Clinical Analysis

Interpreting the Findings

• Initially: Posterior fontanelle at 5 o'clock → this means the occiput is at 5 o'clock → Right Occipito-Posterior (ROP) position
• 1 hour later: Posterior fontanelle at 3 o'clock → occiput rotated to 3 o'clock → Right Occipito-Transverse (ROT) position (sagittal suture now transverse)

Deep Transverse Arrest is defined as arrest of labour in the second stage with the fetal head at or below the level of the ischial spines and the sagittal suture in the transverse bispinous diameter, with no progress in descent even after an hour following full dilatation.

Why is This DTA?

Next Step in Management

Step 1: Reassess (Immediate)

• Assess pelvic adequacy clinically (diagonal conjugate, bi-ischial diameter)
• Confirm head level — at or below ischial spines?
• Assess uterine contractions — are they adequate? (If not, consider oxytocin augmentation first if no contraindication)
• Maternal condition — analgesia, hydration, exhaustion

Step 2: Active Management — Options (in preference order)

• Normal CTG (no fetal distress)
• Only Grade 1 caput (no significant CPD)
• Head below spines

Option A — Ventouse (Vacuum) with rotation (preferred in modern obstetrics)

• Ideal because the ventouse cup allows autorotation of the fetal head as it descends
• Apply cup to the flexion point (3 cm anterior to the posterior fontanelle, on the sagittal suture)
• Traction with contractions facilitates rotation from ROT → OA and delivery
• First choice for DTA where vaginal delivery is possible

Option B — Manual Rotation followed by forceps/assisted delivery

• Right Occipito-Transverse (ROT): Use right hand (4 fingers placed anteriorly to the fetal head, ulnar border applying pressure) — whole hand or half-hand method
• Rotate head to Occipito-Anterior (OA) position
• Then proceed with low-forceps or ventouse delivery

Option C — Kielland's Rotational Forceps

• Specifically designed for rotation from transverse/posterior to anterior
• Requires skill and experience; now less commonly used
• For ROT: wandering method or direct application

Option D — Caesarean Section

• If vaginal delivery is NOT feasible (e.g., suspected CPD, failed rotational attempt, or where operator skill for instrumental delivery is unavailable)
• In modern obstetrics, CS is considered a safe alternative but should not be the first choice in a multiparous patient with normal CTG and minimal moulding

Summary — Next Step

DTA (ROT) + G3P2 + Normal CTG + Grade 1 caput only
                    ↓
Assess pelvis + contractions
                    ↓
If pelvis adequate + head ≤ spines:
    → VENTOUSE (preferred) with rotational traction
    OR manual rotation + low forceps
    OR Kielland's forceps (if skilled)
                    ↓
If pelvis inadequate / failed instrumental:
    → Caesarean Section

In a multiparous patient with a normal CTG, only Grade 1 caput/moulding, and head well-engaged — the favourable prognosis supports an attempt at instrumental vaginal delivery before resorting to caesarean section. The 60° rotation already achieved (ROP → ROT) is a positive sign that the pelvis is accommodating the head.

• Posterior fontanelle = occiput
• 12 o'clock = OA (ideal)
• 6 o'clock = OP
• 3 o'clock = ROT (right transverse)
• 9 o'clock = LOT (left transverse)
• Movement from 5→3 o'clock = anterior rotation is occurring, but has arrested in the transverse diameter

Clinical Analysis

Interpreting the Findings

What Does "Chin Under Symphysis Pubis" Mean?

• Mentoanterior position, head fully engaged, at/below the perineum
• This is the crowning equivalent in face presentation
• The mechanism of delivery involves: the chin under the symphysis → the face, brow, vertex, and occiput sweep over the perineum by flexion (the reverse of vertex delivery)
• This is a deliverable position — vaginal delivery is imminent and possible

The Critical Differentiator: Late Decelerations

1. Mentoanterior face presentation with chin under symphysis = head at perineum, about to deliver
2. Late decelerations = fetal compromise, cannot wait

Next Step in Management

IMMEDIATE ASSISTED VAGINAL DELIVERY — Outlet/Low Forceps

• Cervix is fully dilated ✓
• Head is fully engaged, chin at symphysis (station +3 or outlet) ✓
• Position is mentoanterior (favourable for vaginal delivery) ✓
• CTG shows late decelerations → fetal distress → need immediate delivery

Why forceps over ventouse?

• Ventouse (vacuum) is CONTRAINDICATED in face presentation — the cup cannot be applied correctly to the face and risks severe facial/orbital injury
• Forceps are the instrument of choice for face presentation

Forceps application in face presentation:

• Applied in the mentoanterior position (chin at 12 o'clock/symphysis)
• Blades applied to the sides of the head (mento-occipital diameter)
• Traction downward initially, then upward to allow face, brow, and occiput to sweep over the perineum
• Do NOT attempt flexion — delivery occurs by extension followed by flexion of the delivered head

Why NOT Caesarean Section here?

CS is indicated for mentoposterior face presentation or if there is an obstruction. Here, the chin is already at the symphysis — this is an outlet delivery situation.

Summary

Face presentation (MA) + chin at symphysis + Late decelerations
                        ↓
           FETAL DISTRESS → Expedite delivery NOW
                        ↓
        Outlet FORCEPS delivery (Wrigley's)
        [Vacuum CONTRAINDICATED in face presentation]
                        ↓
        Paediatric team on standby (neonatal resuscitation)
        Anticipate neonatal compromise (low Apgar possible)

• Place patient in left lateral tilt / lithotomy
• Call for senior obstetrician and neonatal team
• Ensure IV access and bloods
• Administer oxygen to mother
• Stop oxytocin if running
• Episiotomy as needed during delivery