Overview
Definition:
Malrotation is a congenital anomaly where the intestines fail to undergo normal 270-degree counter-clockwise rotation during embryonic development, leading to an abnormal fixation of the bowel
Midgut volvulus is a surgical emergency that occurs when the malrotated bowel twists around its mesentery, compromising blood supply and potentially leading to ischemia and necrosis.
Epidemiology:
Malrotation occurs in approximately 1 in 500 to 1 in 5000 live births
Midgut volvulus is the most common and serious complication of malrotation, occurring in about 25-60% of patients with malrotation, often presenting in infancy
However, it can occur at any age.
Clinical Significance:
Malrotation with midgut volvulus is a life-threatening condition
Delayed diagnosis and management can lead to bowel necrosis, short gut syndrome, sepsis, and death
Prompt recognition of bilious emesis and initiation of emergent management are critical for favorable outcomes, making it a high-yield topic for pediatric and surgical board examinations.
Clinical Presentation
Symptoms:
The hallmark symptom is sudden onset of bilious vomiting, which is a critical red flag
Other symptoms may include abdominal distension (though sometimes absent early on), abdominal pain, lethargy, poor feeding, and in severe cases, bloody stools or signs of shock
Some infants may have intermittent symptoms for days or weeks prior to presentation.
Signs:
Vital signs may be normal initially but can rapidly deteriorate to include tachycardia, hypotension, and fever in cases of ischemia or sepsis
Abdominal examination may reveal distension, tenderness, or a palpable mass
Bowel sounds can be hyperactive early on, but become hypoactive or absent with progression of obstruction or ischemia.
Diagnostic Criteria:
There are no formal diagnostic criteria for malrotation with volvulus
Diagnosis is primarily clinical, supported by imaging
The presence of bilious emesis in an infant, particularly with abdominal pain or distension, is highly suggestive and warrants urgent investigation
Imaging findings such as a dilated stomach/duodenum with a collapsed distal bowel, corkscrew appearance of the twisted mesentery, or malposition of the small bowel on contrast studies are key.
Diagnostic Approach
History Taking:
A detailed history focusing on the onset, frequency, and character of vomiting is paramount
Inquire about any prior episodes, abdominal pain, feeding difficulties, and bowel movement patterns
A history of duodenal atresia or other congenital anomalies may increase suspicion
Always ask about the color of the vomitus – bilious indicates an obstruction distal to the ampulla of Vater.
Physical Examination:
A thorough abdominal examination is essential
Assess for distension, tenderness (generalized or localized), guarding, and rigidity
Palpate for any masses
Auscultate bowel sounds and note their character and frequency
Assess hydration status and overall infant well-being
Rectal examination may reveal blood or meconium.
Investigations:
Abdominal X-ray may show signs of obstruction, such as dilated loops of bowel and air-fluid levels, but can be normal in up to 50% of cases
A contrast upper gastrointestinal (UGI) series is the investigation of choice for diagnosing malrotation and volvulus, demonstrating the position of the duodenojejunal junction (normally left of the midline at or above the duodenal sweep) and a narrowed twisted mesentery (whirlpool sign)
A contrast enema can show abnormal position of the cecum
Ultrasound can sometimes show the whirlpool sign or malposition of mesenteric vessels but is less sensitive for malrotation itself.
Differential Diagnosis:
Other causes of bilious emesis in infants include duodenal atresia/stenosis, jejunal atresia, annular pancreas, pyloric stenosis (vomiting is non-bilious typically), Hirschsprung disease, and functional intestinal obstruction
Distinguishing between these requires careful clinical assessment and appropriate imaging.
Management
Initial Management:
This is a surgical emergency
Immediate resuscitation with intravenous fluids is crucial to correct dehydration and electrolyte imbalances
Nasogastric (NG) tube decompression should be initiated promptly to relieve gastric distension and reduce vomiting
Broad-spectrum antibiotics should be administered intravenously to cover for potential sepsis
Pain control should be addressed
The child should be made NPO (nil per os).
Medical Management:
Medical management is limited to supportive care and resuscitation
There are no definitive medical treatments for midgut volvulus itself
The definitive treatment is surgical detorsion and Ladd's procedure.
Surgical Management:
Emergent laparotomy or laparoscopy is indicated
The primary goals are: 1) Detorsion of the volvulus by counter-clockwise rotation to restore blood flow
2) Assessment of bowel viability
if bowel is necrotic, resection and possible ostomy may be required
3) Correction of malrotation using Ladd's procedure, which involves dividing the Ladd bands, widening the mesenteric base, and repositioning the colon.
Supportive Care:
Postoperatively, patients require close monitoring of vital signs, fluid balance, and electrolyte levels
NG tube drainage should be continued until bowel function returns
Pain management is critical
Nutritional support, including parenteral nutrition if bowel resection is extensive, is essential
Close monitoring for signs of infection or anastomotic leak is vital.
Complications
Early Complications:
Bowel necrosis requiring resection, short bowel syndrome, intra-abdominal sepsis, wound infection, anastomotic leak, or dehiscence, recurrence of volvulus if Ladd's procedure is incomplete, and post-operative ileus.
Late Complications:
Adhesions leading to later intestinal obstruction, malabsorption due to short bowel syndrome, growth retardation, and failure to thrive
Long-term risk of recurrence of volvulus is low after Ladd's procedure but can occur.
Prevention Strategies:
Early recognition and prompt surgical intervention are the most effective strategies for preventing complications
Ensuring adequate bowel decompression and fluid resuscitation preoperatively also plays a role in improving outcomes.
Prognosis
Factors Affecting Prognosis:
The most critical factor is the duration of ischemia before surgical intervention
Early diagnosis and treatment lead to excellent outcomes
Extent of bowel resection and development of short bowel syndrome significantly impact long-term prognosis
Comorbidities also play a role.
Outcomes:
If diagnosed and treated promptly with minimal or no bowel resection, the prognosis is excellent with a high chance of normal growth and development
However, significant bowel resection can lead to long-term malabsorption and the need for specialized nutritional support.
Follow Up:
Regular follow-up is necessary to monitor growth and development, assess for signs of malabsorption, and manage any long-term complications
This may involve nutritional support, regular clinic visits, and imaging as needed
Patients should be educated about the signs of recurrent obstruction.
Key Points
Exam Focus:
Bilious emesis in an infant is an absolute surgical emergency and strongly suggests malrotation with midgut volvulus
UGI series is the investigation of choice
Ladd's procedure is the definitive surgical management
Early resuscitation is critical.
Clinical Pearls:
Always consider malrotation with volvulus in any infant presenting with bilious vomiting, even if the abdominal exam is benign
Do not delay surgical consultation or intervention
The "whirlpool sign" on UGI series or Doppler US is pathognomonic for volvulus.
Common Mistakes:
Misinterpreting bilious emesis as non-surgical, delaying surgical consultation, delaying NG tube decompression, or not adequately resuscitating the patient before surgery
Failure to perform a UGI series in a timely manner can lead to delayed diagnosis.