Pediatric Superior Mesenteric Artery Syndrome: A Rare Case Report and Literature Review From Sudan

ABSTRACT

A 10‐year‐old Sudanese boy with chronic bilious vomiting, cachexia, and scaphoid abdomen was diagnosed with Superior Mesenteric Artery Syndrome (SMAS) via CT angiography. After failed conservative management, side‐to‐side duodenojejunostomy resolved symptoms. This first reported pediatric SMAS case from Sudan highlights early CT diagnosis to prevent prolonged morbidity.

Abbreviations

CBC

Complete blood count

CT

Computed tomography

NGT

Naso gastric tube

SMA

Superior mesenteric artery

SMAS

superior mesenteric artery syndrome

Key Clinical Message.

In children with bilious vomiting, abdominal pain, cachexia, scaphoid abdomen, and failure to thrive, suspect SMAS after excluding common causes. Early CT angiography aids diagnosis; duodenojejunostomy is definitive if conservative treatment fails.

1. Introduction

Superior mesenteric artery syndrome (SMAS) also known as Wilkie's syndrome is defined as intestinal obstruction caused by extrinsic compression of the third part of the duodenum between the abdominal aorta and the superior mesenteric artery [1]. Due to the deficiency of retroperitoneal and visceral adipose tissue, the angle between the superior mesenteric artery and the abdominal aorta is typically reduced to 6°–25°, compared with the normal range of 38°–56°, thereby contributing to the development of this rare syndrome [2].

The estimated incidence of SMAS in pediatrics ranges from 0.01% to 0.3%, with a reported female‐to‐male ratio of approximately 3:2 [3].

This syndrome can occur whenever there is any disease or illness that causes a loss of weight due to its effect on an individual's ability to absorb food through their GI tract, typically due to an obstruction of the duodenum (this leads to an increase in symptoms of vomiting) which may ultimately develop into a self‐perpetuating cycle. Once SMA syndrome is suspected, the medical provider will usually recommend imaging with one or more of the following modalities: plain film x‐ray; endoscopy; computed tomography (CT); ultrasound; magnetic resonance angiography (MRA) [4].

Many patients who suffer from upper GI disorders have experienced problems due to improper treatment and delayed diagnosis. These problems may include: food intolerance, malnutrition, weight loss, electrolyte imbalance, decreased quality of life [5].

The initial course of treatment is primarily medical in nature, with emphasis on correcting electrolyte imbalances and restoring fluid levels to normal. If required, placement of a nasogastric tube can also be performed, as it will assist in decompression [4]. Nutritional Support represents the basis for conservative therapy with the goal of enlarging the fat pad located between the aorta and superior mesenteric artery (SMA). Patients who do not successfully respond to medical therapy may require surgical intervention and endoscopic procedures, depending on their specific condition and symptoms [4]. This case report complies with the SCARE Criteria [5].

2. Case Presentation

A 10‐year‐old Sudanese boy presented to Alnao Teaching Hospital to the ER department on the 13th of September 2024 during war time with a 4‐year history of chronic, severe colicky abdominal pain and vomiting.

His illness began when he was 2 years old, at the time of starting complementary feeding, with early satiety, poor weight gain, and failure to thrive. His family sought medical advice many times with different diagnoses and treatment with just vitamin supplements without any improvement. When he was 3 years old, he started to develop vomiting if he had a full stomach but not with small frequent meals.

At 6 years old, he began experiencing attacks of abdominal pain two or three times per month, occurring approximately half an hour postprandially mainly after a full meal followed by greenish vomiting containing food particles and a large amount of water. He again sought medical advice; results showed recurrent episodes of hypoglycemia and electrolyte disturbances. He subsequently developed difficulty walking and became bedridden (Figure 1).

FIGURE 1.

Clinical photograph of the 10‐year‐old patient showing severe cachexia, scaphoid abdomen (hollowed appearance), prominent ribs and iliac bones, and kyphosis.

At 9 years the pain and vomiting became more frequent and severe even with small meals. Diagnosed as having gastroenteritis, Giardiasis, and inflammatory bowel disease. An abdominal ultrasound was performed, which showed Gastric Outlet Obstruction, received medical treatment but without improvement. No other symptoms related to other systems including genitourinary system.

