Isolated unilateral severe fetal hydrothorax: spontaneous resolution after birth

Introduction

Hydrothorax is the accumulation of fluid in the pleural space. It can be primary or secondary and unilateral or bilateral. Prenatal diagnosis of hydrothorax was first reported in 1977 [1]. If isolated, it is commonly due to congenital primary chylothorax, with an estimated incidence of 1/10,000–15,000 pregnancies [2], [3]. For diagnosis, the workup should be the same as that for hydrops [3]. A thorough anatomy scan by an expert in order to detect structural anomalies and a complete echocardiographic evaluation are necessary. An isolated unilateral hydrothorax is more likely to be primary rather than secondary [3]. Although intrauterine management has been recommended, spontaneous resolution of both intrauterine as well as postnatal hydrothorax has been reported. Postnatal intubation, ventilation and thoracocentesis are the therapeutic options for those who have a late diagnosis [4], [5].

Case

A large fetal pleural effusion (hydrothorax) was identified within the right hemithorax in a 22-year-old woman at 39 weeks of gestation (Figure 1 and Figure 2). The patient reported that all obstetric examinations were normal until 39 weeks of gestation. The patient, with gravida 1, had no history of diabetes mellitus. There was no consanguinity. She did not use alcohol, tobacco or illicit drugs. The blood group of the patient was O positive. Her blood pressure was normal. The patient did not have any antenatal screening test.

Figure 1:

Severe unilateral fetal hydrothorax.

Figure 2:

Fetal hydrothorax (transverse view).

Fetal biometry was within the normal range with a normal amniotic fluid volume and estimated fetal weight of 3400 g. The anatomy scan was normal, except for a severe unilateral hydrothorax within the right hemithorax. Antenatally, it was decided that it was a severe case because the underlying lung parenchyma was totally compressed (Figure 3 and Figure 4). The fetal echocardiography revealed a normal structure and rhythm.

Figure 3:

Fetal hydrothorax: underlying lung parenchyma was totally compressed.

Figure 4:

Fetal hydrothorax: underlying lung parenchyma was totally compressed.

Hematological and biochemical parameters were all within the normal range, only the hemoglobin level was 10.3 mg/dL. In the presented case, the etiology could not be documented antenatally and there was no hydrops.

Because the fetal hydrothorax was detected at 39 weeks of gestation, we did not perform any intervention antenatally. A male fetus was delivered by an elective cesarean section at 39 weeks of gestation, with a fetal weight of 3670 g. The Apgar score of the baby was 9 at birth and 10 at 5 min. He did not require intubation, ventilation or resuscitation in the operating room, and had a good health status. The baby was followed-up in the neonatal intensive care unit. His blood group was O positive. The direct Coombs test and TORCH titers were negative. A complete blood count (CBC) revealed a total leukocyte count of 9920/μL with 48.6% neutrophils, platelet count of 215,000/μL and hemoglobin in level of 17.7 g/dL, C-reactive protein (CRP) of 0.07 mg/dL and procalcitonine of 0.072 ng/mL. Blood culture was sterile. His abdominal ultrasonography and echocardiography were normal. The pediatric cardiologist did not diagnose any heart disorders. Thoracic ultrasonography and the chest X-ray of the baby showed a 3-cm pleural effusion on the right side (Figure 5). He remained asymptomatic and had a normal examination except for hydrothorax. Subsequently, he was started on breastfeeding from the day of birth. Two days after the birth, the pleural effusion was 2 cm, diagnosed by ultrasonography. Because of a good health status, the baby was followed-up without any interventions. Six days after the birth, the pleural effusion (hydrothorax) was completely resolved spontaneously (Figure 6) probably because collateral lymphatic channels developed, and he was discharged by day 7. He has been followed-up regularly and echocardiography was still normal at 14 days of age. The chromosomal analysis of the patient revealed a normal karyotype (46, XY). His development and examination were normal at 1 month after birth.

Figure 5:

The chest X-ray of the neonate showed pleural effusion on the right side.

Figure 6:

The chest X-ray of the neonate, 6 days after the birth, the pleural effusion (hydrothorax) was completely resolved spontaneously.

We obtained informed consent from the patient’s mother.

Discussion

Fetal hydrothorax is an uncommon diagnosis, with an estimated incidence of 1/10,000–15,000 pregnancies [2], [3]. Isolated fetal hydrothorax has a male:female ratio of 2:1, and occurs more frequently on the right side [6]. Our case was also a male fetus, and hydrothorax was detected on the right side. It can be primary or secondary and unilateral or bilateral. On initial evaluation of a fetus with hydrothorax, secondary causes such as chromosomal abnormalities, structural anomalies, cardiac anomalies, infections and hydrops fetalis must be excluded. In our case, we did not find any etiology antenatally. And postnatally all the test results were normal including the chromosomal analysis, therefore we called it isolated (primary) fetal hydrothorax.

The reported perinatal mortality rate associated with primary pleural effusions ranges between 22% and 53% [7]. Aubard et al. [7] reported spontaneous regression in 22% of 204 cases with fetal hydrothorax identified from a literature review of 64 articles, including 10% of hydropic fetuses. Petersen et al. also reported spontaneous regression typically in cases with mild, unilateral effusions without hydrops at presentation. And consistent with spontaneous regression as an accepted positive prognostic factor, survival occurred in all cases that had regression [8]. Because of the late development of hydrothorax in our case, at 39 weeks of gestations, we did not perform any interventions antenatally. Even after birth, there was no intervention as the baby was in good health; with follow-up hydrothorax resolved spontaneously.

Conclusion

Conservative management may be regarded as an option for isolated fetal hydrothorax in uncomplicated, stable cases without hydrops.