Introduction
Gastric Outlet Obstruction (GOO) describes a mechanical obstruction of the proximal gastrointestinal tract, occurring at some level between the gastric pylorus and the proximal duodenum, resulting in an inability in the stomach to empty.
Whilst overall an uncommon condition, there are multiple causes for GOO. Causes include peptic ulcer disease (resulting in a stricturing of the stomach/duodenum), gastric cancer or small bowel cancer (including lymphoma or GIST), iatrogenic (such as an anastomotic stricture following a Bilroth I gastrectomy), pancreatic pseudocyst, Bouveret Syndrome (see below), or a gastric bezoar.
Figure 1 – Anatomical Regions of the Stomach
Clinical Features
Patient with GOO will present with epigastric pain, postprandial vomiting, and early satiety. Due to the proximal nature of the obstruction, often no change in bowel habit is reported initially.
On examination*, due to persistent vomiting and obstruction, patients will be significantly dehydrated and often hypovolaemic, therefore will be tachycardic +/- hypotensive +/- oliguric. Patients will often have a tender and distended upper abdomen; localised peritonism or guarding can be present.
*Classically, a “succession splash” is reported on auscultation during sudden movement by the patient.
Bouveret Syndrome
Bouveret Syndrome is a gastric outlet obstruction secondary to a gallstone impacted at the pylorus or proximal duodenum. It occurs in patients with a cholecystoduodenal fistula, typically developing from episodes of recurrent cholecystitis.
Patients present with the clinical features of gastric outlet obstruction. If possible, endoscopic removal of the obstructing gallstone can be attempted (Fig. 2), however is this is not feasible, then surgical intervention is required (with an enterotomy to remove the stone).
Differential Diagnosis
A key differential for GOO is gastroparesis, where patients have delayed gastric emptying and have similar clinical features to GOO, However, gastroparesis is caused by neuromuscular dysfunction and there is no mechanical obstruction present. Endoscopy (Fig. 2) and / or CT imaging (as discussed below) will help to differentiate.
Figure 2 – A gallstone impacted in the duodenal bulb, causing a Bouveret Syndrome, as seen on endoscopy
Investigations
Patients with suspected GOO should have routine bloods performed, including FBC ad CRP (to assess inflammatory markers), U&Es (to assess for an AKI, in the context of dehydration and hypovolaemia), and a clotting screen and Group and Save (for work-up for surgery)
Abdominal plain film radiograph may show a gastric fluid level, however most cases will warrant a CT scan with IV contrast for confirmation of GOO, as well as suggesting a potential underlying cause.
Depending on the suspected underlying cause, a upper GI endoscopy can be performed (following stomach decompression). This can be used to both confirm the diagnosis (e.g. biopsy in suspected malignancy) and for potential therapeutic purposes (see below).
Figure 3 – A plain film abdominal radiograph (in decubitus position) of Gastric Outlet Obstruction
Management
In all cases, resuscitative IV fluids should be started and the patient catheterised. A NG tube should be placed to decompress the stomach (this is the most important initial step) and the patient started on IV proton pump therapy (PPI).
In certain cases, endoscopy can be used in attempt to dilate benign stricturing (either balloon dilatation or endoscopic stenting) where feasible or remove any luminal obstruction (bezoars, gallstones).
However, surgical intervention forms the mainstay of treatment in most cases, especially in cases caused by malignancy or where endoscopic intervention has failed. The specific procedure performed depends on the underlying cause, and whilst certain cases can have a primary resection, often the obstruction can be bypassed more easily by forming a gastrojejunostomy.
Key Points
- Gastric Outlet Obstruction (GOO) describes a mechanical obstruction of the proximal gastrointestinal tract resulting in an inability in the stomach to empty.
- Patient will present with epigastric pain, postprandial vomiting, and early satiety, and will often be severely dehydrated and hypovolaemic
- CT imaging and endoscopy form the mainstay of investigation
- Whilst endoscopy has a role in certain causes, surgical intervention is often needed to help bypass the obstruction