CTG Case 16 – Pseudosinusoidal pattern

Summary

A 32 year old G1 P0. Gestation week 40+4 admitted to hospital in early spontaneous labour.  VE on admission at 22.00: Cx fully effaced, 2 cm dilated, vx-2. Normal pregnancy.  External CTG tracing is normal on admission.

• 00.18 VE: Cx fully effaced, 2 cm dilated, vx -2, status quo. ARM performed, clear liquor draining. FSE applied. Epidural sited on maternal request.
• 03.30 Labour continues. VE: Cx fully effaced, 5 cm dilated, vx -1, clear liquor.
• 05:50 VE: Cx  fully effaced, 8 cm dilated, vx at the spines.
• 08.00 Patient feels an urge to push. VE: Cx fully dilated, vx +2. Epidural is topped up to avoid too early pushing.
• 09.00 Tachycardia is noted, maternal temperature 37.9. Extra fluid is given.
• 09.10 VE: Cx fully dilated, vx+2, caput visible. Active pushing started.
• 10.05 SVD. Babygirl born.

Cord gases

Comment

Between 00:18 and 01:20 there is a pseudosinosoidal pattern, a temporary sine-wave pattern. It recurs at 03:20–06:28 and thereafter spontaneous accelerations can be seen, which is a sign that the fetus is well oxygenated.

A pseudosinusoidal pattern is a normal pattern and must not be confused with abnormal sinusoidal pattern. Sinusoidal pattern has higher amplitude. It is unusual but can be seen in severe fetal anemia.