RESUMEN
Fentanyl is an opiate-like, pain-killing drug. It was found in the 1950s and prescribed from the 1960s. Fentanyl shows its effect by acting on opiate-like receptors. This case was a case of a 24-year-old primiparous woman who was referred from local clinic due to fetal pleural effusion in the left lung on antenatal ultrasonographic examination at 32 weeks of gestational age. The amount of pleural effusion increased and fetal heart deviated to the right side. We injected fentanyl 2 microgram intramuscularly into the fetal left thigh under ultrasound-guide for fetal anesthesia at 34 weeks of gestational age. After 5 minutes, we inserted 22 gage spinal needle to the left pleural cavity and aspirated 50 mL pleural fluid under ultrasound-guided. After aspiration, follow-up was performed oat one week interval and there was no more pleural fluid until delivery. At gestational age 41 weeks, the fetus was delivered vaginally as a 3.2 kg, healthy male baby. This is a case of fentanyl injection to fetus as a fetal anesthesia during thoracentesis for fetal pleural effusion at gestational age 34 weeks, we think that fentanyl is useful drug for fetal anesthesia.