Superior mesenteric artery syndrome and right paraduodenal hernia causing intestinal obstruction during pregnancy: A case report

Abstract

BACKGROUND

Superior mesenteric artery (SMA) syndrome is exceptionally rare in pregnancy and may be misattributed to common gestational complaints. Coexistence with a right paraduodenal hernia further complicates presentation and increases the risk of obstruction. This report highlights diagnostic challenges in pregnancy-adapted imaging, where non-contrast computed tomography identified the hernia and raised suspicion for aortomesenteric compression, and illustrates operative decision-making in a scenario where definitive diagnosis was established intraoperatively.

CASE SUMMARY

An 18-week primigravida presented with a month of postprandial pain, emesis, and significant weight loss consistent with severe malnutrition. Pregnancy-adapted non-contrast computed tomography identified a right paraduodenal hernia with a whirlpool sign and suggested aortomesenteric duodenal compression, though the latter remained non-diagnostic owing to lack of contrast. Conservative management failed. Laparoscopy revealed proximal duodenal obstruction from SMA compression (Wilkie’s syndrome) and a paraduodenal hernia containing transverse colon, with evolving mesenteric torsion prompting conversion to supraumbilical laparotomy. The hernia was reduced and repaired transomentally. A wide, tension-free side-to-side duodeno-duodenostomy restored duodenal continuity while preserving physiological pyloroduodenal transit. Postoperative gastroparesis resolved after endoscopic confirmation of anastomotic patency, and maternal-fetal outcomes were favorable.

CONCLUSION

Timely operative intervention permitted duodeno-duodenostomy to preserve physiological pyloroduodenal transit in pregnancy-associated SMA obstruction with paraduodenal hernia.

Key Words: Superior mesenteric artery syndrome; Duodenal obstruction; Paraduodenal hernia; Pregnancy; Laparotomy; Case report

Core Tip: Superior mesenteric artery syndrome is exceptionally rare, and its coexistence with a right paraduodenal hernia during pregnancy adds diagnostic and operative complexity. In this patient, pregnancy-adapted non-contrast computed tomography identified a right paraduodenal hernia and suggested aortomesenteric duodenal compression, with definitive superior mesenteric artery obstruction established intraoperatively. After internal hernia reduction, operative anatomy permitted a wide, tension-free side-to-side duodeno-duodenostomy - an uncommon but physiologically favorable alternative to duodeno-jejunostomy in this isolated setting. This case underscores the importance of early surgical decision-making, physiology-preserving reconstruction, and selective postoperative endoscopic assessment to safely enable early enteral nutrition in high-risk pregnant patients.

INTRODUCTION

Superior mesenteric artery (SMA) syndrome or Wilkie’s syndrome is characterized by extrinsic compression of the third portion of the duodenum between the SMA and the aorta, with an estimated prevalence of 0.013%-0.78% and a predilection for young women (median age approximately of 23 years). Typical manifestations include postprandial epigastric pain, nausea/vomiting and weight loss; yet diagnosis remains challenging owing to non-specific symptoms and overlap with other gastrointestinal disorders[1,2]. Intestinal obstruction in pregnancy is uncommon but high-risk for mother and fetus, demanding rapid recognition and decisive management[3]. Occurrence during pregnancy is exceptional; a 1986 report highlighted its “unique obstetrical interest” and proposed pregnancy-related mechanisms - raised intra-abdominal pressure, accentuated lumbar lordosis narrowing the aortomesenteric angle, delayed gastric emptying and hormonally mediated ligamentous laxity - that may exacerbate duodenal compression[4].

We present a primigravid patient with SMA syndrome coexisting with a right paraduodenal internal hernia (Waldeyer) containing transverse colon. The dual pathology shaped diagnosis and operative strategy. Definitive management comprised transomental repair of the hernia defect together with a side-to-side duodeno-duodenostomy to bypass the compressed duodenum - an alternative that preserves physiological pyloroduodenal transit when anatomy permits a wide, tension-free duodenal bypass, thereby obviating duodeno-jejunostomy. This case report has been prepared in accordance with the case reports guidelines[5].

