Congenital anomalies of the gallbladder
- Lesion
The gallbladder can be folded, doubled, missing or in the wrong place; most of these cause no trouble.
What it is
Congenital anomalies of the gallbladder come from errors in the budding of the hepatic diverticulum. The most common is the Phrygian cap, a folded fundus. Less common are agenesis, duplication, bilobed gallbladder, septation and ectopic positions (intrahepatic, left-sided, floating). Most are incidental, but some favour stasis and stones, or confuse imaging and surgery.
Step by step
- In the fourth week, the hepatic diverticulum of the foregut gives off a caudal bud that forms gallbladder and cystic duct.
- Failure of the bud causes agenesis; splitting causes duplication or a bilobed organ.
- Incomplete vacuolization leaves septa.
- Abnormal position of the bud gives ectopic gallbladders.
Congenital anomalies of the gallbladder
| Anomaly | What it is | Relevance |
|---|---|---|
| Phrygian cap | Fundus folded over the body | Incidental, can mimic a mass on imaging |
| Agenesis | No gallbladder | Rare; may be missed as 'contracted' gallbladder |
| Duplication or bilobed | Two gallbladders or two lobes with one or two cystic ducts | Stasis, stones, surgical surprises |
| Septation | Internal septa | Stasis and stones |
| Ectopia | Intrahepatic, left-sided or on a long mesentery | Floating gallbladder may twist (torsion) |
Test yourself
Think of the answer, then tap the question to see it.
What is the most common congenital anomaly of the gallbladder?
The Phrygian cap, a folding of the fundus.
Which gallbladder anomaly predisposes to torsion?
A floating gallbladder suspended on a long mesentery.
Why can duplication of the gallbladder matter clinically?
It can cause bile stasis and stones and complicate cholecystectomy if not recognized.
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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Gallstones (Cholelithiasis) (StatPearls (NCBI Bookshelf), 2026).
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Representative model, for educational purposes only.