Resolution of Fetal Hydrops in a Case of Congenital Pulmonary Airway Malformation

A 33-year-old gravida 1 initially presented for a detailed ultrasound in our office with fulminant fetal hydrops and a noted mass in the left chest. Initial evaluation included maternal viral studies (negative parvovirus, CMV, toxoplasmosis), maternal karyotype (46XX), and amniocentesis (46XX, microduplication in the 16p11.2 region). Given concern for CPAM and hydrops at 20 weeks and 3 days, the patient was referred to a fetal therapy center. Ultrasound at the fetal therapy center showed an estimated fetal weight of 824 grams (>97^th percentile) and fetal hydrops (scalp edema of 8mm, skin edema of 4mm, and ascites of 14mm). The diaphragm was intact and the maximal vertical pocket was 6.8 cm. The left chest mass measured 6.6 x 5.3 x 4.4 cm and was multiloculated with microcystic and macrocystic lesions (type 1); the dominant cyst measured 4.0 x 3.2 cm, Figure 1. Secondary to mass effect, the heart was severely displaced into the right chest with a CVR of 3.9cm². There was no noticeable peristalsis of the cystic structures and no systemic identifiable arterial blood supply. Fetal echocardiogram showed a structurally normal heart significantly shifted in the right chest. After extensive counseling, the patient opted for administration of antenatal corticosteroids and thoraco-amniotic shunt placement. The patient received betamethasone 12mg intramuscularly prior to shunt placement at 21 weeks and 4 days and 21weeks 5 days. Two double pigtail Harrison thoraco-amniotic shunts were placed by inserting a 13 Ga cannular-trocar into the maternal abdomen and uterus (the first shunt into the largest cyst (left, anterior, inferior) and the second into an additional dominant cyst (anterior, central portion of the mass). Both cysts drained completely after insertion. Epidural anesthesia with IV sedation were used as well as tocolytics as needed during the procedure. The post-procedure CVR was 1.3cm² with decreased mass effect on the heart. Post-operative plan consisted of genetic consultation, fetal MRI, and serial monitoring of the CVR.

Figure 1.CPAM noted at initial fetal surgery consultation; sagittal view on the left and transverse view on the right

Follow-up parental microarray showed that the 16p11.2 microduplication was maternally inherited. This duplication can be linked with an increased risk of autism or other early onset psychological or neurodevelopmental abnormalities. Fetal MRI was performed at 25 weeks 5 days, noting a large left hemithorax multicystic lesion consistent with CPAM as well as right lung hypoplasia, fetal hydrops, and polyhydramnios. Serial ultrasounds following shunt placement (Figure 2) and CVR (Table 3) noted dislodged shunts on three occasions. With the dislodged shunts, the dominant cyst significantly increased, as did the CVR. On these three occasions (at 24 weeks 3 days, 28 weeks 3 days, and 31 weeks 3 days) repeat thoraco-amniotic shunts, two per procedure, were placed. Immediately after each shunt placement the CVR was notably decreased (Table 3). Amniodrainage was performed at shunt placement when necessary.

Figure 2.Two thoraco-amniotic shunts can be seen in the dominant CPAM cyst

On ultrasound at 36 weeks 6 days two shunts were clearly identified in the fetal chest, the amniotic fluid level was 28cm, and the CVR was 1.5cm². Six shunts were seen free floating in the amniotic cavity. The dominant cyst measured 2.5 x 1.3 x 0.9 cm with no evidence of fetal hydrops. Regular antenatal testing was reassuring until delivery, which was performed via cesarean at 37 weeks and 2 days. At delivery one thoracic shunt was noted to be intact in the fetal chest.

The infant, born weighing 3,015 grams, was intubated at 1 minute of life due to noted bradycardia and no respiratory effort. With positive pressure ventilation on 100% oxygen, the infant had oxygen saturations of 80% and a heart rate of 150. Apgar scores were 6 and 7 at 1 and 5 minutes respectively. The neonate ultimately required vasopressor support and a left sided tension pneumothorax was noted requiring chest tube placement. Thoracotomy, Figure 3, was performed at 21 hours of life to remove the mass. On post-operative day one the neonate had improved hemodynamics and decreased ventilation pressures with ongoing vasopressor support. The neonate was extubated on day of life 19 and ultimately discharged from the NICU on day of life 34, weighing 3.87 kilograms, with oxygen (1/8 L at 100%) via nasal cannula, continued for 56 days. She was meeting appropriate milestones and scoring well on her Ages and Stages Questionnaires at 4 and 6 months. At 7 months of age she weighed 17lb 15oz and was meeting all appropriate milestones for her age.

Figure 3.Neonatal thoracotomy

Fetuses diagnosed with hydrops secondary to CPAM will likely die if no intervention is made. Retrospective studies have shown that death is the ultimate outcome of all of fetuses that presented with hydrops and underwent expectant management alone ⁶. When thoraco-amniotic shunts are the method of treatment, data has shown that one procedure often decompresses the cystic lesion ⁷. This retrospective review discussed 11 CPAM cases, 6 with hydrops, which had thoraco-amniotic shunts placed. All were successful after the first attempt in decompressing the dominant cyst and ultimately resulted in vaginal delivery (with a mean gestational age of 38.2; range 35.6 – 40.0) with the exception of one fetus that demised one day after shunt placement. Of note, this fetus had a CVR of 3.2cm² at 17 weeks (for reference, our patient presented with hydrops and a CVR prior to first shunt placement of 3.9 cm²). All had thoracotomy after delivery, and all but one noted the shunt to be in place. Also, administration of antenatal corticosteroids has been shown, particularly in those with microcystic CPAMs, to reduce the CVR and possibly resolve fetal hydrops ⁸. Given that the lesion in our case had microcystic components with early hydrops, steroids were administered. Our steroid administration was earlier than the gestational age of those in the study given the severity of the hydrops at such an early gestational age.

In the literature, multiple thoraco-amniotic shunt placements to treat CPAM were not found. In CPAM cases presenting with advanced hydrops, aggressive surgical treatment with thoraco-amniotic shunts is reasonable with appropriate preoperative workup and patient counseling. The typical expectation can be resolution of the dominant cyst after one procedure. This case illustrates that multiple procedures may indeed be necessary and can be successful in maintaining a stable dominant cyst, a low CVR, and resolution of hydrops. Although unconventional, these multiple procedures allowed an initially hydropic fetus to be born, at a term gestation, without any signs of hydrops and undergo thoracotomy after delivery with no complications.