Doppler velocimetry for predicting fetal death in a twin pregnancy.

Diagnosis of discordant twins is easily accomplished with modern ultrasound equipment, though diagnosing twin-to-twin transfusion syndrome (TTS) at an early stage might be a problem. The possibility of excluding TTS by Doppler ultrasound is demonstrated in a case with early severe growth restriction of one fetus. Characteristic blood velocity changes in a dying fetus are also illustrated.

The Doppler technique has become an accepted method in obstetrics for antenatal surveillance, permitting evaluation of fetal circulation in a non-invasive manner and providing important physiological information on the fetal condition. Absent end-diastolic flow in the umbilical artery (UA) can warrant operative delivery for fetal distress (1).

Perinatal mortality is increased fivefold in multiple gestation, as compared with singleton pregnancy (2). The major complications include preterm labor, intrauterine growth retardation (IUGR), TTS, polyhydramnios, oligohydramnios, fetal malformations, and pre-eclampsia. Twin fetuses are generally smaller than singletons and IUGR and intrauterine fetal deaths are more common (3).

Before the introduction of the Doppler technique, ultrasound-imaging evaluation of discordant fetal size in twin pregnancy was a problem. Differential diagnosis of TTS and a true growth retardation of one fetus was a frequent worry for the clinician. Doppler examination of the fetal venous circulation with pulsating flow in the umbilical vein has been found helpful in the diagnosis of fetal congestive heart failure (4, 5). The general ultrasound imaging and Doppler findings in TTS are listed in Fig. 1. The information provided by ultrasound imaging and Doppler can thus distinguish between TTS and growth retardation of one fetus and assist the clinician in making a diagnosis and predict the outcome. The following case illustrates characteristic blood velocity findings in a dying fetus.