CASE PRESENTATION

Chief complaints

A 21-year-old primigravida at 18 weeks gestation presented with one month of progressively worsening postprandial epigastric pain (visual analog scale 10/10), nausea, and recurrent vomiting.

History of present illness

The patient reported persistent postprandial epigastric pain and emesis for four weeks, initially attributed to common pregnancy-related gastrointestinal symptoms. Symptoms progressively intensified, leading to inability to tolerate oral intake and an unintentional 8 kg weight loss over four weeks. At the first prenatal visit, the patient weighed 68 kg (height 170 cm; body mass index 23.5 kg/m²); at presentation, her weight was 60 kg (body mass index 20.8 kg/m²). Given the magnitude (> 10%) and timing of the weight loss during the second trimester, the evolving clinical picture raised obstetric concern for hyperemesis gravidarum; however, the severity and progression of symptoms prompted further investigation to exclude an underlying mechanical cause.

History of past illness

The patient had no prior medical or surgical history, and no known gastrointestinal, metabolic, or vascular disorders. Before admission, the patient was taking routine pregnancy-related supplementation, including folic acid 400 μg daily, oral elemental iron 60 mg daily, a standard prenatal multivitamin, low-dose aspirin 81 mg daily for preeclampsia prophylaxis based on the presence of two moderate-risk factors for preeclampsia: Nulliparity and a positive family history of preeclampsia, and oral calcium supplementation. She reported no known drug allergies, no prior adverse drug reactions, and denied the use of nonprescription or herbal medications.

Personal and family history

She reported no familial history of hernias, connective tissue disorders, or gastrointestinal disease. She denied alcohol, tobacco, or illicit drug use. No hereditary conditions were noted.

Physical examination

On admission, the patient was ectomorphic, pale, and clinically asthenic, with reduced subcutaneous tissue consistent with severe protein-calorie malnutrition. She was alert, oriented, and her vital signs were within normal limits (normotensive, afebrile, with normal heart and respiratory rates).

Abdominal examination showed a gravid uterus appropriate for 18 weeks gestation, without distension. Palpation revealed a soft abdomen with focal epigastric and left upper quadrant tenderness, without guarding, rebound, or palpable masses. Percussion demonstrated normal upper-abdominal tympanism. Bowel sounds were preserved. Obstetric ultrasonography confirmed a viable fetus appropriate for gestational age.

Laboratory examinations

Laboratory testing demonstrated leukocytosis (white blood cell count 14.59 × 10³/μL) with neutrophilia, moderate normocytic anemia (hemoglobin 9.0 g/dL; hematocrit 27.9%; mean corpuscular volume 92.2 × 10^-14 L) with hypochromia on peripheral smear, and a normal platelet count (376 × 10³/μL). Mild electrolyte abnormalities included hyponatremia (serum sodium 128 mmol/L) and hypocalcemia (serum calcium 7.5 mg/dL). Liver and renal function were within normal limits. Findings were consistent with severe protein-calorie malnutrition according to Global Leadership Initiative on Malnutrition criteria. Serum albumin (24 g/L) and transthyretin (0.1 g/L) levels were markedly reduced.

Imaging examinations

Pregnancy-adapted non-contrast abdominal computed tomography demonstrated a right paraduodenal internal hernia (Waldeyer fossa) with a characteristic whirlpool sign and non-visualization of the third portion of the duodenum (D3). The aortomesenteric angle and distance appeared reduced; however, these findings were illustrative only, as the absence of intravenous and enteric contrast precluded definitive radiologic diagnosis of SMA syndrome (Figure 1). Further stepwise imaging (transabdominal ultrasound and magnetic resonance imaging) was not pursued because of progressive obstructive symptoms with clinical deterioration, severe gastric and intestinal distension limiting sonographic assessment, persistent intolerance to oral intake precluding adequate gastrointestinal magnetic resonance imaging evaluation, and the need for urgent operative management, making additional imaging unlikely to alter management.

