not really see intrahepatic ducts, especially on angio

• Kasai classification

• Need liver transplant or will typically die

• Nuclear medicine testing

  • Give Tc-99m Diosgenin (DISIDA) or Mebrofenin (BRIDA) —> high hepatic excretion rate and short transit time

  • In biliary atresia will see good uptake of the radiotracer with no excretion at 24 hours

  • Phenobarbital —> increases biliary excretion

  • Administered 5mg/kg (divided in half for a BID dosing) for 3-5 days before procedure

  • Giving phenobarbital helps the excretion process so that there is not a false positive (i.e. very slow excretion with otherwise normal biliary anatomy)

  • Should seen radiotracer excretion into bowel, typically do not see well in the ducts but should be excreted and seen in the bowel (if normal), this will not be seen in BA

Duodenal hematoma

• Expect in setting of trauma (abuse, handlebar injury, EGD) or Henoch-Schonlein purpura

• Will see narrowing of second and third portions of duodenum

Bowel Obstruction

• Draw a line horizontal to the abdomen at the level of the umbilicus

  • If there are more dilated loops of bowel above the line —> proximal bowel obstruction —> upper GI is next step

  • If there are more dilated loops of bowel below the line —> distal bowel obstruction —> contrast enema is next step

• High bowel obstruction = obstruction proximal to the mid-ileum

  • Normal caliber colon will be present - there is enough normal proximal small bowel to make secretions which can feed the colon

  • Ex - high ileal atresia, jejunal atresia will cause this

• Low intestinal obstruction = obstruction in distal ileum or colon

  • Will have micro-colon because not enough proximal small bowel to make secretions to nourish the colon

  • Ex - low ileal atresia, meconium ileus

• Easy DDx for SBO in kids after immediate newborn period = AAIIMM

  • Adhesions

  • Apendicitis

  • Intussception

  • Inguinal hernia (incarcerated typically)

  • Midgut Volvulus

  • Meckel’s Diverticulum

Contrast Enema

• Will help you gather information via the following algorith

• No microcolon

  • Normal

  • Hirschsprung

  • Meconium plug

• Microcolon present

  • Ileal atresia (long segment microcolon)

  • Meconium ileus (long segment microcolon)

  • Colonic atresia (short segment microcolon)

Meconium Ileus

• Will see diffuse micro-colon

• Highly related to cystic fibrosis

• US findings

  • Dilated and hyperechoic bowel proximal to the stomach

• 2 types

  • Uncomplicated

    • Only an obstruction

    • Treated with high osmolar enema

    • Want contrast to get to bowel proximal to obstruction so that the high osmolar contrast can draw fluid into the bowel and flush it out

  • Complicated

    • Aka meconium peritonitis - leakage of GI contents into peritoneal cavity after bowel rupture

    • Intraperitoneal calcifications!

      • Note you can have other abdominal calcs like benign shit but look for calcs along the inferior aspect of the diaphragm and along the liver edge but not in the liver, these are intraperitoneal and are more suggestive of meconium peritonitis

      • In males can see calcs in the scrotum due to peritoneum extending through patent processus vaginalis

      • CMV will cause calcs within the liver and spleen itself

    • Free fluid within the abdomen, may be complex,

      • Meconium pseudocyst - basically an abscess with matted bowel surrounding it

    • Typically need surgery

Malrotation

• Midgut = bowel supplied by the SMA

• In utero the midgut will push through the umbilical space

  • Then rotate 90 degrees

  • Bowel will then come back through the umbilicus and rotate another 270 degrees

  • If you have a space occupying lesion, or oligohydramnios (decreases space to rotate) then you will have increased risk of malro

• Normal Anatomy

  • D3 is retroperitoneal, should pass between SMA & aorta

  • SMV on same side as portal vein

  • SMA on same side as spleen

    • Note that the SMA will have an echogenic halo around it and the SMV will not, important when there is concern for volvulus the SMV may be collapsed and you may just seen SMA which can be identified by that halo

  • May be helpful to look for left renal vein crossing over midline to orient yourself too