On physical examination, the patient appeared cachectic (Figure 1), has kyphosis, unwell but not pale, jaundiced with normal vitals. Cardiovascular and respiratory exams were unremarkable. On abdominal examination, had scaphoid abdomen with prominent iliac bones, costal margin and ribs; otherwise, soft, lax abdomen with epigastric tenderness and positive bowel sounds and empty rectum. With a weight of 16.3 kg.

Based on cachexia, chronic history of bilious vomiting, and abdominal pain, our main differential diagnoses included Superior Mesenteric Artery (SMA) syndrome or malrotation.

His blood test including CBC was normal, chemistry (blood urea 51 mg/dL, serum creatinine 1.4 mg/dL, serum sodium 128 mmol/L, serum potassium 3.6 mmol/L, serum calcium 7.7 mmol/L, serum magnesium 1.2 mmol/L), serum albumin 2.7 g/dL, normal urine analysis test and negative viral screening.

Ultrasound abdomen shows feature of Gastric Outlet Obstruction so a contrast‐enhanced CT abdomen was requested, which revealed a severely narrowed aortomesenteric angle of 17° (normal 38°–56°) and a markedly reduced aortomesenteric distance of 5 mm (normal 10–28 mm), resulting in extrinsic compression of the third part of the duodenum between the aorta and the superior mesenteric artery. Importantly, the SMA itself showed no intrinsic stenosis (Figure 2).

FIGURE 2.

Contrast‐enhanced abdominal CT (axial view) demonstrating reduced aortomesenteric angle of 17° (normal 38°–56°) and decreased aortomesenteric distance of 5 mm (normal 10–28 mm), consistent with superior mesenteric artery syndrome.

Left renal vein was compressed between aorta and SMA “Nutcracker syndrome”.

Based on this clinical picture and CT findings, the diagnosis of SMAS was made. We attempted conservative treatment; however, the patient could not tolerate it and required surgical relief, so surgery was planned.

Intraoperative findings showed that the stomach was dilated up to the third part of the duodenum, which was compressed by the SMA. A side‐to‐side duodenojejunostomy bypass and a prophylactic appendectomy were performed (Figure 3), Although laparoscopic duodenojejunostomy has been reported to yield excellent outcomes in elective settings, it was not feasible in this case.

FIGURE 3.

Intraoperative photograph showing side‐to‐side duodenojejunostomy (white arrow: Anastomosis between duodenum and jejunum) after decompression of the dilated stomach and proximal duodenum.

During the open procedure, we specifically considered the option of releasing the ligament of Treitz. However, we elected not to perform this maneuver for two primary reasons. Firstly, in a severely malnourished and cachectic patient with a scaphoid abdomen (weight 16.3 kg), the tissue planes surrounding the ligament are often attenuated and indistinct, increasing the risk of inadvertent injury to the duodenum, pancreatic duct, or the mesenteric vessels. Secondly, a side‐to‐side duodenojejunostomy provides a reliable, low‐tension bypass of the obstructed third part of the duodenum and is considered a definitive and effective surgical solution for SMAS when conservative management fails.

Laparoscopic pediatric surgery is not widely available in Sudan, and the current wartime conditions have further limited access to advanced equipment and specialized training. Given the patient's severe malnutrition and the need for urgent symptom relief, we opted for an open side‐to‐side duodenojejunostomy, which is the most reliable and safe surgical option in our resource‐constrained environment.

NG tube was in place and was on close observation and monitoring at the ward, NGT removed at Day 3 postoperative when we had positive bowel sounds.

We start with gradual feeding which was tolerated and he was discharged home at Day 7 when there was no pain and vomiting.

After a while he started regular physiotherapy, and his parents were advised to follow up with a pediatrician for optimal outcomes.

One year postoperatively, he developed colicky central abdominal pain and was diagnosed with an incarcerated umbilical hernia, which was surgically repaired.

The patient and his family showed a very good attitude regarding adherence to the treatment plan and regular surgical and medical follow‐up. The patient shows improvement in appetite, weight, and normal walking.