Figure 1 Non-contrast abdominal computed tomography in a 21-year-old primigravida demonstrating primary aortomesenteric (Wilkie’s) duodenal compression with a concomitant right paraduodenal hernia. A-C: Axial images demonstrate a right paraduodenal hernia through Waldeyer’s fossa (orange arrow in A). The ascending colon and part of the hepatic flexure are contained within the hernia defect (orange circles in A and B). This anatomic distortion alters the course of the superior mesenteric artery, which is visualized centrally within the hernia defect (orange arrow in C). The third portion of the duodenum is poorly delineated and compressed at the aortomesenteric crossing, indicating that the duodenal obstruction arises from primary aortomesenteric compression rather than from the hernia itself; D and E: Sagittal reconstructions demonstrate a reduced aortomesenteric angle of approximately 19° (orange angle marker in D) and a reduced aortomesenteric distance of approximately 8 mm (orange arrow indicating the measurement in E). Because this pregnancy-adapted study lacked oral and intravenous contrast, these measurements are illustrative rather than diagnostic and are included to highlight the limitations of non-contrast computed tomography in pregnancy. Definitive confirmation of Wilkie’s syndrome was established intraoperatively.

FINAL DIAGNOSIS

The final diagnosis was SMA syndrome causing proximal duodenal obstruction due to aortomesenteric compression, coexisting with a right paraduodenal hernia (Waldeyer fossa) containing transverse colon, without evidence of bowel necrosis. Diagnosis of SMA syndrome was established intraoperatively, as non-contrast computed tomography could not provide confirmatory aortomesenteric measurements during pregnancy.

TREATMENT

After failure of 48 hours of conservative management, diagnostic laparoscopy was performed and confirmed SMA-related duodenal obstruction with a concomitant right paraduodenal hernia. Concern for evolving mesenteric torsion prompted conversion to supraumbilical laparotomy. The paraduodenal hernia was reduced and the mesenteric defect closed via a transomental approach.

Given the favorable operative anatomy, a wide, tension-free side-to-side duodeno-duodenostomy was constructed to bypass the compressed third portion of the duodenum while preserving physiological pyloroduodenal transit and avoiding duodeno-jejunostomy (Figure 2). Intraoperative endoscopy confirmed anastomotic patency with a negative air-leak test. A nasojejunal tube was placed distal to the anastomosis, and a 19 French Blake drain was positioned adjacent to the reconstruction. Intraoperative and postoperative fetal ultrasonography remained reassuring.

Figure 2 Intraoperative sequence demonstrating laparoscopic confirmation of aortomesenteric duodenal compression, identification of a concomitant right paraduodenal defect, and definitive reconstruction. A: Laparoscopic view showing the third portion of the duodenum (blue circle) passing beneath the superior mesenteric artery (black arrow) and the superior mesenteric vein (white arrow), with extrinsic aortomesenteric compression causing focal luminal narrowing of third portion of the duodenum at the crossing; B: Laparoscopic view demonstrating the right paraduodenal (Waldeyer) defect, occupied by herniated transverse colon with adjacent bowel loops (white circle), such that the defect itself is not directly visualized because it is filled by the herniated intestinal contents; C: Open view following conversion to laparotomy, showing the completed side-to-side duodeno-duodenostomy (yellow arrow) restoring duodenal continuity.

OUTCOME AND FOLLOW-UP

Early postoperative recovery was notable for transient gastroparesis with persistent intolerance to enteral intake. Upper gastrointestinal fluoroscopy with water-soluble contrast demonstrated no evidence of anastomotic leak or distal obstruction. Given ongoing symptoms, upper gastrointestinal endoscopy was subsequently performed on postoperative day 10, confirming a widely patent side-to-side duodeno-duodenostomy with viable mucosa (Figure 3). Enteral feeding was then gradually advanced. The surgical drain was removed on postoperative day 10. The patient resumed oral intake without difficulty and was discharged in good condition on postoperative day 13, with reassuring maternal and fetal parameters.

