Malrotation And Volvulus Flashcards
What should be suspected in a child with bilious emesis?
A: Malrotation with volvulus should be suspected until proven otherwise, as a few hours make the difference between recovery and massive bowel necrosis.
What happens during the normal development of the bowel that can lead to malrotation?
The developing bowel leaves the abdominal cavity at about 8 weeks gestation and returns at 10 weeks, undergoing 270° anticlockwise rotation around the axis of the superior mesenteric artery. This rotation is followed by retroperitoneal fixation of the ascending and descending colon.
How does the broad small bowel mesentery contribute to malrotation?
The broad small bowel mesentery, fixed from the duodeno-jejunal flexure to the ileo-caecal valve, is a key feature in malrotation, and its abnormal positioning can lead to volvulus.
What is the result if normal rotation and fixation of the intestines does not occur?
If normal rotation and fixation do not occur, the result is malrotation or non-rotation, leading to a narrow mesenteric base.
How does a narrow mesenteric base contribute to midgut volvulus?
The narrow mesenteric base allows the unfixed bowel to rotate on the mesenteric root, leading to midgut volvulus.
What occurs during a midgut volvulus?
In a midgut volvulus, the entire midgut (from the 2nd part of the duodenum to the distal 2/3rds of the transverse colon) twists on its mesentery, which is supplied by the superior mesenteric artery.
What happens if midgut volvulus is left uncorrected?
If uncorrected, ischemia and strangulation of the bowel may occur, leading to devastating loss of the midgut, which is not compatible with long-term survival.
What are the long-term survival challenges for patients after midgut loss due to volvulus?
Patients may require bowel transplants, which currently have a poorer 5-year survival rate (<50%), and they often die from sepsis or loss of intravenous access, as long-term intravenous nutrition remains a major challenge.
How common is malrotation and what is its relation to midgut volvulus?
About 3% of the population has malrotation of the intestines, which predisposes them to midgut volvulus.
What is the hallmark symptom of midgut volvulus in a previously healthy child?
The sudden onset of bile-stained vomiting must be regarded as midgut volvulus until proven otherwise.
What other symptoms might be present in advanced cases of midgut volvulus?
Bloody stools may be present in advanced cases, and abdominal distension and tenderness are not early signs (the abdomen is often soft and not tender).
What complications can arise from untreated midgut volvulus?
Ischaemic bowel and peritonitis can result from untreated midgut volvulus.
How might older children present with midgut volvulus?
Older children may present with failure to thrive and chronic vomiting (bilious or non-bilious) due to a partial or intermittent volvulus. A high index of suspicion is needed for these cases.
What abdominal wall defects are commonly associated with malrotation?
Malrotation is commonly present in patients with congenital diaphragmatic hernia, exomphalos, and gastroschisis.
What lateralism disorders can be associated with intestinal malrotation?
Disorders of lateralism such as situs inversus (heart on the right side of the chest) and left/right isomerism (polysplenism/asplenism, abnormalities of major blood vessels, cardiac anomalies) can be associated with intestinal malrotation.
What are the characteristics of left/right isomerism in patients with malrotation?
Left/right isomerism can result in polysplenism or asplenism and abnormalities of major blood vessels and cardiac anomalies, where organs usually found on one side of the body are in a “mirror-image” position.
How is the diagnosis of malrotation typically made?
The diagnosis is made based on clinical suspicion, signs of duodenal obstruction, and radiological features.
What are the typical AXR features of malrotation with volvulus?
• Dilatation of the stomach and possibly the duodenum, but the “double bubble” sign is not usually seen.
• Paucity of gas in the rest of the bowel.
• A normal-looking x-ray may be possible.
• Small bowel predominantly on the right side of the abdomen (though small and large bowel cannot always be differentiated on neonatal x-ray).
What is the investigation of choice for diagnosing malrotation and midgut volvulus?
Contrast meal and duodenal C-loop follow-through is the investigation of choice and is diagnostic.
How can a contrast meal help differentiate malrotation with volvulus from other conditions?
• A normal configuration of the duodenum excludes malrotation and midgut volvulus in patients with bile-stained vomiting.
• A “beaked” cut-off of contrast (indicating volvulus) or an “S-shaped”/spiral-shaped flow of contrast from the 2nd part of the duodenum (indicating malrotation) suggests the need for urgent exploratory laparotomy.
• In a normal configuration, the 3rd and 4th parts of the duodenum cross the midline and ascend to the level of the 2nd lumbar vertebra and pylorus.
What other investigations may be used to detect malrotation and midgut volvulus?
• Contrast enema: May show the caecum in the right upper quadrant but has a 25% false-negative or false-positive rate, so it is not highly sensitive for diagnosing malrotation.
• Doppler ultrasound or CT scan: Can detect a whorl-pool configuration of the superior mesenteric artery and vein, but it is not a very sensitive sign.
What are some differential diagnoses of bile-stained vomiting in a newborn?
• Duodenal atresia is one of the most common differential diagnoses in a newborn with bile-stained vomiting.
• Other causes of distal bowel obstruction should also be considered, along with medical causes of vomiting.
What are the initial management steps for midgut volvulus?
Nasogastric tube decompression to relieve any gastric distension.
• Resuscitation with intravenous fluids and correction of metabolic derangements. However, this should not delay transfer to definitive care.
• Ongoing fluid resuscitation may be necessary on the operative table.
What is the surgical management once midgut volvulus is diagnosed?
Immediate surgical intervention is required if midgut volvulus is confirmed via contrast meal and follow-through. The goal is to untwist the bowel, assess for any ischemic damage, and possibly resect necrotic tissue.
What is involved in the surgical management of midgut volvulus?
• Laparotomy and de-rotation of the bowel is performed as an emergency procedure.
• Peritoneal bands are released, the duodenum is straightened, and the mesentery is broadened.
• The bowel is repositioned in the non-rotated position (Ladd’s procedure), with the small bowel on the right and the colon on the left.
• In some cases, the appendix is removed to avoid confusion during future abdominal evaluations.
What should be done if the viability of the bowel is questionable after surgery?
• If bowel viability is uncertain, a re-look laparotomy may be required 24 hours after the de-rotation procedure to assess its status.
• If all the midgut is necrotic, palliative care (comfort measures without bowel resection) should be discussed with the parents.
• Timely diagnosis and referral are crucial to prevent such devastating outcomes.
What is the outcome if the bowel is viable after midgut volvulus surgery?
• Most children will return to the ward stable and have an uncomplicated post-operative course.
• Severe consequences such as mortality, short bowel syndrome, and malabsorption due to ischemic mucosal injury are largely preventable with early diagnosis and management.
• Total bowel necrosis can develop within 6 hours of blood supply cut-off, emphasizing the need for rapid referral and transfer.
What are other causes of volvulus aside from midgut volvulus?
• Omphalomesenteric remnant
• Duplication cyst
• Adhesive small bowel obstruction
• Internal hernia
• Volvulus caused by intestinal worm bolus
These can also result in volvulus, typically involving less bowel with normal rotation.
When do most patients with midgut volvulus present?
75% of patients with midgut volvulus are symptomatic within the first month of life.
