Selected Pediatric Surgical Conditions (HPS, Malrotation and Midgut volvulus, Duodenal Atresia)

Children are not small adults

• Affected by Congenital, common diseases and trauma

• Unique Fluids & Electrolytes

• Medication needs based on body weight

• Can deteriorate rapidly (Need careful observation)

• Parents

Approach to a vomiting child

Hx & Px

Normal vs. Pathologic vomiting?

• The look?

• Time of vomit?

• General condition? Ill, dehydrated…..

• Nature?

• Bilious? Needs careful investigations

• Age of onset

• Any other abnormalities?

• Any other GI symptoms?

General Treatment

• Assessment

• Stabilization

• Fluids and electrolytes resuscitation

• NPO

• NG tube

• Treat according to cause

Duodenal atresia and small bowel atresia\\\\ Hirshprung\\\\intussepetation

• Hypertrophic Pyloric Stenosis:

Hypertrophy and hyperplasia of circular muscles of

pylorus Resulting in constriction and obstruction

of gastric outlet.

• 0.5–5:1000 live births

• Male to female ratio is nearly 5:1

• Increased risk in first Born boys

• Most common surgical

cause of nonbilious vomiting in an infant

Etiology

• The cause has not been fully determined

• Possible risk factors :

1. Environmental Factors:

Exposure to nicotine during pregnancy

Bottle feeding, why?

2. Macrolides; Erythromycin or azithromycin exposure (motilin receptor), especially when administered within 2 weeks after birth

3. Familial link (Genetic Factor)

4. Prone position

5. Prematurity? Controversial

Pathophysiology

Hypertrophy and hyperplasia of the circular muscle layer of the pylorus narrowed and elongated pyloric channel Gastric outlet obstruction and vigor-ous peristalsis Projectile vomiting of a large volume of gastric content and dehydration

.

• Onset Between 2nd and 7th week of age (rarely after the 12th week)

• Frequent regurgitation progressing to Projectile nonbilious vomiting (30 to 60 min after eating) that becomes increasingly projectile over the course of several days to weeks

• As the pyloric muscle thickening progresses, the infant develops a complete gastric outlet obstruction and is not able to tolerate any feeds.

• “Hungry vomiter”: demands re-feeding after vomiting, demonstrates a strong rooting and sucking reflex, irritable

• Dehydration (wet diapers become less)

Classic Clinical Presentation

Classic Physical Examination

**An enlarged, thickened, "olive-shaped”, non-tender pylorus (diameter of 1–2 cm) should be palpable in the epigastrium (and this is diagnostic with no need for further imaging) ** Visible Reverse peristaltic waves may also be seen in the upper abdomen. (From left upper quadrant to epigastrium) ** Signs of dehydration

Labs: CBC/ABG/Electrolytes/KFT/Urinalysis Hypochloremic, hypokalemic metabolic alkalosis is a classic result which is uncommon these days +/- Hyponatremia or Hypernatremia may be present. Paradoxical Aciduria Q:First Imaging Study to Obtain? The gold-standard imaging modality is ultrasonography sensitivity and specificity close to 100%. Shows Enlarged and thickened Pylorus *Thickness greater than 3–4 mm and length greater than 15–16 mm diagnostic of HPS.

Diagnostic and complication Work-up :

Abdominal ultrasound of a six weeks old, male infant:

The circular muscles of the pylorus (red area) is thickened to 4 mm (normal: < 3 mm) and appears elongated. This finding confirms the diagnosis.

Two additional signs of an hypertrophic pyloric stenosis can be seen: the antral nipple sign refers to the mucosa protuding into the antrum (green area), while the cervix sign describes the general protrusion of the whole pyloric muscle into the stomach.

•What if the Diagnosis Is Still Uncertain?

• If ultrasound is equivocal do upper gastrointestinal (UGI) contrast study.

Typical findings : • Delayed gastric emptying.

• Narrow pyloric orifice

• Retrograde peristalsis in the stomach.

• String sign: elongated, thickened pylorus.

• Beak sign: The pylorus is only partially open to the stomach because of hypertrophy, resulting in two muscular layers adjacent to one another in an "open beak

• Contrast UGI studies have a risk of causing aspiration in infants, especially those with HPS (since they have gastric outlet obstruction), and should therefore be reserved for cases where the diagnosis is uncertain or malrotation with midgut volvulus cannot be ruled out.