Figure 3 Postoperative assessment for transient gastroparesis demonstrating anastomotic patency. A: Duodenoscopy in the operating room under real-time fluoroscopy shows advancement of the scope to the third portion of the duodenum (orange circle) with instillation of water-soluble contrast; no leak or collection is identified, and contrast passes freely into the proximal jejunum; B: Endoluminal duodenoscopic view demonstrating a widely patent side-to-side duodeno-duodenostomy with a nasojejunal tube traversing the anastomotic lumen.

DISCUSSION

SMA syndrome represents obstructive compression of the third duodenal portion between the aorta and the SMA[1,6], leading to proximal intestinal obstruction. Its incidence is extremely low, and presentation during pregnancy is exceptionally rare[4]. Because symptoms overlap with common gestational complaints, SMA syndrome is frequently a diagnosis of exclusion[6]. This distinction is critical, as persistent weight loss and complete oral intolerance should prompt evaluation for mechanical obstruction rather than attribution to functional gestational vomiting alone. Accurate diagnosis requires correlation of clinical and radiological findings. Contrast-enhanced computed tomography remains the most informative modality, revealing duodenal dilatation with a reduced aortomesenteric angle[7]; prospectively, diagnostic cut-offs of aortomesenteric angle ≤ 22° and distance ≤ 8 mm have been used[8]. However, imaging alone is insufficient, and clinical suspicion remains decisive.

In our patient, the combination of persistent oral-intake intolerance, severe protein-calorie malnutrition, electrolyte derangements, and a concomitant right paraduodenal hernia with SMA-mediated D3 obstruction and evolving mesenteric torsion defined a high-risk clinical state. In this context, further diagnostic delay carried a substantial risk of clinical decompensation and intestinal ischemia, warranting urgent operative management. Accordingly, further stepwise imaging typically used during pregnancy (transabdominal ultrasound or magnetic resonance imaging) was unlikely to alter management and would have delayed definitive treatment.

Although transient postoperative gastroparesis is a recognized phenomenon following corrective surgery for SMA syndrome, this patient developed persistent postoperative intolerance to enteral intake in the setting of a recent duodenal anastomosis. Targeted investigation was therefore warranted to exclude early structural complications, particularly anastomotic leak or functional obstruction, which could pose increased maternal-fetal risk if unrecognized. Upper gastrointestinal fluoroscopy with water-soluble contrast was selected as the initial diagnostic modality because it permits assessment of anastomotic integrity and functional transit with lower radiation exposure than computed tomography. When symptoms persisted, upper gastrointestinal endoscopy was performed as a second-line investigation to directly confirm anastomotic patency and mucosal viability. In this sequential approach, endoscopy complemented fluoroscopy, allowing definitive exclusion of mechanical complications while minimizing fetal radiation exposure.

Although duodeno-jejunostomy remains the standard operation for Wilkie’s syndrome - with low perioperative risk and quality-of-life gains in selected series[1,8-10], long-term outcomes are heterogeneous and worse in patients with concomitant dysmotility[11]. Intraoperative findings permitted wide, tension-free apposition of proximal and distal duodenum; therefore, a side-to-side duodeno-duodenostomy was chosen to bypass D3 while preserving physiological pyloroduodenal transit and avoiding jejunal diversion (blind loop, bile reflux, marginal ulceration)[8]. This technique is sparsely reported for Wilkie’s but has greater precedent in other duodenal outlet obstructions - particularly annular pancreas[12] - when generous, tension-free coaptation is feasible. It is technically demanding and requires extensive mobilization to secure a broad, durable lumen; otherwise, decompression may be inadequate. The concomitant right paraduodenal hernia was managed separately by transomental repair of Waldeyer’s defect after reduction. Previously reported cases of SMA syndrome in pregnancy, highlighting differences in clinical presentation, management strategies, and maternal-fetal outcomes, are summarized in (Table 1). Conversely, favorable outcomes with non-operative management have been reported. Hillyard et al[13] described a pregnant patient with SMA syndrome who declined surgery and, after receiving supportive nutritional therapy, experienced spontaneous resolution of the obstruction in the postpartum period, with sustained remission at 18 months. This isolated report suggests that, in very selected cases, the dynamic physiological changes of pregnancy and the postpartum period, together with adequate nutritional support, may contribute to relief of the obstruction; however, such scenarios remain exceptional. In the setting of severe protein-calorie malnutrition and systemic inflammation, as in our patient, conservative management carries an unacceptable risk for both mother and fetus.

