Placenta grading
What is placental grading
In the 1970s, when ultrasound became available for pregnancy screening, Grannum et al. established a set of grading criteria for describing the placental presentation on ultrasound, classifying the placenta into four grades: 0, I, II and III. Since the placenta appears in different grades sequentially on ultrasound as the gestational week increases, the placental grading is considered to correlate with the maturity of the placenta as well as the function of the placenta.
There is a great deal of variability and subjectivity in placental grading
The placenta as an organ is bound to behave somewhat differently from one tissue to another, and on this point experts quickly reached a consensus that the grade of the placenta is defined by the grade presented by the vast majority of tissues throughout the placenta (rather than by the highest grade of placental tissue).
Since there are no absolute objective criteria, the process of placental grading is subject to significant subjective influence and variability. Different placental grade judgments may be made between different operators, as well as when the same operator repeats the examination.
Different parameters set by different ultrasound machines may also lead to different results.
It is unclear whether placental grading correlates with placental maturity, placental function, or obstetric outcome
There is no conclusive evidence, either on microscopic examination or on blood tests, that ultrasound presentation of placental grade correlates with placental maturation (as evidenced by microscopic changes in the placental vasculature and other structures) or placental function (showing several hormones of the placental secretory function).
Several clinical studies in recent years have also not found a relationship between placental grading and maternal and child outcomes.
All obstetric protocols do not intervene in pregnancies with so-called “placental overmaturity”.
Because of the lack of conclusive evidence on the clinical relevance of placental grading, a post-full-term placental presentation of grade III or III+ cannot be used as an indication for induction of labor or cesarean delivery. Nor is there any domestic or foreign routine advocating the timing or mode of delivery based on placental grading.
Likewise, the presence of so-called “placental overmaturity” in midtrimester does not mean “placental aging”, and in the absence of further evidence it may be necessary to pay attention to routine monitoring (e.g., careful self-counting of fetal movements after 28 weeks, attention to the growth curve of the uterine height during labor and delivery, etc.). However, blood sampling for placental function is totally unnecessary and there is no evidence to support such a test.
Calcium supplementation does not cause “placental overmaturity”
Many pregnant women and even doctors believe that the high level of the placenta is due to calcium supplementation and therefore stop taking calcium supplements. This is a very incorrect approach. Calcium is one of the most important and most deficient elements during pregnancy. And the later in pregnancy, the more rapid the fetal growth, the more obvious the relative deficiency of calcium. And since our Chinese diet is relatively deficient in calcium, we recommend that calcium supplementation continues until delivery, without having to take into account the placental grading factor.
Outlook and recommendations
With more evidence, the outdated criteria of “placental grading” will probably be eventually eliminated. For the time being, obstetricians and sonographers should ignore this grading index, or at least should not over-interpret the results of placenta grading to avoid unnecessary psychological burden on the pregnant woman.
For a pregnant woman who is worried that her placenta grade is too high, I usually tell her that it is equivalent to judging a person’s physiological function by her appearance. The same person appears in front of her eyes, different people may judge her to be in her 20s, 30s or 40s (placental grading), but no matter how old she is judged to be, how old she actually is is how old she is (placental maturity), while her physiological function (placental function) is It is a completely different matter. I wonder if this will solve everyone’s question?
Key points.
Placental grading is the classification of the placenta into 0-Ⅰ-Ⅱ-Ⅲ according to its performance under ultrasound, which was once thought to be related to the maturity of the fetus and the function of the placenta
Placental grading is related to the parameter settings of the ultrasound machine and the subjective judgment of the sonographer, and therefore there is great variability
Recent studies generally do not support a relationship between placental grading and placental maturity, placental function or obstetric outcome
All obstetric protocols do not recommend interventions for so-called “placental overmaturity” in pregnancy
Calcium supplementation does not cause “placental overmaturity”
In conclusion, there is no need to worry about the information on placental classification