In this picture, you can see the RN doing an ultrasound scan. The gel on mom's belly helps the soundwaves connect to the sounds inside the uterus. While it is possible to see the pictures or hear the baby's heartbeat without gel, we get a much less clear image and a pretty spotty sound. The gel helps conduct the information from doppler/transducer to sound/image.
What we are looking at, however, is the shape of this woman's 38 week belly. See the elevated part on the our left/her right? Right above where the blob-line of gel is? That is the baby's bottom under there.
The transducer in the nurse's hand is almost directly on top of the baby's head. Follow the baby's body around our left, curving around, "seeing" the back, somewhat turned sideways, directly under and then rolling over the line of gel. The highest point is the baby's butt, pooching out is part of the back of the bottom and part of the hip. All baby's wiggle around, sticking out their body parts, but it was great to catch the baby stretching somewhat, showing us her booty.
So, "look" where the raised area drops down quickly. That would be where the legs begin to be tucked under the body. If you need to use a doll to demonstrate the position, it can really help with visualizing the baby inside the uterus. Remember, the baby is in a ball, usually with legs crossed and arms closed or near the face... the closer to birth, the tighter in there.
If I was being shown this photo, I might say this is merely an optical illusion, but I checked by looking head-on and yes, the butt is poking out.
The position of this baby is Right Occiput Transverse.