Dominique Thomas, MD*; J. Goedseels, MD**; R. Lejeune, MD*; C. Fellemans, MD*; P. Barlow, MD***.

*   Department of Obstetrics and Gynecology, Hôpitaux Iris Sud site Ixelles, Brussels, Belgium;
**  Pediatric Department, Hôpitaux Iris Sud site Ixelles; Brussels, Belgium;
*** Department of Obstetrics and Gynecology, Hôpital Universitaire St Pierre, Brussels, Belgium.

Abstract

We report a case of a post-term pregnancy in which a routine echography reveled a bilateral fetal lungs hyperechogenicity associated with a hyper-echogenic amniotic fluid. The labor was induced and after the rupture of membranes, the amniotic fluid had a milky appearance. Shortly after the birth the baby developed bilateral pneumonia. The association of echogenic amniotic fluid, fetal echogenic lungs and milky amniotic fluid may lead to the diagnosis of intrauterine fetal pneumonia.

Case report

A 30 years old woman (G1P0) was referred to our unit due to a post term evaluation of the fetus (the mother had completed the 41st week of pregnancy). The course of the pregnancy and mother"s medical history were uneventful. The maternal blood pressure and fetal non-stress test were normal. The ultrasound examination revealed normal fetal biometry, but a bilateral echogenic appearance of the lungs was found (Images 1, 2). The amniotic fluid had a hyper-echogenic appearance (Image 3). The fetal behavior was normal, the umbilical Doppler resistance index was 0,50 (normal). The previous second trimester ultrasound scanning was reviewed and revealed no lungs abnormality. At that time, our suspected diagnosis was an intrauterine meconial aspiration of stained amniotic fluid. The patient was informed about the risk of such situation and transferred to a tertiary care unit. After a normal stress test, and normal maternal tests, the labor was induced. The course of the labor was normal, but the amniotic fluid had milky appearance. The  neonate was delivered 1 hour and 42 minutes after the artificial rupture of the membranes. The early postpartal course of the neonatal period was normal (Apgar 9, 10; boy; 3960 g), the neonate was apyretic, the arterial pH was 7.3 and the base excess was -3. The C reactive protein (CRP) in the umbilical cord blood was elevated (2.5 mg/100 ml). The mother and the baby were returned to the maternity department, but after 12 hours, the baby became pyretic, irritable and dyspneic. The laboratory markers showed an inflammatory reaction with the CRP 10 mg%. The pulmonary X-ray showed bilateral dispersed small opacities (Image 4). The final diagnosis was bilateral infectious broncho-pneumopathy. The mother described a vaginal loss of a liquid one week before the delivery, probably a loss of the amniotic fluid with the chorioamnionitis. The baby received an empiric intravenous treatment of antibiotics (amoxicillin/clavulanatic acid and amikacine). No bacteria’s were isolated from the different swabs. The baby was discharged 10 days later with the complete normalization of the chest X-ray.

Images 1, 2: The images show transverse and parasagittal scans of the fetal chest with the hyperechoic appearance of the fetal lungs.

Images 3, 4: The image 3 shows hypoechoic amniotic fluid. The image 4 shows postnatal X-ray of the fetal chest with the dispersed small opacities at the level of the lungs.

Discussion

The echogenic appearance of the lungs is can be operator dependant. Many pitfalls make impossible to standardize the fetal lungs changes during gestation. In our case the lungs appeared more echogenic than the liver, with a contrast of the shadows of the ribs. One publication tried to determine the fetal maturity by the comparison of the echogenicity of the lungs to the liver echogenicity (1).

The differential diagnosis of sonographic appearance of bilateral echogenic lungs includes:

• Bilateral microcystic congenital adenomatoid malformation Stocker type III (2), Achiron type IV (3). It is usually associated with the fetal ascites and placentomegaly. The prognosis is poor (4).

• Airway obstruction as prenatal tracheal obstruction caused by cartilaginous bar (5) or possibly associated with maternal pertussis infection (6).

• Chicken pox during pregnancy may lead to the lung hyperechogenicity (7).

• Fetal Candida infection due to retained intrauterine contraceptive device (8).

• Congenital syphilis is an unusual cause of bilateral pulmonary spirochete"s abscesses (9), but no prenatal description was made.
  

In our case, the amniotic fluid was hyperechoic. Previous studies (10, 11, 12, 13), have shown that homogenous echogenic amniotic fluid does not necessarily signify meconium stained amniotic fluid. Sepulveda et al (10) have shown that this finding refers more often to a considerable amount of vernix caseosa, rather than meconium and is not necessarily associated with post maturity. In a prospective study of 19 twin pregnancies Petrowsky et al (13) have shown that meconium was found in 5% of echogenic amniotic fluid and in 21% of anechoic amniotic fluid.

We conclude that bilateral hyperechoic appearance of the fetal lungs associated with echogenic appearance of the amniotic fluid can be the sign of early fetal lung inflammation due to chorioamnionitis. Further observations are needed to confirm this hypothesis.

References

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