Lech Dudarewicz, MD, PhD*; Prof. Jan Deprest, MD**; Léonardo Gucciardo, MD***.
* Polish Mother’s Memorial Hospital, Department of Genetics, 281/289 Rzgowska St. 93-338 Lodz, Poland; Ph: 48 42 271 11 83;
** Leuven, Belgium;
*** Obstetrics and Gynecology specialist, PhD Research Fellow, Centre for Surgical Technologies, Fetal Medicine Unit Department of Obstetrics and Gynecology, University Hospitals Leuven.
A 30-year-old primipara with an uneventful family and environmental history was referred to our Department of Genetics for karyotyping at 15 weeks’gestation. The observation of an hydropic fetus in a monochorionic diamniotic twin pregnancy was the main indication.
During the pre-amniotic fluid sampling scan, absence of heartbeat in the hydropic fetus was noticed. The procedure was stopped, and the pregnancy was finally diagnosed as monochorionic monoamniotic with a twin reversed arterial perfusion (TRAP) sequence. The presentation was quite atypical with an acardiac fetus showing relatively well-developed cranial structures with underdeveloped lower part of body and lower limbs. The biometry of the donor (pump) fetus was compatible with a 15 weeks pregnancy. The acardiac fetus biometric measurements were difficult to assess because of hydrops and abnormal anatomy. Visible jugular sac, almost fully developed cranial vault, two cerebral hemispheres with ventriculomegaly, abnormal diencephalon and cerebellum, cystic structure in the chest and rudimentary limbs were observed. A reversed blood stream with present end-diastolic velocities was detected in the acardiac fetus, no fetal movements were noticed. At that time the scan of the pump twin was considered as normal. The patient was discharged home after the amniocentesis, and an ultrasound control was scheduled at 17 weeks. In the meantime, because of the absence of established fetoscopic surgical facility in Poland, we asked Pr Jan Deprest from Leuven in Belgium, for help and advice.
The proposed therapy was clamping and transsection of the acardiac cord. In the opinion of Dr Deprest the intervention should be taken into consideration at a later stage as very early fetoscopy is related with high risk of premature rupture of the membrane (PROM), particularly if the procedure is within the same sac. At the 17 weeks scan, no flow was detected in the umbilical cord nor in the body of the acardiac twin. There was only a marked twinkling Doppler artefact behind the bony structures. Additionally, the pump twin showed significantly decreased heart contractility with a suspected subvalvular VSD and pericardial effusion, inversed A wave in ductus venosus and pulsatile flow in the umbilical vein. The FHR was 135/min. The bowels were hyperechogenic, interpreted as a marker of ischemia that was associated with a observed centralisation of fetal circulation. The bladder was empty during the whole examination (45 minutes). The biometry of the pump fetus at that time was compatible with a 17+4 weeks pregnancy, and the CRL of the acardiac fetus was equivalent to 15 weeks’ gestation. Between the two ultrasound examinations the growth of the acardiac fetus was significant.
The above mentioned signs were indicators of a cardiac failure of the pump twin. Cardiovascular decompensation of the pump fetus is a possible explanation for absence of Doppler signal in a still growing acardiac fetus, the blood flow is too slow to be detected by usual color Doppler. Decompensation of the pump fetus made the decision of an urgent intervention obvious. The patient was referred to the Clinic of Obstetrics and Gynaecology of the Catholic University of Leuven in Belgium for a fetoscopic treatment.
Unfortunately at the pre-procedure scan death of the pump fetus was diagnosed.
Here are some images and videos of a second trimester acardiac twins sequence (twin reversed arterial perfusion).
Images 1 and 2: Head of the acardiac twin (transverse planes).