Now it's almost 18 months follow up without complaint. His last weight is 22 kg.

3. Differential Diagnosis

Malrotation with volvulus: Intermittent bilious vomiting can present beyond infancy.

Duodenal web/annular pancreas: Partial chronic obstruction, usually from birth.

Chronic intestinal pseudo‐obstruction: Functional obstruction with no mechanical cause.

Giardiasis/chronic gastroenteritis: Common misdiagnosis; typically non‐bilious vomiting.

Inflammatory bowel disease: Abdominal pain, weight loss, but often diarrhea/bloody stools.

Celiac disease: Failure to thrive, diarrhea; vomiting less prominent.

Rumination syndrome/ARFID: Behavioral, non‐bilious regurgitation.

Nutcracker syndrome: May coexist (as in this patient), but presents with hematuria/flank pain, not primarily vomiting.

Posterior fossa brain tumor: Chronic vomiting with neurologic signs.

Key distinguishing feature of SMAS: Bilious vomiting + scaphoid abdomen + cachexia + narrowed aortomesenteric angle on CT.

4. Discussion

Rokitansky discovered Wilkie's syndrome (SMAS) as early as 1861. Although it has not been common enough to warrant large studies on the incidence of proximal small‐bowel obstruction caused by this syndrome [6, 7], the estimated incidence is between 0.2% and 0.78% [8, 9]. A decrease in fat mass and a significant increase in lean body mass due to the early stages of puberty contribute to the aortomesenteric space being narrowed in boys. Prior research on risk factors associated with SMA syndrome found growth spurts to be a contributing factor [10, 11, 12, 13]. In Sudan, no previous case of SMAS has been documented in the literature to our knowledge, making this the first reported pediatric case from the country.

The etiologies of SMA syndrome can be classified as primary or secondary [8, 14, 15]. Primary etiologies include duodenal levels that are elevated beyond normal limits, spinal dysplasia, and anatomical deformity of the superior mesenteric artery [16, 17, 18]. The case in this paper demonstrates the necessity of weight loss as a contributing factor to the formation of SMA syndrome in children as in previous study [19, 20, 21].

Clinically, SMA syndrome diagnoses rely on presenting signs and symptoms and imaging tests [9, 14, 16]. While knowing that SMA syndrome is often diagnosed in the context of a diagnostic workup for other reasons, many clinicians are still unfamiliar with the syndrome [16], as its meaning does not yet exist in the medical community. This patient was falsely diagnosed with gastric outlet obstruction and giardiasis and had no benefit from just symptomatic treatment. In this situation, the delays had an effect on the patient and were also not solely an academic concern to the extent that they contributed to the patient suffering from severe malnutrition, electrolyte imbalance, failure to grow, and low quality of life. These were also all evident in this case.

Because of our upright position, the aorta to SMA angle will be anywhere between 38 degrees and 65 degrees. The primary anatomical feature of SMA syndrome is a narrowing of the aorta to SMA angle below 25 degrees, therefore the aortomesenteric distance becomes < 10 mm. (Normally measuring anywhere between 10 mm and 28 mm.) [16, 22], Contrast‐enhanced abdominal CT confirmed the diagnosis with a 17° (normal being ≥ 45°) aortomesenteric angle and a distance of 5 mm (normal being ≥ 28 mm) between the aorta and superior mesenteric artery; both values are significantly below normal. Another associated finding was also noted; the left renal vein was compressed (nutcracker syndrome), as previously reported along with SMAS due to the same anatomical reduction of the aortomesenteric space.

The SMAS treatment choice will depend on the severity of the condition. Patients who have SMAS are treated initially with conservative means, such as fasting, gastrointestinal decompression, and parental nutrition, which have an estimated 83% success rate [9, 14, 23]. Recent evidence supports the efficacy of surgical intervention for SMAS [24], which included 91 patients, demonstrated excellent outcomes with laparoscopic duodenojejunostomy, reinforcing that surgical bypass is a safe and effective treatment for patients who do not respond to conservative management. Because this patient was unable to be managed conservatively (such as through the use of electrolyte therapy, nasogastric decompression, and nutritional support) because of the severe symptoms experienced by the patient, a side‐to‐side duodenojejunostomy and preventive appendectomy were performed. The patient had a very smooth and uncomplicated postoperative course, was discharged after 7 days, and continues to demonstrate improvement in appetite, weight, ambulation, and quality of life (the patient also underwent a separate procedure to repair post‐operative incarcerated umbilical hernia 1 year after the duodenojejunostomy). This case also supports that clinicians should include SMAS as part of their differential diagnosis for children with chronic bilious vomiting, abdominal pain, and failure to thrive and that early CT or magnetic resonance angiography imaging may prevent delays in diagnosis. Additionally, surgical bypass is effective for patients with SMAS when conservative treatment fails.

