Quantification of contact surface pressure exerted during external cephalic version.

BACKGROUND

The amount of force exerted on the uterus and fetus during external cephalic version (ECV) may be associated with fetal effects or complications. We have designed an instrument to quantify the contact pressure exerted during the performance of ECV, as an indirect measurement of the applied force.

METHODS

We have designed a pair of custom-made gloves. Each glove contains 16 piezo-resistive sensors positioned on the palmer surface of the fingers, thenar and hypothenar areas. Pressure readings were recorded simultaneously from all sensors every 0.22 s during each version procedure. Each recording was analyzed with a computer program written according to specified algorithms to ascertain the number of attempts in a version operation, and the duration and pressure changes of each attempt during the operation.

RESULTS

Ten subjects having a singleton breech presentation at term underwent an operation of ECV. The number of attempts of version in each operation ranged from one to four. The median pressure-time integral and the duration of an attempt were 19,227 mmHg s (range 5089-42,597 mmHg s) and 42.5 s (range 11.9-80.3 s), respectively. The median pressure-time integral of a whole version operation was 38,110 mmHg s (range 5089-107,511 mmHg s). Subjects with a failed version operation received a higher pressure-time integral (p < 0.05). The number of attempts of each operation was accurately identified by the program.

CONCLUSIONS

Measurement of force applied during ECV can be quantified indirectly in terms of contact surface pressure. The indirect measurement of the applied force may further improve the safety of this procedure by preventing excessive use of force by the operator.