• Last resort or very atypical presentation endoscopy

What is your DDx?

Management:

## HPS is a medical emergency, not a surgical one. ** evaluate infants for signs of dehydration and assess the degree of fluid loss ** correction of the electrolyte imbalance, restoration of the normal acid-base balance, and replacement of fluids should be prioritized. Initial NS bolus of 20 ml/kg should be given to children with severe volume deficits. So in brief:

• Correct electrolyte imbalance (e.g., replace K+; 2 to 4 mEq/kg/24 Hrs )

• IV rehydration (Bolus, Maintenance, Deficit and losses)

• Frequent administration of small meals (12–24 per day)

• Elevate head

• Ramstedt pyloromyotomy is the gold standard: a longitudinal muscle-splitting incision of the hypertrophic sphincter; incise and split the muscular layers, leaving the mucosa and submucosa intact

• Laparoscopically or through a small transverse right upper quadrant incision.

• https://youtu.be/hvfye6nokpQ

Timing of Surgery?

Depends upon the clinical status of the infant:

1-Well-hydrated with normal electrolytes: on the day of diagnosis

2-Dehydrated and/or electrolyte derangement :delayed until effective fluid resuscitation and electrolyte replacement

Definitive treatment

Complications of pyloromyotomy : 1) perforation of the mucosa (1%–3%), 2) bleeding 3) wound infection 4) recurrent symptoms due to inadequate myotomy

• Midgut: The middle part of the gastrointestinal tract that includes the distal duodenum (2nd part) to the proximal two-thirds of the transverse colon. Supplied by the SMA.

• Intestinal malrotation: arrest in the normal rotation of the gut in utero, resulting in an abnormal orientation of the bowel and mesentery within the abdominal cavity

• It is caused by defective rotation of primitive intestinal loop around the axis of SMA during embryogenesis that results in abnormal short mesenteric root which predisposes small bowel to twist around it and lead to midgut volvulus as complication

Malrotation and midgut volvulus

Normal intestinal rotation:

The midgut starts to elongate in utero (4th week) → herniation of the midgut out of the umbilicus (6th week) (1) → 90° counter-clockwise rotation of the midgut → re-entry of the midgut into the abdominal cavity(10th week) → 180° rotation inside the abdominal cavity (a total of 270°) (2) → fixation of the duodenojejunal flexure (ligament of Treitz) and cecum to the posterior abdominal wall (3)

Notes:

1. The midgut herniates out of the abdominal cavity because the developing liver and kidneys limit the intra-abdominal space

2. The 180° rotation within the abdominal cavity places the cecum in the right upper quadrant (RUQ) of the abdomen, adjacent to the liver.

3. The duodenojejunal flexure (ligament of Trietz) is fixed to the left upper quadrant (LUQ). The cecum descends from the RUQ to the right lower quadrant (RLQ) and gets fixed there. Hence, the line of mesenteric attachment is wide-based, running from the ligament of Trietz (LUQ) to the ileocecal junction (RLQ).

In Malrotation The mesenteric attachment Of the midgut particularly the portion from duodenojejunal Junction to the cecum Is abnormally short with excessive mobility makes it prone to kink, twist and be compressed.

What is Ladd’s bands?

• fibrous stalks of peritoneal tissue that attach the cecum to the retroperitoneum in the right lower quadrant (RLQ).

• In malrotation instead of its normal anatomical position in the RLQ it pass over the second part of the duodenum, causing extrinsic compression and obstruction result in obstructive symptoms.

Displacements caused by malrotation:

A. Cecum: not in the right lower quadrant (RLQ), and the duodenum does not pass posteriorly to the superior mesenteric artery B. Base of the small bowel: Instead of being fixed From the ligament of treitz to the cecum in the RLQ, the whole midgut is anchored on the superior mesenteric artery. C. Cecum fixation: Various stages can be seen, but it is usually fixed to the right upper quadrant (RUQ) with the bands (Ladd bands) that extend across the duodenum.

