Anatomy
Abdomen
The common bile duct is formed from which of the following structures:
Answer:
The common hepatic duct and the cystic duct combine to form the common bile duct.Biliary Tree
Anatomy / Abdomen / Liver and Biliary Tract
Last Updated: 11th April 2019
The biliary tree begins in the liver parenchyma with the formation of the left and right hepatic duct which drain bile from the liver where it has been synthesised. These two ducts meet to form the common hepatic duct which runs near the liver, with the hepatic artery proper and portal vein in the free margin of the lesser omentum.
As the common hepatic duct descends, it is joined by the cystic duct, which is a continuation of the neck of the gallbladder. The common hepatic duct and the cystic duct combine to form the common bile duct. At this point the bile duct lies to the right of the hepatic artery proper and usually to the right of, and anterior to, the portal vein in the free margin of the lesser omentum.
As the common bile duct descends, it passes posterior to the first part of the duodenum before joining with the pancreatic duct from the pancreas, forming the hepatopancreatic ampulla (ampulla of Vater) at the major duodenal papilla, located in the second part of the duodenum. Surrounding the ampulla is the sphincter of Oddi, a collection of smooth muscle which can open to allow bile and pancreatic fluid to empty into the duodenum.
Common Bile Duct
The common bile duct can be divided into three main regions, based on its relation to the duodenum:
- The first supraduodenal region is the upper one-third which lies in the free margin of the lesser omentum with the hepatic artery and portal vein. The common bile duct lies anterior to the portal vein and to the right of the hepatic artery proper.
- The second retroduodenal region is the middle one-third which lies posterior to the first part of the duodenum. The gastroduodenal artery lies on its left aspect and the portal vein on its posterior aspect.
- The third infraduodenal region is the lower one-third which lies in a groove on the posterior surface of the head of the pancreas, to the left of the second part of the duodenum and anterior to the right renal vein and inferior vena cava.
![Modified by FRCEM Success. Original by Jmarchn (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/02/Biliary-tree.png)
Biliary Tree. (Image modified by FRCEM Success. Original by Jmarchn (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0), via Wikimedia Commons)
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
