SMAS Surgery: Procedures, Outcomes, Complications, and the SMAS-Nutcracker Connection

Surgery for Superior Mesenteric Artery Syndrome (SMAS) is not one single operation. Different procedures either bypass the compressed duodenum, mobilize it away from the vascular angle, or reconstruct the duodenum so the compressed segment is no longer in the food pathway. Because SMAS is rare, most evidence comes from retrospective series and case reports rather than randomized trials.

1. Duodenojejunostomy (DJ)

Duodenojejunostomy connects the duodenum above or near the obstruction directly to the jejunum, allowing food to bypass the compressed segment. It may be performed open, laparoscopically, or robotically. It has been the most commonly reported modern operation for refractory SMAS.

Older reviews often quote success rates of about 80%-100%, but newer long-term data show that results are more complicated. A 2015 minimally invasive series reported initial improvement in all 14 patients, with 11 of 14 (79%) maintaining improvement at a mean 20-month follow-up. Reported complications included an anastomotic stricture requiring balloon dilation, J-tube-site infection, and dumping syndrome.

A 2025 Cleveland Clinic long-term study followed 25 patients for a median 5.3 years. By final follow-up, abdominal pain persisted or worsened in 32%, nausea in 40%, vomiting in 28%, and weight loss in 48%. Twenty-eight percent still required supplemental tube or parenteral nutrition, and 28% underwent later major abdominal operations. Four patients died during long-term follow-up; the study did not report these as immediate operative deaths, and several deaths reflected severe underlying intestinal disease or malnutrition. These results show why short-term 'success rates' should not be treated as the whole story.

2. Strong's procedure

Strong's procedure divides the ligament of Treitz and mobilizes the duodenum so it can fall away from the aortomesenteric angle. Its advantage is that it can avoid creating a bowel anastomosis. However, published reviews commonly cite a failure rate around 25%, partly because vascular attachments may limit how far the duodenum can be moved. It is now used less often than duodenojejunostomy.

3. Gastrojejunostomy (GJ)

Gastrojejunostomy connects the stomach directly to the jejunum. It decompresses the stomach but does not remove the duodenal compression itself. Persistent duodenal stasis can remain, and reported concerns include recurrent symptoms, bile reflux, marginal ulceration, blind-loop problems, and the need for later revision. Case reports describe patients who ultimately required duodenojejunostomy after a gastrojejunostomy failed to resolve symptoms.

4. Duodenal derotation

Duodenal derotation moves the third and fourth portions of the duodenum out from under the superior mesenteric artery rather than simply bypassing them. In the 2008 Alvear series, 18 of 19 surgically treated patients (about 95%) had symptom relief. One required a gastrojejunostomy for persistent obstruction. Two patients developed later small-bowel obstruction from adhesions and were treated with adhesiolysis. The mean follow-up was more than four years.

A 2026 paper reviewing the evolution of this approach notes that some patients treated with derotation alone later required duodenoduodenostomy, which helped motivate adding a duodenal reconstruction to the derotation procedure.

5. Duodenal derotation with duodenoduodenostomy — the emerging 'Alvear' approach

What many patients now call the Alvear procedure is described in the current surgical literature as duodenal derotation with duodenoduodenostomy. The operation derotates and relocates the duodenum out of the vascular compression and reconnects healthy duodenum to healthy duodenum. This is intended to restore a more direct food pathway while avoiding a jejunal bypass.

A 12-patient series published online in 2024 and in print in 2025 reported 3-year outcomes after duodenoduodenostomy: 75% of patients gained weight and BMI, and 83% maintained BMI in the normal range. Iron levels also improved. The authors described the procedure as promising, but the cohort was small.

The newest published series, first published online in May 2026, reported 33 patients who underwent robotic duodenal derotation with duodenoduodenostomy between 2023 and 2025. There were no intraoperative complications or operative deaths, one conversion to open surgery, and six postoperative complications. Among patients with follow-up, 90.6% reported significant pain relief, 81.3% no longer needed supplemental nutrition, and 84.4% had significant weight regain. Follow-up ranged from only a few weeks to two years, so these are encouraging early/intermediate results rather than definitive long-term proof.

Nineteen of the 33 patients in that 2026 series also had MALS surgery at the same operation, underscoring how often surgeons treating complex patients are encountering more than one abdominal compression or pain generator.

6. Other and less common approaches

Other reported procedures include anterior transposition of the duodenum, Ladd-type mobilization, duodenal lowering, rare transposition or reimplantation of the superior mesenteric artery, and Roux-en-Y variants of duodenojejunostomy. Vascular transposition is generally reserved for unusual situations because it carries substantially greater vascular operative risk and has far less outcome data.

