Overview
Definition:
Malrotation is a congenital anomaly of intestinal rotation and fixation during fetal development, leading to abnormal positioning of the small and large intestines
Midgut volvulus occurs when a malrotated intestine twists on its mesentery, potentially causing vascular compromise and bowel ischemia.
Epidemiology:
Malrotation occurs in approximately 1 in 500 to 1 in 1000 live births
The risk of symptomatic presentation, including volvulus, is highest in neonates and infants
About 50% of symptomatic cases present within the first month of life, and 75% by the end of the first year.
Clinical Significance:
Malrotation and subsequent midgut volvulus represent a surgical emergency due to the high risk of intestinal gangrene, perforation, and death if not diagnosed and treated promptly
Understanding diagnostic modalities like the Upper GI series and appropriate surgical timing is critical for pediatric residents preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Sudden onset of bilious vomiting is the hallmark symptom
Other symptoms may include abdominal distension, abdominal pain (irritability in infants), feeding intolerance, and failure to pass stool or meconium
Signs of shock, such as lethargy, hypotension, and tachycardia, may indicate severe ischemia.
Signs:
Physical examination may reveal abdominal distension, tenderness, and palpable masses
Bowel sounds may be hyperactive, hypoactive, or absent depending on the degree of obstruction and ischemia
Signs of dehydration and shock can be present in advanced cases.
Diagnostic Criteria:
There are no strict diagnostic criteria for malrotation itself, as it is a developmental anomaly
However, a clinical suspicion combined with characteristic findings on imaging studies (especially Upper GI series showing duodenal obstruction and abnormal ligament of Treitz position) and evidence of vascular compromise or obstruction confirms the diagnosis of symptomatic malrotation with volvulus.
Diagnostic Approach
History Taking:
A detailed history focusing on the onset and character of vomiting (bilious vs
non-bilious), abdominal distension, feeding difficulties, and bowel habit changes is crucial
Inquire about any previous episodes or prior surgical interventions
Red flags include sudden onset of copious bilious emesis and signs of shock.
Physical Examination:
A thorough abdominal examination is essential
Assess for distension, tenderness, guarding, and masses
Evaluate hydration status and signs of systemic compromise
Rectal examination may reveal absence of meconium or bloody stool.
Investigations:
The cornerstone diagnostic investigation for suspected malrotation and volvulus is the Upper GI series
It can demonstrate the location of the duodenojejunal junction (ligament of Treitz), which is usually positioned to the right of the midline in malrotation
Findings suggestive of volvulus include a narrowed or effaced duodenal sweep and a corkscrew appearance
Plain abdominal radiographs may show signs of high-grade small bowel obstruction, such as dilated loops of bowel and paucity of gas in the colon, but are often non-specific
Abdominal ultrasound can show a "whirlpool sign" indicative of volvulus, but its sensitivity is variable
CT scan can also be useful but may require contrast and is less readily available in emergency settings in some regions.
Differential Diagnosis:
Conditions to consider include other causes of intestinal obstruction in neonates and infants, such as duodenal atresia, jejunal atresia, pyloric stenosis, Ladd's bands, intussusception, Hirschsprung disease, and functional intestinal obstruction
Differentiating volvulus from other causes relies heavily on imaging findings.
Management
Initial Management:
Immediate resuscitation is paramount
This includes NPO status, intravenous fluid resuscitation to correct dehydration and electrolyte imbalances, nasogastric (NG) tube decompression to relieve distension and vomiting, and broad-spectrum antibiotics to cover potential sepsis
Blood gas analysis is important to assess for acidosis and metabolic derangements.
Surgical Management:
Surgical intervention is mandatory for midgut volvulus
The primary surgical procedure is the Ladd procedure, which involves detorsion of the volvulus, division of Ladd's bands (which may obstruct the duodenum), and widening of the base of the small bowel mesentery to prevent recurrence
Appendectomy is often performed during the Ladd procedure to reduce the risk of future appendicitis due to the abnormal appendiceal position
The goal is to perform surgery as soon as diagnosis is confirmed to minimize the extent of bowel ischemia.
Surgical Timing:
Urgent surgical intervention is indicated in all cases of confirmed midgut volvulus
Delay can lead to irreversible bowel necrosis, necessitating extensive bowel resection and leading to short bowel syndrome
Prompt surgical management significantly improves outcomes and reduces morbidity and mortality
In cases of suspected malrotation without volvulus, elective surgery is typically performed, but the risk of developing volvulus necessitates intervention.
Supportive Care:
Postoperative care includes continued NG tube decompression, meticulous fluid and electrolyte management, pain control, and monitoring for signs of infection or anastomotic leak
Nutritional support, including gradual reintroduction of feeds, is essential
Close monitoring for signs of recurrence or complications like adhesions is vital.
Complications
Early Complications:
Intestinal gangrene and perforation are the most critical early complications, leading to peritonitis, sepsis, and death
Short bowel syndrome can result from extensive bowel resection
Postoperative complications include wound infection, intra-abdominal abscess, and ileus.
Late Complications:
Adhesions leading to subsequent intestinal obstruction are a significant late complication
Recurrent volvulus can occur if the mesenteric base is not adequately widened
Chronic abdominal pain and malabsorption can also be long-term sequelae.
Prevention Strategies:
Preventing complications primarily relies on early diagnosis and prompt surgical intervention
Adequate widening of the mesenteric base during the Ladd procedure aims to reduce the risk of recurrent volvulus
Careful surgical technique and diligent postoperative care help minimize adhesion formation and other surgical complications.
Prognosis
Factors Affecting Prognosis:
The most significant factor influencing prognosis is the degree of intestinal ischemia at the time of surgery
Prompt diagnosis and intervention in the absence of significant ischemia lead to excellent outcomes
Extensive bowel resection and short bowel syndrome negatively impact long-term prognosis.
Outcomes:
With timely diagnosis and surgical management, the survival rate for malrotation and midgut volvulus is high
Neonates and infants who do not require extensive bowel resection generally have a good long-term prognosis
Patients requiring significant bowel resection may face lifelong challenges related to malabsorption and nutritional support.
Follow Up:
Postoperative follow-up should include regular clinical assessments to monitor for signs of obstruction, malabsorption, or growth failure
Nutritional status should be periodically evaluated
Patients with short bowel syndrome require specialized long-term care, often involving a multidisciplinary team.
Key Points
Exam Focus:
DNB and NEET SS exams will focus on the classic presentation of bilious vomiting in neonates, the role of Upper GI series in diagnosing malrotation (ligament of Treitz position), the radiological signs of volvulus (corkscrew appearance), and the urgent management via Ladd procedure
Understanding the indications for surgery and potential complications is key.
Clinical Pearls:
Always consider malrotation and volvulus in any infant presenting with bilious vomiting, regardless of other symptoms
A normal abdominal X-ray does not rule out malrotation
the Upper GI series is the investigation of choice
Prompt surgical intervention is critical to preserve bowel viability.
Common Mistakes:
Delaying surgical intervention due to vague symptoms or non-specific initial investigations
Misinterpreting plain abdominal X-rays as normal when a subtle obstruction is present
Failing to adequately widen the mesenteric base during the Ladd procedure, increasing the risk of recurrence
Overlooking malrotation in older children with intermittent abdominal pain or vomiting.