{'fraction_non_alphanumeric': 0.015285126396237508, 'fraction_numerical': 0.007642563198118754, 'mean_word_length': 5.257352941176471, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
[Doppler ultrasound to detect Rh: a systematic review].

BACKGROUND
Red cell alloimmunization is an important cause of perinatal morbidlity and mortality. Invasive procedures used to diagnose fetal anemia are associated with serious fetal and maternal complications. The development of noninvasive techniques as Doppler ultrasound can help us in the fetal anemia diagnosis.


OBJECTIVES
To evaluate the effect of the Doppler ultrasound in prediction of fetal anemia caused by red cell alloimmunization. Strategy search: Relevant studies were identified by reviewing the registry of COCHRANE, and OVID, PROQUEST, MEDLINE and EMBASE data bases from 1966 to 2004.


SELECTION CRITERIA
All prospective studies with clinically relevant results with comparison of Doppler ultrasound in fetal umbilical artery, fetal descendent aorta, middle cerebral fetal artery or esplecnic fetal artery with hemoglobin or fetal hematocrit.


DATA COLLECTION AND ANALYSIS
Data were extracted from each report. The quality revision of the studies and the data compilation were made by the reviewers.


MAIN RESULTS
Eighteen articles were included. Two studies reached the level of evidence 1 for diagnostic tests. The diagnostic tests had variations depending on the different cut-off of each study. Studies with level 1 of evidence reported detection of 100% for moderate to severe fetal anemia.


CONCLUSIONS
Implementation of Doppler ultrasound for prediction of fetal anemia in complicated pregnancies with alloimmunization could reduce the number of invasive procedures and therefore its complications. The level of present evidence reveals to us that the studies do not fulfill the criteria of methodological quality.