1.-Servicio de Ginecología y Obstetricia, Departamento de Ultrasonografía; Hospital Guillermo Grant Benavente, Concepción Chile.

2.-Servicio de Imagenología, Hospital Guillermo Grant Benavente, Concepción, Chile

Synonyms: cholelithiasis, calculi.

Definitions: Single or multiple hyperechogenic foci in the fetal gallbladder:

Cases reports:

Case 1

33-year-old, G2P1, no remarkable personal or familial history, with previous normal ultrasound examination at 34 and 37 weeks. During a routine US examination performed at 41 weeks, a hyperechoic structure with a posterior acoustic shadow was observed inside the fetal gallbladder measuring 10.5 x 7.0 mm diameter with regular and flat borders. No other associated anomalies could be seen. (Figure 1). Spontaneous normal vaginal delivery occurred at 41 weeks. The 2-month-old infant is developing normally.

There was no evidence of neither ABO nor Rh (D) incompatibility, nor sepsis or other pathology. Two days after birth, an abdominal sonography was performed, confirming the finding of a normal sized gallbladder with thin walls, containing a 9 mm diameter gallstone with posterior acoustic shadow, in the neck. (Figure 2).

An ultrasound examination performed three months later showed no findings, demonstrating the complete spontaneous resolution of the gallstone.

Case 2

19-year-old, primigravida, unremarkable personal or familiar history, with previous normal ultrasound controls. During a routine US examination performed at 39 weeks of gestation, a hyperechoic structure with a posterior acoustic shadow inside the fetal gallbladder measuring 10,3 x 5,0 mm diameter was observed. (Figure 3).

No other anomalies were detected. A female neonate was born by cesarean section at 39 weeks of gestation. That same day an abdominal ultrasound was performed confirming the presence of a 10,5 x 4,5 mm gallstone in the neck. (Figure 4).

There was no evidence of ABO or Rh (D) incompatibility, sepsis or other pathology.

An ultrasound performed 29 days later showed no findings, demonstrating the complete spontaneous resolution of the gallstone.

Case 3

29 years patient, G₄P₃, with a prior twin gestation and previous normal ultrasound controls. She had been receiving iron supplementation between 12^th and 36^th weeks of gestation. During an ultrasound examination performed at 41 weeks, a hyperechoic structure with regular flat borders and no posterior echogenic shadow was observed inside a distended fetal gallbladder measuring 6.6 x 3.4mm diameter. (Figure 5).

No other anomalies were detected. The day after, a male neonate was born delivered by cesarean section, weighing 3620 gr; Apgar score was 9 at 1st and 9 at 5 minute.

Abdominal ultrasound performed the next day showed a distended gallbladder containing multiple echogenic tiny nodules with no posterior echogenic shadow. (Figure 6).

Case 4

An 18-year-old primigravida, with unremarkable personal or familiar history had been receiving iron and calcium supplementation from the 26^th week. During a routine ultrasound examination in the 38th week, 4 hyperechoic structures of 1mm in diameter each and no posterior echogenic shadow were observed inside the fetal gallbladder (Figure 7).

The following day after, a female neonate was delivered vaginally, weight 3180 gr. The Apgar score was 9 at 1' and 9 at 5' minute.

Abdominal ultrasound performed the next day showed a distended gallbladder containing multiple mobile echogenic tiny nodules with no posterior echogenic shadow. (figure 8).

Prevalence:

Fetal gallstones are an uncommon sonographic finding despite the increasing number of US scans performed during pregnancy¹. The etiology is unknown and their presence is benign. The described incidence is quite variable, ranging between 5/1000 to 1/3000 live newborn^2,3,4. The prevalence is unknown, suspected to be around 0.5-0.7:10.000⁴; as well as the risk factors. For some authors they are more common in boys⁵; and some have even suggested a link between fetal cholelithiasis and adult gallstones⁶.

Pathogenesis: Gallstones are found more frequently in infants who develop hemolytic anemias, ileum pathologies, biliary tract congenital anomalies and/or cholestasia related to septic states, furosemide use, phototherapy, overfeeding, prolonged hospitalizations, cephalosporin use and Down's syndrome^6,7-11.

Several hypotheses for the formation of this echogenic material have been formulated. Fanaroff et al. suggested that hemoglobin transformed in bilirubin passed through the placenta, increasing fetal indirect bilirubin serum levels^12,13. Brown et al. proposed that an increase in estrogen serum levels could increase the risk of pigmented stone formation by increasing the cholesterol excretion and diminishing the biliary pigment synthesis^9,11. It has also been suggested that narcotic use during pregnancy, hemolytic anemia, Rh (D) incompatibility, and anomalies such as choledochal cysts might be considered as risk factors¹⁴. Finally, pregnancy induced cholestasia has also been considered as a risk factor, which has not been confirmed¹³, and which we consider not valid in circumstances that in our country the incidence of this disease is around 3.5-10% of all pregnancies, and yet we do not have a higher incidence of fetal cholelithiasis compared with other countries^15,16.

Sonographic findings: Single or multiple hyperechoic structures with a posterior acoustic shadow inside the  fetal gallbladder, with/without regular flat borders and no posterior echogenic shadow.

Differential diagnosis: Single or multiple liver echogenic foci.

Associated anomalies: None.

Prognosis: Good. In fact, cholelithiasis is an unusual finding in the first year of life, being more frequent in patients with bile duct pathology, with an incidence around 1,5%⁷. But in all our cases, as well as the literature reported, ultrasound showed no biliary tract abnormality and neither the mothers nor the patients had clinical or laboratory findings with liver or biliary diseases.⁶

Recurrence risk: Unknown.

Management: In most cases fetal gallstones disappear spontaneously weeks or months after birth^6,15, or by using ursodeoxycholic acid 15-20 mg/kg ^2,5,17. Careful follow-up US examinations are necessary for fetal cholelithiasis in the pre- and postnatal period and conservative management is mandatory¹⁷; because as well as seen in this study and others previously reported, they may spontaneously resolve.¹⁸

In the majority of cases, gallstones with undistended bladder or gallbladder sludge mimicked intrahepatic calcification or echogenic bowel, and all neonates were born in normal condition with no identifiable malformations.¹⁹

 

 

References

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