# Engagement, Station and Descent of the Fetal Head > NEET-PG Obstetrics and Gynaecology notes on engagement, station and descent of the fetal head covering fifths, ischial spines and Hodge planes. - Canonical URL: https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/engagement-station-and-descent-of-fetal-head - Exam / course: NEET-PG · Subject: Obstetrics and Gynaecology - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-14 - Last updated: 2026-10-14 - Reference basis: Williams Obstetrics; Dutta's Textbook of Obstetrics - How to cite: "Engagement, Station and Descent of the Fetal Head", PrepElephant, https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/engagement-station-and-descent-of-fetal-head ## Direct answer Engagement, station and descent of the fetal head describe how far the presenting part has moved into the maternal pelvis. Engagement means the widest diameter of the head has passed the pelvic inlet, and it is judged by abdominal fifths. Station is the position of the presenting part in centimetres relative to the ischial spines, from minus 5 to plus 5, and descent is its progress through the pelvic planes. ## What you must remember - **Engagement:** the widest diameter of the presenting part, the biparietal diameter in a vertex, has passed the pelvic inlet. - **Fifths:** five palpable fifths means the head is above the brim, and two or fewer palpable fifths is conventionally taken as engaged. - **Zero fifths:** no part of the head is palpable above the brim, which corresponds to a deeply engaged head. - **Station:** the lowest point of the presenting part in centimetres from the ischial spines, with minus 5 at the high end and plus 5 at the introitus. - **Station zero:** the presenting part is level with the ischial spines, which corresponds to Hodge plane III. - **Hodge planes:** plane I is the pelvic brim, II the lower border of the symphysis, III the ischial spines and IV the pelvic floor at the tip of the coccyx. - **Floating head:** a mobile, non-engaged head above the brim, which is normal in a first pregnancy before labour. ## A stepwise approach to assessing the head Assessment combines abdominal palpation with vaginal examination, and the two findings must agree before progress is interpreted. The steps below follow the order in which a clinician reaches a conclusion. 1. **Abdominal fifths:** palpate the head above the pubic symphysis and count the fifths that remain palpable, using the fingers as a unit of measure. 2. **Engagement decision:** decide whether the head has passed the inlet. Two or fewer fifths is conventionally called engaged, while five fifths means the head is floating. 3. **Vaginal station:** on examination, note the lowest part of the presenting part relative to the ischial spines in centimetres, from minus 5 to plus 5. 4. **Hodge plane mapping:** relate the presenting part to the Hodge planes, because the head passes through them in sequence and station zero corresponds to plane III. 5. **Serial descent:** record the station at each examination, since descent is judged by progress over time rather than a single reading. The partograph records abdominal descent in fifths alongside cervical dilatation. 6. **Interpreting progress:** a station that fails to descend during the active phase, despite adequate contractions, prompts review for malposition or cephalopelvic disproportion. ## Where the exam tries to catch you Most traps come from mixing up fifths with station, and from the sign of the station number. - **Trap:** equating zero fifths with station zero — **Correct:** zero fifths means no part of the head is palpable above the brim, while station zero means the presenting part is level with the ischial spines. - **Trap:** calling a negative station abnormal — **Correct:** a station of minus 2 simply means the head is above the ischial spines, which is expected early in labour. - **Trap:** calling a non-engaged head abnormal before labour — **Correct:** in a first pregnancy the head often engages only in the weeks before labour, so a floating head is normal. ## Frequently asked questions ### What does two-fifths palpable mean in engagement? Two-fifths palpable on abdominal examination means that two fingers' breadths of the head remain above the pelvic brim, which is conventionally taken as engagement. Most texts regard two or fewer fifths palpable as engaged, although the exact cut-off varies slightly between books. ### What is station zero of the fetal head? Station zero is the level at which the presenting part lies at the ischial spines, which correspond to Hodge plane III. Stations above the spines are recorded as minus values and stations below them as plus values, with plus five representing the head visible at the introitus. ### Is a non-engaged head normal before labour? A non-engaged, floating head is normal before labour in a first pregnancy, because engagement usually occurs in the weeks before labour. In a multipara the head often engages only once labour begins, so a floating head is not by itself a sign of abnormal labour. ### What are the Hodge planes of the pelvis? The Hodge planes are four imaginary planes that describe the descent of the presenting part through the pelvis. Plane I is the pelvic brim, plane II the lower border of the symphysis pubis, plane III the level of the ischial spines and plane IV the pelvic floor at the tip of the coccyx. ### How is descent documented during labour? Descent is documented by recording the station at each vaginal examination and the abdominal fifths on the partograph beside cervical dilatation. A station that fails to descend across serial examinations is more informative than any single reading.