In his earlier review of Six Rivers, stephenhongsohn noted that the collection contains six parts organized around rivers: "The first four rivers move us primarily autobiographically and autoethnographically (The Perfume River, The Mississippi River, The Charles River, The Hudson River), then we move to two more metaphorical and figurative rivers (The Aorta, and the River Styx)." What sticks out to me is the fifth section, which takes on as its organizing river the largest artery leading out of the heart. Unlike the other section titles, which include parenthetical notes about the location of the rivers in the world, The Aorta instead includes its location in the human body: (Left Ventricle of the Heart). This shift in scale, from the landscape of the Earth to the interior workings of the human body, is really quite fascinating and certainly is a great example of how poetry can work adeptly from small to large.
The six poems in this section focus the speaker as a medical doctor, on medical history, and on the human body. I often like poetry about the body, and Le's verse resonates with the work of other doctor-poets like Raphael Campo and C. Dale Young (in terms of "medicinal poetics," as stephenhongsohn noted) as well as with medicine and body-oriented (especially women's) poetry by laypersons like Mei-mei Berssenbrugge's Four Year Old Girl and Leslie Adrienne Miller's The Resurrection Trade.
Le also takes on particular poetic forms across the poems in the collection. As I always liked to emphasis to students, using established forms is powerful because doing so connects a specific poem to a tradition of writing and creates a depth of reference and meaning that would otherwise not be available. I also remind students that poetic forms often suggest more than just rigid line lengths, meters, and stanzas; they often tend towards specific emotions, content, or other poetic characteristics. In that vein, Le's tanka, villanelles, haibun, and other forms connect her work to the longer cultural history of those forms.
I wasn't familiar with a haibun before, but apparently it is a hybrid prose-haiku form. Le's haibun, titled simply "Haibun," concerns the lyrical speaker's concerns with sex, losing her virginity, becoming pregnant, and having an abortion. The haiku that ends the piece is elliptical in its relationship to the prose section's preoccupation with sex, life, and death: "Noon sun dries, but cannot heal, / an umbrella / the storm turned inside-out." Linking the image of the broken umbrella to the prose section about sexuality suggests a kind of hurt that is irreparable for the speaker's body.