PEDIATRIC SURGICAL PROBLEM :
INTESTINAL MALROTATION WITH MIDGUT VOLVULUS
INTESTINAL MALROTATION WITH MIDGUT VOLVULUS
NORMAL EMBRYOLOGICAL ROTATION OF THE MIDGUT
Definition
Intestinal malrotation is a congenital anomaly that results when the normal sequence of rotation and fixation of the bowel fails. Midgut volvulus is a complication of malrotation when the bowel twists around a fixed point usually mesentery that has adhesed to the bowel causing obstruction (see Figure 4).
FIGURE 4
Epidemiology
Malrotation is uncommon, and its prevalence in children younger than 1 year of age is 3.9/10,000 live births; however, it can lead to irreversible intestinal necrosis, which can be fatal, and so one must have a high index of suspicion to make the diagnosis.
Most children present within the first month of age and the majority within the first year of life. Morbidity and mortality largely depend on the extent of bowel ischemia, which has been largely attributed to a delay in diagnosis.
Males are slightly more affected than females (2:1).
Pathophysiology
During normal embryologic development a counterclockwise turn of both the proximal and midgut portions of the intestine occurs around the fourth to tenth week of gestation, prior to the intestine retracting into the abdomen.
Abnormalities of rotation physiology result in excessive mobility and compression of the bowel, leading to twisting or volvulus.
Mesentery can stick to the bowel and act as a fixed point that the intestine can rotate around, or the bowel may not be fixated correctly to the posterior abdominal wall, which allows the whole midgut to lie free within the abdomen.
Any part of the intestine may twist and become obstructed, resulting in midgut, cecal, or duodenal volvulus.
Clinical Features
Classically, malrotation with obstruction presents with bilious vomiting, but overall presentation varies.
Bilious emesis indicates obstruction below the ampulla of Vater, which is a common place for obstruction to occur in the setting of malrotation; although bilious emesis is not pathognomonic for volvulus, it is important to emphasize midgut volvulus should be highly considered in the neonate presenting with bilious emesis.
The age of the infant affects appearance of disease. Neonates may be fussy and parents may complain of feeding difficulties, intermittent apnea, or even failure to thrive. Older infants may appear to have abdominal pain and diarrhea with or without hematochezia and vomiting. Physical exam findings are non-specific; peritoneal signs indicative of perforation that can lead to sepsis and shock are late signs and indicate a poor prognosis.
Diagnostic Studies
The diagnostic studies performed largely depend on the clinical appearance of the child. A broad net with respect to testing is needed in the toxic-appearing infant. Upper gastrointestinal (UGI) contrast study to assess the third and fourth part of the duodenum is the gold standard to make the diagnosis.
A classic “corkscrew” appearance in the volvulus can be identified with sensitivity of 96%.
Figure 5 shows the X-ray of a newborn presenting with bilious vomiting. The flat and decubitus X-ray shows asymmetry of the bowel gas with distended loops of bowel in the right side and left side of the abdomen. This patient had malrotation with midgut volvulus.
Figure 5. Decubitus (A) of Neonate with Midgut Volvulus
Asymmetry of the bowel gas with a moderately distended loop of bowel in the right and left side of the abdomen. This newborn has midgut volvulus. A Decubitus view
Figure 5. X-ray flat (B) of Neonate with Midgut Volvulus
Asymmetry of the bowel gas with a moderately distended loop of bowel in the right and left side of the abdomen. This newborn has midgut volvulus. B Flat view
Figure 6 is an upper gastrointestinal study depicting midgut volvulus in a newborn; the study shows that the duodenal jejunal junction crossed to the left of midline but did not extend superiorly as expected, and there was no peristalsis identified within the stomach or duodenum.
Figure 6. Upper Gastrointestinal Study Depicting Midgut Volvulus in a Newborn
The duodenal jejunal junction crossed to the left of midline but did not extend superiorly as expected, and there was no peristalsis identified within the stomach or duodenum.
Ultrasound of the mesenteric vessels can also be obtained looking for a “whirlpool sign,” which is a swirling shape seen when the superior mesenteric vein (SMV) and mesentery encompass the superior mesenteric artery (SMA), or for “reversal sign.”