Finally, as the first documented case of SMAS in Sudan highlights an urgent need for clinicians throughout Sudan, primarily pediatricians, radiologists, and surgeons, to have a better understanding of this disorder so they may make more timely diagnoses and lower the morbidity associated with the condition.

5. Conclusion

The current report describes SMAS as an infrequently seen but significant cause of chronic vomiting and pain in the abdomen of pediatric patients and represents the first case in a Sudanese child diagnosed at 10 years old with symptom onset at 2 years. The substantial delay in this child's diagnosis also highlights a general lack of clinical recognition for this condition in our environment. His chronic bilious vomiting, abdominal pain, cachexia, and scaphoid abdomen had persisted despite 6 months of attempted medical management and therefore he underwent a successful side‐to‐side duodenojejunostomy with good postoperative results; 18 months after surgery he continued to demonstrate excellent resolution of his previous symptoms. This case report demonstrates the need for physicians to include SMAS in their differential diagnosis of children who present with chronic bilious vomiting, abdominal pain, cachexia, or scaphoid abdomen, particularly if they are failing medical management for more common diagnoses. Early identification of SMAS and proper surgical intervention will improve the affected pediatric patient's quality of life.

6. Limitation

Single case report: Research results cannot necessarily be extrapolated to the overall structure of children diagnosed with SMAS.

No preop/postop nutrition score: Not all parameters including BMI percentile were recorded in a systematic or reliable manner.

No comparison to other surgical procedures: There has been no study conducted on the comparison of results between this operation and other approaches such as gastrojejunostomy or laparoscopic techniques.

Imaging limitations: A CT angiogram was the only imaging modality used to assess this case. MR angiography (MRA) would be an alternative that eliminates exposure to ionizing radiation.

7. Recommendation

Elevating clinical awareness of SMAS among pediatrics is key to finding the diagnosis—this can be accomplished through identifying patients with chronic bilious vomiting, abdominal pain, cachexia and a scaphoid (concave) abdomen.

To help expedite diagnosis and minimize treatment delays, initial CT or MRA angiography studies should be done to verify the diagnosis.

All patients who are stable can have conservative management as initial treatment (wherein nutritional support & electrolyte replacement can be considered).

If conservative measures do not work or if symptoms are severe, surgical interventions (i.e., duodenojejunostomy) should be evaluated as a possible treatment pathway.

Pediatric‐specific rare disease registries need to be established in Sudan to provide more complete information and increase public awareness.

Author Contributions

Alaa Yousif Yagoob Mohammed: writing – original draft, writing – review and editing, conceptualization, resources. Ismael Mohammed Saeed Ali: writing – review and editing. Adli Khalil Abdulrahman: writing – review and editing. Ahmed Mohamed Ahmed Abdelrahman: writing – original draft. Doaa Ali Abubaker Ahmed: writing – original draft. Amina Alfatih Idris Hajhamd: writing – original draft. Ahmed Alshafei Elmahi Ahmed: writing – original draft, writing – review and editing, supervision, conceptualization, software, project administration.

Funding

The authors have nothing to report.

Ethics Statement

This study is exempt from ethical approval in our hospital.

Consent

Written informed consent was obtained from the legal guardians of the child for publication of anonymized medical data, images, and genetic findings in accordance with the journal's policy. The guardians acknowledged the report's public availability and confirmed that all identifiable information has been removed to protect the patients' privacy. This consent adheres to the journal's ethical guidelines, ensuring confidentiality while contributing to medical understanding of SMAS in underrepresented populations.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.