Intestinal malrotation is a congenital condition where the intestines do not settle into their usual positions within the abdomen. While often diagnosed in infancy, it can remain undetected and asymptomatic until adulthood, leading to various symptoms or being discovered incidentally.
Understanding Intestinal Malrotation
Intestinal malrotation originates from an anomaly in the complex process of gut rotation during fetal development. Typically, during the fifth to tenth weeks of gestation, the midgut temporarily protrudes outside the embryo’s body cavity. This midgut then undergoes a 90-degree counterclockwise rotation around the superior mesenteric artery (SMA) before returning to the abdominal cavity.
A further 180-degree counterclockwise rotation occurs around the eleventh week, completing a total of 270 degrees of rotation. This process positions the duodenum in a C-shape behind the SMA, with the small intestine primarily on the left side and the large intestine (colon) on the right and across the top. In intestinal malrotation, this rotational sequence is disrupted, leaving the intestines in abnormal positions and often resulting in a narrow mesenteric base. Fibrous bands, known as Ladd’s bands, can also form, extending from the cecum to the right abdominal wall, potentially obstructing the duodenum.
Prevalence in Adults
Intestinal malrotation is significantly less common in adults compared to pediatric cases, with most diagnoses occurring in the first year of life. Estimates for its incidence in adults vary, with autopsy studies suggesting a population figure around 0.03%.
Precise figures are challenging to obtain because many adults with malrotation remain asymptomatic. The condition may also be discovered incidentally during surgery or imaging performed for unrelated reasons. Factors contributing to its less common diagnosis in adults include the non-specific nature of symptoms, which can mimic other common gastrointestinal issues, and the fact that it is often overlooked by healthcare providers unfamiliar with its adult presentation.
Recognizing Symptoms and Potential Complications
Adults with intestinal malrotation may experience a variety of symptoms, which are frequently non-specific and intermittent, making diagnosis difficult. Common complaints include chronic abdominal pain, nausea, vomiting, and bloating. Some individuals may also experience weight loss, malabsorption, and alternating constipation and diarrhea. These symptoms can often lead to multiple hospital visits before a diagnosis is made.
The most severe complication of intestinal malrotation is a midgut volvulus, a life-threatening twisting of the small intestine around its blood supply. This twisting can cut off blood flow to the bowel, leading to tissue damage or necrosis within hours without intervention. Acute symptoms of a midgut volvulus include sudden, severe abdominal pain, bilious (greenish-yellow) vomiting, and abdominal swelling. Rapid heart rate, rapid breathing, and bloody stools can also occur. Urgent medical attention is necessary if these acute symptoms appear.
Diagnosis and Treatment Approaches
Diagnosing intestinal malrotation in adults often involves various imaging techniques to visualize the abnormal positioning of the intestines. An upper gastrointestinal (GI) series can reveal if the duodenojejunal junction fails to cross the midline or if the small bowel is primarily located on the right side of the abdomen. Computed tomography (CT) scans are frequently used and can identify characteristic anatomical distortions, such as the small bowel occupying the right side of the abdomen and the large bowel on the left. CT scans can also show an abnormal relationship between the superior mesenteric artery and vein, which is a common indicator of malrotation.
Surgical intervention, specifically the Ladd’s procedure, is the definitive treatment for intestinal malrotation. This procedure involves untwisting any volvulus, dividing Ladd’s bands to relieve obstruction, widening the base of the mesentery, and repositioning the intestines. An appendectomy is typically performed during this surgery because the appendix’s location can be altered, making future appendicitis difficult to diagnose. Surgical intervention is generally recommended even for asymptomatic adults due to the potential for a midgut volvulus. Laparoscopic approaches to the Ladd’s procedure are increasingly reported, offering a minimally invasive option for stable patients without acute volvulus.