ICU · Anatomy
Gastrointestinal Anatomy
Also known as GI anatomy · Oesophagus · Stomach · Small intestine · Large intestine · Liver blood supply · Pancreas · Spleen · Portocaval anastomoses · Couinaud liver segments · Splanchnic circulation · Biliary tree · Sphincter of Oddi · Portal triad
Gastrointestinal anatomy from mouth to anus for the ICU First Part: the oesophagus and its three sphincters/constrictions, the stomach and its secretory cells, the small intestine (duodenum at the ampulla of Vater, jejunum, ileum — villi and microvilli), the large intestine (caecum, colon, rectum), the liver's dual blood supply and eight Couinaud segments, the portal triad, the biliary tree and sphincter of Oddi, the exocrine and endocrine pancreas, the spleen, and the splanchnic circulation (coeliac trunk, SMA, IMA) with its portocaval anastomoses.
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Meet the patient
A 58-year-old with alcohol-related cirrhosis is wheeled in having vomited three mugfuls of bright red blood. The nurses have two large-bore cannulae in and are running saline; he is pale, diaphoretic, HR 124, BP 88/52. The gastroenterologist and the banding scope are both ten minutes away.[1]
The question that decides his next hour is the question that decides every variceal bleed: where is the blood coming from, and what anatomy is it exploiting? The answer is a portocaval anastomosis at the gastro-oesophageal junction — the same thin-walled, unsupported veins that dilate whenever portal pressure rises. Hold that one anatomy fact and the whole of GI falls into place around it.[1][2]
References18ShowHide
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- [3]Rockall TA, Logan RF, Devlin HB, Northfield TC Risk assessment after acute upper gastrointestinal haemorrhage Gut, 1996.PMID 8675081
- [4]Blatchford O, Murray WR, Blatchford M A risk score to predict need for treatment for upper-gastrointestinal haemorrhage Lancet, 2000.PMID 11073021
- [5]Cotton PB, Durkalski V, Romagnuolo J, et al. Effect of endoscopic sphincterotomy for suspected sphincter of Oddi dysfunction on pain-related disability following cholecystectomy: the EPISOD randomized clinical trial JAMA, 2014.PMID 24867013
- [6]Omole AE Anatomy, Abdomen and Pelvis: Large Intestine StatPearls, 2026.PMID 29261962
- [7]Omole AE Anatomy, Thorax, Esophagus StatPearls, 2026.PMID 29494119
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- [11]Shaikh H Anatomy, Abdomen and Pelvis: Superior Mesenteric Artery StatPearls, 2026.PMID 30137844
- [12]Skinner D Anatomy, Abdomen and Pelvis: Inferior Mesenteric Artery StatPearls, 2026.PMID 29489246
- [13]Zafer S Acute Mesenteric Ischemia StatPearls, 2026.PMID 28613722
- [14]Amini A Bowel Ischemia StatPearls, 2026.PMID 32119414
- [15]Betzler M [Surgical technical guidelines in intestinal ischemia]. Chirurg, 1998.PMID 9522064
- [16]Aoyama T Clinical Course of Vitamin B12 Deficiency and Associated Risk Factors in Patients After Total Gastrectomy for Gastric Cancer Anticancer Res, 2023.PMID 36697109
- [17]Bahardoust M Vitamin B12 deficiency after total gastrectomy for gastric cancer, prevalence, and symptoms: a systematic review and meta-analysis Eur J Cancer Prev, 2024.PMID 37669168
- [18]Moleiro J Efficacy of Long-Term Oral Vitamin B12 Supplementation after Total Gastrectomy: Results from a Prospective Study GE Port J Gastroenterol, 2018.PMID 29761147