* Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Strong Memorial Hospital, The University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Box 8668, Rochester, New York 14642-8668, Ph: 716-275-3620, Fax: 716-256-1416

Synonyms: Incomplete duplication of gallbladder, internal subdivision of gallbladder, trabeculation of gallbladder.

Prevalence: 2.5-3.3:10,000.

Definition: Internal subdivision of the gallbladder with septa or trabeculae transversing the lumen.

Etiology: Unknown.

Associated anomalies: None.

Differential diagnosis: Post-inflammatory pseudodiverticula, Phrygian cap.

Prognosis: Excellent.

Recurrent Risk: Unknown.

Management: Standard obstetric care.

MESH Gallbladder -abnormalities BDE 0404 ICD9 751.60 CDC 751.640

Introduction

Although congenital anomalies of the gallbladder are fairly common, most are of little clinical significance and are encountered as incidental findings on diagnostic imaging, surgical exploration, or at autopsy¹. Gallbladder disease of the fetus is rare, although prenatal sonographic diagnosis of the fetal cholelithiasis, choledochal cyst, and fetal biliary "sludge†have been reported^2-4. The following case describes the prenatal sonographic diagnosis of a rarely diagnosed congenital anomaly of the gallbladder.

Case report

An 18-year-old G₁P₀, black female was followed during her first pregnancy at Strong Memorial Hospital. At 16 weeks, her maternal serum alpha-fetoprotein was noted to be elevated (2.18 multiples of the median). Sonographic examination revealed a singleton fetus with normal anatomy⁵. The patient declined amniocentesis. A repeat examination at 38 weeks demonstrated decreased amniotic fluid, a breech presentation and an estimated fetal weight of 2713 grams.

A transverse image of the abdomen demonstrated a hyperechoic, non-shadowing linear structure within the fetal gallbladder (fig. 1). With magnification (fig. 2), this was shown to be a projection of the gallbladder wall in the lumen, thought to represent an incomplete septation. An elective cesarean section was performed at 39 weeks due to the breech presentation. A female infant weighing 2750g with Apgar scores of  7 and 9  (1 and 5 minutes) was delivered. Neonatal sonography performed within the first hour of life⁶ confirmed the diagnosis (fig. 3). The mother"s postoperative course was normal. The infant remained asymptomatic and was discharged after five days.

Figure 1: Transverse scan of the fetal abdomen. The arrow points to the septation.

Figure 2: Magnification of figure 1. The arrow points to septation.

Figure 3: Neonatal longitudinal scan of the gallbladder. Arrow points to septation.

Discussion

Congenital internal subdivisions of the gallbladder may take the shape of septa or trabeculations transversing the lumen¹. Contrary to the majority of gallbladder anomalies, this lesion does not require immediate correction. However, diagnosis is important, inasmuch as these septations may produce diverticula or pockets in which biliary material may stagnate, predisposing to gallstone development¹. The longitudinal septation with the free-floating end pointing towards the gallbladder neck seen in our case (fig. 1-3) may represent an incomplete duplication of the gallbladder^7-10, a rare anomaly also known to promote biliary stasis⁸. Knowledge of the presence of this minor anomaly will dictate follow-up and permit early intervention if symptomatology appears.

The differential diagnosis is that of post-inflammatory pseudo­diverticula (which is not known to occur in fetuses) and the so-called Phrygian cap, which describes a gallbladder with one wall shorter than the other such that the fundus forms an angle with the body⁹. A Phrygian cap is of no clinical importance and is caused, as described above, by kinking or folding of the fundus¹. Transverse scanning of the fetal abdomen, performed routinely for estimated fetal weight measurements in addition to anatomic scanning, may at times reveal unusual gallbladder anatomy.

References

1. Netter FH. The CIBA Collection of Medical Illustrations. Volume 3: Digestive System: Part III Liver, Biliary Tract and Pancreas. New York: CIBA Medical Illustrations, 1957, p. 123.1

2. Beretsky I, Lanken DH. Diagnosis of fetal cholelithiasis using real-time, high resolution imaging employing digital detection. J Ultrasound Med 2:381-383, 1983.

3. Elrad H, Mayden KL, Agart S, et al. Prenatal ultrasound diagnosis of choledochal cyst. J Ultrasound Med 4:533, 1985.

4. Nyberg D. Intra-abdominal anomalies. In: Nyberg D, Mahony BS, Pretorious DH (ed). Diagnostic Ultrasound of Fetal Anomalies: Text and Atlas. Chicago: Year Book Medical Publishers, 1990, p. 387.

5. Advanced Technologies Laboratory, Bothell, WA, ATL Mark 9, 5.0 MHz transducer

6. Acuson, Mountain View, CA, Model 128, 5 MHz linear transducer..

7. Taybi H. The biliary tract in children. In: Margulis AR, Burhenne HJ (eds). Alimentary Tract and Roentgenology. St. Louis: The CV Mosby Company 1973, p. 1513.

8. Guyer PB, McLoughlin M. Congenital double gallbladder: A review and report of two cases. Br J Radiol 40:214, 1967.

9. Spiro HM. Congenital lesions of the biliary tract. In: Spiro HM (ed). Clinical Gastroenterology, 3rd Ed. New York: MacMillan Publishing Co., Inc.1983; p. 1056.

10. Sutter W, Jeanty P: Gallbladder duplication. The Fetus 7516-1-2, 1991.