Clinical presentation : Intestinal malrotation :

Mostly asymptomatic (Incidentally found)

Clinical findings in infants and young children with Midgut volvulus (more common in patients with incomplete rotation of the bowel due to the narrow-based mesentery):

Vomiting, typically bilious (green or fluorescent yellow)

Abdominal distension (not always present, especially in neonates)

Hematochezia\hematemesis\hypotension\tachychardia indicating bowel ischemia and possible necrosis due to volvulus

Hemodynamic instability from hypovolemia and/or septic shock

Abdominal tenderness (can be difficult to elicit, especially in infants and young children)

Peritonitis (eg, rigid abdomen, rebound tenderness) indicating volvulus with perforation

In older children : clinical presentation is variable But the most common :

• Recurrent Abdominal pain

• Vomiting (may not be bilious)

• Failure to thrive

• Malabsorption.

• Symptoms are often chronic >6 m

• Features of duodenal obstruction: bilious vomiting without abdominal distension

• May result from Ladd’s bands or Intermittent volvulus.

Differential Dx

• In neonates/infants with recurrent vomiting: duodenal atresia and stenosis , hypertrophic pyloric stenosis

• In neonates with features of bowel ischemia/gangrene: necrotizing enterocolitis (NEC)

• In older children with abdominal pain and vomiting: intussusception

• In older children/adults with nonspecific symptoms: GERD; chronic mesenteric ischemia; food allergy

Intestinal malrotation Double-contrast barium enema The small bowel can be seen on the right side whereas the cecum and colon appear on the left. These findings are consistent with intestinal malrotation during fetal development.

Management : Midgut volvulus with/without peritonitis: >> Initial resuscitation: NPO, nasogastric tube insertion; IV fluids; correction of electrolyte imbalance; broad-spectrum IV antibiotics >> Emergency surgery (Ladd procedure) For Incidentally detected/asymptomatic intestinal malrotation >> elective surgery (Ladd procedure). Can be done Laparoscopically in this case.

The Ladd’s procedure. >>> The goals of surgery are to relieve any intestinal obstruction and prevent recurrent volvulus. By widening the base of the mesentery, placing the bowel in a position of nonrotation how its done? >> First, because volvulus typically occurs in a clockwise direction, the volvulus must be reduced by gently rotating the gut counterclockwise. >> Next, Ladd’s bands, or the peritoneal attachments from the right upper quadrant to the ascending colon, must be divided. The duodenum is then straightened and examined for intrinsic obstruction. The base of the mesentery must be widened by dividing peritoneal adhesions. >>Finally, the small bowel is positioned on the right side of the abdomen and the large bowel on the left. These positions ensure the maximum distance between the duodenum and the ileocecal junction. Because the cecum and appendix are now in the left upper quadrant, most surgeons perform an appendectomy to avoid future misdiagnosis in the event that the patient develops appendicitis.

Duodenal Atresia

• Around 1/5000–10,000 live births

• ∼ 50% of cases are associated with further anomalies, e.g., bile duct and VACTERL association.

• 20–25% of cases are associated with chromosomal abnormalities, especially Down syndrome.

• Duodenal atresia occurs when recanalization of the closed duodenum fails to occur or occurs only partially during the embryonic period (usually between the 8th–10th week of gestation). Because the development of the duodenum is connected to the growth of the pancreas and the hepatobiliary system, duodenal atresia is commonly associated with anomalies of these organs as well.

Presentation

• Intrauterine

Polyhydramnios

• Postpartum

Vomiting, that is typically bilious if the stenosis is distal to the major duodenal papilla

Atresia or high-grade stenosis: vomiting few hours after birth

Mild stenosis: vomiting after a few days

Distended upper abdomen and scaphoid lower abdomen

Delayed meconium passage

Diagnostics

• Prenatal Ultrasound

• Polyhydramnios

• Dilation of the stomach and duodenum (proximal to the obstruction) is common.

• Double bubble sign

•Postnatal X-ray of the abdomen

• Double bubble sign: air and fluid build up proximal to the obstruction and are separated by the pyloric sphincter, which resembles two bubbles on imaging – one in the stomach and one in the duodenum

• Gasless distal bowel

Duodenal Atresia Jejunal Atresia

Tx

• Preoperative management

Parenteral nutrition via a central catheter shortly after birth

Fluid replacement and restoration of the electrolyte balance

Gastric decompression

• Surgery: bypass the atresia or stenosis

The exact procedure depends on the anatomic findings and associated anomalies

Common procedure: duodenoduodenostomy or duodenojejunostomy with a proximal transverse-to-distal longitudinal (diamond-shaped) anastomosis