Maternal and fetal monitoring
Continuous monitoring is required during the second stage of labor. Maternal pulse, respiratory rate, and blood pressure are assessed, as the cardiovascular system undergoes tremendous strain with a risk of decompensation.
Fetal status is monitored by auscultation or continuous cardiotocography (CTG). Normally, the baseline FHR is 110–170 beats per minute with a regular rhythm. During pushing or when the head passes through the pelvic narrow (due to transient blood flow restriction and increased intracranial pressure), decelerations may be recorded on CTG: early, U-shaped (dropping to 80 bpm) or V-shaped (to 75–85 bpm). Under strict indications, Saling method is used — fetal scalp blood sampling to assess acid-base balance (ABB) and oxygen tension.
Uterine contractile activity is assessed using tocography. Uterine tone increases to 16–25 mm Hg. Normally, one pushing effort lasts 90–100 seconds, with an interval of 2–3 minutes between them.
Monitoring fetal descent and birth canal status
The obstetrician must closely monitor the descent of the fetal head. If it stays in the same plane of the pelvis for too long, compression of the soft tissues of the vagina, rectum, and bladder occurs. This leads to ischemia and a formidable complication — the formation of vesicovaginal or rectovaginal fistulas.
Visual inspection allows timely detection of external genitalia edema, which signals an obstruction to the passage of the head. The appearance of spotting is a serious symptom. It may indicate:
- cervical trauma, vaginal or vulvar lacerations;
- placental abruption;
- rupture of umbilical cord vessels (risk is particularly high with velamentous cord insertion).
Palpation of the lower uterine segment and round ligaments is also mandatory. Their constant tension, tenderness, and overstretching (assessed by the position of the retraction ring) are signs of a clinically narrow pelvis or impending uterine rupture.
Proper management of pushing
In most facilities, delivery is conducted in the supine position on a Rakhmanov bed, where the woman rests her flexed legs on special supports.
The physiological urge to push occurs when the fetal head descends into the sacral hollow. Prior to this, the parturient woman must be guided: during contractions, she is advised to breathe deeply so that the fetus moves down the birth canal independently. Pushing should only be allowed when the head begins to crown. Premature pushing is extremely dangerous: it provokes an increase in caput succedaneum and elevates intracranial pressure in the baby.
Technique of proper pushing: at the peak of a contraction, the woman takes a deep breath, engages her abdominal muscles, and pushes. During a single contraction, the woman usually manages to push three times.
Manual obstetric assistance
When the head begins to emerge (pass through the vulvar ring), the obstetrician proceeds with manual assistance. Its main goal is to protect the perineum from tearing and safeguard the fetal head from trauma. The assistance consists of four classical moments:
- Prevention of premature extension of the head. The obstetrician places the left hand on the pubic symphysis (symphysis pubica) and the emerging head, gently restraining its rapid advance. This is necessary for the head to pass the vulvar ring in a flexed state — with its smallest circumference (around the suboccipitobregmatic diameter of 32 cm).
- Reduction of perineal tissue tension. Performed simultaneously with the first moment to protect tissues from excessive stretching and rupture.
- Delivery of the anterior shoulder (and humeral bone).
- Delivery of the posterior shoulder.
Class and exam questions
Why is pushing forbidden before the head descends into the sacral hollow?
Premature pushing leads to an increase in caput succedaneum and a dangerous rise in fetal intracranial pressure.
What are the dangers of prolonged arrest of the head in a single pelvic plane?
This causes ischemia of the soft tissues of the birth canal, bladder, and rectum, which can subsequently lead to fistula formation.
What does edema of the external genitalia in the second stage indicate?
Edema indicates prolonged soft tissue compression and is a sign of a potential obstruction to fetal head descent.
Why does the obstetrician prevent head extension during crowning?
So that the head passes through the vulvar ring with its smallest circumference (along the suboccipitobregmatic diameter — 32 cm), which significantly reduces the risk of maternal and neonatal trauma.
What else to study on this topic
- Saling method: indications and blood sampling technique
- CTG evaluation in the expulsion stage: types of decelerations
- Signs of impending uterine rupture and assessment of the retraction ring
- Differential diagnosis of spotting in the second stage
- Formulation of a complete obstetric diagnosis
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