Ninety five percent of fetal presentations are?

DSSSB - 29 August 2019 (Shift-1)

Obstetrics & Gynaecology

Easy

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

Cephalic presentation, where the fetal head enters the pelvis first, is the most common, occurring in approximately 97% of term deliveries.
This high incidence is due to the natural accommodation of the fetus to the pear-shaped uterus; the wider fundus accommodates the bulkier fetal breech and legs, leaving the smaller head to engage in the lower uterine segment.
The fetal head is the largest and least compressible part, making it the most effective dilating wedge for the cervix during labor, which is why this presentation is most favorable for vaginal birth.

Option A: Breech presentation, where the buttocks or feet present first, is a form of malpresentation and is not the most common.
Option B: Shoulder presentation results from a transverse lie, where the fetus is positioned horizontally. It is a rare malpresentation.
Option D: A leg presentation is not a primary category of fetal presentation. It is a subtype of breech presentation, specifically a footling breech.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Fetal Presentation and Lie as background academic context rather than a clinical decision trigger.
Identifying fetal presentation via Leopold's maneuvers and vaginal examination is a critical nursing assessment before and during labor to anticipate the mechanism of labor and plan for a safe delivery.
Malpresentations like breech or shoulder are associated with higher risks of complications such as cord prolapse, obstructed labor, and birth trauma, often necessitating a Cesarean section.
What if? If a breech presentation is identified at term (around 37 weeks), an external cephalic version (ECV) may be offered to manually turn the fetus to a cephalic presentation. A successful ECV can significantly increase the chances of a safe vaginal delivery.

How to Approach the Question

This is a factual recall question asking for the most common fetal presentation.
First, understand the term 'fetal presentation,' which refers to the part of the fetus that enters the pelvic inlet first.
Recall the main types of presentations: cephalic (head), breech (buttocks/feet), and shoulder (transverse).
Remember the typical orientation of the fetus at term. The uterus is pear-shaped (pyriform), wider at the top (fundus). The fetus naturally orients itself with its bulkier lower body in the spacious fundus and its head in the narrower lower part of the uterus.
This anatomical fit results in the head-first (cephalic) presentation being overwhelmingly the most common.
Evaluate the options based on this knowledge. 'Cephalic' corresponds to the highest frequency (97%), while 'Breech' (2-3%) and 'Shoulder' (<1%) are known malpresentations with much lower frequencies. 'Leg' is a subtype of breech presentation.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 19-36