Table 1 Reported cases of superior mesenteric artery syndrome in association with pregnancy: Clinical presentation, management, and reported outcomes.

Ref.	Maternal characteristics	Pregnancy context	Gestational age	Predisposing factors	Diagnosis and intervention	Outcomes
Iko et al[4], 1986	28 years; history of four pregnancy losses	Recurrent severe gastrointestinal symptoms during multiple pregnancies	24 weeks	Long-standing gastrointestinal symptoms	Upper gastrointestinal barium study; postpartum surgical transposition of the third and fourth portions of the duodenum anterior to the superior mesenteric artery	Maternal: Complete symptom resolution after surgery; fetal: Two subsequent term deliveries following surgical correction
Hillyard et al[13], 2019	38 years; parity not reported	Pre-existing SMA syndrome diagnosed prior to pregnancy; pregnancy occurred during preoperative evaluation	Not reported	Recent intentional weight loss	CT and upper gastrointestinal series; conservative management with oral liquid nutritional support	Maternal: Complete symptom resolution postpartum; fetal: Term delivery
Our study	21 years; first pregnancy	De novo presentation during pregnancy	18 weeks	Rapid weight loss during pregnancy; right paraduodenal hernia	Non-contrast abdominal CT (suggestive); definitive intraoperative diagnosis; antepartum surgical management including reduction of paraduodenal hernia and side-to-side duodeno-duodenostomy	Maternal: Complete recovery with preserved gastrointestinal continuity; fetal: Ongoing viable pregnancy

SMA: Superior mesenteric artery; CT: Computed tomography.

Management of SMA syndrome in pregnancy remains challenging, as available evidence is limited to isolated case descriptions. Clinical decisions must therefore be individualized, integrating maternal nutritional status, gestational age, and overall physiologic reserve. In patients with significant metabolic compromise, as in this case, timely operative intervention remains the most reliable and lifesaving strategy.

This report has several strengths, including detailed documentation of an exceptionally rare presentation - pregnancy-associated SMA syndrome with a concurrent right paraduodenal hernia - and a coherent correlation of clinical, radiologic, and operative findings. The pregnancy-adapted diagnostic approach and the rationale for selecting a duodeno-duodenostomy provide practical guidance for surgeons managing complex duodenal obstruction. As a single-patient observation, it cannot inform comparative effectiveness or establish generalizable outcomes; nevertheless, its detailed characterization contributes useful context to the limited literature available for similar high-risk scenarios.

From a clinical perspective, this case highlights several practical implications for surgeons managing intestinal obstruction during pregnancy. Persistent oral intolerance with progressive weight loss should prompt early consideration of mechanical obstruction rather than attribution to physiological gestational symptoms alone. In malnourished patients requiring duodenal reconstruction, timely restoration of enteral nutrition is essential for anastomotic healing and maternal-fetal well-being. When postoperative intolerance persists, selective investigation aimed at excluding structural complications is justified. In this context, minimal-insufflation upper gastrointestinal endoscopy - used judiciously - may serve as a targeted tool to confirm anastomotic patency and mucosal viability, thereby safely enabling early enteral feeding. Finally, when operative anatomy permits, a physiology-preserving duodeno-duodenostomy represents a rational alternative to duodeno-jejunostomy, avoiding jejunal diversion while maintaining normal pyloroduodenal transit.

CONCLUSION

In pregnancy, non-contrast computed tomography may raise suspicion for SMA syndrome but cannot confirm aortomesenteric obstruction, making operative assessment critical when clinical deterioration or failure of conservative therapy occurs. In this case, surgical exploration established true SMA compression and enabled concurrent repair of a right paraduodenal hernia. A wide, tension-free duodeno-duodenostomy restored physiological continuity without the morbidity of jejunal diversion. When imaging is constrained and multiple mechanical factors contribute to obstruction, timely, anatomy-guided intervention remains the most reliable path to definitive resolution.