Esto es si se refieren a extracción con fórceps:

Forceps delivery is classified according to the level and position of the head in the birth canal at the time the forceps are applied. In 1965, the ACOG issued a classification of low/outlet forceps, mid forceps, and high forceps. The low/outlet forceps categories were strictly defined and applied when the fetal scalp was visible or when the scalp had reached the pelvic floor, and only when the sagittal suture was in the anteroposterior diameter of the pelvis. In contrast, the category of mid forceps was very broad. It included many positions of the fetal head, and stations from engagement at zero station to the perineum.
Source: http://emedicine.medscape.com/article/263603-overview

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Note added at 14 mins (2009-09-10 23:20:47 GMT)
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Mi ejemplo anterior no decía mucho sobre los "high forceps".

High forceps: The leading point of the skull is 2cm or less above the spine but head is engaged. Rotation not considered.

(Pero ya estoy dudando. Este método es obsoleto y por el contexto, seguramente la extracción a que se refiere tu texto es una cesárea, i.e., abdominal, como tú dijiste, Andrea. Veamos qué dicen los colegas).