7. Endoscopic gastrojejunostomy (EUS-GJ / LAMS)

Advanced endoscopists have also reported creating a gastrojejunostomy using a lumen-apposing metal stent. This can bypass the obstruction without abdominal surgery, but the published evidence for SMAS is still largely limited to case reports and small experiences. It should be considered an emerging specialized option rather than an established equivalent to surgical procedures.

Why the published percentages seem to conflict

SMAS studies are difficult to compare. Some report immediate relief, others follow patients for years. Some define success as weight gain, some as pain relief, some as freedom from tube feeds, and some as overall symptom improvement. Patient populations also differ substantially in gastroparesis, intestinal dysmotility, connective-tissue disease, prior surgery, malnutrition, and additional vascular compressions. A procedure can be technically successful and still leave a patient with major symptoms from another condition.

SMAS and Nutcracker Syndrome: the same anatomic space

The duodenum and the left renal vein both pass through the aortomesenteric region. SMAS occurs when the third portion of the duodenum is compressed between the SMA and aorta. Anterior Nutcracker Syndrome occurs when the left renal vein is compressed in that same angle. This shared anatomy explains why the two conditions can coexist.

Several published cases are particularly relevant. One 20-year-old woman underwent Roux-en-Y duodenojejunostomy for SMAS; four weeks later her left-flank pain became substantially worse and she developed pelvic and urinary symptoms. Review of the original CT showed that the left renal vein had already been compressed, with an enlarged ovarian vein and pelvic collateral veins. Venography confirmed Nutcracker Syndrome, and she later improved after left renal vein transposition.

Another report described a patient treated years earlier with gastrojejunostomy for SMAS who later presented with severe left-sided loin pain and was diagnosed with Nutcracker Syndrome. Other reports describe SMAS and Nutcracker being diagnosed at the same time.

Does SMAS surgery make Nutcracker worse?

At this point, the medical literature does not prove that SMAS surgery itself causes Nutcracker Syndrome or routinely worsens another compression. The evidence is mainly individual case reports and small series. A more defensible explanation is that a bypass operation can relieve the duodenal obstruction without changing the narrow SMA-aorta angle and without directly relieving left renal vein compression. If Nutcracker anatomy was already present, those symptoms may remain, emerge, or become more noticeable after the SMAS symptoms improve.

For VCA, this is an important research question. Patients with SMAS—particularly children, adolescents, young adults, and patients with multiple compression syndromes—may benefit from careful review of the left renal vein, gonadal vein reflux/collateralization, pelvic venous circulation, and other relevant vascular anatomy before and after treatment when symptoms suggest another compression.

Questions families may want to ask before SMAS surgery

Which operation is being recommended, and does it bypass the compression or actually move the duodenum out of it? What are this surgeon's own long-term outcome and revision rates? Has the original imaging been reviewed for Nutcracker anatomy or another vascular compression? Is there evidence of a refluxing gonadal vein or pelvic collaterals? Has gastroparesis or broader intestinal dysmotility been evaluated? What symptoms should trigger repeat vascular imaging after surgery?

Selected peer-reviewed research

Ha CD, Alvear DT, Leber DC. Duodenal Derotation as an Effective Treatment of Superior Mesenteric Artery Syndrome: A Thirty-Three Year Experience. Am Surg. 2008. DOI: 10.1177/000313480807400712

Wills MV, et al. Long-term outcomes of laparoscopic duodenojejunostomy for superior mesenteric artery syndrome. Surg Endosc. 2025. DOI: 10.1007/s00464-025-11774-6

Ang D, et al. Outcomes After Duodenoduodenostomy for Superior Mesenteric Artery Syndrome. Am Surg. 2025. DOI: 10.1177/00031348241300361

Lozano GV, Chen SC, Shouhed D. Can Duodenal Derotation With Duodenoduodenostomy Be Performed Safely Robotically, and Is It the Optimal Surgical Intervention for SMAS? Am Surg. 2026. DOI: 10.1177/00031348261450568

Sun Z, et al. Minimally invasive duodenojejunostomy for superior mesenteric artery syndrome: a case series and review of the literature. Surg Endosc. 2015. DOI: 10.1007/s00464-014-3984-6

Nunn R, et al. A Model Example: Coexisting Superior Mesenteric Artery Syndrome and the Nutcracker Phenomenon. Case Rep Surg. 2015. DOI: 10.1155/2015/649469

Oh MJ. Superior mesenteric artery syndrome coexists with Nutcracker syndrome in a female: a case report. BMC Gastroenterol. 2019. DOI: 10.1186/s12876-019-0932-1

Nutcracker Syndrome Accompanying With Superior Mesenteric Artery Syndrome: A Case Report. Clin Med Insights Case Rep. 2019. DOI: 10.1177/1179547619855383

Important limitation

There are no large randomized trials comparing all SMAS operations head-to-head. Numbers from different case series should not be read as proof that one operation is best for every patient. The patient's anatomy, age, nutritional status, motility, prior operations, other vascular compressions, and the experience of the treating surgical team all matter.