Ob-Gyn #9 Abnormal Uterine Bleeding: Neonatal Mastaux


Lessons Complete: 



Next Step: Make Cards on the Automatic Key Concepts, and Vignettes

Remember, the more you automatically know what each sentence means on your test, the better you will do. There are 4 stages in making interpretation more automatic:

  • Stage 1: Unable to Make Pathophysiologic Chronologies in Either Timed or Untimed setting
  • Stage 2: Basic Pathophysiologic Chronologies, but with Significant Gaps
  • Stage 3: Detailed Pathophysiologic Chronology Without Time, but Unable to Consistently Generate PC During Timed Setting
  • Stage 4: Consistent Pathophysiologic Chronologies in Timed Setting

My goal with these vignettes is to help you reach Stage 4. How do you do so?

  • With the Automatic Key Concept cards, you can master the underlying information to move past Stages 1 + 2.
  • Then, with the Vignette/Pathophysiologic Chronology cards, you can teach yourself to make these connections on your exam.


summary of key concepts:



automatic key concepts:

Copy + paste these into your cards, to make these key concepts more automatic.


Caffeine – will this cross the placenta? How would you know?

It WILL cross the placenta

You can either 1) know that, or 2) realize that to get to the brain and give us a buzz, caffeine must cross the blood brain barrier. If it can passively diffuse across the BBB (it can), then it would also be expected to cross the placenta (it can)


Estrogen and progesterone – where is the receptor for this located, within the cell or at the cell surface? Why does this make sense?

Within the cell

Estrogen is small, nonpolar (highly lipophilic), and uncharged. As such, it can cross cell membranes


Maternal estrogen and progesterone – would these cross the placenta? Why or why not?

These WOULD cross the placenta

Remember, cell membranes are all composed of lipids – they are fundamentally the same thing. Thus, in all cases I am aware of, if something can passively diffuse across one cell membrane, they can also passively diffuse across the others. Thus, they would cross the placenta, skin (estrogen/progesterone can be given as a patch), GI tract (you can take them as pills), and blood-brain barrier


Breast enlargements in neonates – how common is this? Why would this make sense?

Very common (up to 70% of newborns).

Maternal estrogen crosses the placenta (like it can cross virtually all cell membranes) → causes breast tissue growth

It is sometimes called “neonatal mastaux


Neonatal endometrium – after birth, what will happen to the levels of maternal hormones in the neonatal circulation?

Maternal hormones would drop after birth

Following birth/delivery, maternal hormones would no longer be crossing the placenta to reach the neonate → maternal levels of hormones would drop


Neonatal vaginal bleeding – why is this thought to occur? Use the mechanism to explain the typical management

Neonatal estrogen/progesterone withdrawal bleeding

Recall that the fetus is exposed to maternal estrogen/progesterone → endometrial hyperplasia and decidualization. Then, after delivery → no estrogen/progesterone traveling to placenta → neonate is no longer receiving a supply of maternal estrogen/progesterone → neonatal estrogen/progesterone levels ↓ → sloughing of the endometrial tissue

Note this is not unlike how regular menses occur, simply with the withdrawal of estrogen/progesterone coming from delivery rather than regression of the corpus luteum



Note that we did NOT include the actual content-related questions / QI process in these vignettes, as they don’t make great cards. Instead, we focused on the pathophysiologic chronologies, which are the only kind of cards you should make that have a vignette on the front.


A neonate has a routine evaluation in the newborn nursery. She was born at term 1 day ago to a 26-year-old woman. Birth and prenatal courses were unremarkable; she was born via vaginal delivery. On exam, the infant shows 2-cm palpable masses under the nipples. Labia are slightly swollen with blood-tinged vaginal discharge visualized.

​​What is the pathophysiologic chronology?


Concepts: Likes Dissolves Likes, Hyperplasia, Etymologies​​


Transplacental estrogen/progesterone transfer → delivery → neonatal withdrawal bleeding


Conception → maternal estrogen/progesterone ↑ → cross placenta → fetal estrogen/progesterone ↑ → fetal endometrial hyperplasia/decidualization → delivery → remove placenta/connection between maternal + fetal circulations → maternal delivery of estrogen/progesterone ↓ → neonatal estrogen/progesterone ↓ → withdrawal bleeding of endometrium




Figure 28 02 07.jpg. (2021, September 7). Wikimedia Commons, the free media repository. Retrieved 17:59, October 23, 2021 from https://commons.wikimedia.org/w/index.php?title=File:Figure_28_02_07.jpg&oldid=589438914.

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