Figure 7 is an ultrasound showing SMV/SMA reversal sign in midgut volvulus. The sensitivity and specificity of ultrasound are slightly lower than UGI contrast studies, and, as such, ultrasound usually is used as an adjunct.
Figure 7. Ultrasound Showing SMV/SMA Reversal Sign in Midgut Volvulus
Unstable neonates with sepsis, severe metabolic acidosis, or systemic shock presenting with bilious emesis and abdominal distension should likely forgo imaging and proceed with surgical exploration. CT scanning is not routinely performed unless the child’s presentation is ambiguous or an alternative pathology, such as intra-abdominal mass, is high in the differential.
Differential Diagnosis
The differential diagnosis for malrotation largely depends on the age of the child, although many will present with abdominal pain. Malrotation volvulus usually presents in children younger than 1 month of age, so the differential diagnosis will include illnesses more common in this age group. However, one should suspect malrotation midgut volvulus in a child of any age presenting with bilious vomiting and abdominal pain.
Necrotizing enterocolitis should be considered if the child is premature and presents with changes in feeding and abdominal distention.
Older infants presenting with signs of intestinal obstruction and altered mental status should raise concern for intussusception.
Pyloric stenosis can present with vomiting; however, vomiting is always non-bilious. It is important to note that malrotation volvulus can present in children of any age and has been diagnosed in adults as well.
Management
Malrotation volvulus is a surgical emergency and requires a laparotomy. Intravenous access should be obtained promptly and aggressive fluid resuscitation started. Nasogastric tube should be placed and antibiotics initiated to cover gram-positive, gram-negative, and anaerobes.
Immediate surgical consultation, perhaps even prior to obtaining imaging, may be indicated if the patient is unstable and malrotation volvulus suspected. Morbidity and mortality increase if the obstruction is not treated within 24 hours.
Surgery is performed to correct the obstruction and minimize risk of future volvulus; the surgery will not correct the actual malpositioning of the bowel. The surgical approach, laparotomy or laparoscopic, does not affect length of stay or the complication rate.
If bowel necrosis is found, bowel resection will occur, placing the patient at risk for short bowel syndrome, again, emphasizing the need for prompt diagnosis and treatment. The longer the bowel stays obstructed the more likely ischemia and necrosis ensue.
Disposition
Children diagnosed with malrotation volvulus require admission at a facility with pediatric surgical resources. Transfer should be considered even prior to diagnosis if malrotation volvulus is suspected.
Summary
Intussusception is usually diagnosed in children younger than 2 years of age. It affects males slightly more often than females. The exact etiology is unclear; however, there is an association with gastroenteritis and viral syndromes such as upper respiratory tract infection, otitis media, and influenza. Most frequently, the intussusception occurs between the ileum and the colon. Children can present with intermittent abdominal pain, vomiting, and currant jelly or red stools; however, the latter is a late sign. Intussusception should be considered in a child presenting with altered mental status. Non-invasive radiological reduction should be attempted; however, if the child appears critically ill, pediatric surgery should be consulted promptly.
Malrotation midgut volvulus most commonly presents in children younger than 1 month of age. Bilious emesis in a neonate should be considered a surgical emergency until proven otherwise. Patients can present with irritability, feeding difficulties, failure to thrive, and abdominal pain. The diagnosis can be challenging and delays in diagnosis increase morbidity and mortality significantly. Signs of bowel ischemia, such as hematochezia or sepsis, indicate a poor prognosis. UGI contrast study is the gold standard diagnostic modality, and pediatric surgical consultation is required since an operation is required.
Overall, children presenting to the ED with abdominal pain can be challenging to diagnose. ED physicians are charged to differentiate between self-limited pathology and more life-threatening surgical emergencies. Intussusception and malrotation midgut volvulus both can present with abdominal pain, vomiting, and irritability. Both can be fatal if the diagnosis is delayed or missed, and so one must have a high index of suspicion.
REFERENCE :
RELIAS FORMERLY AHC MEDIA , Intussusception and Midgut Volvulus. June 2015.
[https://www.ahcmedia.com/articles/135491-intussusception-and-midgut-volvulus]
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