Intestinal Malrotation, Midgut Volvulus, and Gastric Volvulus

Intestinal malrotation is a congenital anomaly of intestinal rotation and fixation during fetal development. It leaves the midgut with an abnormally narrow mesenteric attachment.

This predisposes to midgut volvulus, a catastrophic, life-threatening complication in which the entire midgut twists around the narrow mesenteric pedicle. The result is acute obstruction of both the bowel lumen and, critically, the superior mesenteric artery blood supply.

It is one of the most time-critical true surgical emergencies in paediatric practice. Rapid, extensive and irreversible bowel ischaemia and necrosis follow if it is not recognised and surgically corrected within hours of onset.

The overriding clinical principle is that bilious vomiting in an infant is malrotation with volvulus until proven otherwise. It warrants immediate, urgent surgical evaluation, without delay for extensive preliminary investigation.

Pathophysiology

• Normal embryological rotation and fixation occur during the tenth to twelfth week of gestation. The duodenojejunal junction is fixed in the left upper quadrant and the caecum in the right lower quadrant. A broad-based mesenteric attachment spans between them, giving the midgut a wide, stable base and substantially reducing the risk of volvulus.
• Malrotation reflects incomplete or abnormal rotation during this critical period. The duodenojejunal junction and caecum are abnormally positioned, with the caecum often lying in the right upper quadrant or midline rather than the right lower quadrant. The midgut mesenteric attachment is abnormally narrow, which creates the anatomical predisposition to volvulus.
• Ladd bands are abnormal peritoneal bands that may form between the malpositioned caecum and the posterolateral abdominal wall. They can cause direct duodenal obstruction independent of any volvulus, a further mechanism of obstruction.
• Midgut volvulus occurs when the midgut twists around the narrow mesenteric pedicle. It produces acute obstruction of the bowel lumen and, critically, compression and obstruction of the superior mesenteric artery, which supplies the entire midgut.
• Volvulus is therefore not merely a bowel obstruction but a vascular emergency. Rapid, extensive and catastrophic bowel infarction follows if the vascular compromise is not promptly relieved.

• Bilious vomiting is the cardinal presenting symptom of malrotation with volvulus, reflecting obstruction distal to the ampulla of Vater. The great majority of cases present within the first month of life, though presentation can occur at any age, less commonly in older children and even adults.
• Onset is frequently sudden in acute volvulus. A previously well infant develops acute bilious vomiting and abdominal pain (irritability and drawing up of the legs in an infant).
• As bowel ischaemia progresses, abdominal distension and tenderness become increasingly severe and diffuse. Signs of systemic illness include lethargy and poor feeding.
• If the condition remains unrecognised and untreated, ischaemia progresses to infarction and the infant deteriorates. Signs include peritonitis (abdominal wall rigidity and tenderness), haemodynamic instability and shock. In the most advanced cases blood is passed per rectum, reflecting established bowel necrosis. This rapid, catastrophic deterioration underscores the extreme time-sensitivity of the condition.
• Gastric volvulus is a related but distinct entity, involving twisting of the stomach itself rather than the midgut. It presents with the classical Borchardt triad of severe epigastric pain, retching with inability to vomit, and difficulty or inability to pass a nasogastric tube.
• Gastric volvulus occurs with an associated diaphragmatic abnormality or, particularly in older children and adults, in isolation. It is a further surgical emergency requiring prompt recognition and treatment.
• Any infant with bilious vomiting needs immediate, urgent evaluation for malrotation with volvulus, regardless of overall clinical appearance. Deterioration can be rapid and catastrophic, and prompt diagnosis and surgical correction are time-critical before extensive, irreversible bowel infarction occurs.

• An upper gastrointestinal contrast study is the investigation of choice for suspected malrotation. It demonstrates the abnormal position of the duodenojejunal junction, which should normally lie to the left of the vertebral column pedicles at the level of the duodenal bulb.
• A corkscrew or "bird's beak" appearance of the contrast column at the point of obstruction is a classic finding when volvulus is present.
• Abdominal ultrasound assesses the relative position of the superior mesenteric artery and vein. An abnormal relationship supports the diagnosis of volvulus, including reversal of the normal anatomical position or the characteristic "whirlpool sign" of the twisted mesenteric vessels.
• Ultrasound is a valuable, increasingly used modality, particularly where rapid assessment is required or an upper gastrointestinal contrast study is not immediately available.
• Imaging should never delay urgent surgical consultation and preparation for emergency surgery in an infant whose presentation strongly suggests volvulus. Examples are bilious vomiting with significant abdominal pain, distension, or any sign of clinical deterioration.
• In a clinically unstable or rapidly deteriorating infant, a high index of suspicion and urgent surgical involvement proceed in parallel with imaging, not after it.
• Plain abdominal radiography is non-specific and often unremarkable in early volvulus. It may show a paucity of distal bowel gas. In advanced cases with established bowel ischaemia it may show pneumatosis intestinalis or free intraperitoneal air reflecting perforation.
• A normal plain radiograph does not exclude the diagnosis. Never use it to reassure against this possibility in a clinically concerning presentation.

• Immediate surgical exploration is the definitive, essential management for confirmed or strongly suspected midgut volvulus. Perform it as a genuine surgical emergency without delay, because the duration of vascular compromise directly determines the extent of bowel ischaemia and infarction.
• The Ladd procedure is the standard surgical approach. Its components are:
  • detorsion of the volvulus (untwisting the midgut, characteristically in a counterclockwise direction, to relieve the vascular obstruction)
  • division of any associated Ladd bands to relieve duodenal obstruction
  • widening of the narrow mesenteric base by careful separation of the small and large bowel mesentery
  • appendicectomy, because the appendix is left in an abnormal, non-standard position, which could otherwise create diagnostic confusion if appendicitis is suspected later in life
  • placement of the bowel in a position of non-rotation, with the small bowel on the right side of the abdomen and the large bowel on the left, the safest, most stable configuration achievable given the congenital abnormality
• Where established bowel necrosis is found at exploration, resect the non-viable segment. The extent of resection is determined by the extent of irreversible ischaemic injury.
• Extensive resection risks short bowel syndrome, a significant, potentially substantial long-term consequence of delayed diagnosis and treatment. This underscores the importance of the earliest possible recognition and surgical correction.
• A "second look" procedure, some hours after the initial surgery, may be undertaken where the viability of marginally compromised bowel is uncertain. It allows reassessment after a period of reperfusion before committing to more extensive resection.
• Perioperative supportive care is an essential component alongside surgical correction. It includes fluid resuscitation, correction of any metabolic derangement, and broad-spectrum antibiotic therapy, given the risk of bacterial translocation and sepsis in bowel ischaemia.
• Long-term follow up addresses nutritional status and, where significant bowel resection was required, management of short bowel syndrome. Monitor development and growth.
• Prognosis is directly and substantially related to the promptness of diagnosis and surgical correction. Bilious vomiting in an infant demands immediate, urgent evaluation and surgical involvement without delay.