• Bilious vomiting

  • Because twisting occurs at the third portion of the duodenum which is distal to the ampulla of vater

• Midgut volvulus is the feared outcome

  • The abnormal orientation of the bowel causes it to twist on its mesentery creating the corkscrew bowel

    • Normally the mesentery is broad and extended from the ligament of treitz in the left upper quadrant to the ileocecal valve in the RLQ

  • Whirlpool appearance

  • Secondary findings may include distended stomach (shit cant pass beyond the distal duodenum)

• Ladd Bands

  • Bands of fibrous tissue between the mal-positioned cecum and the RUQ (abdominal wall, liver)

  • When the gut mal-rotates the cecum will typically be located in the RUQ next to the duodeum

  • The peritoneum will then further form and lay down fibrous tissue between the mal-positioned cecum and the RUQ abdominal wall/liver and will have to cross the duodeum in the process

  • These bands of fibrous tissue then compress the duodeum and cause obstruction

• Ladd procedure

Necrotizing Enterocolitis

• Highest risk around 28 weeks gestation age regardless of when delivery is

  • blood supply in utero is highly protected to the fetus and so perfusion is almost always present, unless mom is in near death situation

  • This is why NEC is really only seen in pre-mature babies after delivery because in utero they are protected by moms blood supply

• Bacteria dissect between the muscularis and mucosal layers which then develop air between the bowel layers

  • The air in the bowel wall will eventually spread to the veins which drain the bowel (superior mesenteric vein)

    • Air in the SMV will drain back to the portal vein

      • This is why portal venous gas is seen with NEC!!

• When evaluating on a radiograph you look for the findings below but a key feature to keep in mind

  • If you see what you suspect to be air by the liver or free air or whatever, get a left lateral decubitus film to evaluate for free air

    • If negative and you are still unsure wait 20 minutes with the patient remaining in the left lateral decubitus position and re-image

      • The reason for this is because the peritoneum will be full of shit and sticky crap which makes the transit of air slower in bad cases of NEC so will take more time for the air to move and may not be seen on the initial lateral film

• Findings

  • Pneumatosis

  • Focally dilated bowel, classically in RLQ - will be fixed = not change over time

    • Terminal ileum and right colon is most commonly affected

  • Featureless small bowel

  • Unchanged bowel gas pattern

• Who gets this

  • Premature children

  • Low birth weight

  • Prenatal hypoxia/asphyxia

  • Patients with cardiac disease (can be otherwise normal)

Congenital Diaphragmatic Hernia

• Left > Right

• Not a surgical emergency

• Presents with bowel in hemi-abdomen, may appear as a hemi-thorax white out rather than typical appearance of bowel as baby has not “eaten” enough air yet

Stomach

• Normally visualized around week 13/14 - not a definitive timeline though

  • If do not see in an age where you should, repeat study in few days

• Can be better or poorly visualized based on distention from baby drinking amniotic fluid

• Large stomach

  • Obstruction

  • Note pyloric stenosis is very rare to diagnose in utero

• Small stomach

  • Esophageal atresia

• Hyperechoic material in stomach

  • Ingested material/ skin cells

  • Ingested blood - look for concurrent subchorionic hemorrhage

Esophageal Atresia

• Suspect if stomach is not visualized on multiple attempts

• Polyhydraminos

• Many have tracheo-esophageal fistula so can still have atresia and have fluid in stomach

• On radiographs look for no bowel gas

• Look for high NG tube, dont mistake for ET tube, enteric tube should not be that high

• Look for presence of a right sided arch

  • Changes surgical approach

• Tracheo-esophageal fistulas

  • Blind esophageal pouch with connection between distal esophagus and trachea (85%)

    • Lots of air in stomach

  • No fistula, so blind pouch and stomach connects to nothing proximally

  • H type - 1% - air in stomach

• Associated with VACTERL

Duodenum

• Not normally seen in utero

• DDx for dilated fluid filled duodenum

  • Duodenal atresia (most common)

  • Webs

  • Extrinsic obstruction —> annular pancreas , malrotation